SUPPLEMENT A. Field Sampling
Thirty-one samples were collected from the summit region of Erebus volcano in
December 2011 for surface exposure age determinations. Samples locations are listed by lava
flow in Table A.1 and by sample ID in Table A.2. Areas that were sampled include each of the
ten known post-collapse lava flows identified by Harpel et al. (2004), one lava flow pre-dating
the older caldera collapse (referred to as the old pre-caldera lava flow), and one lava flow predating the younger caldera collapse (referred to as the young pre-caldera lava flow). Sample
E11-12, located in the newly identified West flow, was thought to be in the Northwest flow at
the time of collection. Samples E11-03 and E11-08 are lava bombs that were dated using 3He but
not used in the interpretation or conclusions of this study.
Table A.1. Sample locations listed by lava flow.
Lava Flow or Feature
Northeast lava flow
Lower Hut lava flow
Nausea Knob lava flow
Tramways lava flow
Northwest lava flow
Lower Ice Tower Ridge lava flow
Upper Ice Tower Ridge lava flow
Southwest lava flow
South lava flow
Southeast lava flow
West flow
Old pre-caldera lava flow
Young pre-caldera lava flow
Lava bombs
Samples
E11-02, E11-26, E11-27
E11-01, E11-16, E11-17
E11-06, E11-18, E11-19
E11-07, E11-14, E11-15
E11-05, E11-13
E11-22, E11-25
E11-21, E11-23
E11-09, E11-20, E11-24
E11-10, E11-28
E11-11, E11-29, E11-30
E11-12
E11-31
E11-04
E11-03, E11-08
In order to collect samples whose exposure ages reflect lava flow emplacement ages as
accurately as possible, sample locations within each flow were selected based on the following
criteria:
 Rock is part of the lava flow and not a lava bomb. Rocks from flows and bombs can
generally be distinguished by their densities and degree of vesiculation.
 Surface is planar and has a dip of less than 15 degrees.
 Surface is not shielded from cosmic rays by surrounding outcrops.
 Surface is elevated above the surrounding area (e.g., on top of a ridge or tumulus), such
that the potential for past snow coverage of significant depth and duration is minimal.




Minimal likelihood that the surface has shifted since emplacement of the flow. For this
reason, large blocks that were obviously detached were avoided.
Surface shows little evidence of erosion. Ideally, evidence of flow texture (such as
pahoehoe ropes and folds in the surface) can be seen nearby.
Sample is away from edges and large cracks in the rock.
Visible pyroxene phenocrysts present.
Not all criteria could be met for all of the sample locations. For the Southwest, South, and
Upper Ice Tower Ridge flows and large areas of the Nausea Knob, Tramways, and Lower Ice
Tower Ridge flows, it was especially difficult to find rock exposures that were elevated, flat, not
eroded, and did not show evidence of surface shift. As the quality of the sample location
decreases (based on the above characteristics), the likelihood that its exposure age is younger
than its emplacement age increases.
Each sample was collected from the top 5 cm of rock using a hammer and chisel and
stored in a canvas bag. All samples consisted of multiple pieces of rock collected from a
contiguous portion of the same surface. Sample masses ranged from 1 to 5 kg. The following
information was recorded at each sample location during sample collection (see table B.2):
 GPS latitude, longitude, and elevation (measured using a handheld Garmin Oregon 300
GPS).
 Profile of the horizon. This was documented by standing or sitting at the sample location
and measuring the azimuth (relative to True North) and inclination angle of high and low
points along the horizon using a Brunton compass/clinometer.
 Surface dip and dip direction.
 Notes describing the sample area, surface texture, evidence of weathering and erosion,
potential for past snow coverage, likelihood that the surface being sampled has shifted
since eruption, and any nearby visible flow texture.
 Pictures documenting the sample location before and after sample collection (taken from
north, east, south, and west) and the horizon in all directions (taken every 45 degrees).
For each of the 10 post-caldera collapse lava flows sampled, one of the samples collected
was from a location as close as possible to that of the sample dated for that flow by Harpel et al.
(2004) or Kelly et al. (2008) using the 40Ar/39Ar technique. Additional samples were collected
from different areas of the flow. Generally the sample collected near the Ar/Ar location was the
one dated using both 36Cl and 3He, while the replicate samples were dated using only 3He.
Samples from the older and younger pre-caldera lava flows were collected from locations
as close to the edge of the collapse as possible while still having good cosmic ray exposure.
Based on field observations, it is uncertain whether these samples have been exposed to cosmic
rays since emplacement of their respective lava flows or if they were not exposed until collapse
of the caldera.
Two samples—E11-03 (Upper Hut Slump) and E11-08 (Upper Ice Tower Ridge flow)—
were determined to be lava bombs shortly after sample collection. Field notes, clinopyroxene
compositions, 3He concentrations, and exposure ages are reported for these samples in
Supplements A through D but are left out of the Results and Discussion sections of this paper.
Table A.2. Sample location data and field notes.
Sample
ID
E11-01
E11-02
E11-03
E11-04
Horizon profile:
Collection
Azimuth & Inclination
Collected by
date/time
(degrees)
Az: 0, 45, 90, 135, 180,
-77.508017
12/12/2011 Dave Parmelee
Lower Hut
3,283
13 W
225, 270, 315
167.096200
18:55
Nels Iverson
In: 0, 6, 9, 16, 7, 0, 0, 0
Notes: Sample is from a pahoehoe rope on top of a tumulus. Significant past snow coverage unlikely, surface
shift unlikely. Some glassy patches are visible on surface, although most of surface is not glassy. Rock is very
hard and very difficult to sample (breaks in small chips), not vesiculated. Anorthoclase crystals prominent on
surface. Sparse pyroxene phenocrysts (<0.5 cm).
Az: 0, 45, 110, 145, 180,
-77.508667
215, 270, 280, 315, 325
12/13/2011
Northeast
3,360
2 SW
Dave Parmelee
167.200433
In: 0, 0, 9, 11, 10, 14, 4, 0,
22:40
2, 0
Notes: Sample is from flat surface of a broad, low tumulus. Surface appears similar to Lower Hut flow, but with
a bit more erosion and no patches of glassy texture. No ropes visible. Past snow coverage possible, surface shift
possible but unlikely. Rock breaks easily and crumbles, inside is glassy and vesiculated w/ lots of yellow salts.
Sparse pyroxene phenocrysts.
Az: 0, 40, 80, 120, 160,
-77.525117
12/14/2011 Dave Parmelee
Lava bomb
3,617
7 NE
190
167.136117
13:40
Nels Iverson
In: 0, 8, 26, 25, 22, 0
Notes: Location is within Upper Hut Slump. Sample location is on a low, eroded, rounded ridge extending north
from door-end of Upper Hut. Most rock on ridge is broken and moveable, and most of area is covered with
bombs. Significant erosion may have occurred. Cannot tell if sample location is part of a very large bomb. Rock
is soft, easy to sample, inside is very vesiculated and more closely resembles bomb than flow.
Az: 15, 30, 50, 70, 90,
110, 120, 160, 180, 195,
Young Pre- -77.529833
12/14/2011 Dave Parmelee
3,473
5E
205, 220, 350
caldera
167.084450
16:12
Nels Iverson
In: 7, 0, 5, 11, 11, 6.5, 7,
0, 5, 4, 8, 0, 0
Notes: Sample location is on top of exposed ridge near edge of eastern cliff. Minor nearby snow cover; light past
snow coverage possible, but significant past snow coverage is very unlikely. Surface shift unlikely. Some erosion
Lava flow
Latitude/
Longitude
Elevation
(m)
Surface
dip
(degrees)
Sample
ID
E11-05
E11-06
E11-07
E11-08
Surface
Horizon profile:
Collection
dip
Azimuth & Inclination
Collected by
date/time
(degrees)
(degrees)
evidenced by gravel in the area; some evidence of flow texture may be preserved. Rock is fairly hard, inside is
only a little vesiculated and has lots of yellow salts.
Az: 0, 45, 100, 120, 160,
-77.520367
12/14/2011 Dave Parmelee
Northwest
3,298
8W
180
167.079500
17:35
Nels Iverson
In: 0, 4, 13, 13, 9, 0
Notes: Sample location is flat area near middle of an elongate tumulus sloping to the west. Semi-eroded ropes
visible on south side. Minor coverage by windblown snow in area, past significant snow coverage possible but
unlikely, surface shift unlikely. Surface is weathered gray with some yellow salts. Rock breaks fairly easily,
inside is glassy with minor vesiculation. Small pyroxene phenocrysts visible.
Nausea
-77.519417
Az: 0, 80, 110, 160, 225
12/14/2011
3,502
3S
Dave Parmelee
Knob
167.140183
In: 0, 0, 16, 25, 0
22:26
Notes: Sample location is fragmented tumulus on N-facing slope. Fairly significant shielding to south.
Significant past snow coverage unlikely; small possibility of surface shift. Surface has a greater degree of
whitish-grayish alteration than flows sampled so far; no ropes visible in area. Inside of rock is vesiculated, with
some yellow salts.
Az: 40, 60, 80, 135, 160,
-77.522200
12/15/2011
Tramways
3,534
0
210
Dave Parmelee
167.131333
22:58
In: 0, 11.5, 13.5, 17, 12, 0
Notes: Sample location is near top of the flow, ~0.1 mi from Ar/Ar sample location (confident that it is the same
flow). Two rectangular pits at the sample location look like previous samples. Past significant snow coverage
possible but unlikely, surface shift possible but unlikely. Surface is grayish-pinkish-yellowish, fairly weathered,
no ropes visible in area. Rock breaks easily and crumbles, vesiculated inside, permeated by yellow salts.
Anorthoclase crystals less prominent on surface than in previously-sampled flows.
Az: 0, 50, 60, 100, 135,
160, 165, 200, 225, 270,
-77.532217
12/16/2011 Dave Parmelee
Lava bomb
3,556
5 NE
315
167.121100
18:00
Aaron Curtis
In: 0, 15, 19, 4, 0, 0, 2, 2,
11, 11, 0
Notes: Location is within area of Upper Ice Tower Ridge flow. Sample area is heavily eroded, with few areas of
flow exposure. Area is characterized by small hills of broken lava (cinder cones?). Sample location is near base
Lava flow
Latitude/
Longitude
Elevation
(m)
Sample
ID
E11-09
E11-10
E11-11
E11-12
Surface
Horizon profile:
Collection
dip
Azimuth & Inclination
Collected by
date/time
(degrees)
(degrees)
of one of these hills (SW of Western Crater). Location is eroded and may have been previously buried; past snow
coverage likely, surface shift possible. No flow texture is apparent in area, and location is not definitely part of a
flow (could be a very large bomb, possibly erupted from western or side crater). Weathering rind on surface is ~1
cm thick. Rock breaks easily, crumbles. Inside is fairly vesiculated, seems to be between typical bomb and
typical flow. LATER: Returned to location, positively identified sample surface as part of a large bomb.
Az: 0, 5, 30, 100, 285,
-77.535250
320, 325, 355
12/17/2011 Dave Parmelee
Southwest
3,544
5 ENE
167.134250
In: 23, 13, 20, 0, 0, 11, 2,
15:00
Nels Iverson
13
Notes: Sample area is eroded and has very few good flow exposures. Sample location is on a small, low outcrop
with high likelihood of past snow coverage. Slope has southern exposure. Not definite that location is same flow
as the Ar/Ar location; probable, but not definite, that the location is a flow feature. No flow texture preserved in
vicinity. Surface has ~1 cm thick weathering rind. Rock breaks easily and crumbles, inside is vesiculated and has
some yellow salts. Anorthoclase crystals very prominent on surface.
-77.534000
Az: 0, 75, 280, 320
12/17/2011
South
3,653
7 SW
Dave Parmelee
167.159667
In: 22, 0, 0, 17
16:25
Notes: Sample area is exposed broken outcrop on side of steep S-facing slope, significantly shielded to the N.
Appears to be part of a ridge (flow levee?). Light past snow coverage possible, significant past snow coverage
possible but not likely. Surface shift possible. Surface is weathered, gray, no flow texture preserved in vicinity.
Rock is hard and brittle, little vesiculation inside, yellow salts inside. Anorthoclase crystals less prominent on
surface compared to most other flows.
-77.536633
Az: 0, 80, 270, 340, 350
12/17/2011
Southeast
3,502
11 S
Dave Parmelee
167.175483
In: 20, 0, 0, 22, 22
19:50
Notes: Sample location is on a tumulus on a lava ridge on S-facing slope. Location is uphill from, but probably
on same ridge as, Ar/Ar sample. Past snow coverage possible, surface shift unlikely. Surface is gray, some eroded
flow texture may be visible. Rock breaks easily, inside is fairly vesiculated and heavily permeated by yellow
salts.
-77.524833
Az: 0, 110, 130, 160, 340
12/18/2011
West
3,199
6W
Dave Parmelee
167.052717
In: 4, 17, 17, 0, 0
14:25
Notes: Sample area is on a tumulus with well-preserved flow structure, including a rope ~1 m S of sample
Lava flow
Latitude/
Longitude
Elevation
(m)
Sample
ID
E11-13
E11-14
E11-15
E11-16
Surface
Horizon profile:
Collection
dip
Azimuth & Inclination
Collected by
date/time
(degrees)
(degrees)
location. Other nearby tumuli have lots of well-preserved ropes. Flow appears young. Past snow coverage is
possible but unlikely, surface shift unlikely. Surface is blackish-gray with yellow salts. Rock is hard but easy to
sample, inside is fairly vesiculated, has some yellow salt. Pyroxene difficult to find.
Az: 30, 90, 120, 135, 200,
-77.524917
215, 225, 260, 270
12/18/2011 Dave Parmelee
Northwest
3,436
8 NW
167.102667
In: 0, 17, 18, 14, 0, 5, 3,
16:20
Nels Iverson
16, 0
Notes: Sample location is on outcrop near head of the flow. Shielded by a higher portion of the ridge to the west.
Past snow coverage possible, surface shift unlikely. Lots of gravel in sample area. Surface appears relatively
fresh; grayer than E11-12. Inside is vesiculated, has yellow and white salts. Anorthoclase crystals prominent on
surface. Pyroxene larger and more abundant than in E11-12.
Az: 20, 70, 135, 195, 225,
-77.515433
12/18/2011
Tramways
3,372
0
245
Dave Parmelee
167.110383
18:10
In: 0, 4, 15, 3, 4, 0
Notes: Sample location appears to be a large rope, possibly detached. All lava in area consists of large rubble,
very difficult to find a good, stable exposure age location. Past snow coverage possible but not likely, surface
shift very possible. Surface has weathered gray appearance. Rock breaks easily, inside fairly vesiculated.
Anorthoclase crystals prominent on surface. Small pyroxenes.
Az: 0, 5, 40, 45, 90, 120,
-77.518950
12/19/2011
Tramways
3,453
0
140, 225
Dave Parmelee
167.124833
14:40
In: 0, 3, 8, 3, 11, 16, 19, 0
Notes: Sample location is a boulder or outcrop near top of a mound on the flow levee. Location is not ideal for
exposure age (there are no good locations in this part of the flow). All lava along the levee and below is
brecciated. To the NW two levees clearly bound a channel. Past snow coverage of the sample site in its current
location is unlikely, but surface shift is very possible, as the block appears detached. Surface is gray with some
orange alteration. Rock is very hard and brittle, difficult to sample; inside is not vesiculated, has some yellow
salt. Anorthoclase crystals prominent on surface.
Az: 30, 90, 110, 135, 180,
-77.514850
12/19/2011
Lower Hut
3,285
5S
200, 350
Dave Parmelee
167.081250
18:55
In: 5, 13, 6, 13, 7, 0, 0
Lava flow
Latitude/
Longitude
Elevation
(m)
Sample
ID
E11-17
E11-18
E11-19
E11-20
Surface
Horizon profile:
Collection
dip
Azimuth & Inclination
Collected by
date/time
(degrees)
(degrees)
Notes: Sample location is on a low, flat bulge. Surrounding area shows lots of flow texture, including ropes.
Good location for exposure age sample. Past snow coverage possible, surface shift very unlikely. Surface is gray
with a little orange alteration. Rock is hard (but not as hard as E11-01), inside is farily vesiculated, has some
yellow salt. Anorthoclase crystals very prominent on surface. Pyroxene very small and sparse.
-77.517300
Az: 90, 150, 165, 190, 225 12/19/2011
Lower Hut
3,488
0
Dave Parmelee
167.155433
In: 0, 11, 17, 15, 0
22:42
Notes: Sample area is in a large exposed portion of flow (tumulus?) that has cracked apart into large pieces.
Good flow texture preserved nearby, including ropes. Past snow coverage possible but unlikely, surface shift very
unlikely. Surface is gray and orange, texture is similar to E11-01 and E11-01. Rock is easy to sample, crumbles;
inside is vesiculated, has some yellow salt. Anorthoclase crystals are prominent on surface, but slightly less so
than E11-16. Pyroxenes slightly larger and more abundant than E11-16.
Nausea
-77.521183
Az: 85, 150, 180, 230, 240 12/20/2011
3,618
8 NW
Dave Parmelee
Knob
167.146200
In: 0, 15, 8, 2, 0
14:15
Notes: Sample area is on a steep N-facing slope; sample location is on a low bulge that drops steeply to the N.
Rock appears fairly eroded, with lots of gravel in the area. Faint flow texture visible nearby. Past snow coverage
unlikely, surface shift unlikely. Past coverage by other rock is possible. Surface is gray and orange, weathered.
Rock is soft, easy to sample; inside is fairly vesiculated, has some yellow salt. Anorthoclase crystals less
prominent on surface than in Lower Hut flow samples. Pyroxene more abundant than in Lower Hut flow samples.
Az: 5, 25, 50, 110, 160,
Nausea
-77.516233
12/20/2011
3,396
0
185, 270
Dave Parmelee
Knob
167.130633
16:45
In: 0, 10, 6, 12, 17, 13, 0
Notes: Sample area characterized by scattered loose outcrops, which area heavily weathered and have lots of
gravel. Sample location is on only outcrop with a flat surface. Outcrop may be detached, therefore surface shift is
very possible. Side of outcrop shows eroded flow texutre, but in wrong orientation. Past snow coverage is
unlikely in current orientation. Surface appears weathered. Rock is hard and brittle, however most of sample is
from a surface flake that was easy to detach. Inside is not very vesiculated, has some yellow salts. Anorthoclase
phenocrysts appear smaller and possibly less abundant here than in other flows, they are worn almost flat at the
surface (i.e. not prominent). Pyroxene is small but visible.
-77.538350
Az: 5, 20, 60, 100, 270,
12/23/2011 Dave Parmelee
Southwest
3,447
5E
167.133217
280
11:25
Nels Iverson
Lava flow
Latitude/
Longitude
Elevation
(m)
Sample
ID
E11-21
E11-22
E11-23
Horizon profile:
Collection
Azimuth & Inclination
Collected by
date/time
(degrees)
In: 14, 19, 12, 0, 0, 4
Notes: Sample area is on a tumulus on south-facing slope. Very nice flow exposure. Light snow covering on
much of tumulus, so significant past snow coverage is possible. Surface shift is unlikely. Surface is dark with a
little yellow salt, inside of rock is vesiculated. Anorthoclase crystals prominent. Pyroxenes are small and medium
size, moderately abundant.
Az: 320, 350, 5, 20, 40,
Upper Ice
-77.535633
65, 75, 95, 120
12/23/2011 Dave Parmelee
Tower
3,510
5S
167.113550
In: 0, 7, 12, 11, 10, 14, 16,
12:55
Nels Iverson
Ridge
5, 0
Notes: Sample area is in a somewhat exposed flow area lightly covered in freshly-blown snow. Flow texture,
including ropes, is visible in the vicinity. Past snow coverage possible, surface shift unlikely (sample area
connects to exposures with ropes). Sample "outcrop" is very small and low-lying and is shielded by its higher end
(to the NE). Surface is dark, a little yellow salt, same color as Southwest flow. Rock is hard, brittle, difficult to
sample; inside is somewhat vesiculated (vesicles are flat). Anorthoclase crystals slightly smaller and less
prominent than those in Southwest flow. Pyroxene medium size, relatively abundant.
Az: 0, 40, 60, 70, 110,
Lower Ice
-77.532967
150, 160, 180, 190, 200
12/23/2011 Dave Parmelee
Tower
3,526
7 NE
167.107650
In: 0, 7, 14, 11, 5, 0, 7, 0,
14:30
Nels Iverson
Ridge
6, 0
Notes: Sample area is on N side of Ice Tower Ridge. In line with a series of outcrops. Unsure whether it is in the
upper or lower flow, but source appears to be cinder cone above sample site and to the east. Outcrop is low and
small, past snow coverage possible, surface shift possible but not likely. Possible faint flow features are visible in
an adjacent low outcrop to the west. Surface is dark, rock fairly soft and easy to sample, inside vesiculated.
Pyroxene relatively abundant.
Az: 0, 30, 50, 60, 90, 120,
Upper Ice
-77.534283
290, 330, 350, 355
12/23/2011 Dave Parmelee
Tower
3,535
6E
167.116400
In: 4, 13, 15, 16, 3, 0, 0,
15:30
Nels Iverson
Ridge
10, 4, 10
Notes: Sample area is in middle of a rubbly flow field on large chunk of rock sloping to the east. Surface appears
to be eroded surface of flow. May be detached; slope indicates that surface shift is likely. Rock has light snow
Lava flow
Latitude/
Longitude
Elevation
(m)
Surface
dip
(degrees)
Sample
ID
E11-24
E11-25
E11-26
E11-27
Surface
Horizon profile:
Collection
dip
Azimuth & Inclination
Collected by
date/time
(degrees)
(degrees)
coverage. Heavier snow coverage in past is possible but not very likely (based on current orientation). Rock is not
too hard, not vesiculated. Anorthoclase crystals are prominent on the surface. Pyroxene not very abundant.
Az: 10, 30, 45, 80, 100,
-77.533933
280, 285, 320, 335
12/23/2011 Dave Parmelee
Southwest
3,558
15 E
167.129233
In: 9, 20, 22, 4, 0, 0, 3, 6,
17:35
Nels Iverson
4
Notes: Sample area is sloping slab of rock near head of flow. More likely part of the Southwest flow (vent could
be crater to NE beneath ice towers) than Upper Ice Tower Ridge flow. Past snow coverage possible, surface shift
fairly unlikely. In line with similar exposures to N and S. Surface is weathered and cracked, shows no flow
texture. Rock is soft, crumbly, and very vesiculated. Anorthoclase crystals fairly prominent on the surface.
Pyroxene hard to find.
Az: 35, 70, 90, 130, 165,
Lower Ice
-77.534867
175, 305, 315, 330, 345
12/23/2011 Dave Parmelee
Tower
3,465
0
167.094983
In: 10, 12, 7, 5, 3, 0, 0, 3,
19:00
Nels Iverson
Ridge
0, 2
Notes: Sample area is on a large, low tumulus. Good location for exposure age sample. Surface looks relatively
fresh, dark, unweathered. Flow texture, including ropes (slightly eroded), is visible nearby. Past snow coverage
possible, surface shift very unlikely. Glass on surface is dull, has a "fibrous" appearance. Rock somewhat hard,
fairly vesiculated inside, easy to sample. Anorthoclase crystals prominent on surface. Pyroxene relatively
abundant.
-77.516167
Az: 95, 120, 195, 215, 280 12/25/2011
Northeast
3,453
5 SW
Dave Parmelee
167.212850
In: 0, 3, 9, 12, 0
13:50
Notes: Sample area is a low rounded exposure (tumulus?). Good location for exposure age sample. Past snow
coverage possible, surface shift very unlikely. Exposures to north (towards crater rim) appear to be same flow.
Little flow texture has been preserved, however surface appears uneroded. Rock is hard, moderately difficult to
sample, little vesiculation inside. Anorthoclase crystals are prominent on the surface. Pyroxenes crystals are
moderately large and abundant.
Az: 10, 180, 195, 200,
-77.523367
12/25/2011
Northeast
3,538
5 SE
225, 250, 280, 315, 345
Dave Parmelee
167.204933
15:50
In: 0, 0, 2, 5, 12, 14, 7, 8,
Lava flow
Latitude/
Longitude
Elevation
(m)
Sample
ID
E11-28
E11-29
E11-30
Lava flow
Latitude/
Longitude
Elevation
(m)
Surface
dip
(degrees)
Horizon profile:
Azimuth & Inclination
(degrees)
Collection
date/time
Collected by
3
Notes: Sample area is on a bulging outcrop in area of lots of exposed rock (flow). Past snow coverage is
possible, surface shift unlikely. Eroded flow texture, including ropes, is visible on nearby outcrops. Surface is
slightly more weathered than E11-26. Rock not too hard, fairly easy to sample; inside is flaky and a little
vesiculated; large hollow area under one part of sample. Anorthoclase crystals slightly less prominent than E1126. Pyroxene smaller and less abundant than E11-26.
Az: 260, 280, 330, 355,
-77.534017
12/26/2011 Dave Parmelee
South
3,633
0
40, 70
167.164717
16:15
Tehnuka Ilanko
In: 0, 10, 19, 18, 7, 0
Notes: Sample area is on a small outcrop in a small area of lava flow exposure. Outcrop is low to the ground, and
past coverage by snow or bombs is possible (area is not great for exposure age sample, but is one of only 2
exposures of the South lava flow). Surface shift is possible. Eroded ropes visible in multiple locations on nearby
exposures. Most of the sample consists of a single bulge (rope?) from a small outcrop. Surface is gray; rock is
hard and brittle with little vesiculation inside. Anorthoclase crystals not prominent on surface. Pyroxenes are
small, moderately abundant.
Az: 230, 240, 245, 255,
290, 310, 330, 340, 10,
-77.532650
12/27/2011 Dave Parmelee
Southeast
3,519
5S
25, 55, 65
167.194367
15:00
Nels Iverson
In: 0, 5, 2, 11, 16, 21, 11,
8, 4, 9, 1, 0
Notes: Outcrop is a low bulge in an area of exposed lava where the slope steepens downhill. Some flow texture,
such as eroded ropes, visible in nearby outcrops. Past snow coverage fairly unlikely, surface shift unlikely.
Surface dips in all directions. Surface fairly weathered, grayish-brownish-yellowish, rock is hard and somewhat
difficult to sample, a little vesiculated inside. Anorthoclase crystals not prominent on surface. Pyroxenes are
moderately size and moderately abundant.
Az: 255, 295, 310, 325,
-77.533483
335, 10, 40, 55, 90
12/28/2011 Dave Parmelee
Southeast
3,458
7 SE
167.210867
In: 0, 12, 16, 14, 9, 7, 8, 7,
19:55
Nels Iverson
0
Notes: Sample area is on low bulging outcrop at a change in slope angle (steeper downhill). Good location for
Sample
ID
E11-31
Surface
Horizon profile:
Collection
dip
Azimuth & Inclination
Collected by
date/time
(degrees)
(degrees)
exposure age sample. Past snow coverage unlikely, surface shift unlikely. Ropes visible on nearby outcrops.
There are other good flow exposures in the area, however it is difficult to tell where Southeast flow ends and
Northeast flow begins. Rock is somewhat hard, not too difficult to sample, inside is vesiculated. Surface is a light
grayish-tannish color. Anorthoclase crystals large and prominent on surface. Visible pyroxene present but not
abundant.
Az: 30, 50, 120, 150, 170,
180, 195, 210, 225, 265,
Old Pre-77.505367
12/29/2011
3,365
10 N
285
Dave Parmelee
caldera
167.178500
13:50
In: 0, 10, 14, 6, 12, 12, 8,
3, 3, 4, 0
Notes: Sample is located on a small outcrop that appears to be a fixed, eroded portion of lava flow. Outcrop
correlates well with other outcrops in area that also appear to be lava flow. Outcrop is "hollow" underneath. Past
snow coverage very unlikely, surface shift very possible. Significant erosion evidenced by exfoliation visible on
the surface. Surface is light gray, rock is hard, somewhat difficult to sample. Anorthoclase crystals are worn, not
prominent. Pyroxene is abundant (more abundant here than in any other sample).
Lava flow
Latitude/
Longitude
Elevation
(m)
Latitude, longitude, and elevation were measured using a handheld Garmin Oregon 300 GPS unit.
Azimuth (Az) and inclination (In) of high and low points defining the skyline around the sample location were measured using a Brunton compass and
clinometer. All azimuth angles are measured relative to true north, and all inclination angles are measured relative to a horizontal line extending from the sample
location toward the horizon. The direction of true north was determined using the handheld GPS. The measurements are listed such that the inclination values are
in the same order as their corresponding azimuths. For example, if Az = 0, 45 and In = 0, 6, then the horizon at an azimuth of 0° from the sample has an
inclination of 0°, and the horizon at an azimuth of 45° has an inclination of 6°.
SUPPLEMENT B. Sample characterization
B.1. Sample thickness and bulk density
Before each whole rock sample was crushed, its thickness was measured. Each sample
consisted of multiple pieces of rock from the same surface. The average thickness of the all
pieces composing a sample was estimated using a ruler and is considered accurate to ± 0.25 cm.
All samples have an average thickness of less than 4 cm. Sample thicknesses are shown in Table
1 (samples E11-03 and E11-08, which are excluded from Table 1, have thicknesses of 3.75 cm
and 4 cm, respectively).
The bulk density of each sample was measured using rock that was collected from the
same surface as the sample but was not crushed for analysis. A piece of rock was selected and
weighed. The rock was dipped in hot wax to seal vesicles and then submerged in water in a 1 L
graduated cylinder to determine its volume. Measurements were made using the largest piece of
rock available that would fit in the graduated cylinder. If there was no piece of rock available
that was large enough to have a bulk density representative of the sample then multiple smaller
pieces were used. The measured bulk densities are considered accurate to ± 0.2 g/cm3. Sample
bulk densities are shown in Table 1 (samples E11-03 and E11-08, which are excluded from
Table 1, have bulk densities of 1.7 g/cm3 and 1.2 g/cm3, respectively).
B.2. Clinopyroxene and olivine analyses
Major element oxide concentrations were measured in all clinopyroxene and olivine
separates prepared for 3He analysis (Tables B.1 and B.2). Measurements were made at the New
Mexico Bureau of Geology and Mineral Resources using a Cameca SX-100 electron microprobe.
A 1 μm beam was used at 20 nA and 15 kV. Detailed analytical conditions are shown in Tables
B.3 and B.4. Total Fe is reported as FeO and listed as FeO*. The materials used as primary
calibration standards, analyzed approximately once per week, are shown in Table B.5. Diopside
and olivine standards were run immediately before and after each set of sample analyses to
monitor calibration accuracy and inter-run reproducibility; measured and accepted values of
these are shown in Table B.6.
For each sample, 4-8 grains were analyzed with 2-4 points per grain. Points were
measured in the core, rim, and intermediate sections of grains in each sample. Backscattered
electron (BSE) imaging of the grains showed that they are heavily included by apatite, magnetite,
glass, and olivine. Inclusions composed approximately 1-10% of the grains by volume. Inclusion
content was variable between grains but fairly consistent between samples. In all samples, there
did not appear to be any compositional zoning of the clinopyroxene or olivine in BSE images.
Overall, the clinopyroxene and olivine grains are geochemically nearly identical between
samples. However, clinopyroxenes from the older samples (E11-04, E11-12, and E11-31) can be
distinguished by slight differences from the post-caldera flows in TiO2, Al2O3, FeO, MnO, and
MgO. For instance, clinopyroxenes from the West (E11-12) and Young Pre-caldera (E11-04)
flows are clearly distinct from the post-caldera flows on a plot of Na2O vs. FeO (Figure B.1),
supporting the conclusion that the area in which sample E11-12 was collected is not part of the
Northwest flow as it was originally mapped.
B.3. Whole rock analyses
Whole-rock major and trace-element analyses were done for each 36Cl sample (Table
B.7). Powdered whole-rock samples were sent to SGS Mineral Services in Toronto, Canada for
analysis. No effort was made to remove weathered or altered surface material from the sample
prior to crushing and analysis. Major-element oxide concentrations were measured using X-ray
fluorescence spectrometry (XRF). Trace elements and some major elements were measured
using inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma
atomic emission spectroscopy (ICP-AES).
B.4. Anorthoclase analyses
Major-element oxide concentrations were measured in anorthoclase separates for each
36
Cl sample (Table B.8). Powdered anorthoclase samples sent to the Department of Geological
Sciences at Michigan State University for XRF analysis using the analytical techniques described
in Rooney et al. (2012). Measured and accepted values for calibration standards are shown in
Table B.9.
Table B.1. Electron microprobe analyses of clinopyroxene in the 3He samples. Major-element
oxide concentrations are given in wt%. The grain number and position of each analysis (C=core,
I=intermediate, R=rim) is given under “Grain.” Pyroxene end-members wollastonite (Wo;
Ca2Si2O6), enstatite (En; Mg2Si2O6), and ferrosilite (Fs; Fe2Si2O6) are given in %.
Sample
Pt
E11-01
Grain
SiO2
TiO2
Al2O3
FeO*
MnO
MgO
CaO
Na2O
Total
Wo
En
Fs
1
1I
2
1R
3
2I
4
2I
13
2I
5
3C
6
3I
7
4C
8
4I
9
5I
10
5I
11
6I
12
6R
14
7I
15
7C
16
8I
17
8I
18
9I
19
9C
Average
50.05
50.25
49.88
50.10
50.34
51.03
50.85
50.96
50.99
50.41
51.12
50.86
50.30
51.55
50.45
50.65
51.09
51.18
50.85
50.68
1.52
1.55
1.50
1.55
1.46
1.17
1.25
1.26
1.23
1.47
1.30
1.31
1.55
1.11
1.55
1.38
1.27
1.26
1.15
1.36
3.11
3.01
3.20
3.54
3.15
2.38
2.92
2.61
2.73
3.32
3.02
2.88
3.20
2.39
2.86
2.84
2.68
2.43
2.52
2.88
9.56
9.63
9.60
9.82
9.83
9.42
9.86
9.50
9.60
9.86
9.81
9.64
9.84
9.57
9.82
9.42
9.65
9.29
9.54
9.65
0.61
0.63
0.66
0.69
0.63
0.63
0.68
0.69
0.61
0.63
0.64
0.59
0.65
0.59
0.61
0.60
0.62
0.60
0.62
0.63
11.90
12.00
11.91
11.56
11.92
12.11
11.88
12.11
12.25
11.74
12.06
12.12
11.86
12.40
11.66
12.01
12.14
12.39
12.27
12.02
21.61
21.35
21.10
21.01
21.32
21.83
20.71
21.20
21.36
20.97
20.68
21.25
21.14
21.52
21.80
21.62
21.28
21.67
21.44
21.31
0.92
0.87
1.00
1.13
0.95
0.83
1.05
0.84
0.93
1.10
1.07
0.94
0.99
0.94
0.81
0.89
0.91
0.78
0.90
0.94
99.28
99.31
98.84
99.40
99.64
99.40
99.25
99.17
99.71
99.50
99.73
99.59
99.56
100.08
99.55
99.41
99.62
99.61
99.28
99.47
47.4
46.9
46.7
46.9
46.8
47.4
46.1
46.6
46.5
46.6
45.8
46.6
46.6
46.5
47.7
47.3
46.6
46.9
46.7
46.8
36.3
36.6
36.7
35.9
36.4
36.6
36.8
37.1
37.1
36.3
37.2
36.9
36.4
37.3
35.5
36.6
37.0
37.3
37.1
36.7
16.4
16.5
16.6
17.1
16.8
16.0
17.1
16.3
16.3
17.1
17.0
16.5
17.0
16.1
16.8
16.1
16.5
15.7
16.2
16.5
E11-02
1
1C
2
1I
3
2R
4
2I
5
3I
6
3I
7
4I
8
4I
9
5I
10
5C
11
6I
12
6C
13
7C
14
7I
15
8I
16
8C
17
9I
18
9I
Average
51.16
50.76
51.14
50.88
51.04
50.98
51.02
50.97
50.35
50.29
51.08
51.09
51.06
50.91
51.29
50.90
50.94
50.58
50.91
1.20
1.28
1.11
1.20
1.33
1.26
1.30
1.21
1.64
1.52
1.23
1.19
1.20
1.11
1.17
1.27
1.23
1.38
1.27
2.75
2.70
2.47
2.83
2.71
2.97
2.77
2.64
3.50
3.45
2.57
2.60
2.58
2.58
2.35
2.60
2.59
3.18
2.77
9.97
9.96
9.83
9.87
9.60
9.84
9.68
9.58
10.04
10.01
9.74
9.67
10.09
10.17
10.11
10.21
9.56
9.82
9.88
0.67
0.62
0.67
0.64
0.55
0.65
0.65
0.61
0.59
0.61
0.66
0.66
0.73
0.69
0.66
0.70
0.62
0.63
0.65
11.86
11.98
12.06
11.97
12.07
12.14
12.04
12.14
11.42
11.44
12.02
12.00
11.89
11.83
11.78
11.80
12.14
11.74
11.91
20.91
21.23
21.37
21.10
21.59
20.80
21.18
21.23
20.88
20.87
21.36
21.72
21.29
20.99
21.59
21.26
21.45
20.98
21.21
1.04
1.01
0.86
0.98
0.87
1.07
0.92
0.92
1.15
1.07
0.94
0.85
0.99
0.97
0.84
0.97
0.85
1.11
0.97
99.56
99.55
99.51
99.47
99.76
99.71
99.56
99.31
99.58
99.29
99.61
99.76
99.82
99.24
99.79
99.71
99.39
99.42
99.56
46.3
46.5
46.6
46.4
47.1
45.9
46.6
46.6
46.8
46.8
46.7
47.2
46.6
46.2
47.1
46.6
46.8
46.6
46.6
36.5
36.5
36.6
36.6
36.6
37.2
36.8
37.0
35.6
35.7
36.6
36.3
36.2
36.3
35.7
36.0
36.9
36.3
36.4
17.2
17.0
16.7
16.9
16.3
16.9
16.6
16.4
17.6
17.5
16.6
16.4
17.2
17.5
17.2
17.5
16.3
17.0
16.9
E11-03
1
1I
2
1C
3
2I
4
2I
5
3R
6
3C
7
4C
8
4I
Average
50.83
50.60
50.44
50.16
50.70
50.39
50.22
51.79
50.64
1.29
1.28
1.40
1.43
1.32
1.28
1.40
1.06
1.31
2.67
2.87
3.06
3.21
3.14
2.72
2.82
2.22
2.84
9.20
9.56
9.29
9.78
10.06
9.56
9.39
9.51
9.54
0.56
0.60
0.67
0.62
0.62
0.63
0.64
0.67
0.63
12.04
11.92
11.98
11.89
11.63
11.95
11.85
12.29
11.94
21.13
20.93
21.01
21.03
20.54
21.26
21.33
21.64
21.11
0.90
1.00
0.91
1.04
1.17
0.89
0.86
0.84
0.95
98.62
98.75
98.76
99.15
99.16
98.67
98.50
100.02
98.95
46.9
46.5
46.8
46.5
46.1
46.9
47.3
46.9
46.7
37.2
36.9
37.1
36.6
36.3
36.7
36.5
37.0
36.8
15.9
16.6
16.1
16.9
17.6
16.4
16.2
16.1
16.5
E11-04
1
2
3
4
5
51.04
51.08
51.37
51.16
50.79
1.19
1.03
1.00
1.02
1.21
2.51
2.37
2.25
2.23
2.64
11.03
10.89
10.84
10.81
11.14
0.72
0.75
0.78
0.84
0.76
11.34
11.44
11.55
11.45
11.41
20.96
20.67
20.97
21.04
20.62
1.00
1.04
0.96
0.99
0.99
99.81
99.25
99.75
99.53
99.56
46.2
45.9
46.1
46.3
45.6
34.8
35.3
35.3
35.1
35.1
19.0
18.8
18.6
18.6
19.2
1I
1I
2I
2I
3I
Sample
Pt Grain
8
3I
6
4I
7
4C
9
5I
10
5I
11
6I
12
6I
13
7I
14
7I
Average
SiO2
51.04
51.65
51.33
51.09
50.94
51.36
51.61
51.23
51.22
51.21
TiO2
1.07
1.09
1.20
1.16
1.17
1.03
0.97
1.21
1.01
1.10
Al2O3
2.59
2.31
2.39
2.24
2.59
1.81
2.06
2.60
2.13
2.34
FeO*
11.00
10.99
10.71
10.67
10.67
10.52
10.89
11.07
10.71
10.85
MnO
0.70
0.79
0.72
0.71
0.80
0.73
0.72
0.69
0.78
0.75
MgO
11.29
11.44
11.42
11.65
11.70
11.94
11.69
11.30
11.41
11.50
CaO
20.96
20.62
21.13
21.33
20.46
21.59
20.91
20.34
20.92
20.89
Na2O
1.02
1.11
0.93
0.84
1.02
0.78
0.88
1.06
1.06
0.98
Total
99.67
100.00
99.85
99.70
99.34
99.77
99.74
99.53
99.23
99.62
Wo
46.3
45.7
46.6
46.5
45.4
46.5
45.8
45.5
46.3
46.1
En
34.7
35.3
35.0
35.3
36.1
35.8
35.6
35.2
35.2
35.3
Fs
19.0
19.0
18.4
18.2
18.5
17.7
18.6
19.3
18.5
18.7
E11-05
1
1I
2
1I
3
2I
4
2C
5
3I
6
3C
7
4I
9
5R
10
5I
11
6C
12
6C
13
7I
14
7C
15
8I
16
8C
17
9R
18
9C
Average
50.73
51.06
50.93
50.43
50.48
51.06
51.36
51.14
51.14
50.98
50.55
50.42
50.48
51.39
51.34
50.73
51.12
50.90
1.37
1.29
1.33
1.48
1.41
1.26
1.22
1.28
1.22
1.25
1.53
1.61
1.44
0.97
1.03
1.36
1.29
1.31
2.94
2.74
2.95
3.31
3.21
2.85
2.56
2.57
2.59
2.47
3.24
3.40
3.10
2.17
2.20
2.82
2.61
2.81
9.51
9.47
9.69
9.30
9.47
9.93
9.39
9.29
9.36
9.04
9.60
9.66
9.71
10.00
9.98
9.72
9.43
9.56
0.58
0.67
0.64
0.61
0.60
0.65
0.65
0.64
0.66
0.54
0.65
0.63
0.64
0.72
0.69
0.64
0.67
0.64
12.01
12.22
12.04
11.90
11.77
11.91
12.21
12.43
12.21
12.24
11.75
11.47
11.93
11.83
11.89
11.99
12.22
12.00
21.19
21.29
20.92
21.16
21.15
20.80
21.26
21.73
21.10
21.76
21.08
21.22
21.18
21.41
21.31
20.91
21.12
21.21
0.98
0.92
1.07
0.93
0.99
1.09
0.89
0.79
0.92
0.79
1.01
0.97
0.96
0.85
0.91
1.01
0.99
0.95
99.31
99.66
99.56
99.12
99.07
99.55
99.55
99.86
99.22
99.06
99.40
99.38
99.44
99.34
99.38
99.21
99.47
99.39
46.8
46.6
46.3
47.0
47.1
46.1
46.7
47.0
46.5
47.5
46.9
47.4
46.7
46.9
46.7
46.3
46.4
46.8
36.9
37.2
37.0
36.8
36.4
36.7
37.3
37.4
37.4
37.1
36.4
35.7
36.6
36.0
36.2
36.9
37.4
36.8
16.4
16.2
16.7
16.1
16.5
17.2
16.1
15.7
16.1
15.4
16.7
16.9
16.7
17.1
17.1
16.8
16.2
16.5
E11-06
1
1I
2
1C
3
1I
4
1R
5
2C
6
2R
7
2I
8
3I
9
3C
10
4C
11
4I
12
5I
13
5C
14
6I
15
6I
Average
50.68
51.17
50.95
49.97
51.47
51.17
51.08
51.09
51.28
50.56
50.04
51.07
51.00
50.97
50.49
50.87
1.31
1.17
1.29
1.61
1.06
1.18
1.08
1.34
1.16
1.42
1.59
1.30
1.32
1.38
1.51
1.31
3.05
2.63
2.59
3.70
2.04
2.42
2.46
2.93
2.32
3.02
3.35
2.86
2.74
3.12
3.22
2.83
9.72
9.48
9.41
9.77
9.79
9.93
9.66
9.59
9.25
9.65
9.65
9.67
9.32
9.91
9.38
9.61
0.63
0.61
0.62
0.60
0.71
0.71
0.70
0.59
0.60
0.60
0.60
0.58
0.61
0.56
0.59
0.62
11.96
12.05
12.37
11.53
12.18
11.90
12.04
11.99
12.48
12.03
11.77
11.99
12.24
11.81
11.94
12.02
20.66
20.98
21.59
20.64
21.48
21.29
21.26
21.04
21.58
21.04
21.20
20.95
21.29
20.84
21.31
21.14
1.04
0.94
0.80
1.17
0.79
0.96
0.93
0.93
0.77
0.90
0.97
0.99
0.85
1.14
0.93
0.94
99.05
99.02
99.63
98.99
99.52
99.57
99.23
99.51
99.44
99.23
99.19
99.43
99.38
99.77
99.39
99.36
46.0
46.5
46.8
46.6
46.6
46.7
46.7
46.5
46.8
46.4
47.0
46.4
46.7
46.3
47.1
46.6
37.1
37.1
37.3
36.2
36.8
36.3
36.8
36.9
37.6
36.9
36.3
36.9
37.4
36.5
36.7
36.9
16.9
16.4
15.9
17.2
16.6
17.0
16.6
16.6
15.6
16.6
16.7
16.7
16.0
17.2
16.2
16.5
E11-07
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
51.09
50.87
50.13
50.07
51.04
50.92
50.32
50.74
50.80
50.88
50.62
50.67
50.67
50.78
50.92
1.28
1.37
1.50
1.61
1.19
1.18
1.25
1.35
1.34
1.30
1.44
1.37
1.29
1.38
1.28
3.28
2.91
3.13
3.24
2.38
2.62
2.74
3.07
3.35
2.98
3.04
2.57
2.47
2.94
2.57
9.66
9.50
9.82
9.68
9.31
9.60
9.44
9.69
9.62
9.67
9.45
9.09
9.06
9.47
8.99
0.61
0.63
0.61
0.58
0.62
0.66
0.67
0.59
0.62
0.60
0.62
0.61
0.59
0.64
0.59
12.02
12.06
11.92
11.86
12.42
12.27
12.06
12.06
11.89
11.96
12.02
12.31
12.41
12.04
12.49
21.05
21.20
21.22
21.19
21.48
21.05
21.12
20.91
20.62
20.95
20.88
21.81
21.81
21.16
21.92
1.04
0.94
0.93
0.96
0.87
0.98
0.95
0.95
1.10
1.01
1.04
0.73
0.79
0.97
0.76
100.06
99.51
99.27
99.21
99.32
99.30
98.54
99.37
99.35
99.37
99.11
99.17
99.10
99.38
99.50
46.5
46.7
46.7
46.8
46.7
46.2
46.7
46.2
46.2
46.4
46.4
47.4
47.3
46.7
47.3
36.9
37.0
36.5
36.5
37.5
37.4
37.1
37.1
37.0
36.9
37.2
37.2
37.4
37.0
37.5
16.6
16.3
16.9
16.7
15.8
16.4
16.3
16.7
16.8
16.7
16.4
15.4
15.3
16.3
15.1
1C
1I
2I
2I
3C
3I
3R
4C
4R
5I
5C
6R
6I
6C
6C
Sample
Pt Grain
Average
SiO2
50.70
TiO2
1.34
Al2O3
2.89
FeO*
9.47
MnO
0.62
MgO
12.12
CaO
21.22
Na2O
0.93
Total
99.30
Wo
46.7
En
37.1
Fs
16.2
E11-08
1
1C
2
1I
3
1I
4
1R
5
2R
6
2I
7
2C
8
3I
9
3I
10
4I
12
5C
13
5I
14
6I
15
6I
Average
50.46
50.93
50.76
50.32
50.68
51.35
51.29
51.27
51.15
51.11
51.27
50.80
50.83
50.73
50.93
1.39
1.36
1.49
1.51
1.40
1.24
1.35
1.20
1.27
1.12
1.23
1.27
1.26
1.40
1.32
3.31
2.78
2.95
3.39
3.18
2.69
2.88
2.57
2.59
2.52
2.60
2.81
2.58
2.74
2.83
9.56
9.50
9.52
9.72
9.50
9.53
9.73
9.44
9.40
9.79
9.51
9.63
9.34
9.42
9.54
0.63
0.65
0.58
0.67
0.60
0.56
0.66
0.61
0.65
0.63
0.61
0.65
0.65
0.66
0.63
12.20
12.19
11.85
11.64
11.96
12.24
12.19
12.24
12.24
11.97
12.27
11.97
12.23
12.06
12.09
20.91
21.37
21.18
20.59
20.99
21.21
21.01
21.56
21.37
21.33
21.27
21.01
21.41
21.39
21.19
0.97
0.91
0.89
1.13
0.99
0.94
1.00
0.88
0.88
0.93
0.91
1.06
0.88
0.81
0.94
99.44
99.69
99.22
98.99
99.30
99.77
100.12
99.80
99.58
99.39
99.67
99.20
99.20
99.24
99.47
46.1
46.7
47.0
46.4
46.6
46.4
46.1
46.9
46.7
46.8
46.5
46.5
46.8
47.0
46.6
37.4
37.1
36.6
36.5
36.9
37.3
37.2
37.1
37.2
36.5
37.3
36.9
37.2
36.9
37.0
16.5
16.2
16.5
17.1
16.5
16.3
16.7
16.0
16.0
16.7
16.2
16.6
15.9
16.2
16.4
E11-09
1
1C
2
1I
3
2C
4
2I
5
3R
6
3I
7
3C
8
4I
9
4C
10
5I
11
5C
12
6R
13
6I
14
6C
15
6I
Average
50.58
50.69
50.58
49.69
51.34
50.96
51.31
50.13
50.54
50.72
50.82
50.20
50.47
48.38
50.59
50.47
1.44
1.29
1.45
1.83
1.17
1.31
1.19
1.63
1.52
1.32
1.20
1.51
1.35
2.12
1.43
1.45
2.89
2.63
3.22
3.87
2.67
2.57
2.67
3.77
3.31
3.15
2.54
3.13
3.04
5.28
3.08
3.19
9.02
8.85
9.40
9.52
9.15
8.85
9.15
9.54
9.40
9.42
9.29
9.30
9.25
9.40
9.51
9.27
0.62
0.60
0.62
0.63
0.59
0.54
0.59
0.68
0.62
0.62
0.57
0.56
0.63
0.50
0.61
0.60
11.93
12.37
11.87
11.48
12.18
12.30
12.19
11.48
11.94
11.92
12.24
11.81
11.84
11.35
11.88
11.92
21.36
21.56
21.00
20.67
21.15
21.77
21.12
20.29
20.75
20.54
21.06
20.89
20.95
20.48
20.80
20.96
0.93
0.78
1.06
1.16
0.96
0.82
0.93
1.17
1.06
1.08
0.89
0.99
1.05
1.19
0.96
1.00
98.77
98.79
99.20
98.87
99.22
99.12
99.14
98.73
99.15
98.77
98.64
98.41
98.59
98.73
98.87
98.87
47.5
47.2
46.8
46.9
46.8
47.5
46.7
46.4
46.4
46.2
46.4
46.9
46.9
47.0
46.5
46.8
36.9
37.7
36.8
36.2
37.4
37.4
37.5
36.5
37.2
37.3
37.6
36.8
36.9
36.2
36.9
37.0
15.7
15.1
16.4
16.9
15.8
15.1
15.8
17.0
16.4
16.5
16.0
16.3
16.2
16.8
16.6
16.2
E11-10
1
1C
2
1I
3
2I
4
2C
5
3R
6
3I
7
3I
8
3C
9
4C
10
4I
11
5I
12
5I
13
6R
14
6I
15
6C
Average
50.90
51.24
51.46
51.33
52.29
51.39
50.93
51.19
50.96
51.19
50.66
51.10
51.38
50.79
50.72
51.17
1.12
1.07
1.09
1.10
1.04
1.14
1.17
1.24
1.20
1.18
1.28
1.20
1.10
1.38
1.25
1.17
2.64
2.32
2.44
2.61
2.28
2.53
2.70
2.84
2.89
2.67
2.57
2.55
2.45
2.92
2.70
2.61
10.02
10.12
10.05
9.75
9.57
10.04
10.03
10.02
10.14
10.11
9.77
9.98
9.72
10.03
10.31
9.98
0.65
0.75
0.69
0.73
0.67
0.75
0.68
0.66
0.67
0.75
0.70
0.68
0.70
0.69
0.72
0.70
11.83
11.94
11.99
12.06
12.63
12.00
11.95
11.93
11.67
11.94
11.85
11.76
12.23
11.63
11.63
11.94
20.92
20.99
21.09
21.00
21.29
20.96
20.80
20.79
20.49
20.75
21.31
21.25
21.29
20.79
20.98
20.98
1.05
1.01
1.01
1.02
0.84
1.00
1.02
1.07
1.20
1.09
0.81
0.94
0.95
1.01
1.06
1.01
99.17
99.48
99.81
99.62
100.61
99.81
99.30
99.73
99.22
99.68
98.96
99.45
99.83
99.23
99.37
99.55
46.3
46.1
46.2
46.3
45.9
46.1
46.0
46.0
45.9
45.9
46.9
46.8
46.4
46.4
46.4
46.2
36.4
36.5
36.6
37.0
37.9
36.7
36.7
36.7
36.4
36.7
36.3
36.0
37.1
36.1
35.8
36.6
17.3
17.4
17.2
16.8
16.1
17.2
17.3
17.3
17.7
17.4
16.8
17.2
16.5
17.5
17.8
17.2
E11-11
1
2
3
4
5
6
7
8
9
10
11
50.70
50.05
51.29
50.95
50.38
51.06
51.30
50.59
51.15
51.32
51.75
1.28
1.54
1.14
1.19
1.46
1.17
1.17
1.22
1.14
1.13
1.05
2.79
3.50
2.27
2.59
3.35
2.60
2.35
2.77
2.63
2.41
1.95
9.66
9.53
9.15
8.98
9.80
9.66
9.49
9.89
9.97
9.91
9.59
0.63
0.61
0.70
0.61
0.71
0.61
0.70
0.64
0.64
0.70
0.67
11.88
11.75
12.33
12.31
11.53
11.99
12.29
11.72
11.96
12.02
12.31
20.96
20.94
21.73
21.61
20.70
21.32
21.45
21.01
20.79
21.10
21.60
0.96
1.01
0.79
0.76
1.19
0.93
0.84
0.99
1.02
0.93
0.84
98.86
98.94
99.42
99.00
99.11
99.36
99.58
98.84
99.31
99.53
99.77
46.5
46.8
47.2
47.2
46.6
46.8
46.7
46.7
46.0
46.3
46.7
36.7
36.5
37.3
37.4
36.1
36.6
37.2
36.2
36.8
36.7
37.1
16.8
16.6
15.5
15.3
17.2
16.6
16.1
17.1
17.2
17.0
16.2
1R
1I
1I
1C
2R
2I
2C
3I
3C
4C
4R
Sample
Pt Grain
12
5C
13
5I
14
6I
15
6I
Average
SiO2
50.94
51.11
51.02
51.29
50.99
TiO2
1.25
1.19
1.19
1.16
1.22
Al2O3
2.71
3.04
2.59
2.44
2.67
FeO*
10.10
10.19
9.63
9.83
9.69
MnO
0.66
0.73
0.59
0.63
0.66
MgO
11.56
11.75
11.78
12.05
11.95
CaO
20.80
20.52
21.39
21.13
21.14
Na2O
0.99
1.03
0.84
0.92
0.94
Total
99.04
99.56
99.05
99.47
99.26
Wo
46.5
45.8
47.2
46.4
46.6
En
35.9
36.5
36.2
36.8
36.7
Fs
17.6
17.7
16.6
16.8
16.7
E11-12
1
1I
2
1R
3
1C
4
1I
5
2C
6
2C
7
2R
8
3I
9
3I
10
4I
11
4C
12
5I
13
5I
14
6I
15
6C
Average
51.36
51.05
51.55
51.44
51.36
51.54
50.27
50.87
50.86
51.19
51.23
51.12
51.75
51.52
50.92
51.20
0.96
1.02
1.01
0.98
0.96
0.98
1.11
1.07
1.25
1.07
1.11
1.03
0.94
0.98
1.13
1.04
2.27
2.43
1.87
2.18
2.10
2.06
2.47
2.47
2.65
2.28
2.59
2.41
2.23
2.20
2.49
2.31
10.70
10.61
10.38
10.68
10.66
10.41
10.72
10.73
10.75
10.10
10.30
10.36
10.16
10.08
10.43
10.47
0.71
0.69
0.64
0.74
0.74
0.68
0.67
0.66
0.72
0.66
0.65
0.73
0.69
0.63
0.69
0.69
11.52
11.57
12.01
11.70
11.52
11.68
11.15
11.57
11.63
11.77
11.51
11.67
11.75
11.84
11.40
11.62
20.81
20.81
21.46
21.04
20.97
21.21
21.12
20.64
20.66
21.14
20.82
20.83
21.38
21.35
21.04
21.02
0.99
1.04
0.83
1.01
0.95
0.86
0.94
1.07
1.05
0.92
1.07
0.98
0.89
0.89
0.94
0.96
99.34
99.25
99.75
99.77
99.27
99.42
98.45
99.07
99.57
99.14
99.26
99.14
99.81
99.50
99.04
99.32
46.1
46.0
46.4
46.1
46.3
46.5
46.9
45.8
45.7
46.6
46.4
46.1
46.8
46.7
46.7
46.3
35.5
35.6
36.1
35.7
35.4
35.6
34.5
35.7
35.8
36.1
35.7
35.9
35.8
36.0
35.2
35.6
18.5
18.3
17.5
18.3
18.4
17.8
18.6
18.6
18.5
17.4
17.9
17.9
17.4
17.2
18.1
18.0
E11-13
1
1C
2
1R
3
2R
4
2I
5
3C
6
3I
7
4I
8
4R
Average
51.46
50.77
51.80
51.52
51.21
51.50
51.17
50.79
51.28
1.31
1.48
1.08
1.30
1.38
1.29
1.47
1.61
1.37
2.45
3.18
2.46
2.66
3.13
2.52
3.02
3.57
2.87
9.68
9.93
10.28
10.11
9.99
9.30
9.66
9.77
9.84
0.68
0.62
0.67
0.66
0.61
0.58
0.64
0.64
0.64
12.04
11.60
11.93
11.80
11.98
12.38
12.04
11.80
11.95
21.65
21.25
20.97
21.28
20.88
21.57
21.46
20.88
21.24
0.80
0.97
0.96
0.92
1.09
0.78
0.89
1.09
0.94
100.06
99.80
100.15
100.23
100.27
99.93
100.36
100.14
100.12
47.1
47.1
46.0
46.7
46.1
46.8
46.9
46.5
46.7
36.4
35.7
36.4
36.0
36.7
37.4
36.6
36.6
36.5
16.4
17.2
17.6
17.3
17.2
15.8
16.5
17.0
16.9
E11-14
1
1C
2
1I
3
2I
4
2C
5
3I
6
3C
7
4R
8
4C
Average
50.83
51.09
51.02
50.31
51.11
51.64
50.72
50.88
50.95
1.51
1.37
1.34
1.62
1.31
1.19
1.52
1.18
1.38
3.25
2.79
3.13
3.81
2.90
2.38
3.31
2.62
3.02
9.74
9.23
9.91
9.93
9.52
9.58
9.52
10.06
9.69
0.68
0.66
0.63
0.57
0.64
0.60
0.63
0.66
0.63
11.85
12.22
11.84
11.69
12.03
12.40
11.96
11.82
11.98
20.93
21.60
20.75
20.64
21.28
21.41
21.09
21.05
21.09
1.06
0.82
1.05
1.11
0.93
0.86
0.93
0.92
0.96
99.85
99.78
99.67
99.68
99.71
100.06
99.67
99.19
99.70
46.5
47.2
46.2
46.2
46.8
46.4
46.7
46.4
46.6
36.6
37.1
36.6
36.4
36.8
37.4
36.9
36.3
36.8
16.9
15.7
17.2
17.4
16.3
16.2
16.4
17.3
16.7
E11-15
1
1R
2
1I
3
2I
4
2I
5
3I
6
3C
7
4C
8
4I
Average
48.42
50.23
50.07
49.59
50.54
50.95
50.38
50.51
50.09
1.79
1.43
1.67
1.40
1.30
1.23
1.14
1.31
1.41
4.54
3.15
2.89
2.90
2.92
2.49
2.58
2.71
3.02
9.68
9.48
9.19
9.62
9.67
9.52
10.23
9.75
9.64
0.56
0.63
0.56
0.57
0.59
0.60
0.70
0.62
0.60
11.68
11.89
12.12
12.00
12.07
12.41
11.55
11.79
11.94
20.43
20.96
21.56
21.18
20.94
21.25
20.70
21.24
21.03
1.08
0.98
0.87
0.96
0.97
0.82
1.06
0.92
0.96
98.18
98.75
98.93
98.21
98.99
99.26
98.35
98.86
98.69
46.2
46.7
47.3
46.7
46.3
46.3
46.2
46.9
46.6
36.7
36.8
37.0
36.8
37.1
37.6
35.9
36.3
36.8
17.1
16.5
15.7
16.5
16.7
16.2
17.8
16.8
16.7
E11-16
1
1C
2
1I
3
2R
4
2I
5
3I
6
3I
7
4I
8
4C
Average
50.96
51.30
51.16
51.10
48.99
50.36
51.01
51.04
50.74
1.11
1.25
1.23
1.20
1.98
1.46
1.17
1.27
1.33
2.69
2.94
2.74
2.57
4.37
3.21
2.72
2.72
3.00
10.02
10.15
10.05
10.02
9.54
9.69
9.92
9.77
9.90
0.71
0.62
0.63
0.64
0.60
0.64
0.64
0.67
0.64
11.89
12.04
11.78
11.84
11.49
11.89
11.84
12.18
11.87
20.77
20.57
21.08
21.17
20.65
21.17
21.02
21.36
20.97
0.98
1.14
0.97
0.97
1.13
1.02
1.02
0.85
1.01
99.13
100.01
99.64
99.49
98.75
99.44
99.35
99.86
99.46
46.0
45.5
46.5
46.6
46.8
46.7
46.5
46.5
46.4
36.6
37.0
36.2
36.2
36.3
36.5
36.4
36.9
36.5
17.3
17.5
17.3
17.2
16.9
16.7
17.1
16.6
17.1
E11-17
1
51.05
1.30
2.75
9.63
0.63
12.01
21.15
0.99
99.50
46.6
36.8
16.6
1R
Sample
Pt Grain
2
1C
3
2I
4
2R
5
3R
6
3C
7
4I
8
4C
Average
SiO2
50.75
50.53
50.08
50.91
51.42
51.35
51.12
50.90
TiO2
1.65
1.44
1.52
1.22
1.11
1.20
1.18
1.33
Al2O3
3.16
3.25
3.38
2.79
2.26
2.45
2.28
2.79
FeO*
9.36
9.90
9.77
9.73
9.58
9.41
9.19
9.57
MnO
0.56
0.64
0.63
0.66
0.63
0.60
0.57
0.62
MgO
11.99
11.81
11.66
12.03
12.35
12.43
12.42
12.09
CaO
21.25
20.94
20.88
20.95
21.67
21.75
21.66
21.28
Na2O
0.87
1.04
1.07
1.01
0.81
0.73
0.71
0.90
Total
99.58
99.54
99.00
99.29
99.84
99.93
99.12
99.48
Wo
47.0
46.4
46.7
46.3
46.8
46.9
47.0
46.7
En
36.9
36.4
36.3
37.0
37.1
37.3
37.5
36.9
Fs
16.2
17.1
17.1
16.8
16.1
15.8
15.6
16.4
E11-18
1
1C
2
1C
3
2I
4
2I
5
3I
6
3R
7
3I
8
3C
9
4C
10
4I
11
5I
12
5I
13
5C
14
6I
15
6R
Average
50.87
51.24
50.65
50.58
51.07
50.65
51.42
50.66
51.52
51.00
51.40
50.52
50.22
50.65
50.32
50.85
1.30
1.20
1.22
1.32
1.30
1.25
1.22
1.26
1.19
1.31
1.18
1.26
1.28
1.43
1.43
1.28
2.89
2.83
2.75
3.00
2.77
2.84
2.68
2.84
2.39
2.98
2.42
2.81
2.86
2.79
3.10
2.80
9.45
9.57
9.30
9.33
9.53
9.63
9.65
9.43
9.22
9.62
9.48
9.54
9.40
9.45
9.70
9.49
0.60
0.64
0.61
0.62
0.61
0.67
0.65
0.64
0.61
0.68
0.66
0.59
0.58
0.62
0.58
0.62
12.01
12.10
11.92
11.71
12.20
11.95
12.16
12.01
12.52
12.02
12.37
11.96
12.20
12.02
11.88
12.07
21.01
20.78
21.04
21.08
20.80
20.88
21.06
20.92
21.57
21.10
21.18
20.88
21.15
21.21
21.00
21.04
0.91
0.97
0.87
1.01
1.00
0.93
0.98
0.92
0.79
1.05
0.89
1.03
0.92
0.85
0.99
0.94
99.06
99.33
98.37
98.65
99.30
98.79
99.82
98.68
99.82
99.76
99.57
98.59
98.61
99.05
99.01
99.09
46.6
46.1
46.9
47.2
46.0
46.4
46.3
46.5
46.7
46.5
46.3
46.4
46.5
46.8
46.6
46.5
37.1
37.3
37.0
36.5
37.5
36.9
37.2
37.1
37.7
36.9
37.6
37.0
37.3
36.9
36.6
37.1
16.4
16.6
16.2
16.3
16.5
16.7
16.5
16.4
15.6
16.6
16.2
16.6
16.1
16.3
16.8
16.4
E11-19
1
1R
2
1C
3
2C
4
2R
5
3C
6
3R
7
4I
8
4C
Average
50.76
50.48
51.35
51.15
51.14
51.19
51.18
51.37
51.08
1.54
1.38
1.35
1.31
1.27
1.18
1.23
1.18
1.31
3.47
3.16
3.04
2.97
2.98
2.71
2.63
2.52
2.94
10.01
9.68
9.94
9.80
9.70
9.57
9.52
9.53
9.72
0.64
0.69
0.71
0.67
0.63
0.55
0.63
0.57
0.64
11.65
11.92
11.91
11.93
11.96
12.19
11.98
12.16
11.96
20.99
21.11
20.69
20.85
20.90
21.65
21.26
21.49
21.12
1.14
1.03
1.10
1.05
1.01
0.89
0.89
0.88
1.00
100.21
99.45
100.08
99.72
99.58
99.92
99.32
99.70
99.75
46.6
46.7
46.0
46.2
46.3
47.0
46.9
46.9
46.6
36.0
36.6
36.8
36.8
36.9
36.8
36.8
36.9
36.7
17.4
16.7
17.2
17.0
16.8
16.2
16.4
16.2
16.7
E11-20
1
1C
2
1I
3
2C
5
3C
6
3R
7
4C
8
4I
Average
51.12
50.74
51.10
50.74
51.51
50.84
51.03
51.01
1.44
1.46
1.23
1.38
1.25
1.38
1.24
1.34
2.91
3.34
2.87
3.12
2.74
2.80
2.90
2.95
9.25
9.78
9.77
9.76
9.59
9.47
9.94
9.65
0.51
0.58
0.62
0.58
0.63
0.64
0.62
0.60
12.19
11.79
12.07
11.91
12.08
12.20
12.05
12.04
21.81
21.25
21.22
20.91
21.41
21.59
21.07
21.32
0.81
1.06
1.00
1.05
0.99
0.88
1.02
0.97
100.03
100.01
99.87
99.45
100.19
99.79
99.88
99.89
47.4
46.9
46.5
46.4
46.9
47.0
46.2
46.76
36.9
36.2
36.8
36.7
36.8
36.9
36.8
36.73
15.7
16.9
16.7
16.9
16.4
16.1
17.0
16.5
E11-21
1
1I
2
1C
3
2I
4
2C
5
3C
6
3R
7
4I
8
4I
Average
50.98
50.63
51.01
51.13
51.41
51.58
51.94
51.85
51.32
1.42
1.33
1.42
1.27
1.13
1.17
1.09
1.13
1.25
2.79
2.83
2.85
2.85
2.28
2.46
2.24
2.47
2.60
10.22
10.01
9.81
9.95
9.99
10.30
9.86
9.82
10.00
0.64
0.67
0.56
0.67
0.67
0.73
0.67
0.72
0.67
11.90
11.77
12.17
11.87
12.15
11.98
12.22
12.04
12.01
21.27
21.23
21.55
21.02
21.58
21.28
21.45
21.39
21.35
0.94
0.92
0.87
1.11
0.85
0.98
0.88
0.95
0.94
100.15
99.40
100.25
99.87
100.05
100.48
100.35
100.36
100.11
46.4
46.8
46.7
46.4
46.6
46.3
46.5
46.7
46.6
36.1
36.0
36.7
36.5
36.5
36.2
36.8
36.6
36.4
17.4
17.2
16.6
17.1
16.8
17.5
16.7
16.7
17.0
E11-22
1
1I
2
1I
3
2I
4
2C
5
3I
6
3R
7
4I
8
4I
Average
51.12
51.71
50.76
51.06
51.41
51.10
51.09
51.80
51.26
1.31
1.05
1.35
1.15
1.13
1.10
1.25
1.04
1.17
2.87
2.00
2.83
2.41
2.22
2.32
2.84
2.46
2.49
10.28
9.90
10.22
9.99
10.14
9.92
9.76
9.91
10.02
0.72
0.72
0.70
0.64
0.72
0.67
0.64
0.64
0.68
11.65
12.33
11.66
12.08
12.14
12.08
11.91
12.09
11.99
21.02
21.51
21.09
21.26
21.21
21.52
21.25
21.41
21.28
1.00
0.87
0.98
0.89
0.89
0.83
0.92
0.99
0.92
99.97
100.09
99.57
99.49
99.86
99.55
99.66
100.33
99.82
46.5
46.4
46.6
46.3
46.1
46.7
46.8
46.6
46.5
35.8
37.0
35.8
36.7
36.7
36.5
36.5
36.6
36.5
17.7
16.7
17.6
17.0
17.2
16.8
16.8
16.8
17.1
Sample
Pt
E11-23
Grain
SiO2
TiO2
Al2O3
FeO*
MnO
MgO
CaO
Na2O
Total
Wo
En
Fs
1
1C
2
1I
3
2I
4
2R
5
3I
6
3I
7
3R
8
4I
9
4C
11
5I
12
5R
13
6I
14
6I
Average
50.92
51.16
51.12
50.91
50.51
51.12
50.07
50.91
50.86
51.36
50.62
50.48
51.34
50.88
1.08
1.16
1.06
1.31
1.19
1.18
1.19
1.25
1.24
1.21
1.08
1.35
1.03
1.18
2.24
2.32
2.23
2.85
2.57
2.49
2.42
2.95
2.93
2.57
2.35
2.80
2.25
2.54
9.59
9.36
9.36
9.51
9.60
9.67
9.39
10.04
9.92
9.32
9.19
9.84
9.85
9.59
0.69
0.61
0.59
0.63
0.70
0.63
0.64
0.65
0.69
0.66
0.69
0.66
0.70
0.66
12.06
12.00
12.14
11.85
11.74
11.85
11.90
11.60
11.70
12.19
12.11
11.76
11.98
11.91
21.28
21.56
21.39
20.90
21.04
21.08
21.16
20.61
20.40
21.21
21.49
21.20
21.17
21.11
0.89
0.79
0.84
1.01
1.01
0.95
0.83
1.14
1.10
0.97
0.82
0.96
0.88
0.94
98.77
98.97
98.74
98.97
98.39
98.99
97.60
99.20
98.83
99.51
98.36
99.04
99.20
98.81
46.7
47.3
46.9
46.6
46.9
46.7
47.0
46.2
45.9
46.7
47.2
46.9
46.5
46.7
36.8
36.6
37.0
36.8
36.4
36.6
36.8
36.2
36.6
37.3
37.0
36.2
36.6
36.7
16.4
16.0
16.0
16.6
16.7
16.7
16.3
17.6
17.4
16.0
15.8
17.0
16.9
16.6
E11-24
1
1C
2
1I
3
1R
4
2C
5
2I
7
3I
8
3I
9
4I
10
5R
11
5I
12
5I
13
5C
14
6C
15
6I
Average
50.16
50.16
50.46
50.80
50.57
50.35
50.91
51.27
51.09
50.52
50.58
50.52
51.28
50.59
50.66
1.48
1.39
1.43
1.25
1.35
1.47
1.36
1.24
1.25
1.42
1.46
1.47
1.22
1.43
1.37
3.12
3.00
2.87
2.57
2.63
3.24
2.78
2.66
2.88
3.48
3.24
2.84
2.75
3.07
2.94
9.27
9.39
8.97
9.14
8.82
9.31
9.11
9.22
9.40
9.36
9.21
8.84
9.27
9.18
9.18
0.61
0.58
0.61
0.53
0.58
0.61
0.60
0.64
0.65
0.58
0.63
0.55
0.61
0.54
0.59
11.76
11.86
11.96
12.23
12.17
11.79
12.12
12.10
11.84
12.08
11.82
12.27
11.94
11.83
11.98
20.84
21.04
21.32
21.33
21.56
20.75
21.46
20.99
20.74
20.32
20.76
21.30
21.20
21.21
21.06
1.05
0.96
0.92
0.82
0.76
1.00
0.86
0.93
1.01
1.08
1.14
0.85
0.96
0.96
0.95
98.30
98.38
98.54
98.68
98.44
98.50
99.21
99.10
98.86
98.83
98.85
98.64
99.23
98.82
98.74
46.9
46.9
47.4
46.9
47.5
46.7
47.2
46.6
46.6
45.7
46.8
47.1
47.1
47.3
46.9
36.8
36.8
37.0
37.4
37.3
36.9
37.1
37.4
37.0
37.8
37.0
37.7
36.9
36.7
37.1
16.3
16.3
15.6
15.7
15.2
16.4
15.6
16.0
16.5
16.4
16.2
15.2
16.1
16.0
16.0
E11-25
1
1C
2
1I
3
2C
4
2I
6
3C
7
3R
8
3C
9
4I
10
4I
11
5C
12
5I
13
6R
14
6I
Average
51.14
50.88
50.95
50.84
50.91
50.65
51.32
50.96
50.94
51.19
51.04
50.49
51.21
50.96
1.20
1.26
1.27
1.27
1.20
1.29
1.05
1.23
1.19
1.11
1.12
1.36
1.15
1.21
2.43
2.80
2.88
2.86
2.65
2.89
2.46
2.92
2.70
2.41
2.56
2.85
2.41
2.68
9.50
9.78
9.75
9.67
9.60
9.39
9.48
9.92
9.66
9.66
9.82
9.22
9.23
9.59
0.63
0.69
0.65
0.67
0.69
0.58
0.62
0.66
0.66
0.69
0.64
0.63
0.67
0.65
11.95
11.72
11.65
11.58
11.90
11.85
11.99
11.71
11.80
11.86
11.91
11.95
12.13
11.85
21.34
20.94
20.83
20.84
21.01
20.97
21.28
20.76
21.18
20.95
21.11
21.14
21.39
21.06
0.83
0.99
1.02
1.01
0.98
1.00
0.88
1.11
0.93
0.90
0.97
0.92
0.89
0.96
99.06
99.06
99.01
98.77
98.94
98.64
99.12
99.28
99.07
98.79
99.17
98.58
99.08
98.97
47.0
46.7
46.7
46.8
46.6
46.8
46.9
46.3
46.9
46.6
46.6
47.0
47.0
46.8
36.6
36.3
36.3
36.2
36.7
36.8
36.8
36.4
36.4
36.7
36.5
37.0
37.1
36.6
16.3
17.0
17.0
17.0
16.6
16.4
16.3
17.3
16.7
16.8
16.9
16.0
15.8
16.6
E11-26
1
1I
2
1C
3
2I
4
2C
5
3C
6
3I
7
4I
8
4I
Average
50.72
50.10
50.82
50.51
51.36
50.19
50.03
50.15
50.49
1.28
1.43
1.31
1.37
1.22
1.43
1.65
1.54
1.40
2.92
3.17
3.09
3.28
2.82
3.02
3.32
3.16
3.10
10.11
10.22
10.02
9.88
10.17
9.92
10.08
10.13
10.07
0.67
0.62
0.60
0.57
0.66
0.60
0.64
0.58
0.62
11.69
11.56
11.92
11.74
11.80
11.78
11.52
11.74
11.72
20.93
20.94
20.74
20.81
20.89
21.06
21.08
21.10
20.94
1.05
1.04
1.09
1.12
1.05
0.94
1.00
1.04
1.04
99.37
99.07
99.59
99.28
99.95
98.93
99.32
99.43
99.37
46.4
46.5
46.0
46.4
46.2
46.6
46.9
46.5
46.4
36.1
35.7
36.7
36.4
36.3
36.3
35.6
36.0
36.1
17.5
17.7
17.3
17.2
17.5
17.1
17.5
17.4
17.4
E11-27
1
2
3
4
5
6
7
50.25
50.14
51.19
50.13
50.63
50.55
51.12
1.60
1.47
1.18
1.60
1.34
1.44
1.12
3.60
3.35
2.75
3.68
3.05
3.12
2.36
10.12
10.26
9.93
9.90
9.80
9.84
9.90
0.64
0.58
0.62
0.65
0.63
0.61
0.68
11.47
11.53
12.07
11.42
11.89
11.81
12.09
20.60
20.93
21.08
20.65
20.93
21.17
21.28
1.18
1.10
1.01
1.14
1.00
0.93
0.97
99.45
99.35
99.82
99.15
99.27
99.46
99.52
46.3
46.5
46.2
46.7
46.4
46.7
46.4
35.9
35.7
36.8
35.9
36.7
36.3
36.7
17.8
17.8
17.0
17.5
17.0
17.0
16.9
1I
1C
2I
2C
3I
3C
4C
Sample
Pt Grain
8
4I
Average
SiO2
50.44
50.56
TiO2
1.35
1.39
Al2O3
2.86
3.10
FeO*
9.97
9.97
MnO
0.65
0.63
MgO
11.69
11.75
CaO
21.40
21.01
Na2O
0.89
1.03
Total
99.25
99.41
Wo
47.1
46.5
En
35.8
36.2
Fs
17.1
17.3
E11-28
1
1I
2
1I
3
2I
4
2I
5
3I
6
3C
7
4I
8
4I
Average
51.44
50.94
51.54
50.72
51.25
51.33
51.16
51.26
51.21
1.01
1.38
1.04
1.17
1.26
1.03
1.13
1.11
1.14
1.96
2.67
2.20
2.39
2.74
2.43
2.67
2.32
2.42
9.53
9.81
9.87
9.78
10.04
9.98
10.29
10.03
9.92
0.64
0.72
0.69
0.68
0.68
0.63
0.70
0.65
0.67
12.35
11.83
12.23
12.11
11.80
12.21
11.79
11.96
12.04
22.04
21.55
21.58
21.56
20.86
21.14
20.78
21.07
21.32
0.68
0.87
0.91
0.80
0.96
0.90
0.99
0.92
0.88
99.66
99.77
100.04
99.21
99.59
99.64
99.51
99.33
99.59
47.2
47.2
46.6
46.8
46.2
46.0
46.0
46.3
46.5
36.8
36.0
36.7
36.6
36.4
37.0
36.3
36.5
36.5
15.9
16.8
16.6
16.6
17.4
17.0
17.8
17.2
16.9
E11-29
1
1C
2
1C
3
2C
4
2I
5
3R
6
3C
7
4C
8
4I
Average
50.85
51.19
50.58
51.14
51.32
51.14
50.80
51.19
51.03
1.08
1.10
1.28
1.15
1.25
1.15
1.13
1.34
1.19
2.44
2.43
2.87
2.44
2.82
2.29
2.67
2.78
2.59
9.83
9.73
9.90
9.76
9.90
9.87
9.88
10.19
9.88
0.64
0.65
0.63
0.67
0.70
0.70
0.59
0.67
0.66
11.94
11.95
11.79
12.04
11.85
12.02
11.88
11.62
11.89
21.28
21.00
21.06
21.14
20.98
21.32
21.25
20.96
21.12
0.90
0.93
1.02
0.99
1.03
0.88
0.99
1.00
0.97
98.96
98.97
99.13
99.34
99.85
99.36
99.18
99.74
99.32
46.7
46.4
46.6
46.5
46.4
46.6
46.7
46.5
46.6
36.5
36.8
36.3
36.8
36.5
36.6
36.3
35.9
36.5
16.8
16.8
17.1
16.7
17.1
16.8
17.0
17.6
17.0
E11-30
1
1C
2
1R
3
2I
4
2C
5
3I
6
3I
7
4I
8
4C
Average
50.17
50.55
50.86
50.17
50.74
51.32
51.57
51.01
50.80
1.38
1.20
1.25
1.55
1.34
1.08
1.08
1.25
1.27
3.03
2.69
2.70
3.83
3.23
2.31
2.44
2.72
2.87
10.08
9.84
9.86
9.76
9.75
9.81
9.42
9.65
9.77
0.60
0.66
0.64
0.63
0.59
0.67
0.64
0.57
0.63
11.69
11.86
11.97
12.09
11.82
12.06
12.34
12.09
11.99
21.08
21.24
20.98
20.36
20.74
21.47
21.02
21.26
21.02
0.94
0.94
0.96
1.01
1.11
0.84
0.85
0.80
0.93
98.98
98.97
99.23
99.40
99.32
99.55
99.35
99.34
99.27
46.6
46.8
46.3
45.4
46.3
46.8
46.2
46.6
46.4
36.0
36.3
36.7
37.6
36.7
36.5
37.7
36.9
36.8
17.4
16.9
17.0
17.0
17.0
16.7
16.1
16.5
16.8
E11-31
1
1C
2
1C
3
2I
4
2C
5
3C
6
3C
7
4I
8
4R
Average
50.33
50.17
50.78
50.37
50.37
50.28
51.14
50.96
50.55
1.45
1.59
1.34
1.47
1.43
1.39
1.25
1.33
1.41
3.29
3.38
2.66
2.84
3.04
3.01
2.66
2.94
2.98
9.34
9.31
8.91
9.04
9.48
9.28
9.34
9.04
9.22
0.62
0.51
0.50
0.53
0.58
0.58
0.57
0.54
0.55
12.13
11.96
12.69
12.46
12.22
12.20
12.38
12.46
12.31
20.72
20.81
21.64
21.25
20.75
20.99
21.14
21.17
21.06
1.04
0.97
0.76
0.79
1.02
1.01
0.97
0.88
0.93
98.92
98.69
99.26
98.75
98.88
98.74
99.44
99.33
99.00
46.2
46.5
46.8
46.6
46.0
46.4
46.3
46.5
46.4
37.6
37.2
38.2
38.0
37.6
37.5
37.7
38.0
37.7
16.2
16.2
15.0
15.5
16.4
16.0
16.0
15.5
15.9
*Total Fe reported as FeO.
Table B.2. Electron microprobe analyses of olivine in the 3He samples. Major-element oxide
concentrations are given in wt%. The grain number and position of each analysis (C=core,
I=intermediate, R=rim) is given under “Grain.” Olivine end-members forsterite (Fo; Mg2SiO4),
fayalite (Fa; Fe2SiO4), and Tephroite (Te; Mn2SiO4) are given in %.
Sample
SiO2
TiO2
FeO*
MnO
MgO
CaO
Total
Fo
Fa
Te
2
1I
34.85
3
2C
34.64
4
2C
34.47
5
3I
34.62
6
3I
34.84
7
4I
34.54
8
4C
34.66
9
5I
34.46
10
5I
34.66
11
6I
34.57
12
6C
34.46
13
7I
34.55
14
7I
34.47
15
8I
34.77
16
8C
34.47
Average
34.60
E11-05 1
1I
34.94
4
1I
34.79
2
2C
34.88
3
2C
35.16
5
3I
34.79
6
3C
34.77
7
4I
37.45
8
4I
34.58
9
5I
34.93
10
5I
34.65
11
6I
34.70
12
6C
34.84
13
7I
34.73
14
7I
34.56
15
8C
34.80
16
8I
34.93
Average
34.97
E11-31 1
1C
35.79
2
1I
35.21
3
2I
35.31
4
2I
35.12
5
3C
34.99
6
3I
35.21
7
4I
35.05
8
4I
35.34
Average
35.25
*Total Fe reported as FeO.
0.01
0.06
0.06
0.01
0.02
0.03
0.04
0.06
0.06
0.04
0.03
0.07
0.03
0.05
0.07
0.04
0.04
0.05
0.05
0.02
0.00
0.03
0.08
0.04
0.05
0.06
0.03
0.05
0.06
0.07
0.04
0.07
0.05
0.053
0.054
0.03
0.058
0.055
0.041
0.057
0.08
0.05
39.30
38.86
39.16
38.15
38.33
39.27
39.43
39.16
39.54
38.42
38.80
38.81
38.76
38.16
38.58
38.85
37.71
38.68
38.45
37.95
38.30
38.76
40.54
38.22
37.82
38.46
38.31
38.52
38.25
38.79
38.49
38.38
38.48
36.40
36.49
36.17
36.53
36.22
36.40
36.17
36.15
36.32
2.13
2.20
2.12
2.14
2.18
2.04
2.14
2.14
2.07
2.21
2.14
2.07
2.08
2.12
2.12
2.13
2.05
2.14
2.12
2.08
2.10
2.15
2.26
2.08
2.11
2.12
2.05
2.06
2.14
2.11
2.19
2.21
2.12
1.72
1.71
1.82
1.72
1.66
1.77
1.70
1.73
1.73
24.18
24.33
24.30
24.53
24.76
24.36
24.25
24.08
24.16
24.36
24.44
24.32
24.60
24.73
25.01
24.43
24.72
24.89
24.71
24.64
24.53
24.70
26.83
24.95
24.97
24.85
24.74
24.82
24.79
24.54
24.85
24.83
24.90
26.41
26.68
26.53
26.58
26.46
26.73
27.01
26.70
26.64
0.46
0.51
0.46
0.48
0.50
0.43
0.48
0.45
0.41
0.50
0.50
0.45
0.44
0.44
0.46
0.46
0.49
0.47
0.46
0.50
0.45
0.45
0.50
0.42
0.47
0.47
0.44
0.47
0.46
0.48
0.49
0.47
0.47
0.41
0.42
0.51
0.46
0.41
0.45
0.40
0.40
0.43
100.95
100.61
100.56
99.92
100.64
100.69
101.01
100.35
100.91
100.10
100.37
100.29
100.37
100.27
100.71
100.52
99.94
101.02
100.68
100.35
100.18
100.84
107.66
100.29
100.34
100.61
100.27
100.77
100.44
100.55
100.87
100.89
100.98
100.78
100.57
100.36
100.48
99.79
100.59
100.37
100.40
100.42
51.0
51.3
51.2
52.0
52.1
51.2
51.0
50.9
50.8
51.6
51.5
51.4
51.8
52.2
52.3
51.5
52.5
52.1
52.0
52.3
52.0
51.8
52.8
52.4
52.7
52.2
52.2
52.1
52.2
51.7
52.1
52.1
52.2
55.2
55.4
55.4
55.3
55.4
55.5
56.0
55.7
55.5
46.5
46.0
46.3
45.4
45.3
46.3
46.5
46.5
46.7
45.7
45.9
46.1
45.8
45.2
45.2
46.0
45.0
45.4
45.4
45.2
45.5
45.6
44.7
45.1
44.8
45.3
45.3
45.4
45.2
45.8
45.3
45.2
45.3
42.7
42.5
42.4
42.7
42.6
42.4
42.0
42.3
42.5
2.6
2.6
2.5
2.6
2.6
2.4
2.6
2.6
2.5
2.7
2.6
2.5
2.5
2.5
2.5
2.6
2.5
2.5
2.5
2.5
2.5
2.6
2.5
2.5
2.5
2.5
2.5
2.5
2.6
2.5
2.6
2.6
2.5
2.0
2.0
2.2
2.0
2.0
2.1
2.0
2.0
2.0
E11-02
Pt
Grain
Table B.3. Detailed electron microprobe analytical conditions for clinopyroxene.
Common information:
File Name : pyx.qtiSet
File Date: May/21/14-2:0 PM
Column conditions:
Cond 1 :
HV (kV) : 15
I (nA) : 20
Size (µm) : 1
Scanning : Off
RasterLength (µm) : .03
Xtal information:
Xtal parameters:
Na Ka
Mg Ka
Al Ka
Si Ka
Ca Ka
Ti Ka
Mn Ka
Fe Ka
Cr Ka
Sp2
Sp2
Sp2
Sp2
Sp1
Sp1
Sp3
Sp3
Sp3
TAP
TAP
TAP
TAP
PET
PET
LLIF
LLIF
LLIF
(2d= 25.745
(2d= 25.745
(2d= 25.745
(2d= 25.745
(2d= 8.75
(2d= 8.75
(2d= 4.0267
(2d= 4.0267
(2d= 4.0267
K= 0.00218)
K= 0.00218)
K= 0.00218)
K= 0.00218)
K= 0.000144)
K= 0.000144)
K= 0.000058)
K= 0.000058)
K= 0.000058)
Bias
(V)
1281
1278
1292
1292
1329
1350
1819
1819
1809
Dtime
(µs)
3
3
3
3
3
3
3
3
3
Pha parameters :
Elt. Line
Spec
Xtal
Na Ka
Mg Ka
Al Ka
Si Ka
Ca Ka
Ti Ka
Mn Ka
Fe Ka
Cr Ka
Sp2
Sp2
Sp2
Sp2
Sp1
Sp1
Sp3
Sp3
Sp3
TAP
TAP
TAP
TAP
PET
PET
LLIF
LLIF
LLIF
Acquisition information:
Elt. Line Spec Xtal
Peak
Na Ka
Mg Ka
Al Ka
Si Ka
Ca Ka
Ti Ka
Mn Ka
Fe Ka
Cr Ka
Sp2
Sp2
Sp2
Sp2
Sp1
Sp1
Sp3
Sp3
Sp3
TAP
TAP
TAP
TAP
PET
PET
LLIF
LLIF
LLIF
46360
38499
32462
27736
38388
31400
52218
48088
56888
Gain
2508
2543
2579
2625
939
1372
365
365
348
Blin
(mV)
Wind
(mV)
Mode
Inte
Inte
Inte
Inte
Inte
Inte
Inte
Inte
Inte
Pk Time Bg Off1 Bg Off2 Slope/IBg Bg TimeCalibration
Time/Repeat
Range
#Channels
20
-850
850
10
albite_NaSp2_078
20
-1800 1800
10
diop_MgSp2_059
10
-800
800
5
Al2O3_AlSp2_055
20
-1000 1000
10
ortho_SiSp2_250
20
750 1 10
diop_SiSp2_CaSp1_058
20
700 1.02
10
ilm_TiSp1_075
20
-1000 1000
10
MnO_MnSp1_MnSp3_061
20
10001.04
10
mag_FeSp3_187
40
-800
800
20
Cr2O3_CrSp1_CrSp3_054
Intensity
(cps/nA)
56.5
137.6
1001.5
584.4
132.4
201.8
359.9
350.2
281.7
Table B.4. Detailed electron microprobe analytical conditions for olivine.
Common information:
File Name : oliv-parmelee.qtiSet
File Date: May/21/14-2:2 PM
Column conditions:
Cond 1 :
HV (kV) : 15
I (nA) : 20
Size (µm) : 1
Scanning : Off
RasterLength (µm) : .03
Xtal information:
Xtal parameters:
Mn Ka
Ti Ka
Ca Ka
Si Ka
Mg Ka
Ni Ka
Fe Ka
Sp1
Sp1
Sp1
Sp2
Sp2
Sp3
Sp3
PET
PET
PET
TAP
TAP
LLIF
LLIF
(2d= 8.75
(2d= 8.75
(2d= 8.75
(2d= 25.745
(2d= 25.745
(2d= 4.0267
(2d= 4.0267
K= 0.000144)
K= 0.000144)
K= 0.000144)
K= 0.00218)
K= 0.00218)
K= 0.000058)
K= 0.000058)
Bias
(V)
1329
1350
1329
1292
1285
1819
1819
Dtime
(µs)
3
3
3
3
3
3
3
Pha parameters :
Elt. Line
Spec
Xtal
Mn Ka
Ti Ka
Ca Ka
Si Ka
Mg Ka
Ni Ka
Fe Ka
Sp1
Sp1
Sp1
Sp2
Sp2
Sp3
Sp3
PET
PET
PET
TAP
TAP
LLIF
LLIF
Acquisition information:
Elt. Line Spec Xtal
Peak
Mn Ka
Ti Ka
Ca Ka
Si Ka
Mg Ka
Ni Ka
Fe Ka
Sp1
Sp1
Sp1
Sp2
Sp2
Sp3
Sp3
PET
PET
PET
TAP
TAP
LLIF
LLIF
23993
31400
38388
27736
38499
41161
48088
Gain
939
1372
939
2625
2597
365
365
Blin
(mV)
Wind
(mV)
Mode
Inte
Inte
Inte
Inte
Inte
Inte
Inte
Pk Time Bg Off1 Bg Off2 Slope/IBg Bg TimeCalibration
Time/Repeat
Range
#Channels
20
-1000 1000
10
MnO_MnSp1_MnSp3_061
20
700 1.02
10
ilm_TiSp1_075
20
750 1 10
diop_SiSp2_CaSp1_058
20
-1000 1000
10
ortho_SiSp2_250
20
-1800 1800
10
Forst-Ol_MgSp2_059
60
-500
500
30
NiO_NiSp3_039
20
10001.04
10
mag_FeSp3_187
Intensity
(cps/nA)
337.6
201.8
132.4
584.4
464.4
328.9
350.2
Table B.5. Primary calibration standards used for electron microprobe analysis.
Element
Si
Ti
Al
Fe
Mn
Mg
Ca
Na
K
Material
Orthoclase
Ilmenite
Anorthoclase
Magnetite
MnO
Forsteritic olivine
Beeson apatite
Albite
Orthoclase
Table B.6. Standard reference materials analyzed by electron microprobe immediately before
and after sample analyses. All values are wt%. Uncertainties are 1σ standard deviation.
TiO2
Al2O3
FeO*
MnO
MgO
CaO
Na2O
Total
Diopside (n=12)
Measured
55.91 ± 0.19
Accepteda
55.46
SiO2
0.02 ± 0.02
0.03 ± 0.01
0.03
0.09 ± 0.03
0.06
0.01 ± 0.02
18.38 ± 0.11
18.56
25.77 ± 0.17
25.87
0.01 ± 0.01
0.02
100.22 ± 0.23
100.00
Olivine-USNM (n=12)
Measured
40.85 ± 0.41
Accepteda
40.81
0.00 ± 0.01
9.85 ± 0.17
9.55
0.10 ± 0.02
0.14
48.97 ± 0.12
49.42
0.10 ± 0.01
100.26 ± 0.23
99.92
Olivine-forsterite (n=12)
Measured
42.90 ± 0.43
Accepteda
42.70
0.01 ± 0.01
0.02 ± 0.02
0.00 ± 0.00
57.26 ± 0.22
55.30
0.01 ± 0.01
100.20 ± 0.60
100.00
8.54 ± 0.18
8.90
8.38
0.09 ± 0.02
0.10
0.09
14.23 ± 0.10
13.89
14.14
12.31 ± 0.15
12.54
12.42
Kaersutite (n=12)
Measured
39.45 ± 0.47
Accepteda
39.30
LTAb
39.14
4.14 ± 0.09
4.14
4.20
15.78 ± 0.08
15.37
15.68
2.28 ± 0.04
2.36
2.31
100.35 ± 0.49c
100.13
99.78
*Total Fe reported as FeO.
a
Accepted values from https://geoinfo.nmt.edu/labs/microprobe/standards/petrol.html.
b
LTA = long-term average of measurements made on the same standard in the New Mexico Tech electron
microprobe lab.
c
Total includes measured K2O, H2O, F, and Cl concentrations, which are not shown.
Table B.7. Major and trace element composition of the bulk rock in 36Cl samples. Major
elements were measured by XRF and trace elements were measured by ICP-MS and ICP-AES.
E11-01
E11-02
E11-04
E11-05
E11-07
E11-10
E11-11
E11-18
E11-23
E11-24
E11-25
Major-element oxide concentrations (in wt%)
SiO2
55.4
54.9
55.9
54.8
TiO2
1.03
1.08
0.98
0.99
Al2O3
19.7
19.5
18.9
19.8
Fe2O3* 5.56
5.80
6.14
5.38
MnO
0.20
0.22
0.24
0.20
MgO
1.00
1.03
0.90
0.92
CaO
2.79
2.80
2.51
2.81
Na2O
8.34
8.36
8.34
8.45
K2O
4.50
4.48
4.67
4.44
P2O5
0.45
0.47
0.43
0.43
LOI
1.09
1.25
0.74
1.26
Total
100.0
99.9
99.8
99.5
54.5
1.03
19.6
5.64
0.20
0.97
2.75
8.21
4.39
0.46
2.19
100.0
55.3
1.04
19.3
5.89
0.22
1.00
2.63
8.21
4.54
0.44
0.88
99.4
55.6
1.03
19.6
5.77
0.22
1.00
2.66
8.28
4.51
0.43
1.07
100.2
53.0
1.06
19.2
5.79
0.19
0.98
2.64
8.12
4.37
0.48
5.49
101.3
55.8
1.02
19.4
5.65
0.21
0.96
2.75
8.23
4.53
0.44
0.44
99.5
55.0
1.06
19.5
5.73
0.23
1.02
2.75
8.24
4.51
0.44
0.86
99.4
55.2
1.05
19.5
5.80
0.22
1.02
2.81
8.31
4.55
0.46
0.79
99.7
Trace element concentrations (in ppm)
Li
20
20
20
Be
8
8
8
B
<10
<10
<10
Sc
<5
<5
<5
V
13
14
11
Cr
30
30
30
Co
3.0
3.5
2.3
Ni
<5
<5
<5
Cu
40
28
23
Zn
121
126
141
Ga
31
32
32
Ge
2
2
2
As
27
28
14
Rb
106
104
106
Sr
883
846
713
Y
53.1
53.5
59.6
Zr
842
858
863
Nb
257
246
248
Mo
14
15
14
Ag
<1
<1
<1
Cd
<0.2
<0.2
<0.2
In
0.3
0.3
<0.2
Sn
10
7
7
Sb
0.4
0.3
0.2
Cs
1.5
1.5
1.3
Ba
994
995
1100
La
130
133
138
Ce
242
247
261
Pr
25.8
26.6
28.6
Nd
88.2
91.4
100
Sm
14.3
15.2
16.8
Eu
4.88
5.09
5.64
Gd
11.5
12.0
13.4
Tb
1.81
1.83
2.09
Dy
9.91
10.3
11.3
Ho
1.87
1.91
2.05
Er
5.57
5.75
6.08
Tm
0.87
0.91
0.98
Yb
5.0
5.2
5.4
Lu
0.80
0.81
0.91
Hf
21
21
21
Ta
15.4
15.0
15.0
W
4
4
4
Tl
<0.5
<0.5
<0.5
Pb
19
11
12
Bi
0.3
0.2
0.1
Th
20.9
21.2
20.7
U
6.24
6.28
6.04
20
8
<10
<5
12
30
3.0
<5
26
120
32
2
75
102
858
50.5
863
260
15
<1
1.5
0.5
11
0.4
1.3
1010
126
234
25.1
84.9
14.0
5.01
11.5
1.76
9.72
1.78
5.37
0.85
4.8
0.73
21
15.3
4
0.8
20
0.3
21.2
6.49
20
8
<10
<5
13
20
3.2
<5
37
199
32
2
20
105
800
57.0
881
254
14
<1
0.2
<0.2
6
0.6
1.3
1080
136
252
27.4
93.9
15.5
5.44
12.4
1.93
10.6
1.90
5.92
0.94
5.1
0.86
22
15.1
4
<0.5
8
<0.1
21.4
6.63
20
8
<10
<5
15
40
3.3
<5
22
119
32
2
26
106
808
55.1
899
262
15
<1
0.3
<0.2
6
0.3
1.4
1060
132
248
26.3
91.4
15.3
5.19
12.1
1.91
10.1
1.87
5.78
0.90
5.2
0.77
21
15.3
4
<0.5
10
<0.1
21.8
6.74
20
8
<10
<5
13
30
2.9
<5
26
122
32
2
113
104
825
51.3
900
271
16
<1
1.3
0.4
16
0.4
1.6
970
127
237
25.3
86.4
14.3
4.78
11.3
1.77
9.68
1.83
5.48
0.85
5.0
0.77
22
15.7
4
1.4
30
0.4
21.4
6.88
20
8
<10
<5
14
30
3.4
<5
19
122
31
2
9
104
845
54.7
862
252
15
<1
0.2
<0.2
6
0.7
1.3
1080
137
255
27.4
94.2
15.4
5.49
12.4
1.93
10.7
1.97
5.81
0.94
5.4
0.84
21
15.7
4
<0.5
11
0.1
22.2
6.49
20
9
<10
<5
13
30
3.2
<5
21
135
31
2
13
107
811
53.5
887
260
14
<1
0.2
<0.2
6
0.3
1.3
967
130
245
26.0
89.3
14.5
4.78
11.9
1.78
10.1
1.88
5.60
0.91
5.2
0.85
22
15.6
4
<0.5
10
0.1
22.4
6.70
20
9
<10
<5
15
30
3.6
<5
19
127
32
2
15
106
827
55.3
875
256
14
<1
<0.2
0.2
7
0.3
1.5
1030
137
256
27.5
94.8
15.8
5.22
12.3
1.85
10.4
1.96
5.81
0.90
5.2
0.76
21
15.4
4
<0.5
14
0.1
21.9
6.43
20
8
<10
<5
12
20
3.0
<5
9
117
31
2
17
106
899
51.2
837
245
13
<1
0.3
<0.2
6
0.3
1.6
974
130
238
25.4
86.7
14.4
5.01
11.3
1.77
9.57
1.83
5.55
0.88
4.8
0.80
21
14.7
4
<0.5
11
0.2
21.2
6.12
*Total Fe reported as Fe2O3. LOI = Loss on ignition.
Table B.8. Major element composition of anorthoclase separated from the 36Cl samples.
Measured by XRF. Major-element oxides are in wt%, Rb, Sr, and Zr are in ppm, and feldspar
end-members anorthite (An; CaAl2Si2O8), albite (Ab; NaAlSi3O8), and orthoclase (Or;
KAlSi3O8) are in %.
SiO2
TiO2
Al2O3
Fe2O3*
MnO
MgO
CaO
Na2O
K2O
P2O5
Total
Rb
Sr
Zr
An
Ab
Or
E11-01
E11-02
E11-04
E11-05
E11-07
E11-10
E11-11
E11-18
E11-23
E11-24
E11-25
62.63
0.13
22.35
0.42
<0.03
<0.25
3.22
7.63
3.02
0.01
99.41
27
2381
68
15.6
67.0
17.4
62.47
0.12
21.89
0.32
<0.03
<0.25
2.92
7.56
3.21
0.01
98.50
28
2217
59
14.3
67.0
18.7
63.34
0.12
21.68
0.34
<0.03
<0.25
2.48
7.60
3.61
0.01
99.18
33
1957
49
12.1
67.0
20.9
62.27
0.13
22.36
0.37
<0.03
<0.25
3.25
7.57
3.01
0.01
98.97
27
2407
71
15.8
66.7
17.5
62.56
0.13
22.19
0.39
<0.03
<0.25
3.17
7.55
3.03
0.01
99.03
24
2370
74
15.5
66.8
17.6
63.32
0.13
22.14
0.35
<0.03
<0.25
2.79
7.70
3.39
0.01
99.83
29
2136
60
13.4
67.1
19.4
62.72
0.12
21.91
0.35
<0.03
<0.25
2.85
7.66
3.23
0.01
98.85
28
2187
61
13.9
67.4
18.7
62.26
0.13
22.01
0.36
<0.03
<0.25
3.13
7.54
3.04
0.01
98.48
26
2341
74
15.3
66.9
17.7
62.94
0.12
21.93
0.36
<0.03
<0.25
2.87
7.61
3.23
0.01
99.07
31
2175
61
14.0
67.2
18.8
62.66
0.13
22.28
0.38
<0.03
<0.25
3.28
7.59
2.94
0.01
99.27
30
2395
70
16.0
67.0
17.1
63.02
0.12
22.11
0.35
<0.03
<0.25
2.95
7.63
3.24
0.01
99.43
30
2203
60
14.3
67.0
18.7
*Total Fe reported as Fe2O3.
Table B.9. XRF standards run with anorthoclase analyses. Major-element oxides are in wt% and
Rb, Sr, and Zr are in ppm.
Measured (n=3)
SiO2
TiO2
Al2O3
Fe2O3*
MnO
MgO
CaO
Na2O
K2O
P2O5
Total
Rb
Sr
Zr
73.76
0.26
13.68
1.86
0.04
0.26
0.98
4.39
4.32
0.05
99.85
150
108
242
73.74
0.27
13.73
1.87
0.04
0.26
0.98
4.40
4.32
0.05
99.86
150
108
244
RGM-1
Avg
74.16
0.27
13.62
1.88
0.04
0.27
0.99
4.05
4.33
0.05
99.66
163
105
240
73.89
0.27
13.68
1.87
0.04
0.26
0.98
4.28
4.32
0.05
99.85
154
107
242
BHVO-1
SD
Accepted
0.24
0.01
0.06
0.01
0.00
0.01
0.01
0.20
0.01
0.00
--7.5
1.7
2.0
73.45
0.27
13.72
1.86
0.036
0.27
1.15
4.07
4.30
0.048
99.17
155
102
241
Measured (n=4)
49.40
2.74
13.48
12.38
0.17
7.20
11.47
2.25
0.53
0.28
99.90
12
392
185
49.39
2.73
13.48
12.38
0.17
7.21
11.48
2.24
0.53
0.27
99.88
12
393
187
49.33
2.73
13.52
12.38
0.17
7.20
11.46
2.25
0.53
0.28
99.87
12
391
186
50.26
2.73
13.64
12.29
0.17
7.29
11.36
2.25
0.52
0.28
100.79
11
376
174
Avg
SD
Accepted
49.60
2.73
13.53
12.36
0.17
7.23
11.44
2.25
0.53
0.28
100.11
12
388
183
0.44
0.01
0.08
0.05
0.00
0.04
0.06
0.00
0.01
0.01
--0.5
8.0
6.1
49.94
2.71
13.80
12.23
0.168
7.23
11.4
2.26
0.52
0.273
100.53
9.5
390
180
Accepted values for each standard are from Tyrone Rooney (personal communication) at Michigan State University.
SD = Standard deviation
*Total Fe reported as Fe2O3.
1.3
West
Post-caldera flows
Young Pre-caldera
Old Pre-caldera
Na2O (wt%)
1.2
1.1
1
0.9
0.8
0.7
0.6
8
8.5
9
9.5
10
10.5
11
11.5
FeO (wt%)
Figure B.1. Na2O vs. FeO in clinopyroxenes determined by electron microprobe analysis. Each
data point represents a different analytical point on a grain. The newly-identified West flow,
represented solely by sample E11-12, has FeO content higher than the post-caldera flows and
close to that of the Young Pre-caldera flow represented by sample E11-04, supporting the 3He
evidence that it is substantially older than the post-caldera flows.
SUPPLEMENT C. 3He and 36Cl results (expanded version)
C.1. 3He determination
Table C.1 shows the results of the mass spectrometric measurements of helium released
during crushing and melting of the grains. Calculated cosmogenic 3He concentrations are shown
using both the 3He/4He ratio measured during the crushing of each sample (3Hec,meas) as well as
the mean 3He/4He value measured from crushing the DVDP olivines (3Hec,DVDP) as the magmatic
3
He/4He ratio. Table C.2 shows the 3He/4He ratios measured during crushing of the DVDP
olivines. 3He/4He measurements made during melting of three of the crushed samples are also
included. The 3He/4He ratios measured during melting are lower most likely due to the release of
radiogenic 4He that has accumulated in the crystal matrix since eruption.
C.2. 36Cl determination
Table C.3 includes anorthoclase sample mass, spike mass, volume of acid used for
dissolution, measured 35Cl/37Cl and 36Cl/Cl ratios, and calculated Cl and 36Cl concentrations with
and without blank corrections. No AMS data was returned for E11-11 due to high sulfur content.
Table C.4 includes the spike mass, volume of acid used, measured 35Cl/37Cl and 36Cl/Cl ratios,
and calculated Cl and 36Cl concentrations for each blank. Blank concentrations outside of 3σ of
the mean (BS-01 for Cl and BS-02 for 36Cl) were excluded from the blank averages used for
blank-correcting sample concentrations.
C.2.1. Calculation of Cl and 36Cl concentrations
The equations used to calculate Cl and 36Cl concentrations from the AMS results are
show below.
C.2.1.1. Uncorrected concentrations
First the number of chlorine atoms from the spike ([𝐶𝑙𝑠𝑝 ]) was calculated:
35
𝐶𝑙
𝑚𝑠𝑝 𝐶𝑠𝑝 𝑁𝐴 𝑚𝑠𝑝 𝐶𝑠𝑝 𝑁𝐴 1 − ( 𝐶𝑙 )𝑠𝑝
[𝐶𝑙𝑠𝑝 ] = [ 35𝐶𝑙𝑠𝑝 ] + [ 37𝐶𝑙𝑠𝑝 ] =
+
( 35
)
𝐶𝑙
1000𝑊35
1000𝑊35
( 𝐶𝑙 )
𝑠𝑝
where [ 35𝐶𝑙𝑠𝑝 ] and [ 37𝐶𝑙𝑠𝑝 ] are the number of 35Cl and 37Cl atoms from the spike, 𝑚𝑠𝑝 is grams
of spike solution added to the sample, 𝐶𝑠𝑝 is the concentration of 35Cl in the spike in mg 35Cl/g
solution, (
35𝐶𝑙
𝐶𝑙
)
𝑠𝑝
is the 35Cl/Cl ratio in the spike, 𝑁𝐴 is Avogadro’s number (6.02214 x 1023 mol-
), and 𝑊35 is the atomic weight of 35Cl (34.96885268 g/mol).
The number of chlorine atoms in the anorthoclase ([𝐶𝑙𝑎𝑛 ]) was then calculated using the
following equation from Desilets et al. (2006a):
1
35
𝐶𝑙
( 37 )
[ 37𝐶𝑙𝑠𝑝 ] − [ 35𝐶𝑙𝑠𝑝 ]
𝐶𝑙 𝑚𝑒𝑎𝑠
[𝐶𝑙𝑎𝑛 ] =
35
35
𝐶𝑙
where ( 37𝐶𝑙)
𝑚𝑒𝑎𝑠
𝐶𝑙
(1 + ( 37 ) )
𝐶𝑙 𝑟𝑐𝑘
35
𝐶𝑙
𝐶𝑙
( 37 ) − ( 37 )
𝐶𝑙 𝑟𝑐𝑘
𝐶𝑙 𝑚𝑒𝑎𝑠
(
35
)
35
𝐶𝑙
is the 35Cl/37Cl ratio measured in the AgCl target and (37𝐶𝑙)
is the natural
𝑟𝑐𝑘
terrestrial 35Cl/37Cl ratio (3.127). [𝐶𝑙𝑎𝑛 ] was converted to concentration in ppm (𝐶𝑙𝑎𝑛 ) by:
𝐶𝑙𝑎𝑛 =
[𝐶𝑙𝑎𝑛 ]𝑊𝐶𝑙 6
10
𝑁𝐴 𝑚𝑠𝑎𝑚𝑝
where 𝑊𝐶𝑙 is the atomic weight of chlorine (35.453 g/mol) and 𝑚𝑠𝑎𝑚𝑝 is the mass of
anorthoclase separate that was dissolved.
Finally, the number of atoms of 36Cl per gram of anorthoclase separate ( 36𝐶𝑙𝑎𝑛 ) was
calculated by:
(
36
𝐶𝑙𝑎𝑛 =
where (
36
𝐶𝑙
𝐶𝑙
)
𝑚𝑒𝑎𝑠
36
𝐶𝑙
)
𝐶𝑙
([𝐶𝑙𝑎𝑛 ] + [𝐶𝑙𝑠𝑝 ])
𝑚𝑒𝑎𝑠
𝑚𝑠𝑎𝑚𝑝
is the 36Cl/Cl ratio measured in the AgCl target.
C.2.1.2. Blank-corrected concentrations
The concentration of chlorine and number of 36Cl atoms in the blanks (Table C.4) were
calculated using essentially the same equations as above. The number of atoms of non-spike
chlorine in a blank ([𝐶𝑙𝑏𝑙 ]) was determined using the equation for [𝐶𝑙𝑎𝑛 ]. We assume chlorine
contamination in the samples and blanks comes primarily from the HF used to dissolve
anorthoclase during Cl extraction, and so convert the chlorine concentration in the blanks (𝐶𝑙𝑏𝑙 )
to units of atoms of chlorine per mL HF:
𝐶𝑙𝑏𝑙 =
[𝐶𝑙𝑏𝑙 ]
𝑉𝐻𝐹
where 𝑉𝐻𝐹 is the volume of HF in milliliters used to prepare the blank.
Any 36Cl in the samples and blanks is assumed to be introduced unintentionally by
particulates during lab processing and is not a function of the amount of acid, spike, or sample
used. The 36Cl content of the blanks was therefore calculated as the total number of 36Cl atoms
([ 36𝐶𝑙𝑏𝑙 ]), and not as a concentration:
[ 36𝐶𝑙𝑏𝑙 ] = (
36
𝐶𝑙
)
([𝐶𝑙𝑏𝑙 ] + [𝐶𝑙𝑠𝑝 ])
𝐶𝑙 𝑚𝑒𝑎𝑠
𝐶𝑙𝑏𝑙 and [ 36𝐶𝑙𝑏𝑙 ] were calculated for each blank, then averaged (Table C.4). [ 36𝐶𝑙𝑏𝑙 ] for
BS-2 was well outside the analytical uncertainties of BS-1 and BS-3, as well as previous blanks
run in the same lab by the same procedure, and was excluded from the calculated average
[ 36𝐶𝑙𝑏𝑙 ]𝑎𝑣𝑔 . The most likely explanation for the anomalously high [ 36𝐶𝑙𝑏𝑙 ] value is that BS-2
was contaminated by a grain of dust or other particulate during lab processing.
Blank-corrected concentrations of chlorine (𝐶𝑙𝑎𝑛,𝑐𝑜𝑟𝑟 ) and 36Cl ( 36𝐶𝑙𝑎𝑛,𝑐𝑜𝑟𝑟 ) were
calculated for each sample as follows:
𝐶𝑙𝑎𝑛,𝑐𝑜𝑟𝑟 =
(
36
𝐶𝑙𝑎𝑛,𝑐𝑜𝑟𝑟 =
([𝐶𝑙𝑎𝑛 ] − 𝐶𝑙𝑏𝑙,𝑎𝑣𝑔 𝑉𝐻𝐹 )𝑊𝐶𝑙 6
10
𝑁𝐴 𝑚𝑠𝑎𝑚𝑝
36
𝐶𝑙
)
𝐶𝑙
𝑚𝑒𝑎𝑠
([𝐶𝑙𝑎𝑛 ] + [𝐶𝑙𝑠𝑝 ]) − [ 36𝐶𝑙𝑏𝑙 ]𝑎𝑣𝑔
𝑚𝑠𝑎𝑚𝑝
Note that 𝑉𝐻𝐹 in this case refers to the volume of HF used to dissolve the sample.
Table C.1. Complete helium data for clinopyroxene and olivine samples.
Crush
Sample
Grain
size
mm
Mass
g
He
10-10 cc/g
1σ
E11-01
E11-02
E11-02(ol)
E11-03
E11-04
E11-05
E11-05(ol)
E11-06
E11-07
E11-08
E11-09
E11-10
E11-11
E11-12
E11-13
E11-14
E11-15
E11-16
E11-17
E11-18
E11-19
E11-20
E11-21
E11-22
E11-23
E11-24
E11-25
E11-26
E11-27
E11-28
E11-29
E11-30
E11-31
E11-31(ol)
0.5-1
0.5-1
0.5-1
1-2
0.5-1
0.5-1
0.5-1
1-2
0.5-1
1-2
1-2
0.5-1
0.5-1
1-2
1-2
1-2
0.5-1
1-2
1-2
0.5-1
1-2
1-2
1-2
1-2
0.5-1
0.5-1
0.5-1
1-2
1-2
1-2
1-2
1-2
0.5-1
0.5-1
0.31612
0.30873
0.11791
0.28586
0.24059
0.30123
0.12110
0.29985
0.31422
0.26873
0.27791
0.31427
0.31090
0.25662
0.22167
0.31353
0.27611
0.29108
0.27318
0.30359
0.28262
0.28333
0.28760
0.29676
0.31262
0.30203
0.32800
0.27976
0.24568
0.26965
0.23493
0.28591
0.28532
0.11469
1.18
4.71
13.05
11.43
9.68
5.75
11.24
4.81
0.68
16.63
9.06
12.75
1.33
5.20
13.63
14.55
2.47
1.16
10.16
1.51
7.10
11.03
10.39
8.27
4.48
4.06
5.89
5.84
5.52
29.38
2.99
13.61
5.71
6.48
0.02
0.07
0.20
0.17
0.15
0.09
0.17
0.07
0.01
0.25
0.14
0.19
0.02
0.08
0.20
0.22
0.04
0.02
0.15
0.02
0.11
0.17
0.16
0.12
0.07
0.06
0.09
0.09
0.08
0.44
0.04
0.20
0.09
0.10
4
Melt
3
He/4He
x RA
7.71
6.23
6.52
6.06
8.18
2.80
6.24
4.77
4.33
5.10
6.17
6.78
7.60
10.82
4.53
2.42
6.74
9.18
4.15
8.24
5.18
5.53
6.27
5.03
7.84
4.81
7.26
5.83
4.78
7.41
9.45
6.79
22.31
17.26
4
1σ
Mass
g
He
10-10 cc/g
1σ
0.77
0.32
0.36
0.25
0.32
0.21
0.42
0.35
0.97
0.20
0.27
0.23
0.74
0.43
0.20
0.16
0.57
0.80
0.22
0.65
0.28
0.20
0.24
0.28
0.36
0.36
0.34
0.33
0.39
0.18
0.57
0.23
0.69
0.82
0.30747
0.29709
0.10971
0.27799
0.23297
0.29350
0.11418
0.29250
0.30029
0.26093
0.26887
0.30601
0.30143
0.24707
0.21388
0.30658
0.26823
0.28041
0.26566
0.29422
0.27385
0.27407
0.27895
0.28676
0.30535
0.29108
0.32345
0.27388
0.23616
0.26070
0.22567
0.27800
0.27606
0.10807
10.13
20.19
15.47
10.78
51.71
10.24
38.16
11.93
10.31
19.32
19.66
54.52
15.47
49.89
13.80
12.09
14.01
9.27
13.07
11.27
12.22
15.51
19.40
17.44
20.28
14.13
21.92
16.83
21.56
51.94
15.34
27.63
139.86
105.70
0.15
0.30
0.23
0.16
0.78
0.15
0.57
0.18
0.15
0.29
0.29
0.82
0.23
0.75
0.21
0.18
0.21
0.14
0.20
0.17
0.18
0.23
0.29
0.26
0.30
0.21
0.33
0.25
0.32
0.78
0.23
0.41
2.10
1.59
3
3
He/4He
x RA
354.38
247.39
267.94
24.73
275.19
290.57
72.78
338.99
421.53
158.39
174.77
129.01
340.99
344.29
244.36
306.16
257.66
351.89
304.97
388.83
292.90
221.31
298.97
303.30
270.83
216.15
227.96
303.55
246.05
142.12
344.80
186.37
375.30
472.19
1σ
1σ
Hec,meas
107
atoms/g
5.72
4.02
4.56
0.61
4.54
4.82
1.42
5.42
6.81
2.66
2.89
2.12
5.60
5.59
4.02
5.06
4.20
5.80
4.97
6.31
4.94
3.67
4.84
4.87
4.42
3.50
3.77
4.81
4.02
2.30
5.78
3.02
6.17
7.80
1.31
1.81
1.50
0.075
5.14
1.10
0.94
1.48
1.60
1.10
1.23
2.48
1.92
6.19
1.23
1.37
1.31
1.18
1.46
1.60
1.31
1.24
2.11
1.94
1.98
1.11
1.80
1.86
1.94
2.60
1.91
1.85
18.37
17.89
0.03
0.04
0.04
0.003
0.12
0.02
0.03
0.03
0.04
0.03
0.03
0.06
0.04
0.14
0.03
0.03
0.03
0.03
0.03
0.04
0.03
0.03
0.05
0.04
0.05
0.03
0.04
0.04
0.04
0.06
0.04
0.04
0.44
0.42
3
Hec,DVDP
107
atoms/g
1σ
1.31
1.81
1.50
0.071
5.16
1.08
0.94
1.47
1.59
1.09
1.23
2.48
1.92
6.26
1.22
1.35
1.31
1.19
1.45
1.60
1.30
1.24
2.11
1.92
1.99
1.10
1.80
1.86
1.92
2.61
1.93
1.84
19.17
18.30
0.03
0.04
0.03
0.003
0.12
0.02
0.03
0.03
0.04
0.03
0.03
0.06
0.04
0.14
0.03
0.03
0.03
0.03
0.03
0.04
0.03
0.03
0.05
0.04
0.05
0.03
0.04
0.04
0.04
0.06
0.04
0.04
0.43
0.41
All samples are clinopyroxene except Ell-02(ol), E11-05(ol), and E11-31(ol), which are olivine. All helium measurements have been corrected for analytical blanks and standards
run between samples. 4He concentrations are calculated for standard temperature and pressure. 3Hec,meas is the cosmogenic 3He concentration calculated using the 3He/4He ratio
measured during crushing of the exposure age sample for magmatic 3He/4He. 3Hec,DVDP is the cosmogenic 3He concentration calculated using the average 3He/4He ratio measured
in the DVDP olivines for magmatic 3He/4He.
Table C.2. Helium data for DVDP olivines.
Sample
Mass
g
4
Hecr
10 cc/g
-10
(3He/4He)cr
x RA
1σ
4
Hem
10 cc/g
-10
(3He/4He)m
x RA
1σ
DVDP3-268
0.16048
653.41
6.87
0.12
------DVDP3-283A
0.23980
579.75
6.86
0.12
------DVDP3-283B
0.22817 1099.44
6.79
0.11
------DVDP3-289
0.28327
703.52
6.90
0.12
671.99
6.06
0.10
DVDP3-295A
0.20446
724.59
7.06
0.12
------DVDP3-295B
0.28175
503.42
6.96
0.12
------DVDP3-349
0.27844
251.90
7.05
0.13
350.94
6.05
0.11
DVDP3-359
0.22869
332.53
6.90
0.12
------DVDP3-363
0.23665
310.11
6.88
0.12
------DVDP3-370
0.14045
379.40
6.89
0.13
------DVDP3-376
0.20532
217.83
6.92
0.13
393.58
5.77
0.10
Error-weighted mean:
6.91
0.08
cr=crushed, m=melted. 1σ for the error-weighted mean is reported as the standard deviation of the values used to calculate the
mean (n=11).
Table C.3. Complete chlorine data for anorthoclase samples.
Sample
Mass
Spk
mass
HF
HNO3
35
Cl/37Cl
1σ
36
Cl/1015 Cl
1σ
36
1σ
Clan
Clan
1σ
Clan,corr
5
g
g
mL
mL
36
Clan,corr
1σ
5
10
atoms/g
ppm
1σ
ppm
10
atoms/g
E11-01 50.7594 3.0114 201.5
26
14.446
0.022
466.800
10.9988 20.85 0.23
6.44
0.17
9.93
0.75
6.38
0.17
E11-02 53.5758 3.0072
185
27
17.752
0.124
672.218
14.4196 15.08 0.21
8.24
0.20
5.58
0.68
8.18
0.20
E11-04 59.0636 3.0817
220
32
17.574
0.010
2102.62
44.8349 14.20 0.16
24.03
0.57
3.96
0.65
23.98
0.57
E11-05 60.6387 2.0222 206.5
31
10.153
0.011
560.417
14.7291 19.17 0.21
5.05
0.14
9.80
0.63
5.00
0.14
E11-07 52.3684 3.0222 214.5
26
13.500
0.019
536.255
14.5918 22.20 0.25
7.37
0.21
10.93
0.75
7.31
0.21
E11-10 52.6520 3.0265 200.5
31
13.916
0.015
837.266
26.0859 21.23 0.24
11.34
0.37
10.75
0.72
11.28
0.37
E11-11 53.2062 3.0275
210
27
------------------------E11-18 59.1791 3.0757
200
32
9.055
0.019
532.959
14.4567 35.55 0.39
8.00
0.23
26.25
0.72
7.95
0.23
E11-23 49.3166 3.0211 181.5
27
12.652
0.021
637.085
16.8609 25.75 0.29
9.53
0.27
15.62
0.76
9.47
0.27
E11-24 52.3936 3.0026
214
28
11.292
0.021
360.247
10.5518 28.23 0.31
5.29
0.16
17.00
0.77
5.23
0.16
E11-25 50.6565 3.0158
175
26
19.789
0.044
662.877
25.9790 13.94 0.16
8.39
0.34
4.43
0.69
8.33
0.34
36
35
1σ of the calculated Cl concentrations is based on the uncertainty of the AMS analyses reported by PRIME Lab and ± 0.01 mg Cl/g solution uncertainty of the concentration of
35
Cl in the spike. No AMS results were returned for E11-11 because sulfur content was too high. an=anorthoclase, corr=blank-corrected using the data in Table C.4. Clan and 36Clan
are not blank-corrected, Clan,corr and 36Clan,corr are blank-corrected.
Table C.4. 36Cl and total chlorine concentrations of blanks.
Sample
Spk mass
g
HF
mL
HNO3
mL
35
Cl/37Cl
1σ
36
Cl/1015 Cl
1σ
Clbl
1016 atoms
Cl/mL HF
1σ
36
Clbl
1σ
5
10 atoms
BS-1
2.1153
150
25
16.456
0.07
7.4208
2.03188
7.10
0.48
3.50
0.96
BS-2
2.0574
150
25
29.468
0.242
144.165
11.6178
3.33
0.23
58.45
4.75
BS-3
2.1167
150
26
28.325
0.121
6.62402
2.07337
3.60
0.24
2.78
0.87
Average
4.67
0.20
3.14
0.65
Numbers in italics were used to calculate averages. 1σ of the calculated Clbl and 36Clbl concentrations was determined based on the uncertainty of the AMS analyses reported by
PRIME Lab and ± 0.01 mg 35Cl/g solution uncertainty of the concentration of 35Cl in the spike. bl=blank.
SUPPLEMENT D. Exposure age calculation
D.1. Scaling factors
Production rate scaling factors calculated for each sample location using the models of
Lal (1991)/Stone (2000) (St) and Lifton et al. (2014) (LSD) are shown in Table D.1.
D.2. 3He exposure ages (no erosion)
Helium-3 LSD and St exposure ages calculated using both 3Hec,meas and 3Hec,DVDP (see
Supplement C) are shown in Table D.2. Production rates for each sample are also shown. All
cosmogenic production of 3He is assumed to be by spallation, and the same production rate was
used for clinopyroxene and olivine. Only ages calculated using 3Hec,DVDP concentrations are used
in the results and discussion sections of this paper.
D.2.1. Radiogenic correction
In Table D.3, a radiogenic correction is applied to the 3HeDVDP LSD ages. The correction
is based on a gross approximation of the radiogenic 4He content (4Herad) that has accumulated in
clinopyroxene and olivine phenocrysts since eruption and is only intended to give a general idea
the effect of 4Herad on the calculated exposure ages of the samples. Corrected 3He ages are 0.40.9% older than uncorrected ages in clinopyroxene and 0.1-0.2% older than uncorrected ages in
olivine. The difference between corrected and uncorrected ages in clinopyroxene may be
overestimated because the content of apatite inclusions—the main source of 4Herad in
clinopyroxene samples—is likely overestimated below for many samples. For this reason, the
corrected ages are not used in the results or discussion section of this paper.
Radiogenic 4He in most minerals comes primarily from the alpha decay of uranium and
thorium. In Erebus phonolites, the main U- and Th-bearing phases are the matrix glass and
fluorapatite micophenocrysts (Kelly et al., 2008b); a small amount of U and Th also resides in
the clinopyroxene or olivine crystal lattice (Blard and Farley, 2008). To estimate U and Th
concentrations of the clinopyroxene and olivine crystal lattices, we multiply the average whole
rock U (6.46 ppm) and Th (21.5 ppm) concentrations from the whole rock XRF analyses of the
36
Cl samples by diffusion coefficients from Table 1 in Blard and Farley (2008) (0.03 for U and
0.04 for Th in clinopyroxene, and 0.01 for both U and Th in olivine; the latter value is
approximated based on other values in the table). For U and Th concentrations of matrix and
melt inclusion glass, we use the average concentrations measured by Kelly et al. (2008b) in
Erebus lava bombs (9.08 ppm for U and 30.4 ppm for Th), which are lithologically and
geochemically nearly identical to the lava flows. For U and Th concentrations of apatite
inclusions, we extrapolate based on P2O5 concentrations, as neither U nor Th has ever been
measured in Erebus apatite. Kelly et al. (2008b) measured an average P2O5 concentration in
Erebus lava bomb glass of 0.28 wt% and in fluorapatite grains of 41.07 wt%. The average P2O5
concentration measured on whole rock samples in this study is 0.45 wt%. Assuming P2O5 is
concentrated entirely in apatite grains or matrix glass and the lava flows consist of 65% glass and
35% minerals,1 a mass balance calculation indicates that the whole rock is 0.65% apatite. Using
the average U and Th concentrations of the whole rock measured in this study (6.46 ppm and
21.5 ppm, respectively) and assuming that all U and Th in the whole rock is concentrated in
apatite grains or the matrix glass, we estimate the concentrations of U and Th in apatite to be 86
ppm and 267 ppm, respectively.
To approximate the contribution of 4Herad from the decay of U and Th in clinopyroxene
and olivine phenocrysts to the total 4He concentration measured after melting the grains, we start
by assuming a simple cylindrical geometry for all grains (pyroxene = 2 mm in length and 0.75
mm in diameter; olivine = 0.75 mm in length and diameter). Based on backscattered electron
imaging using the electron microprobe (see section B.2), we assume clinopyroxene grains
contain 2 vol% glass inclusions and 2 vol% apatite inclusions and olivine grains contain 2 vol%
glass inclusions and no apatite inclusions (note that actual apatite content observed in
clinopyroxene grains ranged from ~0 to 2 vol%). Specific gravities of 3.4 for pyroxene, 3.7 for
olivine, 3.2 for apatite, and 2.4 for glass are used to calculate the mass of apatite and glass
inclusions in one gram of clinopyroxene or olivine grains. The concentrations given above for U
and Th in glass, apatite, and the grain matrix are combined with the 3HeDVDP LSD from Table
D.2 and known decay constants and nuclide abundances (shown in the notes below Table D.3) to
calculate the number of 4He atoms that have been produced by the decay of 238U, 235U, and 232Th
within clinopyroxene and olivine phenocrysts over the duration of each sample’s exposure.
Additional radiogenic 4He will have been implanted in the surfaces of clinopyroxene and
olivine grains by the decay of U and Th in the surrounding matrix glass. To estimate this
component, all clinopyroxene and olivine grains are assumed to be surrounded by matrix glass,2
the stopping distance of α particles ejected from U and Th nuclei is assumed to be 20 μm (Farley
et al., 1996), and 40% of the α particles ejected within this distance of the grain surface are
assumed to be implanted in the grain (see similar calculation in Ackert et al., 2003).
The number of atoms of 4He implanted in one gram of clinopyroxene or olivine grains
from U and Th decay in the surrounding glass matrix is added to the number of 4He atoms
produced by the decay of U and Th in glass and apatite inclusions and the grain matrix to yield
4
Herad,total—the estimated total number of radiogenic 4He atoms in one gram of clinopyroxene or
olivine separates. The concentration of magmatic 3He is then recalculated as follows:
3
𝐻𝑒
𝐻𝑒𝑚𝑎𝑔𝑚𝑎𝑡𝑖𝑐 = ( 4 )
× ( 4𝐻𝑒𝑚𝑒𝑙𝑡 − 4𝐻𝑒𝑟𝑎𝑑 )
𝐻𝑒 𝑚𝑎𝑔𝑚𝑎𝑡𝑖𝑐
3
1
Estimated using Rb concentrations from the whole rock, glass, and anorthoclase, as well as visual estimates of the
non-anorthoclase mineral content. The modal abundances of minerals and glass in lava bombs determined by Kelly
et al. (2008b) using major-element least squares mass balance are similar.
2
Since many of the clinopyroxene grains are hosted in anorthoclase phenocrysts, the assumption that each grain is
surrounded by glass likely results in overestimation of the 4Herad content implanted in the minerals.
3
𝐻𝑒
The DVDP 3He/4He ratio from crushing is used for ( 4𝐻𝑒)
(see section C.1). We use the
𝑚𝑎𝑔𝑚𝑎𝑡𝑖𝑐
revised value for 3𝐻𝑒𝑚𝑎𝑔𝑚𝑎𝑡𝑖𝑐 to recalculate the concentration of cosmogenic 3He ( 3𝐻𝑒𝑐,𝑐𝑜𝑟𝑟 ),
which is used to calculate revised 3He LSD ages in Table D.3 (shown as Age (corr)).
D.3. 36Cl exposure ages (no erosion)
Chlorine-36 LSD and St exposure ages assuming no erosion are calculated using both
uncorrected and blank-corrected concentrations for 36Cl and total Cl. All samples are assumed to
have zero pore water. For analytical water content of the bulk rock, we use the measured LOI.
Ages and production rates are shown in Table D.4. Because no AMS results were returned for
E11-11, no exposure age is calculated for that sample. Only ages calculated using blankcorrected 36Cl concentrations are used in the results and discussion sections of this paper.
D.4. Effects of erosion and snow burial on 3He and 36Cl ages
Erosion or past snow coverage of the sample surface will cause underestimation of the
exposure age if left unaccounted for in the age calculation. Here we recalculate exposure ages for
various erosion rates and snow burial depths.
D.4.1. Erosion
Table D.5 shows 3He and 36Cl LSD ages calculated for five different erosion rates (1, 3,
5, 7, and 9 mm/ka). The ages are calculated using 3Hec,DVDP and 36Clrck,corr. For the 3He ages, only
clinopyroxene samples are shown.
D.4.2. Snow burial
Table D.6 shows 3He and 36Cl LSD exposure ages recalculated assuming the samples
were previously buried under various snow depths for 50% of their exposure histories (the
erosion rate is assumed to be zero). To account for variable snow depth during a sample’s
exposure history, equations for snow burial correction factors from Gosse and Phillips (2001)
and Zweck et al. (2013) were modified as follows:
𝑆𝑠𝑛𝑜𝑤,𝑠𝑝 = 𝑓 (𝑒
𝑧
− 𝑠𝑛𝑜𝑤,𝑖
𝛬𝑓
𝑆𝑠𝑛𝑜𝑤,𝑒𝑡ℎ = 𝑓 [(𝑎1 𝑧𝑠𝑛𝑜𝑤 + 1)𝑎2 − (
) + (1 − 𝑓)
𝑧𝑠 (𝑧𝑠𝑛𝑜𝑤 )𝑎3
)] + (1 − 𝑓)
𝑎4
−𝑧
𝑆𝑠𝑛𝑜𝑤,𝑡ℎ = 𝑓[(𝑏1 𝑒 𝑏2 𝑧𝑠𝑛𝑜𝑤 + 𝑏3 𝑒 𝑏4 𝑧𝑠𝑛𝑜𝑤 )𝑏5 𝑠 ] + (1 − 𝑓)
𝑆𝑠𝑛𝑜𝑤,𝑠𝑝 , 𝑆𝑠𝑛𝑜𝑤,𝑒𝑡ℎ , and 𝑆𝑠𝑛𝑜𝑤,𝑡ℎ are, respectively, the ratios of the production rate in a snow
cover to that in an uncovered sample for production by spallation, epithermal neutron capture,
and thermal neutron capture. 𝑓 is the fraction of the sample’s exposure history during which it
was covered by snow, 𝑧𝑠𝑛𝑜𝑤 is the mass thickness of the snow covering the sample (equal to the
product of snow depth and snow density), 𝑧𝑠 is the sample thickness, and 𝑎 and 𝑏 are coefficients
given in Zweck et al. (2013) for basalt. We assume a density 0.5 g/cm3 for snow on Erebus.
In the Erebus samples, production of cosmogenic 3He is assumed to be entirely
spallogenic and production of 36Cl is dominated by spallation. The effect of snow coverage on
exposure age is therefore dominated by 𝑆𝑠𝑛𝑜𝑤,𝑠𝑝 . Monte Carlo simulations produced by Zweck et
al. (2013) suggest that the moderating effect of snow on the high-energy neutron flux is
significantly greater than the 𝑆𝑠𝑛𝑜𝑤,𝑠𝑝 equation indicates. The exposure ages calculated in Table
D.6 should thus be considered minimum ages for the given depth and duration of snow coverage.
Table D.1. Production rate scaling factors.
Sample
E11-01
E11-02
E11-02(ol)
E11-03
E11-04
E11-05
E11-05(ol)
E11-06
E11-07
E11-08
E11-09
E11-10
E11-11
E11-12
E11-13
E11-14
E11-15
E11-16
E11-17
E11-18
E11-19
E11-20
E11-21
E11-22
E11-23
E11-24
E11-25
E11-26
E11-27
E11-28
E11-29
E11-30
E11-31
E11-31(ol)
LSD
Sel,n
Sel,μ
18.64 7.15
19.63 7.45
--19.63
--23.25
21.16 7.90
18.83 7.21
--18.83
--21.57
22.02 8.15
--22.34
--22.17
23.79 8.66
--21.57
--17.60
--20.65
--19.79
--20.88
--18.66
--21.37
23.26 8.51
--20.11
--20.80
--21.68
--21.91
22.04 8.16
22.37 8.25
21.05 7.87
--20.88
--22.08
--23.49
--21.81
--20.95
--19.69
--19.69
St
Sel,n
17.82
18.66
18.66
21.67
19.94
17.98
17.98
20.28
20.66
20.92
20.78
22.12
20.28
16.93
19.51
18.79
19.71
17.84
20.12
21.68
19.06
19.64
20.38
20.57
20.67
20.95
19.85
19.71
20.71
21.87
20.48
19.77
18.71
18.71
Sel,μ
7.15
7.45
----7.90
7.21
----8.15
----8.66
--------------8.51
--------8.16
8.25
7.87
---------------
LSD = flux-based scaling model from Lifton et al. (2014). St = Lal (1991)/Stone (2000) scaling model. Sel,n = Scaling factor for
the nucleonic cosmic-ray flux; used to scale rates of 3He production by spallation and 36Cl production by spallation and lowenergy neutron absorption. Sel,μ = Scaling factor for the muonic cosmic-ray flux; used to scale rates of 36Cl production by slow
and fast muons. All samples are clinopyroxene except E11-02(ol), E11-05(ol), and E11-31(ol), which are olivine.
Table D.2. 3He production rates and exposure ages (no erosion).
LSD
P(z)
Sample
E11-01
E11-02
E11-02(ol)
E11-03
E11-04
E11-05
E11-05(ol)
E11-06
E11-07
E11-08
E11-09
E11-10
E11-11
E11-12
E11-13
E11-14
E11-15
E11-16
E11-17
E11-18
E11-19
E11-20
E11-21
E11-22
E11-23
E11-24
E11-25
E11-26
E11-27
E11-28
E11-29
E11-30
E11-31
E11-31(ol)
atoms
He/g/a
2185
2277
2277
2659
2490
2182
2182
2493
2582
2607
2589
2759
2509
2046
2402
2308
2446
2178
2467
2737
2329
2420
2524
2561
2561
2606
2470
2435
2578
2736
2511
2459
2308
2308
3
Age
(meas)
1σ
ka
5.41
7.16
5.96
0.25
18.55
4.53
3.86
5.37
5.59
3.75
4.27
8.00
6.89
27.29
4.61
5.35
4.82
4.90
5.35
5.26
5.07
4.63
7.49
6.80
6.97
3.79
6.56
6.90
6.75
8.46
6.85
6.76
71.80
69.94
St
Age
(DVDP)
1σ
ka
0.11
0.15
0.13
0.01
0.43
0.11
0.13
0.12
0.12
0.12
0.10
0.18
0.15
0.62
0.11
0.13
0.11
0.11
0.13
0.11
0.12
0.12
0.15
0.14
0.16
0.08
0.16
0.14
0.14
0.21
0.16
0.15
1.70
1.63
5.42
7.14
5.95
0.25
18.64
4.46
3.82
5.34
5.55
3.70
4.25
7.99
6.90
27.61
4.57
5.27
4.82
4.93
5.30
5.27
5.04
4.60
7.47
6.76
7.00
3.75
6.57
6.86
6.70
8.50
6.91
6.75
74.94
71.52
P(z)
atoms
He/g/a
2071
2146
2146
2458
2327
2066
2066
2324
2402
2421
2407
2543
2339
1952
2251
2173
2289
2065
2303
2530
2189
2266
2352
2384
2382
2419
2309
2279
2398
2526
2338
2301
2174
2174
3
0.12
0.15
0.13
0.01
0.42
0.11
0.11
0.14
0.12
0.09
0.12
0.18
0.14
0.63
0.11
0.11
0.11
0.13
0.11
0.11
0.14
0.11
0.16
0.15
0.14
0.11
0.16
0.16
0.13
0.19
0.15
0.15
1.71
1.64
Age
(meas)
1σ
ka
6.31
8.44
7.01
0.30
22.08
5.31
4.57
6.38
6.66
4.55
5.12
9.75
8.20
31.71
5.47
6.28
5.71
5.72
6.35
6.31
5.98
5.49
8.98
8.12
8.33
4.59
7.79
8.18
8.07
10.31
8.18
8.02
84.48
82.28
Age
(DVDP)
1σ
ka
0.14
0.19
0.16
0.01
0.51
0.12
0.13
0.14
0.15
0.11
0.12
0.23
0.19
0.73
0.13
0.14
0.13
0.13
0.14
0.14
0.14
0.13
0.20
0.18
0.19
0.10
0.18
0.18
0.18
0.24
0.19
0.18
2.02
1.92
6.32
8.42
7.00
0.29
22.19
5.23
4.53
6.34
6.62
4.50
5.10
9.74
8.22
32.08
5.42
6.19
5.71
5.76
6.29
6.33
5.94
5.46
8.96
8.07
8.36
4.55
7.81
8.15
8.00
10.34
8.24
8.02
88.16
84.15
0.14
0.19
0.16
0.01
0.51
0.12
0.12
0.14
0.15
0.11
0.12
0.23
0.19
0.73
0.12
0.14
0.13
0.13
0.14
0.14
0.14
0.13
0.20
0.18
0.19
0.10
0.18
0.18
0.18
0.24
0.19
0.18
2.01
1.91
P(z) is the sample-specific cosmogenic 3He production rate (scaled to the sample location and corrected for
shielding and sample thickness) at the depth of the middle of the sample. For the LSD calculation, which
implements time-dependent scaling and integrates production rates across the thickness of the sample, the
production rate shown in the table is based on the contemporary strength of the terrestrial and solar magnetic fields
and is the average of the production rates measured at 100 depths within each sample. Age (meas) is the exposure
age calculated using the 3He/4He ratio measured during crushing of each sample for magmatic 3He/4He. Age
(DVDP) is the exposure age calculated using the mean 3He/4He ratio measured during crushing of the DVDP
olivines for magmatic 3He/4He.
Table D.3. 3He LSD ages corrected for radiogenic 4He.
Sample
E11-01
E11-02
E11-02(ol)
E11-03
E11-04
E11-05
E11-05(ol)
E11-06
E11-07
E11-08
E11-09
E11-10
E11-11
E11-12
E11-13
E11-14
E11-15
E11-16
E11-17
E11-18
E11-19
E11-20
E11-21
E11-22
E11-23
E11-24
E11-25
E11-26
E11-27
E11-28
E11-29
E11-30
E11-31
E11-31(ol)
4
Age
(DVDP)
1σ
ka
ka
5.416
7.139
5.950
0.246
18.638
4.458
3.816
5.337
5.552
3.703
4.250
7.987
6.902
27.605
4.568
5.269
4.816
4.928
5.303
5.275
5.043
4.604
7.467
6.756
6.998
3.745
6.572
6.864
6.698
8.497
6.907
6.752
74.940
71.525
0.120
0.152
0.134
0.007
0.424
0.112
0.114
0.138
0.120
0.093
0.118
0.176
0.136
0.627
0.106
0.109
0.108
0.128
0.113
0.106
0.135
0.106
0.157
0.147
0.140
0.105
0.159
0.159
0.135
0.194
0.154
0.146
1.714
1.641
4
Herad,grn
4
4
109
atoms/g
1.03
1.35
0.32
0.05
3.53
0.84
0.21
1.01
1.05
0.70
0.81
1.51
1.31
5.23
0.87
1.00
0.91
0.93
1.00
1.00
0.96
0.87
1.41
1.28
1.33
0.71
1.25
1.30
1.27
1.61
1.31
1.28
14.20
3.86
109
atoms/g
7.07
9.32
0.00
0.32
24.33
5.82
0.00
6.97
7.25
4.83
5.55
10.43
9.01
36.04
5.96
6.88
6.29
6.43
6.92
6.89
6.58
6.01
9.75
8.82
9.14
4.89
8.58
8.96
8.75
11.09
9.02
8.82
97.84
0.00
109
atoms/g
0.58
0.77
0.59
0.03
2.00
0.48
0.38
0.57
0.60
0.40
0.46
0.86
0.74
2.96
0.49
0.57
0.52
0.53
0.57
0.57
0.54
0.49
0.80
0.73
0.75
0.40
0.71
0.74
0.72
0.91
0.74
0.73
8.05
7.06
Herad,ap
Herad,gl
4
Herad,mat
109
atoms/g
1.40
1.85
1.63
0.06
4.83
1.15
1.05
1.38
1.44
0.96
1.10
2.07
1.79
7.15
1.18
1.36
1.25
1.28
1.37
1.37
1.31
1.19
1.93
1.75
1.81
0.97
1.70
1.78
1.74
2.20
1.79
1.75
19.41
19.64
4
Herad,total
3
109
atoms/g
10.08
13.29
2.54
0.46
34.70
8.30
1.63
9.94
10.33
6.89
7.91
14.87
12.85
51.39
8.50
9.81
8.97
9.17
9.87
9.82
9.39
8.57
13.90
12.58
13.03
6.97
12.23
12.78
12.47
15.82
12.86
12.57
139.51
30.55
107
atoms/g
1.32
1.82
1.50
0.07
5.19
1.09
0.94
1.48
1.60
1.10
1.24
2.49
1.94
6.31
1.23
1.36
1.32
1.20
1.46
1.61
1.31
1.25
2.12
1.94
2.00
1.11
1.81
1.87
1.93
2.63
1.94
1.86
19.30
18.33
Hec,corr
Age
(corr)
Age
diff
ka
ka
5.456
7.186
5.957
0.247
18.756
4.501
3.824
5.371
5.587
3.721
4.279
8.028
6.942
27.819
4.604
5.305
4.850
4.965
5.333
5.305
5.079
4.632
7.508
6.803
7.034
3.768
6.613
6.909
6.733
8.543
6.950
6.801
75.459
71.643
0.040
0.048
0.007
0.001
0.118
0.043
0.008
0.034
0.035
0.018
0.028
0.040
0.040
0.213
0.036
0.036
0.034
0.038
0.030
0.030
0.036
0.029
0.042
0.047
0.037
0.023
0.041
0.045
0.035
0.046
0.043
0.049
0.519
0.118
Herad,ap = radiogenic 4He from U and Th in apatite inclusions. 4Herad,grn = radiogenic 4He from U and Th in the grain matrix.
Herad,gl = radiogenic 4He from U and Th in glass inclusions. 4Herad,mat = radiogenic 4He from U and Th in the matrix glass
surrounding the clinopyroxene or olivine grains. Half-lives: 238U = 4.47 x 109 a; 235U = 7.04 x 108 a; 232Th = 1.40 x 1010 a.
Nuclide abundances: 238U = 0.99274; 235U = 0.0072; 232Th = 1. Additional significant figures are shown in the ages to more
effectively illustrate the effect of the radiogenic correction on the calculated exposure age.
4
Table D.4. 36Cl production rates and exposure ages (no erosion).
LSD
Psp(z)
Sample
E11-01
E11-02
E11-04
E11-05
E11-07
E11-10
E11-18
E11-23
E11-24
E11-25
atoms
Cl/g/a
95.51
101.84
118.40
95.35
112.70
127.55
119.37
114.66
112.17
111.52
36
Plen(z)
(uncorr)
atoms
36
Cl/g/a
9.62
7.73
7.25
9.69
11.91
12.98
18.59
14.51
15.82
7.29
Plen(z)
(corr)
atoms
36
Cl/g/a
4.58
2.86
2.02
4.95
5.86
6.57
13.73
8.81
9.52
2.32
Pμ(z)
atoms
Cl/g/a
1.77
1.87
2.15
1.77
2.03
2.25
2.15
2.05
2.00
2.02
36
St
Age
(uncorr)
1σ
ka
5.34
6.62
17.19
4.13
5.16
7.09
5.01
6.44
3.44
6.22
Age
(corr)
1σ
ka
0.16
0.18
0.41
0.14
0.16
0.21
0.15
0.19
0.12
0.26
5.62
6.95
17.95
4.36
5.44
7.41
5.21
6.75
3.66
6.50
Psp(z)
atoms
Cl/g/a
87.89
93.31
107.79
87.63
101.78
114.38
107.13
103.68
101.05
101.37
36
0.16
0.16
0.45
0.14
0.17
0.22
0.14
0.19
0.14
0.25
Plen(z)
(uncorr)
atoms
36
Cl/g/a
8.66
6.92
6.44
8.71
10.52
11.36
16.31
12.82
13.95
6.48
Plen(z)
(corr)
atoms
36
Cl/g/a
4.12
2.56
1.79
4.45
5.18
5.76
12.04
7.78
8.40
2.06
Pμ(z)
atoms
Cl/g/a
1.80
1.90
2.18
1.80
2.06
2.29
2.18
2.09
2.03
2.05
36
Age
(uncorr)
1σ
ka
6.42
8.02
21.05
5.01
6.33
8.80
6.20
7.92
4.33
7.59
Age
(corr)
1σ
ka
0.17
0.20
0.52
0.15
0.19
0.30
0.19
0.23
0.14
0.32
6.76
8.40
21.97
5.27
6.67
9.23
6.43
8.30
4.59
7.93
0.18
0.21
0.55
0.16
0.20
0.31
0.20
0.25
0.15
0.33
Psp(z) = production rate of 36Cl by spallation of K, Ca, Ti, and Fe at the depth of the middle of the sample. Plen(z) (uncorr) = production rate of 36Cl by capture of
low-energy neutrons, including muon-induced neutrons, calculated using uncorrected Cl concentration. P len(z) (corr) = production rate of 36Cl by capture of lowenergy neutrons, calculated using blank-corrected Cl concentration. Pμ = production rate of 36Cl by muons (including fast muons and absorption of slow negative
muons). Age (uncorr) is the exposure age calculated if blank corrections for 36Cl and Cl are not used. Age (corr) is the exposure age calculated if blank
corrections are used.
Table D.5. 3He and 36Cl LSD ages for different erosion rates.
Sample
E11-01
E11-02
E11-03
E11-04
E11-05
E11-06
E11-07
E11-08
E11-09
E11-10
E11-11
E11-12
E11-13
E11-14
E11-15
E11-16
E11-17
E11-18
E11-19
E11-20
E11-21
E11-22
E11-23
E11-24
E11-25
E11-26
E11-27
E11-28
E11-29
E11-30
E11-31
No erosion
He Age 36Cl Age
5.42
5.62
7.14
6.95
0.25
--18.64
17.95
4.46
4.36
5.34
--5.55
5.44
3.70
--4.25
--7.99
7.41
6.90
--27.61
--4.57
--5.27
--4.82
--4.93
--5.30
--5.27
5.21
5.04
--4.60
--7.47
--6.76
--7.00
6.75
3.75
3.66
6.57
6.50
6.86
--6.70
--8.50
--6.91
--6.75
--74.94
---
3
1 mm/ka
He Age 36Cl Age
5.44
5.64
7.17
6.97
0.25
--18.89
18.17
4.47
4.37
5.35
--5.57
5.45
3.71
--4.26
--8.02
7.43
6.92
--28.13
--4.59
--5.29
--4.84
--4.95
--5.31
--5.29
5.21
5.06
--4.61
--7.51
--6.79
--7.02
6.77
3.75
3.66
6.60
6.51
6.90
--6.72
--8.54
--6.94
--6.78
--78.82
---
3
3 mm/ka
He Age 36Cl Age
5.49
5.68
7.23
7.02
0.25
--19.42
18.62
4.51
4.40
5.39
--5.60
5.47
3.71
--4.29
--8.11
7.48
6.98
--29.28
--4.61
--5.31
--4.87
--4.99
--5.36
--5.31
5.21
5.10
--4.64
--7.58
--6.85
--7.09
6.81
3.77
3.67
6.64
6.56
6.96
--6.79
--8.65
--7.01
--6.83
--88.55
---
3
5 mm/ka
He Age 36Cl Age
5.53
5.71
7.30
7.08
0.25
--20.00
19.11
4.53
4.41
5.41
--5.64
5.50
3.73
--4.31
--8.21
7.53
7.03
--30.56
--4.64
--5.34
--4.91
--5.02
--5.40
--5.34
5.21
5.15
--4.67
--7.66
--6.91
--7.15
6.85
3.79
3.68
6.69
6.60
7.03
--6.85
--8.76
--7.09
--6.90
--102.51
---
3
7 mm/ka
He Age 36Cl Age
5.58
5.75
7.36
7.14
0.25
--20.61
19.65
4.56
4.44
5.44
--5.67
5.51
3.75
--4.33
--8.30
7.59
7.09
--32.01
--4.67
--5.37
--4.95
--5.06
--5.44
--5.37
5.22
5.20
--4.70
--7.75
--6.98
--7.21
6.89
3.80
3.69
6.74
6.64
7.11
--6.92
--8.87
--7.15
--6.95
--125.35
---
3
9 mm/ka
He Age 36Cl Age
5.62
5.80
7.43
7.20
0.25
--21.30
20.23
4.60
4.46
5.47
--5.71
5.54
3.76
--4.35
--8.40
7.64
7.14
--33.66
--4.71
--5.41
--5.00
--5.10
--5.48
--5.40
5.22
5.23
--4.73
--7.84
--7.04
--7.27
6.93
3.81
3.70
6.79
6.69
7.17
--6.99
--8.98
--7.22
--7.01
--176.91
---
3
The given erosion rate is assumed to be constant for the duration of the samples exposure. 3He ages use the DVDP 3He/4He ratio for magmatic 3He/4He. Only 3He
ages in clinopyroxene are shown. 36Cl ages are calculated using blank-corrected concentrations for 36Cl and total Cl.
Table D.6. 3He and 36Cl LSD ages for different depths of prior snow coverage (ρsnow = 0.5 g/cm3). Duration of snow coverage is
assumed to be 50% of the duration of the sample’s exposure.
Sample
E11-01
E11-02
E11-03
E11-04
E11-05
E11-06
E11-07
E11-08
E11-09
E11-10
E11-11
E11-12
E11-13
E11-14
E11-15
E11-16
E11-17
E11-18
E11-19
E11-20
E11-21
E11-22
E11-23
E11-24
E11-25
E11-26
E11-27
E11-28
E11-29
E11-30
E11-31
3
No snow coverage
He Age 36Cl Age
5.42
5.62
7.14
6.95
0.25
--18.64
17.95
4.46
4.36
5.34
--5.55
5.44
3.70
--4.25
--7.99
7.41
6.90
--27.61
--4.57
--5.27
--4.82
--4.93
--5.30
--5.27
5.21
5.04
--4.60
--7.47
--6.76
--7.00
6.75
3.75
3.66
6.57
6.50
6.86
--6.70
--8.50
--6.91
--6.75
--74.94
---
3
0.5 m
He Age 36Cl Age
5.90
6.01
7.71
7.44
0.26
--20.30
19.44
4.87
4.68
5.80
--6.03
5.78
4.06
--4.65
--8.70
7.89
7.46
--30.06
--4.99
--5.72
--5.25
--5.38
--5.76
--5.73
5.37
5.49
--5.01
--8.10
--7.32
--7.57
7.19
4.11
3.90
7.14
7.01
7.43
--7.26
--9.26
--7.47
--7.32
--81.66
---
3
1m
He Age 36Cl Age
6.38
6.58
8.31
8.05
0.28
--21.92
21.11
5.27
5.13
6.25
--6.51
6.32
4.41
--5.02
--9.41
8.61
8.04
--32.49
--5.40
--6.18
--5.66
--5.80
--6.21
--6.20
5.99
5.91
--5.42
--8.76
--7.87
--8.17
7.85
4.47
4.34
7.65
7.55
8.00
--7.79
--10.01
--8.03
--7.86
--88.27
---
3
2m
He Age 36Cl Age
7.26
7.54
9.50
9.25
0.31
--25.01
24.20
6.01
5.90
7.11
--7.38
7.26
5.05
--5.72
--10.75
9.96
9.20
--37.08
--6.14
--7.03
--6.45
--6.61
--7.07
--7.05
7.01
6.74
--6.17
--10.01
--9.00
--9.36
9.11
5.14
5.06
8.72
8.62
9.14
--8.90
--11.44
--9.19
--8.99
--100.79
---
3
3m
He Age 36Cl Age
8.01
8.35
10.56
10.26
0.35
--27.75
26.89
6.66
6.55
7.82
--8.14
8.01
5.59
--6.34
--11.95
11.09
10.21
--41.15
--6.81
--7.73
--7.14
--7.30
--7.77
--7.75
7.76
7.43
--6.84
--11.13
--10.00
--10.41
10.14
5.70
5.62
9.68
9.56
10.15
--9.87
--12.70
--10.20
--9.99
--111.86
---
3
4m
He Age 36Cl Age
8.68
9.05
11.46
11.13
0.38
--30.06
29.13
7.20
7.07
8.46
--8.84
8.66
6.05
--6.86
--12.95
12.00
11.10
--44.56
--7.34
--8.36
--7.67
--7.86
--8.41
--8.38
8.37
8.01
--7.37
--12.06
--10.84
--11.30
11.00
6.16
6.08
10.51
10.37
11.02
--10.71
--13.75
--11.07
--10.83
--121.15
---
3
He ages use the DVDP 3He/4He ratio for magmatic 3He/4He. Only 3He ages in clinopyroxene are shown. 36Cl ages are calculated using blank-corrected
concentrations for 36Cl and total Cl.
SUPPLEMENT E. Lava flow surface areas
The surface area of each of the post-caldera lava flows was estimated in ArcMap based
on the mapped surface area of each flow (Table E.1). Areas do not include lava that flowed over
the caldera rim and off the summit plateau. Areas are not given for the West, Young Pre-caldera,
and Old Pre-caldera lava flows because most of the lava erupted flowed off the summit plateau
and was not mapped.
Table E.1. Post-caldera lava flow surface areas.
Lava flow
Area (km2)
South
0.13
UITR
0.24
Northeast
1.61
Southeast
0.49
LITR
0.28
Tramways
0.37
Nausea Knob
0.27
Lower Hut
3.12
Southwest
0.17
Northwest
0.75
Total
7.44
Additional References
The following references are cited in this supplement but not in the main paper:
Blard, P.-H., Farley, K.A., 2008. The influence of radiogenic 4He on cosmogenic 3He
determinations in volcanic olivine and pyroxene. Earth and Planetary Science Letters 276,
20-29.
Farley, K.A., Wolf, R.A., Silver, L.T., 1996. The effects of long alpha-stopping distances on (UTh)/He ages. Geochimica et Cosmochimica Acta 60, 4223-4229.
Rooney, T.O., Hart, W.K., Hall, C.M., Ayalew, D., Ghiorso, M.S., Hidalgo, P., Yirgu, G., 2012.
Peralkaline magma evolution and the tephra record in the Ethiopian Rift. Contributions to
Mineralogy and Petrology 164, 407-426.