AN ABSTRACT OF TUE ThESIS OF
David Clifford Bushnell for the degree of master of scieice in
oceanorapby.
Date thesis is presented: Auaust 5, 1963
Title: Continental Shelf Sediments in the Vicinity of Newport,
Oreon.
Redacted for Privacy
1bstract approved:
Sautples of bottom se4iutents were collected for analysis from
121 different positions on the continental shelf and upper continental slope off Ore:on between lattdcs ;4'2O'N. and 4J°L8'N.
The nature of the sediments suggests that they have been contributed
by the geologically varied physiographic provinces
the Pacific
Northwest which drain to the Pacific Ocean via the coasts of Oreon
0
and Washington..
Well-sorted, fine-grained subangular sands cover the continental shelf to a depth of 52 fathoms. Below this depth the sedi-
ments grade uniformly to clay-silts on the upper continental slope.
ock outcrops, gravel, and coarse sand are present in the vicinity
of Stonewall Bank, alon the shelf break, and on the shoals rising
from the upper part of the continental slope.
Mineralogical iuneturity characterise the nearehore sands and
the sand fraction of the finer-Lrained offshore sediment. Glauconite,
calcium carbonate, and organic matter are essentially absent from
the sands, but nay be abundant in the offshore sediisent; glauconite
up to 91 percent of the sample; calcium carbonate, 14 percent; and
organic matter, 6 percent. Small quantities of organic silica,
mainly sponge spicules and Radiolaria, are irregularly distributed
in the fine sediments.
Textural considerations suggest that the nearshore sands were
deposited in a high-energy littoral environment and may be a late
Plaistocene tranagressive deposit. Although the glauconite-rich
sediments on the offshore shoals and at the edge of the continental
shelf attest to little or no deposition, shallow depressions and
sea valleys of the upper continental slope may be actively receivin<.,
sediment.
CCfIKE)f1AL SHELF SW)IMTS IN THE
VICINITY OF NEWPORT, OREGCN.
by
DAVID CLIFFORD BUSHNELL
A TUESIS
ubijtttd to
OREGON SThTE UNIVERSITY
in partial fu1fil]nt of
the requirement. for the
degree of
t11STER CF SCIEWE
Auguat 1363
APPROVED:
Redacted for Privacy
Assocte Professor ofOceanography
In Charge of Major
Redacted for Privacy
of Department of Oceanography
Redacted for Privacy
Chairuan of School Graduate Conunittee
Redacted for Privacy
Dean of Graduate School
Date thesis is presented:
Typed by Nancy Parrish
-
ACK$OWL1GEMENTS
The writer is indebted to Dr. John V. Byrne for ttLs guidance
in conducting the research and preparing the manuscript.
Dra. Jon
C. Ctradnga, W. Bruce McAlister, and Herbert Curl, Jr., have read
parts of the manuscript and given much helpful advice.
The writer
thanIs Dr. John V. Byrne, Leverne I). Kului, Michael Laura, Donald
Day, and Norman P. Kujala for collecting the samples.
The study was carried out under Office of Naval Research
contract NONR 1926(02).
TABLE CF C(ETENTS
Page
IN'rRc1ucrrIoN.........
. ...
1
THE BOiDERING LANDS..
S
Coast Range Drainage of Washington and northern Oregon...
8
Columbia River. .
9
. .
P1!YSICGRAPHY A1) GEOLOG? CF
Southwestern Oregon
Drainage. .
. . . . . . . . . . . .
. . . . . . . . . . . .
and Northwestern California
. ....... . .
S1JBZ'IARINE TOPOGRAPHY. . . . .
.....
.................
. .
...
................ . . ......... . .
10
1]
* .....
15
Temperature, Salinity, andOxygen ........................
15
Waves...............
16
Currents .................................................
22
Tides ....................................................
24
SED1MTS.....................................................
24
Methods of Sampling and Analysis .........................
24
OCE.NoORAPIr
.....................
Sampling. . .
.................... $ ..................
Mechanical Analysis. . . . .
...........................
24
25
Carbonate and Organic Carbon Analyses ...............
25
Heavy Mineral Separation ............ . . . .
26
Feldspar Staining ......... . .
......................
26
.......
27
....... . . . . . ......
27
Texture . . , ................................. . * . . . . .
Median Diameter .......... . .
. . , . . .
Sand and Percent Terrigenous Sand...
33
Clay-silt Component .................................
38
Sorting ...........................
4].
Percent
. ............ . * . . .
Pare
Skewness
,
414
Roundness... ...
so 0. .00.0.5
.
Areal Pattern of Texture.................
Composition.
.. ........
. . . . . . . . * . . * . . . .
. .
Light Fraction Mineralogy.....5.
.
144
45
149
Heavy Minerals...... 52
AuthigenicConstituents.... ......
53
Nature and Composition of Glauconite Pellets
56
Distribution of Glauconite Pellets .............
60
Formation of Glauconite Pellets .................
60
Organically Produced
Constituents.... ...............
Oranic tiatter ............
.
............
Calcivacarbonate ......
Organic Silica.
ORiGIN
50
'raE 3)lNENT
SXJRCE OP THE s)IMEN'rs
. . . . . . .
65
68
...... . * .............. .
......... .
......
. . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SUt*ARY, . . . . . . . . . . . . . . . . . . . .
65
.............. . . . . ....... . . . . . .
71
73
80
81
BIBLIOGAPHY................................... . . . . . . .......
83
APPDIX. . . . . . . . . . . . . . . . .
88
..................
,
...........
TABLES
Page
TABLE
1
Areas of principle Pacific Northwest drainage
systems .......................................
2
Mineralogy and mineral ratios of eight samples
3
Composition of several samples of glauconite-
4
5
Sample locations and depths ...................
Textural parameters of the sediments ...............
6
Percent heavy minerals in sand and terrLgenous
7
Heavy
bearing sediments .............................
aand fractions ............. . ..................
minera1oy of samples 22, 25, 27, 30, 62,
69, and 119 ...................................
S
51
58
89
95
104
106
ILLUSTRATI ONS
Page
FIGURE
1
Indexmap ..........................................
2
Pacific Northwest drainage systems .................
7
3
Bathymetry and sample locations ....................
13
4
Water temperature and salinity, January ............
18
5
Water temperature and salinity, September ..........
18
6
Oxygen content of water, January ...................
20
7
Oxygen content of water, September .................
20
8
Phi median diameter of the sediment ................
29
9
Index map for profiles .............................
30
10
Profiles of depth; percents of clay-silt,
glauconite sand, and terrigenous sand;
and phi median diameter .......................
32
11
Percent sand in the sediment .......................
35
12
Percent terrigenou8 sand in the sediment ...........
37
13
Cumulative frequency curves of samples from
profile B-B' ..................................
40
14
Ternary diagram of amounts of sand, silt, and
clay in the sediment ..........................
11-3
15
Sedimenttype ......................................
47
16
Diagram of relative proportions of heavy
minerals in samples from profile B-B' .........
55
17
Percent glauconite in the sediment .................
62
18
Percent organic matter in the sediment .............
67
19
Percent calcium carbonate in the sediment ..........
70
CONTINENTAL SHELF SEDIMENTS IN THE VICINITY
CE NEWPORT, OREGON
INTRWUCTION
Although the principle of uniformitarianism has guided geologic
tbinkin since it was first proposed by James ilutton in 1785 (20,
p. 20), its application to the interpretation of marine sedimentary
rocks has been hindered by the great difficulties of observing
modern marine environments.
Only recently has it been poasible to
investigate extensively the sediments of the ocean floor.
Conse-
quently, the study of sedimentation off the coast of Oregon is yet
in its infancy.
Prior to 1960, the only published information concernin;
marine sediments off Oregon consisted of w.de1y scattered notations
on the United States Coast and Geodetic Survey bathymetric charts
(Z1.3, 414, 45).
These notations, such as "gn W' (green mud), 'bk 3"
(black sand), and "lard br C" (hard brown clay), were basco on
observations of sediments found clinging to the sounding leads used
in the older
surveys.
Since 1960 the
study of the bottom sediments off Oregon has
accelerated. Cusininge (11) analyzed samples collected from the
continental shelf near
estuarine deposits.
Coos Bay as part of a
study of the Coos Bay
Samples collected from depths as great as 210
fathoms off Siletz, Yequina, and Alsea Bays were analyzed by Jarman
2
(2L1, p. 28) in conjunction with a study of the benthic Foraminifera
of that area.
in addition, work is currently in progress by the
Department of Oceanography at Oregon
State tlnivers ity
on the geomor-
phology, structure, litho]ogy, end sediments of the continental
slope off the central coast of Oregon; the sediments of Astoria cone
off the Columbia giver; and the continental shelf sediments between
the Columbia River and Cape Blanco.
A small section of the upper continental terrace in the vicinity
20' and 44° 58' north latitude
of Newport, Oregon, bounded by 4L
and extending from the
was selected for a
coast to 12k
'48' west longitude (Pigure 1),
detailed study of sediments and sedimentary pro-
cesses. The area is not influenced by major rivers, nor is it
unique by virtue of special climatic or oceanographic conditions.
Therefore, with respect to external factors, the environments of
deposition contained therein should be typical of the continental
shelf of Oregon and
Washington.
The purpose of this report is twofold:
first, to describe in
detail the texture and composition of the sediments found in this
area; second, to relate the pattern of sedimentation to
and chemical forces which formed it.
the physical
The writer thus hopes to pro-
vide information which will be useful in the further study of nearshore sediments, and also in the interpretation of ancient øedimentary environments.
Figtre 1.
Index uap &icing the 1octicn of the area studied.
45°
0
ABYSSAL
J
"PLAIN"
L D
OREGON
..............
COOS SAY
0
50
NAUTICAL MI.
CALIFORNIA
5
PRYSIOGRAPI! AND GEOLOGY
THE BORDERING LAII)S
The physiography and geology of the Pacific Northwest determine
in pert the amounts end types of sedinents which are supplied
areas of deposition alone the coast of Oregon and Washington.
regions which drain into the Pacific
between latitudes
to
All
41° and 48
north are considered; these include most of Washington, Oregon, and
Idaho, as well as parts of British Columbia, Montana, Wyoming, Utah,
Nevada, and California.
Individual drainage systems
of
the Pacific
Northwest, as outlined by Byrne (8), are shown in Fiure 2; their
areas are given in Table 1.
In order to include all the land area
without undue complexity, the smaller drainages along the coast have
been incorporated into larger composite systems.
Thousand
square miles
Washington Coast
Columbia
259.
North and Central
Oregon Coast
3.7
Umpqua
4.4
Coos-Coquille
1.9
Rogue
5.3
Klawath-Suiith
Total
Table
4.5
1.
1.1.3
290.1
Areas of principle Pacific Northwest
drainage systems, as
outlined in Figure 2 (8).
Figure 2.
Pgcific Northwest drainage systems which drain into the
Pacific Ocean between Cape Flattery, Washington, and the
Kiamath River.
7
NORTHWEST
DRAINAGE SYSTEMS
PACIFIC
DRAINAGE DIVIDE
N
0
50
Io
MILE S
1
0
OLY
WASHIrGTON \MT
COAST
COLUMBIA RIVER
C.
L.
1;-'\
?
OREGON
COAST
-'
-
I::
(;
/ 0
C-,
C/)
UMPQUA RIVER )
C-)
COOS-COQUILLE
ROGUE RIVER
'
SMITH - XLA MATH
I
/-----...-.
BAS'IPJ-RAGE
-J
I
--
'$0
Coast Range Drainage of Washington
and
Northern Oregon
The western slopes of the Ore on Coast Range and the Olympic
Mountains
drain into the Pacific
tbrouh
many short rivers and
creeks. The lgr,er streams flow into estuaries; these include the
Silets, Yaquina, and Alsea
.&ivers, which flow
ifltO
the aree studied.
Accordin,. to Kuim (26), the effect of the Yaquifla River estuary is
to arrest most of the sediment carried by the inf lowing streams, as
well as to trap sand brought into the bay by tidal processes.
Similarities between the Yaquina River estuary and other estuaries
along the Oreon and Washington coasts suggest that the other setu-
aries may collect sediments in a similar manner. In addition to
the larger rivers, many smaller streams debouch directly onto the
beaches. Although most of the drainae areas are small, extremely
heavy rainfall--in places more than 140 inches per year--causes much
higjer runoff than might be expected.
Along the northern coast of Washington, the very rugged Olympic
Moutaina rise
to
over 7000 feet in their central portion.
The
mountains are underlain by Mesozoic sedimentary and metamorphic
rocks, which dip beneath Cenozoic sedimentary rocks
around the peri-
meter of the range (17, p. 455).
The Oreon Coast Range is much lower than the Olympics, with
few peaks exceeding 3000 feet in elevation.
It is composed of
Tertiary marine sedimentary rocks and basalt flows. Intrusions of
more resistant gabbros, basalts, diorites, nepheline syenitea, and
camptonites, cap most of the higher motrntains (3, p. 19).
In places a narrow, discontinuous coastal plain separates the
cregon Coast 1ange from the beach.
This plain consists primarily
of Pleistocene terrace and dune deposits, which contribute much sand
to the beaches.
On the ecaward CdgC of the plain, particularly
between Florence and Coos Bay, large Recent sand dunes are migrating inland from the beacheø, burying previous deposits, and blocking
stream valleys to form lakes.
Columbia River
3y far the largest river in the Pacific Northwest, and one of
the largest in the nation, the Columbia River drains 259,000 square
miles in six of the western states and British Columbia.
At
The Dallas, Oregon, 160 miles above the river's mouth, the average
flow was 223,000 cfa. in 1959; total flew for the same year was
161,800,000 acre-feet (k6, p. 76).
Byrne (9) estimates the sedftnt
load at the mouth to be 30,000 cubic yards per day.
The Columbia watershed spans several physiographic and geologic
provinces.
p
Moit of the andesites and tufts of the Cascades (17,
L22) and the basalte of the Columbia P1ateus (29) are included.
In Washington, Columbia tributaries drain the metamorphosed aedimentary rocks and granitie batboliths of the northern Cascades
(17, p. t22).
In Idaho, Montana, Washington, southern British
Columbia, and part of Wyoming, the western slope of the Rocky
Mountains drains into the Pacific via the Columbia River and its
10
largest tributary, the Snake River. These mountains consist of a
group of distinct high ranges of differing rock types. Sedimentary
rocks from pre-Cambrian to Cenozoic in age, in places metamorphosed.
crop out over large areas. Large Mesozoic batholithe, of which the
Idaho batholith is a well known example, intrude the sediments in
the western part of the range.
Southwestern Oregon and Northwestern California Drainage
Mountains are the dominant geomorphic feature of
The Klaaatb
southwestern Oregon and northwestern California.
than 9000 feet
Rising
to more
they expose Paleozoic end Mesozoic volcanic and
sedimentary rocks which
lite, and marble (3
places serpentenized
are locally metamorphosed to schist, phyl-
p. 66).
Meeozoic intrusions of peridotite, in
and granitic rocks are
connon throughout the
area.
Penetrating the Kiomath Mountains to head in the high Cascades
are the Rogue
and
Kiamath Rivers. The Klamath drains, in addition,
a small section of the Basin and Range Province.
The Umpqua
River
drains the northern tip of the Z1atnath Mountains and part of the
Cascades
but
is mostly confined to the southern Oregon Coast flange.
Alonr. the coast, the Coos,
Coquille, Sixes, Elk, Pistol, Chetco,
and Smith Rivers drain the
western slopes
and the Oregon Coast Range.
of the Kiamath Mountains
11
SUBMARINE TOPOGRAPRf
A narrow continental terrace flanks the mountainous Pacific
coaat of North America. Off Oregon, the terrace ranges f ton 40 to
70 miles vide (7, p. 65) and meets the abyssal plain at about 1600
fathoms.
It is divided into the continental shelf and the conti-
nental slope by a more or Ieas distinct change of elope which
occurs at depth between 80 and 95 fathoms. The shelf varies in
width from 9 to 40 miles, *nd in declivity from 00081 to 0°43.
Several shoals rise from its relatively wide
central portion;
Stonewall Bank and Ueceta Bank are the most prominent. The conti-
nental elope is generally irregular, displaying numerous bills and
small canyons.
Escarpments as
steep as 40° occur locally; however,
the average declivity of the slope, eliminating irregularities, is
only 2° to 3. ror a
re complete discussion of the geomorphology
of the Oregon continental terrace, the
reader is referred to
BYrne (7) and to U.S.0 & G..S Charts 5702, 5802, and 5902 (43, 44,
45).
In the area studied, the continental shelf extends seaward
from the straight but rugged coastline as a gently sloping plain
(Figure 3). The break in slope which marks the outer edge of the
shelf occurs at a depth of about 90 fathoms.
The shelf is narrowest and steepest in the northern part of
the area, where the overall slope is Q°22' (34 ft./ziile) for 1.6
miles; south
of
Stonewall Bank it widens to 36
miles and slopes
12
Figure 3.
Batbyuetry (7) and 8ample locations.
The contour interval
is 10 fathoms above 100 fathoms depth, and 50 fathoms below 100
fathoms depth.
450O____________
II
112
113
0
114
107
115
tc
2
16
17
lOS
104
/);'
ye
103
3
12
2
24
26/
14
IS
6
17
23 5
18
121
02
29::/:////22
/
120
119
9
BATHYMETRY
)
(
I
LOC/\ rios
20
40'
}'
40
41
2(v
Ji1(
39 ,39
42
4
.YAQU
34
37
36
44
45
46
32
47
3
so
52
6263
64
6567
60
69
:T
/ f
44 20'
:J7i:
LSEA BAY
STATUTE
MILES
ESI0J
'4
but 0'lO' (35
ft./mile). Along the shore the shelf is somewhat
steeper to a depth of 20 fathoms, averarinc
Rocky shoals
0037$ (57
ft.Anile).
in this zone are cmnon near Silets Bay and extending
southward from Yaquina }Iead past the Yaquina Bay entrance.
The
resistant rocks composing these shoals are believed to be basic
intrusives similar
to
those of
the adjacent Oregon coast range.
In the southern part of the area, the outer third of the continental shelf is a rough region of rock and gravel only partly
masked by sediments.
Protruding from
the
northern part of this
region is Stonewall Bank, a rock aboal approximately 30 fathoms
high and 115 square miles in area (measured above the 45-fathom
depth contour).
The north-south elongated crest reaches to within
20 fathoms of the surface, and is bisected by a shallow easttrending submarine valley.
Byrne (7, p.
precision depth records across Stonewall
69), from examination of
Bank, suggests
that the
shoal is the surface expression of a north-trending anticline probably produced by
Pliocene or later folding.
Beyond the 90-fathom contour, the continental slope extends
seaward to a maximum depth of nearly 350 fathoms
western corner of the area.
in the north-
The average declivity of the slopes
here is less than 10 (92 ft./mile) discounting irregularities, but
local slopes are coon1y much steeper, up to 1630' (1500 ft./mile)
near Daisy Bank.
Hills, valleys, and shallow basins are the domi-
nant geomorphic features of the upper continental slope.
Some of
the hills have been dredged and were found to be rock-capped.
In
15
general, the topograpity and litbology suggest that the hills had a
structural orgin, and ware modified by deposition below 100 fathoms
and by both erosion and deposition in shallower water.
Teereture Salinity,
Since 1958, the
and
(cygen
Department of Oceanography at Oregon State
University has been collecting hydrographic data from Oregon
coaetal waters. Stations along lines westward from Astoria, Newport,
and Coos Bay are occupied at approximately three-month intervals,
and hydrographic casts made to 1000 meters (545 fathoms), where
water depth permits. Temperature, salinity, and oxyon content of
the water are measured at standard hydrographic depths (0, 10, 25,
50, 75, 100, 150, 200, 300, 400, 500, 600, 800, and 1000 meters).
The Newport hydrographic line (NH) stations are located at distances
of 5, 15, 25, 35, and 45 nautical miles from shore along latitude
44
39.1' north. They provide data control across the central part
of the area of this study. Since large scale water movement and
distribution of properties generally parallels the Oregon coastline, the Nfl data are representative of the water properties in an
extensive area along the coast.
The limits of variation of water characteristics in the area
are set during aur and winter, flydrographic data for January
1961 (rigures Li and 6) show typical winter conditions. Isotherna,
16
isohalinea, and
oxygen isopleths are all neatly
norizontal; beneath
the outface, the water becomes colder, more saline, and less oxygenated with depth.
Areas of low-salinity surface water occur near
shore off the rivera.
When notth and northwest winds prevail during the spring and
sunmier months, surface w5ter is transported offshore, and water
from depth rises to the surface near the
coast.
This upuelling
results in cooler, more saline water near shore than offshore.
Ilydrographic data
a period of
from September 1960
(Figures 5 and 7) following
northwest winds, show the resultant seaward slope of
isotherms and isobalines. The surface water 20 to 40 miles offshore reaches 16 'C during the suir.
Oxygen content of the water
over the continental shelf may drop to 2.0 mi/i at depths less th*n
50 meters during periods of upt.zelling;
few meters
shows values close to
however, water in the surface
saturation--approximately 6.0 mi/i--
throughout the year.
Waves
Waves striking the Oregon coast average less than 2 meters in
height during most days of the year.
There is wide variation about
this average, and severe winter storms, occasionally with winds of
hurricane force, generate much higher waves.
Waves exceeding S
meters may be expected several times each year (32, p. 4).
Marine
National
Consultants, Inc. (32, p. 4) prepared a study of storm waves
from the sector 225° - 315° off Newport. During the 20-year period
17
Fiure 14
Temperature and salinity of the water along the Newport
hydrograph ic 1 mc, January 20
Figure 5.
1961.
Temperature and salinity oi the water along the Newport
hydrographic line, September 11, 1960.
D/STA NCEI
3
(IJAUTICA L
I LES)
/
15
:aa,42.o
1O. 50
:
- 1O.50
C
0
2
uj
k
0
-
/
-
a a -
-
0
0
a
19
Figure 6. thcygen content of the weter along the Newport hydrographie
line
January 20, 1961.
Figure 7. Oxygen content of the water along the Newport hydrographic
line, September 11, 1960.
DISTANCE (NAUTICAL MILES)
L4
---- 6. o
I
25
Liô
I',',
02
mi/i
ZE
21
19k0 to 1960, 16 storms were found which produced waves with deepwater sigz,ificent* heights ranging from 5.8 to 9.k meters, and
significant periods of 12 to 1k seconds (32, Table 1).
Because the currents associated with wave motion are directly
proportional to the wave height, it is just these maximum waves
which muat be investigated for their ability to erode and transport
sediments.
The relationship
x
a cash Ic (y+b)
suib kh
(kx -
gives horizontal velocity at any depth beneath the surface,
he wave characteristics and the water depth (27, p. 367).
iven
Near
the bottom,
-y
then
Li;
cash Ic(y+b)
1.
*Sjgnifjcant wave values refer to the statistical values of the
highest 1/3 of the waves. Ten percent of the w$ves will be at
least 30 percent higher then the significant wave height.
** X
a
horizontal particle velocity
wave amplitude
Ic = wave number = 2 ir /L
Ii
y
x
a
t
L
=
=
=
=
water depth
depth of particle (in negative y direction)
distance in x direction
angular frequency
time
iv: length
22
When the velocity is at wax mum,
cos (lcx - at) = 1,
and the maximum velocity is now Lven by:
wax
Then
h
=
aimb kb
a
SLflb
k
By this means, the greatest depth at
which a
given wave can
Cenerate velocities of sufficient magnitude to move the sediments
can be calculated. According to Sundborg's (39, p. 177) curves of
critical erosion velocities, a 30 cm/sec velocity measured 10 cm
above the bottom is sufficient to erode fine sand and unconsoli-
dated silt and clay. For significant waves 8 meters in height with
a significant period of 13 seconds, approximately the yearly inaximum wave conditions, 104 meters (57 fathoms) is the greatest depth
at which sustained 30 cm/sec velocitiea will occur near the bottom.
Thus, from theoretical considerations, sediments shallower than
about 100 meters would be subjected annually to one or wore periods
of oscillatory bottom velocities of
able to move fine sand,
sufficient magnitude
to be
i1t and clay.
Currents
Currents in Oregon coast&1 waters are variable in manitude
23
and direction.
Throughout the year the California current flows
slu.,gish1y to the south off Oregon and California, but the general
southward drift is normally obscured near shore by local currents
(40. p. 211).
During the eurmr, northerly winds and upwelling
cause strong but inconsistent southerly and offshore surface currents.
With the advent of winter weather and prevailing southerly
winds, upwelling ceases and a north-flowing current may develop
near the shore.
The extent and width of this current is variable
and not accurately known; however, variable north-flowing currents
regularly occur within the area studied during: winter.
Surface and subsurface current dnta were obtained in 1962 using
paractute drogues at a point approximately 55 miles west of Newport
(31).
Drift bottle returns and ship's drift measurements provided
additional data on surface currents.
Surface velocities at the
drogue station ranged from 1.5 cm/sec to 25.8 cm/eec.
direction was seasonally dependent.
Current
A northward component was
generally dominant during winter and a southward component in the
sunmier.
Drift bottle returns indicated similar flow directions
nearer shore, but drift bottle returns can provide only gross eat 1-
metes of current velocittes.
Below 100 meters (55 fathoms) current
measured by drogues were variable and with no apparent relationship
to surface currents.
The modal velocity of currents below 100 meters
was approximately 6 cm/eec, and the maximum velocity was 12.3 cm/sec.
The effect of the sea floor on the subsurface currents is
et knom.
Uowever, the current velocities generally decrease with depth.
24
Since there is no evidence of 30 cm/sec velocfties even at substantial distances above the ocean floor, it is very unlikely that
current velocities sufficient for sediment erosion are attained.
Tides
Because the tidal amplitude averages only one meter and the
continental shelf is narrow and steep, the tidal current velocities
on the continental shelf off 0re.o
are small.
From theoretical
considerations, horisontal velocities due to a tide with an anplitude of one meter should increase from a small value at the coast to
maximum ci approximately three cm/sec offshore (30).
This ctaxi-
mui value wuuld occur at a distance of about 30 miles of fhorc.
Compared to current velocities associated with storm waves, tidal
currents are siial1 and ineffective in influencing the sedimentary
processes on the continental shelf and slope.
S
JI4ENTS
Methods of Saapl
and Ana4rs Lf
Sampling
The bottom
s sampled at 125 locations spaced on a 3 nautical
mile grid over the area.
Sample positions and numbers are shown
in Figure 3, and their locations and depths are listed in Table 4
(Appendix).
All sediment samples were taken in July, 1961, from
the RA Ac, using a Dieta-LaFond
rab swnpltr.
Subsequent
41
dredge hnuie were made on banks and in other places with irregular
bottom topography, and the results were used in conjunction with
precision depth records to locate and outline areas of rock. Eightounce squat
jars were uied to store the sediment samples and retain
the original moisture content.
ieehanical Analysis
A settlin tube (15) was uscd for the mechanical size analysis
of the sand samples. Those samples containin pebbles or very
coarse sand were sievd, using Tyler standard screens. Samples
which contained a uoticeable amount of material finer than sand
were wt-sievud through
a 62 micron screen with a ).2 percent
CaLon (sodium hexainetephosphate) dispersin solution. The fine-
grained portion was filtered with the aid of a bacteriological
filter to remove any dissolved see salts, and was then remixad with
thE Calgon solution and
stirrer.
dLspecsed using a mechanical analysis
Size analyses were then made by the hydrometer method
(4), with the pipette method (25, p. 162) being used to checl
selected samples. aeaults of the analyses were plotted as cumulative curves from which the values necessary to compute
the sedi-
mont parameters were obtained.
Catbonate and Organic Carbon Analyaes
Total carbon content
of the sediments was determined by total
combustion in a Leco induction furnace, coupled with a Leco gaso-
metric carbon analyzer. Carbonate carbon was also analyzed
26
,asometrce1ly, after the
thod described by Curl (12) for marine
plankton or,artisms, and
result8 were subtracted from the total
tue
carbon results to obtain the amount of orenic carbon. The averac
analytical errors were determined to be 3.0 percent in the total
carbon analyses and 0.6 percent in the carbonate carbon analyses.
A correction factor of 1.586, developed empirically by Wakamen (47)
for marine hustus
in sediments from the Gulf of Ma, was used to
convert values of organic carbon
to
total oranic matter.
carbon compounds decomposable by HC1 are
All
iven as their equivalents
in CaCO3 (Fiure 17).
Ueay Mineral Separation
Heavy minerals were separated frost the
total
samples by the
ravity-Lusmel technique. Bromoform (specific gravity 2. 8O) was
usd for the heavy liquid.
The
rains were mounted in Laceside
cement for visual identification.
Feldspar Steinin
A modification of the differential feldspar stainin,
thod
described by Baily and Stevens (2) was used to identify feldsprs.
Grain mounts were made using Lakeside cement. The slides were then
ground to expose the train surfaces for
BtBifljflb.
Althouh 300
grains were counted in each ølide, the abundance of rock fragments
and glauconite pellets impair the accuracy of the analyses. Theae
species are variable in composition and often stain like either
placioclaae or potash feldspar.
27
Texture
Five textural paraxieters--.4ian diateter, percent sand, percent terrisenous sand, * sorting, and alce nesshave been chosen to
illustrate the areal variation of pertical site distribution in
the seent&. Quantities used for
eewneae are the phi
edisn disaeter, sortin;,, and
uree defined by Inmn (22) ..
the treat dissimilarities amon
Because of
sediments, median diameter and per-.
cent sand are sufficient to define the main textural types.
sort in
&th
and sewss. prove valuable in the conparison of the conti-
nental shelf sands with the siailar Oregon beach sands.
The textural
pazameters iaZ each sample are listed in Table 5 (Appendix).
edian Diameter
Generalized isopleths outline the areal pattern of median diameters in Figure 8.
V1ucs range from -0.8W (lJSsmt) in ç:ravelly
areas to 8.5w (0.O02&m) in the clay-silts, with a mode around 2.5
(0, 177uit) in the £nner cont !.nental shelf sands.
Comparison of
riurc S with the bathymetrIc chart Crigurt 3) shows that the sediments become progressively finer as depth increases beyond the 50-
fathom contour; this trend is further emphasized by depth nd median
diameter profiles (F'iure 10).
irre:ularities in the pattern are
* "Terrigencus sand" is used here to denote all inorganic sandsited material other than glauconite pellets.
23
Figure 8.
Phi
dian diaieter of the aediabent.
-o
-o
45°00
I
-o
jo
o
I
/
8.5
3.0
I
/
4.3
I
3.2
/4.0
20
4.2
50
o.o
40
(
.7
30
38
2.4
O
/2.0
3.2
3.4
/
2.6
2.0
44
4.0 ..
32
2.8
2.5
2.3
2.7
2.1
2.6
/
35
2.0
/
/::
::
2.3
fi
MEDIAN
/PHI
D!AMETEi
.7.
roci
24
::
H
4.67.4/73.
2.9
4.1
2.9
YAQUNA BAY
30
29
/6
.6
2 9
2.7
2.4
2.7
)26
2.0
27
26
2.4
2
212408
0 NAUTICAL
(
4420
j..
40
2.6
.
7
1.9
C')
2 5
/28
40-
Tn
,, SILETZ
BAY
3.7
58
7
3
MILES
0
-
I'.,
Figure 9.
Index map for profiles in Figure 10
31
Figure 10.
sand
Profiles of depth; percents of clay-silt1 glauconite
and terrigenous sand; and phi median diaiter.
Dashed
lines indicate areas where locally derived gravels influence
'..he sedixients.
Positions of the profiles are shown in
Ficure 9, page 30.
32
KEY
L..
CI
100
DEPTH IN FATHOMS
200
300
I 0O
% CLY-SlL.T
AA'
PHI MEDIAN DIAMETER
60
40
20
00
1 -2 0
00 H-
-20
C
vv
p
ill
33
caused by the coareer-grained £lauconite concentrations
tinental slope.
on
the con-
horeward of 50 fathoms, the median diameters of
the well-sorted sands (excludin. gravelly areas) appear
to vary ran-
domly from i.6I (0.33Onm) to 2.U0 (0.l44ma), about a mean of 2.1480
(0.lTh), and show
no correlation with either depth or distance
from the beach.
Percent Send and Percent Terrir:enous Sand
The constituents of the sediments can be
roesly ebdivided
into terri,ènous sand, glaeonite* pellet, &nd clay-silt components,
in
each of which may cotapose from 0 to 100 percent of the. saziplc.
addition, locally derived ,ravel may be precnt in any atic..nt, b.t
since it
is generally in close proximity to rock outcrops cnd
believed to be unrelated
portatLon end
to the currently actic procesoo o
trans-
deposition, it is not considered here. In :r&r to
determine the influences
of
terri.enous end authienic constituents
on the texture, the sec1irnta hvc been classified accordin, to
both percent sand,
and, by eubtractin
the percent of
lauconitc
pellets iron each sau..1e, percent terrienous sand. Irea1 distribution
of these quantities crc raped in Fiure
11
end 12, caL
are also plotted on the profiles.
Precnt te rrinous band, as illustrated both by the map and
* The term glauconite is ued here as a purely morphological term
X-ray diffractoram study has shown the mineral
(5, p. 1485).
nature of the pellets
to be heteroenoua (38, p. 81).
34
Figure ii.
Percent sand in the aediaent.
-
4500
2
///I'
50%-"
25%
SI
80
0
0
68
85
0)
/
95
100
SILETZ BAY
/
c
65
83
84
931
fL
tOO
I % SAND
100
ROCK
25%
50:
+ 44 40
40
979
65
YA 0 UI N A
BAY
/39)79 834
57
301
91
67
7
00
89 O)l00\
91
100
ALSEA BAY
STATUTE
(100
L.1.\ ................ ............
44 20
0 NAUTICAL
MILES
MILES
0
10
i .......
c--I
36
Fi,ure 12.
Percent terrienous sand in the sediment.
-o
450O'
-o
tO
-
-o
2
-o
.v
\O
0
0
(V
a)
9
3
24
I
50
/
8)
/
.
43
56
6
::
:,
817
?::
/
r7
OCC
40-2
27
O6//Z
//
40
93/
97
100
98
L
100
r
LJIROCK
100
/
H._440 40
00
58
00
60
7I
37
/
V:°
99
58
49
L
100
78
44
81
9
°
99
70
7
/
95
00
STATUTE
00
MILES
NT4[5 MILES
1
44 20
0
f
iS,
j
4
(.4
38
and the profiles, decreases re .larly with increa8ing depth on the
continental shelf and upper continental slope.
t1ore strikin, how-
ever, is the paralleliari of the terrienous sand contours to the
outer ede ofi the sand zotte which is delineated approximately by
the 95 percent sand contour.
3ediment collected from hi:h areas ofl
the continental slcpc contains less terrienous sand than the sur-
rondin deposits.
Conversely,
laconite is hihly.concentrated on
the huibs, as well as at the shelf de. Both places are areas in
which currents mi2ht be ecpected to hinder or prevent the deposition
of suspended materials. Althou'h laueonite seldom constitutes wore
sample and norially is less than 25 percent, it stronly affects the textural characteristics of the sediment.
than half the
The pattern
distribution appears to be the result of
twu factors; (1) the reular decrease of terri;enotis sand below
2f sand
the O fathou contour and (2) the concentration of
the shelf ede and on rises on the
laueonite at
continental slope, in rc ions
where .iauconite is sparse, the sediments become uniformly Liner in
the seaward direction.
This trend
s illustrated by the cumulative
frequency c rvcs of ociceted samples alon profile B-B' shown in
Fiure 13.
Cly-a Ut Cent
The term "clay-silt" is used to denote all material harin..
particle diameters smaller than 62 microns. Actually the term is
wore refined than its definition implies. When the particle size
Figure 13. Cu1ative frequency curves of selected samples from
profile B-B',
the regular seard decrease in grain
size in a region not greatly influenced by glauconitization.
howin
SAND
/z
/
ILU
SILT
I
0
0::
_____________
TiTiiT
7
75
ClAY
L!J
0
LU
>
H
50
.1
0
25
to
d
0
LU
0
DIALTE1 IN mm
3
IC)
0
6
q
0
0
1
distributions of all the saaples arc plotted on a ternary diarai
according to percent of sand, 3ilt, and clay, it is found that
almost all samples fall very near the line portraying equal parts
clay and silt (Figure 114). Significant variations occur only in
glauconite-rich samples with a clay-silt component lees than
percent
silt.
in
20
which ease the clay is generally more abundant than the
It should be mentioned, however, that the
rather vL,orous
samples underwent
dispersion before analysis. Perhaps particles
which orLinally settled as siit-ized floceules
of clay minerals
and clay-sized fragments, were dispersed and analyzed as clays.
Furthermore, diagenesis may have altered the particle izes of some
ot the finer-grainetl sediment, In extreme cases, such chanea
could be utiicient to destro> the value of texture as an aid to
the interpretation
of
processes of transportation and deposition.
In the saud zone between the beach and the 50 thtboci contour,
the sorting: is excellent, diaplayng an average phi
deviation
of
0.30 end a norl range from 0.20 to about 0.60. Below 50 fathome
the clay-silt component appears, ünd as it increases in abundance
with depth, the de::,ree of sorting. decreases. Predominantly clay-
silt samples from valleys and basins on the continental slope have
ph:. de'iations as bfgh as 7.0. Righly glauconitic sands exhibit
an increase in de,,ree of sorting roughly commensurate to their
increase in median diameter over that of the surrounding sediments.
42
Fiure P4.
Ternary diagram of amounts of sand, silt, and clay in
the sedioent, showing the nearly 1:1 ratio of clay to iilt in
most samples.
The point at the corner labeled "sand" repre-
sents k2 shelf send samples.
C LAY
SAND
50
SILT
U
This may be due to the incorporation of
fine-rained
sediments into
pellets during authigenesis. It is also possible that currents
have winnowed away the silt and cisy in the exposed areas and left
residual deposits of glauconite sand.
Skewness
Skewness, like sorting, is directly proportional to the phi
median diameter of the sediments. in the
sandy zone most samples
have a large negative (coarse) skewness, averaging -0.25
and rang-
ing from -0.74 to +0.20. No relationship La apparent between
skewness and the relatively tioiuogcnoue values of phi median dia-
meter and phi deviation in the sand zone, but in the finer grained
sediments below 50 fathoms, the skewness
becomes positive (fine)
and increases with depth to values between 0.60 and 0.90. Glauco-
nitic sands, unlike the
positively skewed.
inner shelf
sands, are, with one exception,
In glauconitic and terrigenous deposits alike,
the decrease in sediment size acts to increase the positive
skewness.
toundness
The roundness of
sand grains was
determined by visual compari-
son of the complete sand fractions of the samples with Powers' (3L)
roundness scale. Average roundness values decrease only slightly
from subengular for the fine sends of the inner continental shelf
to angular for very fine sand fractions on the outer continental
shelf and upper slope. In no sample arc rounded or
well-rounded
grains abundant.
Quartz grains generally were found to be more
angular than feldspar grains, but were not analyzed separately.
Since no comeon size fraction was used for the roundness determinations, it is poasthie that the decrease in roundness may simply
reflect the fluid dynamics of diminishing particle
than different abrasional histories.
izea rather
Because of the viscosity of
water, fine-grained sediments are cushioned and cannot effectively
abrade one another.
Consequently, the rounding of water-borne
sediments is a function of particle size as well as of duration of
transportation.
Pebbles and cobbles in the samples collected at depths between
27 and 72 fathoms are rounded to some extent.
Two samples at 27
and L8 fathoms consist entirely of subrounded to well-rounded
pebbles and granules.
Below 50 fathoms, the coarser gravels are
angular to well-rounded.
These gravels occur mixed with fine-
grained sediments.
Areal Pattern of Texture
The general textural pattern (Figure 15) reveals that the
textural types closely correspond to depth and, to a lesser extent,
to distance from shore.
Well-sorted, neatively (coarse) skewed,
fine sands cover the inner half of the continental shelf from the
beach to the 52-fathom depth contour.
However, despite the general
conformity of their textural parameters, the sand samples differ
rather markedly from one another in appecrance
Because of the
FL;ure 15.
Sediment type, based on texture and percent of gisuconite.
-
45°00
-
0
fl
44
-c
'J0
CSJ
/
/
)
f-
)
TERRIGENOUS SAND
CLAY-SILT
.
GLAUCONITE SAND
MIXED SEDIMENT
I
ROCK
SEDIMENT
TYPE
30
(
)
0 STATUTE
0 NAUTICAL
I -------------------------- _L
440 20
MILES
10
MILES
10
18
excellent sorting, small deviations from the average median diameter
are quite apparent. These deviations and less evident variations
in sorting and skebstess indicate that the shelf sand zone is quite
heterogenous within the limits of the defining parameters.
Deposits of glauconite pellet sand, outlined by the 50 percent
sand
These
isopletb1
cap protuberances on the upper continental slope.
sediments are positively <fine) skewed and generally poorly
sorted, containing from 5 to 50 percent clay-silt or clay, but
always with lees than 5 percent sand of terri:.enous origin.
Because t[.e lauconite pellets are often medium or coarse sand, the
average phi median diameter of the glauconite
pellet ands is
2.40W (0.190me), slightly coarser than the shelf sand average of
2.M3' (O,l79me).
In the shallow depressions and valleys on the continental
slope, clay-silt is dominant, comprising from 77 to 99 percent of
the sediment. These areas, delineated in rigure 15 by the 25 per-
cent sand isopleth, include very poorly sorted sediments with a
large positive (fine) skew and an average phi median diameter of
7.2w (0.0068 mm).
The sand fraction is composed of very fine ter-
rigenous sand and smell amounts of glauconite.
Between the terrigenous sands of the inner coat inentl shelf
and the clay-silts and glauconite
pellet
sands of the continental
slope, is an area of transition in which the sediments are mixt:res
of the preceding three sediment types. The sand fractions comprise
between 25 and 75 percent of the sediments and are predominantly of
49
terrigenous origin.. The terrigenous portions of the send fractions,
separated magnetically from the glauconite, are unifrizily very fine
sand throughout the mixed sediment zone, except along the shelf sand
boundary.
Except
near the 95
percent sand isopleth, the sand
fractions exhibit a median diameter of 3.60! (O.OSOme), finer than
the finest fraction of most of the inner shelf sands.
Rock outcrops and gravel deposits are scattered throughout the
area. In the southern part, two nudetone protrusions, totaling
approximately 80 square miles in area, have yielded gravel to the
surrounding sediments. Elsewhere gravel and rock are n*rmally con-
fined to the tops of submarine highs. It should be kept in mind,
however, that a three-mile sampling grid is probably much too open
for an accurate portrayal of the distribution of these smeller rock
outcrops.
omposit ion
To facilitate a discussion of composition, the sediments have
been separated into five components:
heavy minerals, and
the sand-sised light minerals,
authigenic minerals; the organically produced
materials; and the clay-silt fraction. Of these, only the first
four readily permit microscopic examination; the clay-silt fraction
demands more refined X-ray and chemical techniques and was less
extensively investigated.
Light rraction Mineralogy
Light minerals constitute
between 86
and
99.8 percent of the
shelf sands and the terrtgenoua sand portions of the glauconite pellet sands, clay-silts, and mixed sediments. &esults of differential
feldspar staining (Table 2) show some variation iu mineralogy
among
the samples. Consistently low qusrtz-ebert/teldspar-rock fragment
ratios, averaging 1.20, indicate mineralogical immaturity. Accord-
ing. to ?ettijohn (33, p. 509), a quarts-chert/feldspar-rocl.. f ragment røtio of 1.2 is the average value for graywacice sandstone,
and a ratio of 1.1 is the average for aricosic sandstone. The prevalence of feldapars over tock fragenta places the sands well
within the norwal aricose composit ion range,
Williams, Turner, arid Gilbert (8, p. 293).
as diagrammed by
No systematic miner-
alogical varIation is noticeable along the eo8st, but potash
feldspar decreases markedly in a seaward direction along profile
B-B'.
The quartz grains are generally unweathered, angular crystal
fragzmnte, rarely rounded and almost always uuigranular. Chalce-
donic varieties are present but uncon.
øny of the shelf sands contain from 5
to 10 percent feldspar
grains which hew been weathered to a dull to bright yellow or
orange color.
Often these are the larger and more rounded grains
in the sample. Kulm (26) Ms studied similar grains from occurrences in the beach and dune sands near Yaquina Bay and finds them
Sample No,
22
24
26
28
34)
32
69
84
Ave.
Quartz
39.5%
51%
57%
57t
47%
43%
65%
56.5%
51.6
Plagioclase
32.5
24
26.5
30
37.5
31.5
12
33.5
28.3
K-spar
24.5
11
9.5
5
7.5
18.5
12
6.5
11.7
2.5
6
6.5
4
5
1].
3.5
5.2
3
1.5
1
1.5
Rock
1
Spicules
Unkncm
7
1
Qtz + Chart
.66
1.24
.5
1.34
1.46
3
.94
1.4
4
1.8
.81
1.86
Feldspar + Rx
Table 2. Mineralogy and mineral ratios of 8 samples,
determined by differential feldspar staining. Samples
22, 24, 26, 28, and 30 are from profile B-B' (Figure 10).
1.30
1.20
52
to be predominantly plagiocl.ase feldspar. Small amounts of potash
feldspar, chart, and volcanic rock fragumnta also may appear yellow.
The source of the yellow
grains is apparently the Pleistocene
terrace deposits along the coest, from which much of the modern
beach sand
is being derived (26). Although weathered feldspar
grains are abundant in most of the shelf sand samples, they are
conspicuously absent from the very find sand fractions offshore
and are uncoimnon in the finer shelf sand samples.
iock fragu*nta in the light fraction are most coemonly aphani-
tic igneous rocks reseuling basalt or audesite. Similar fragnta
with higher proportions of Easfic minerals are abundant in the
heavy fractions. Sedizaentary rocic fragments are not often recognized in most samples, but sediments near submaxine outcrops of
mudatone may contain large quantities of rounded mudatone fragments.
Heavy Minerals
Heavy minerals were separated from the unsieved sand fractions
(>0.062 mn) of 27 samples, including all of the samples along profiles A-A' and B-B'. Abundance of heavy minerals varies from 0.25
to 102 percent of the total sand fraction, but recalculation on
the bsais of terri,enoua sand alone increases sane of the values,
expanding the range to 0 25 to 13.6 percent (Table 6, Appendix).
The
shelf sands are
comparatively low in hea/y mineral
averaging 2.1 percent.
In this
content,
respect, the shelf sands are 8O-
what unlike the adjacent becb sands, which are considerably richer
53
in heavy minerals.
Kuhn (26) finds an average heavy mineral con-
centration of 3.5 percent for lLi samples from the lower foreshore
along L,5 miles of beach near Yaquina Bay and consistently higher
values for sands from the adjacent dunes.
sand fraetion
Farther offshore, the
of the fine-grained aediwents are considerably finer
than the shelf sands and contain higher percentages of heavy
minerals, averaging 7,0 percent.
The exceedingly varied heavy mineral suite includes sz
mineral species and varieties (Table 7, Appendix).
LQ
Rowever, many
of these are z-are, and fewer than 20 species occur consisteutly in
quantities Large enour;b to be of value in sediment correlations.
The dominant minerals are amphib
ea, pyroxenes, epidote, opaque
minerals (principally magnetite), leucoxena, and highly weathered
mineral grains.
Although a few well-rounded grains are present,
notably sphene and diopside, the heavy mineral grains are normally
angular to eubrounded.
In most sample., the heavy mineral grains
are only slightly more rounded than the corresponding light mineral
grains.
Severe alteration of the unstable minerals is coen.
Along profile B-B' grain counts show a seaward increase of amphibolee, mostly horablende, at the expense of garnet, byperathene, and
opaque minerals (Figure 16).
in
No systematic north-south variation
mineralogy was noted.
Authienic Constituents
Minerals which are believed to be autbigenic constitute an
important part of the sediments below a depth of 55 fathoms.
They
54
Fi,urc 16.
Diagram of relative proportions of heavy minerals in
samples from profile B-B', illustrating the seaward increase of
amphiboles at the expense of hypersthene,
minerals.
arnet, and opaque
27.7 MILES -
1*
30
SAMPLE
27
N1JMDEi
25
22
AUGITE - DIOPSIDE - ENSTATITE
EPIDOTE FAMILY
OPAOUES
OTHER
ROCK FRAGMENTS - LEUCOXENE - VJEATHERED GRAINS
H Y PER S
AMPHIBOLE S
GA R
2.8
HEAVY
5.8
MINERAL
6.7
PERCENT
Ku
(.11
s-fl
56
1moat exclusively as green g].auconite pellets, comprising up
occur
to 91 percent of the aediment and inparting to it en olive-green
color.
Phosphorite ihich is a coon suthigenic mineral on banks
and ridges off the coast of southern California (16, p. 68), is
sparse in this area.
thia aectio
The only knows occurrences of phosphorite on
of the continental terrace are as thin coatings on
calcareous rocks dredged from the top of Daisy Dank (4i° 30 'N,
125° 02'W).
Limonite, often authigenic in nearshore marine environ-
ments (1, p. 20), is present in the heavy mineral fractions of some
of the sends, but in such smell quantities that its oriin has not
been determined.
T
distinct
types of glauconite pellets are abundant in the area.
(mc, pos-
Nature and Caspaition of G1aucoite Pellets.
sibly Galliher's (19, p. 1359) "firm type glauconite", is dark
green to nearly black, compact in appearance, but with welldeveloped radial cracks and
ri1leted surfaces.
substance often fills the radial cracks
A libter green
nd surface concavities.
This lighter colored material is most likely due to weatharin
of
the pellet or to the subsequent diagenesis of finer material which
packs into the cracks during alimentary passage through deposit
feeders.
Maximum dimensions of the dark green pellets are normally
0.010 to 0.300 ma.
The smaller of these may be spherical or ovoid in
shape and devoid of cracks.
The second type of glauconite ccnsistø of spongy-appearing pale
green to yellø*-green pellets, which in most samples outnumber the
57
dark green pellets. The light colored variety is generally a1igLtly
smaller than the dark green variety in any one sample, but its total
size range is from approximately 0.0k to 1.5 n. Radial cracks are
less common and generally do not cause lobate surface textures.
The grain surf*cea are quite rough and porous, and the grains are
distinctly softer than the dark green variety. Galliher (19,
p. 1359), describing gleuconite pellets dredged from similar depths
in Monterey Bay, California, also notes "spongy type glauconite",
which he compares chemically with "firm type glauconite". Chemical
analyses show "spongy type glauconite" to be extremely high in
Fe203.
Inasmuch as the morphology and color of the
lets are quite variable, variation
in
glauconite pel-
the mineralogical compositions
of the two types might be expected.
Stump (38, p. 81-82) has made qualitative analyses of several
sediment samples by X-ray diffr*ction (Table 3). Samples 60 and
110, which consiat almost entirely of
glauconite pellets of the
dark green variety, proved to be largely interlayered or disordered
glauconite clay mineral., with smeller
producing the combined
parallel those of
illite-glauconite-.mica peak.
These results
Burst (5, p. k85), who finds glauconite pellets
from ancient deposits to be composed of
minerals.
amounts of the minerals
two distinct glauconite
In order to determine accurately the mineralogy and
mineralogical variations of the authigenic
materials, chemical
analyses and X-ray diffraction studies of monomineralic separations
are needed.
58
Samples 13, 26, 94, 95, 118 (less than 24 percent
glauconite pellets)*
(1)
Silica
(2)
Keolinite
(3)
Expanding montmorillonite class
(4)
Chlorite
(5)
Illite and/or glauconite and/or mica
Sample 6 (contains locally derived pebbles glauconite pellets not analyaed)*
(1)
Kaolinite (small)
(2)
Expanding montzuorillonite class (large)
(3)
Chlorite (small)
(Li)
Illite and/or mica
Sample 60 (90 percent glauconite pelleta)*
(1)
Silica (small)
(2)
Mixed layered glauconite
(3)
huts and/or glauconite and/or mica
* Cozents in the parentheses are the writera.
59
Sample 110 (91 percent glauconite pellets)*
(1)
No evidence of silica
(2)
No evidence of kaolinite
(3)
Mixed layered glauconite
(4)
Illite and/or glauconite and/or mica (small)
Table 3.
Composition of several samples of glauconitebearing sediments, as determined by X-ray
diffraetogrsm study. "Small" refers to
the sise of the diffractogran peak, which
is affected by the diffraction intensity,
as well as by the amount of a particular
mineral (After Stump, p. 81-82).
* Gonents in the parentheses are the writers.
60
Distribution of Glauconite Pellets. The distribution of gisuconite pellets is related to the submarine topography and to the
sediment type (Figure 17). Concentrations of glauconite favor topo-
graphic highs and slope breaks. Banks and smaller rises on the
continental slope bear sands containing up to 91% glauconite pellets
of the dark green type. Along the outer edge of the continental
shelf, concentrations between 10 and 35 percent are coon. Elsewhere below 55 fathous, concentrations of 10 percent, usually of
nixed varieties, are maximum. Most of the clay-silt sediments deep
on the continental slope contain less than two percent glauconite
pellets. Glauconite is ordinarily absent from the well-sorted
sands
shoreward of the 52-fathom contour. Rover, near Stonewall Bank
and along the
outer edge of the
five percent spongy type
sand zone, concentrations of
up
to
glauconite are found.
The pattern of g].auconite
pellet
distribution in the area
closely resembles that found by Emery (16, p. 212) and Pratt (35)
off California and Lower California. There, glauconite is concen-
trated on the crests and upper slopes of banks, ridges, seamounts,
and portions of the continental shelf and slope - regions where
detrital deposition is slow or absent (35). Cloud (10, p. 491)
notes that glauconite forms
under
similar conditions throughout the
world.
Formation of Glauconite Pellets. In the literature, three
theories of blauconite
pellet
formation prevail:
61
Figure 17.
Percent
1auconite in the sedjinente.
-o
45O0
-
-o
-o
I9/\
-
t_o
2
I')
-o
'0
0
C
7
Q
17
(0
0
5
01
61
2
4
2
33
2
0
%
/
GLAUCONITE
2
0
0
7
5 %
4
40
7
/
1
L
4
3
3
2
I
0
0
0
°'
2:
c
8
I9
22
3j
;
MILES
0 STATUTE
0 NAUTICAL
5
MILES
I______________I ------------
44C 20'
10
10
63
(1)
filling of
foraminiferal cavitica (16, p. 213) or the
axial tubes of sponge spicules (35) with fine sediments and subse-
quent authigenesie of the casts to glauconite;
(2)
conversion of fecal pellets
(14.1,
p. 509), rock fragments,
or other pelleted materials to glauconite; end
(3) alteration of
detrital silicate mineral grains (3, p. L82),
particularly biotite (19, p. 158), to glauconite.
Evidence for each of these has been found in this area, and in so
samples glauconite grains in various stages of formation can be used
to outline a particular sequence of formation. Rowever, most grains
cannot be correlated confidently with a unique mode of formation,
and it is difficult, therefore,
dominant one.
to
estcblisbwtLieb mechanism is the
In view of the different environmental codition
end diverse sediment types in which glaucanite pellets appear to be
forming, it hou1d be expected that the authigenie processes will
differ somewhat from area to area.
Early stages of the biotite-gLauconite transformation
by Galliher (19) are found in
the mixed sediments on the
described
continental
shelf. These sediments contain small amounts of biotite in flakes
100 to 300 microns across and approximately 20 to 60 microns thick,
During autbigenesis the brown of the biotite changes to green,
sometimes progressively from the edges of the flake toward the
center. The flakes concurrently expand to perhaps twice their
original thickness, though retaining the micaceous cleavage, and
become soft and easily
powdered.
Beyond this stage the
sequence
64
is broken. The caterpillar-shaped grains illustrated by Gel]iber
(19
p. 1362)
are care; the grains more cosraonly exhibit typical
radial cracks with no hint of parallelism. Possibly, as Galliher
su,gasts, the softefled flakes are molded into fecal pellets by
deposit feeders, end
assume an ovoid
that although a small amount of
shape.
it is felt by the writer
glauconite is being formed in the
area by biotite alteration, the scarcity of biotite in the sediments
precludec considerat ion of this process as a major contributer to
the high glauconite pellet coDcCnttioa.
In the clay.silte on the continental slope, small ovoid lauconite pellets are forming from the feesi pellets of deposit feeders.
These fecal pellets, particularly abundant in sample 111, are nonsculptured ovoid
pellets 70 to 120 microns in J.ength and composed
of clay..eilt bound by organic secretions. !iost are soft,
but some
have hardened internally and begun to change color from pale
greenish-brown to yellow-green or green. From this point a sequence
of pellets can easily be assembled which shows the gradual tram.-
formation from fecal pellet to typical pale green glauconite pellet.
Nany of the glauconite
pellet.
include silt-sized fragments of dark
green glauconite, quartz grains, or other detritus, thus strengthening the argument for their authigencais from the fecal pellets of
non-selective deposit feeders.
it ii apparent that the
transformation described is the donii-
nant mechanism of glauconite format ion in some of the finer sed i-
ments. Elsewhere the fecal pellets are leae abundant, and it
65
beccz difficult to evaluate the importance of the mechanism for
the area as a whole. In shallower water around Stonewall Bank a
similar alteration process affects the numerous mudatone fragments,
although its progress cannot be traced as confidently as can the
fecal pellet conversion.
A third and
certainly minor process contributing to the accumu-
letion of glauconite pellets is the authigenesis of clay-silt casts
in the axial tubes of apone spicules. Only small portions of the
spicules, themselves rather
casts indicate by their
Used. However, it is
scarce,
contain casts,
but many of the
reen color that they have been glauconidoubtful that the chemical
forces involved
in glauconitization are powerful enough to cause the enclosing
spiculea to burst and yield the casts to the sediments.
Organically Produced Constituents
Oranie4atter. The amount of organic matter in the sediments
is closely related to the texture, increasing from essentially none
in the shelf sands to nearly six percent in the clay-silts of the
continental slope basins and valleys. Figure 18 illustrates the
striking linear relationship between organic matter and phi median
diameter in sediments with median diameters greater then 6
(O.Ol6zzi).
0
The high organic contents of sediments finaL'
6
are unrelated to variation in median diameter, depth, or sample
position, In general, the distribution of organic matter follows
cloecly the typical pattern for nearaLiore areas described by
66
Figure 18
Percent organic matter in tht eedimenta.
-o
45°00'
-o
'0o
-o
-o
I'.)
-o
I
I
o\0
I2\\>J2,/4
/
._2.5
.4
/9
8
9
1.9
--
2.0
.9
/ o.s
II
1.6
:/
25/
114
40
2.3
3
BAY
0)
c'I
':.
/
50'
/SILETZ
03
k
))
/0 OGAN1C
MATTER
0.4
çPJROCK_
II
44
I
I
40
I
1
6
YAQUINA
BAY
06
A
)
0/
--:7
/
AL S A BAY
05
[
/09
/
0 NAUTICAL
/
_I____
44020'
MILES
0 STATUTE
-
-
MILES
I
to
0
--------------
0
I
68
Trask ('42), of up to 2 or 3 percent on flat parts of the continental
shelf with
greater amounts in bains
and protected areas.
The nature of the oranic mcterial has not been determined,
but because of the
distance of the
tributing streams and regions of
organic-rich sediments from con-
attached
plants it is assumed that
the organic matter is predominantly decomposed pelagic detritus.
few porous black
etained in
the
A
particles, believed to be carbonaceous were
sand fractions of some fine-grained samples and are
thought to be bits of ash produced by forest fires or by the extensive forest products industries of western
Oregon.
Kuim (26)
finds
up to 50 percent fresh and burned sandust in the modern sediments
of Yaquina
Bay and assumes it
vicinity of the bay.
to be waste from lumber mills in the
us wood waste materials have densities near
that of water when they are partly or completely water-saturated,
It does
not seem unreasonable
arid dispersed, finally
that they can be carried out to sea
to settle in
the
relatively
quiet water of
the outer continental shelf and continental slope regions.
Calcium Carbonate, Although true calcareous sediments are not
found in the area, moat samples contain very smell amounts of mol-
lusk shells or Porareinifera tests as well as fine-grained
material.
calcareous
The nature of the fine-grained material has not been
determined. Figure 19 illustrates the irregular increase in carboate content from less than 0 1 percent in the inner continental
shelf sands to more than 1.0 percent in deposits on the upper
Fiure 19.
Percent calciLwt carbonate in tht sedints.
-o
45°00
-o
-o
202
50
E4
0.3
0.0
.5
0.8'
0.3
0.2
03
0.4. 04
0.9
.
0.6
0.4
0.5
40 -
8.0
0.0
% CaCO3
0.0
0.0
Lii ROCK
0.1
0.3
0.2
44° 40
.3 1
.2
0.8
0.7
0.4
SILETZ BAY
03!
1.7
-o
IO
2
eJ
:
YAQUNA
?L.BAY
.
1)1
0
06
0!
146
30L
....
.0.3
14.0
-
0.4
4.5
7.3
\
.
3.5
0.6D Q\o
O.0.O
44020
0.0
40
01
ALSEA BAY
0
0.0
0
STATUTE
NAUTICAL
5
MILES
5
MILES
10
10
71
continental slope *
Becauee o
the unevaluated contaminatinb effect
of limestone and calcareous rudtone fragments derived from the subetrate, the carbonate ena1yee
and izopleth rasp cannot be relied
upon as en accurate inde: of the organic calcareous contribution to
the sediments.
The highest perntaree of ca Ic ium carbonate, up to 17 3 percent, occur in a zone of irregular carbonate distribution around
Stonewall Bank.
Here, Foreminifera tests are concentrated in the
sands and finer sediments of the predoiinantly rocL.y and grevelly
area.
Caleareous mudatone fragments are also abundant in many
samples.
Outside the areas influenced by the rocky regions the sea-
ward increase of carbonate content is more consistent and appears
to be related only to distance £ run shore.
the continental slope
coarse and fine sediments alike contain 1 to 2 percent calcium
carbonate, nearly all consisting of calcareoua rock fragt nts or
fine-grained material.
Organic 3ilic.
Foraminifera are rare in these sediments.
On the continental slope and the outermost
part of the continental shelf, sand-sized siliceous sponge spiculea,
radiotarian tests,
ud diatom frustulea constitute up to 32 per-
cent of the earnples.*
Spon,e spiculee are the dominant component,
comprising, more than 90 percent of the organic silica in most
* Percent of picu1e was determined by grain counts uncorrected
for the size of the particles. T3ecause the spiculea normally
are larger than the terrigenous and autbigenic constituents, the
weight percent of organic silica may be up to three times larger.
72
samples.
They are composed of opal, although the axial tube is
often filled with anisotropic material simLlar to and probably
derived from the eurroundin
mud.
Calcareos sponge apicules ware
tentatively identified but are exceedingly rare.
Monaxons, tetraxons,
triaxons, spherasteEs, desmas, and simple to complex united forms
(37, p. 76) are eli. coumton, the proportion of each varying randomly
from sample to sample.
Spherasters, quite uniform in sic, in the
shape of triaxial ellipsoids with the length of the long. axis
approximately 90 microns, are invariably noted wherever other Cvi:ule3 are present.
Other spicuic forms, almost always broken, vary
in size, averaging approximately 90 microns in diameter and ranging
in length from S3 to more then 1500 microns.
of the
The broken condition
picules suggests that they may have been passed repeatedly
through the digestive tracts of organisms, probably both spongeeating fish end deposit feeders.
in addition to sponge spiculea, several genera of radiolaria
and diatoms ware observed in the sand fractions of most of the continental slope samples, but in quantities far less than might be
expected considering the fertility of the surface water.
Diatoms,
by far the most prolific organisms in the sea, are particularly
rare in the
edimento.
?robably this is due to re-solution of the
frustules in the water colum and on the bottom (28, p. £151).
1GIN CF THE SWI}1fT PATTERN
The fact that an
orderly pattern appears in the areal diatri-
bution of sediments indicates that systematic processes w.ust control
the deposition and post-depositional
modification of the sediments.
Lour factors contribute to the present sediznt distribution*
(1)
2)
the supply of modern sediments,
th pattern of sediments uherite4 from forner conditiona,
(3)
a.itbigenic processes, and
(Li)
physical processes in the ocean.
The first two
nd in a sense the third, concern the types of
materials; the physical processes distribute these materials into
the final depoøitional pattern.
Compared to deltaic, estuarine, and other nearshore marine
environments, the continental shelf in this area receives only a
small supply of sediments from the land.
Sediment-free banks,
clauconite concentrations, and the absence of cisy and silt in the
to . ipth of 2 fathow.s al] attest to the relatively low
sedimentary influx, in winter, some suspended silt and clay is
introduced by the adjacent coastal rivers, and to a lesser extent
by coastal erosion.
Send cannot be
carried in suspension by the weak oceanic cur-
rents, btt is restricted to transportation along the bottom.
7k
In the beech zone, both lateral movement by longshore currents and
transverse movement by waves and rip-currents are active.
Where
the water is deeper, only oscillatory, wave-induced currents arc
capable of transporting send.
Sand agitation and transportation can occur to considerable
depths on the continental shelf.
Off La Jolla, California, lanan
and Ruank (22, p. 22) have measured cyclic changes of the sand
level in water up to 70 feet deep (the deepest station sampled).
These changes occurred throughout the year.
If waves contribute
to the process, the larger winter storm waves off Oregon should be
expected to move sediments at much greater depths.
The particle
velocities near the bottom, a. calculated above for yearly
xim
waves, are capable of moving fine sand throughout the zone of shelf
sand.
The meny incalculable factors in the sand budget of the
however, preclude accurate estimates of
net offshore or onshore
transportation of
zone,
to be eli,ht.
aand.
Below the surf
beach1
sand transport is apt
At 52 fathoms, the depth of the transition from
clean sand to silty sand, agitation of the sediment is probably only
sufficient to prevent finer particles from filtering down between the
sand grains.
If the water motion were stronger, the
transition zone
would probably be pushed seaward. Considering the errors inherent
both in wave atatiatics nd in particle velocity calculations near
the bottom in shallow water, the theoretically determined 57 fathom
depth limit for erosion by oscillatory, wave-induced currents
75
compares remarkably well with the 52 fathom depth of the transition
from well-sorted sand to silty sand.
Another sotrce of terrigenous material is submarine erosion of
rock outcrops. Accomplished chiefly by
process has been noted
burrowing organisms, the
in mudstcsies dredges from
Stonewall Bank and
nearby areas. Althou
possibly of local importance in regions protected from sedimentation, submarine erosion is probably not a
significant factor in the total sedint budget of the area.
Organisms contribute much less detrital material to the area
than do terrigenous sources, as is indicated by the paucity of calcareous and siliceous skeletal
remains in the seimants. Although
life is abundant both in the overlying waters and on and beneath
the sea floor, most of the organisms apparently do not construct
massive, easily preservable skeletons. However, the organic contribution 18 important
in that
it affects the chemical environment
in the sediments. Decomposing organic matter ordinarIly causes
weakly to strongly reducing conditions in fine-grained sediments.
These canditiona control the kinds of autbigenic processes and the
rates at which they will take place. Also, the deposit feeders
produce fecal pellets, a
further aid
coon glaconite source material (41), to
authihencais.
Autbigenic processes modify the deposits in approximately half
the area. The effect of glauconitization is to coarsen texture,
forming sands and silty sands where physical processes
alone, could
16
not have emplaced them.
Thus the rock-capped hills on the upper
continental elope display glauconite sedisents which are tcxtLrcUly
similar to the predowinaatly terrigenous sediments of the conti-
nental shelf,
but
are entirely unrelated in origin.
rJttere physical processes are strong, the chemical processes of
autbigenesis become aecoda, and the aedimeut
in the depositional environ-
the amount of physical energy inherent
ment.
textures reflect
Several parameters can be used as indices to environmental
energy; among theee are sorting,
median
diameter, skewness, and in
gravels, roundness. In the area studied, decreasing values of
sorting and median
diameter show a general decrease in
depth becomes greater
and the
energy as
sediments grade acaward from well-
sorted sands to essentially unsorted clay-silts.
Some sediments do not
fit this
pattern, however, and their
origins must be explained otherwise. An example is seen in the mudetone gravels found in 40 to 62
fathom depths near Stonewall Bank
and the rock plain southwest of the bank.
and occasional
The rounding
sorting of these gravels presuppose a high-energy environment of
deposition, yet they lie far below the
depth of vigorous
wave action.
Comparison of sample positions with local geomorphology eliminates
the possibility of emplacement by mass movement or turbid flow
a lon. the bottom from shallow water, and Pie istocene
glSC jet ion did
not develop extensively enough on the Pcif ic coast of Washington
and Oregon to have caused transportation by icef lows of such large
77
amounts of
In addition,
gravel.
the consistent similarity of the
gravels to the underlying mudatones
further
strengthens the argu-
ment that the deposits were eroded, rounded, in some cases
sorted,
present
the only
and deposited near their
processes known
to be capable of
position.
In the
ocean,
imparting such large amounts of
energy to the sediments era those acting in shallow water.
fore, even though
can be concluded
shallow-water
unknown, it
the geometry of the gravel bodies is
that they are probably products of a high-energy,
environment which existed
stand of sea level.
Another deposit
during a Pleistocene lower
which may not have formed in
its present environment is the terrigenous
tinental shelf. Pound in depths up to
excellent
There-
sorting
sand on the central con-
514. fathoss, the sands display
and negative skewness, characteristics normally
associated with beach sands (18).
beach sands collected on the
with
Comparison of the shelf sands
adjacent coast
(6, 26, and 36) shows
them to be both texturally and mineralo.ically similar.
Individual
heavy mineral abundances and quartz-feldspar ratios, both variable,
fall in about the same ranges, and the yellow weathered feldpar
grains which are abundant in most shelf samples are also a coimnon
constituent of
the
beach, dune, and Pleistocene marine
terrace asuds
near Yaquina Bay (26).
The occurrence of these apparently shallow-water sand and gravel
deposits at their present depths is most easily
vious relative lowering of sea level.
p. 258; 14), the Wisconsin
explained by a pre-
According to Curray (13,
glacial advance lowered the sea to -65
78
fathoms, 18,000 to 20,000 B. P. (before present). The Holocene sea
level rise was slow
and
unsteady for several thousands of years,
arriving at its present position 3000 to 5000 years B. P.
A sea level drop of 65 fathoms would place the sea well, below
the present deposits of sand and gravel.
At present, the Oreon
beaches are amply supplied with sand, as is evidenced by the many
dunes which are forming behind them.
Coastal energy is high.
Assum-
ing that similar conditions have existed since late Pleistocene, the
rising
Ilolocene sea should have built sand and
advanced.
It is
this tranagressive
modern sediment pattern has
Part of
modified.
the
inherited
beach deposit
upon which the
been developed.
pattern of sediments has been covered or
Any Pleistocene shallow water deposits which may have been
formed below 52 fathoms have been
sediments).
ravel beaches as it
covered
by recent silty s*nd (mixed
The shelf sand zone probably remains much as it was at
the time of deposition, but at least the inner part is continually
being reworked
by waves.
The true relict sands may lie only in a
narrow belt at the seaward edge of the sand zone.
Because the offshore sands cannot be distingtished front the
modern beach sands, it is not feasible to delineate the boundary
between modern and relict deposits.
As shown above, some agitation
of the sediments occurs to a depth of 52 fathoms, but the maximum
depth at which significant amounts of sand are actually transported
across
the sea
floor is unknown.
Possibly continuous transition
79
exists from the mobile modern beach sends to
the stable
relict sands
on the central continental shelf.
As water depth increases, the more feeble bottom currents lose
the ability to sort and transport the deposits as they form.
Authi-
genesis becomes less effective in alterini the grain size distribution.
Thue, where neither physical nor chemical processes are
important environmental factors, the resulting deposits are fine
grained, poorly sorted, sud relatively rich in organic material.
Separating the areas of terrigenous sands, clay silts, and glauconite pellet sands, is the arbitrarily
ments.
Here
fine-grained sediments
defined zone of mixed sedi-
are deposited, but currents,
authigenic processes, and organisms supply moderate amounts
sized particles.
of sand-
Thus, the heterogeneous nature of the sediments
results from two factors, the supply of
diverse sediment types and
the interplay between chemical and physical processes in the alteration and distribution of the materials supplied.
Environments of non-deposition are present in scattered localities throughout the area.
Normally they are confined to topographic
highs, such as Stonewall and Daiay Banks, but even low irregularities
on the sea floor may be sediment free.
The exposed areas are usually
rocic, although gravels may be preaent also.
On Daisy Bank1 thin
phoephorite coatings, indicative of non-deposition of detrital sedi-
ments, have begun to form on gravels at 80 to 90 fathom depths.
Accordin. to Hjulstrom (l94.5), current velocities of less than
0.5 cm/sec are sufficient to transport clay and silt, though erosion
of the same materials requires currents many times stronger.
Since
Maughan (31, p, 30) has found currents up to 14 cm/sec at 100 meters
(55 fathoms) depth and 7 cm/sac, at 1000 meters (550 fathoms) farther
offshore, it is believed
these currents may
lation of clay and silt in
be preventing the accumu-
the areas of non-deposition.
SOURCE OF T
SEDIMEFS
Inferences regarding the source of the shelf sediments can be
made from their mineralogy.
However, the mineralogy of detrital
sediments produced by the various geologic provinces of the bordering
lands has not been studied in sufficient detail to allow precise cor-
relation of individual minerals with their source
now in progress by the Oregon State University
Oceanography on the detailed mineralogy of
coastal rivers from the Kiamath River
information will
greatly aid
to
rocks.
Work is
Department of
sediments carried by the
the Columbia. The resulting
future research on the
source of sedi-
ments of the continental shelf and slope off Oregon.
The high content
of unstable minerals in the light fraction
suggests that much of the sediment has been derived from igneous or
metamorphic rocks.
basalt or
andesite,
Most of the accompanying rock fragments are
augesting derivation from the Oregon Coast
Range, the Cascade Mountains, or the Columbia Plateau.
abundant heavy minerals (augite, bornblende,
The most
hypersthene, diopaide,
and epidote) occur in basic to intermediate intrusive and extrusive
rocks, which crop out throughout the Pacific Northwest.
Small amount
83.
of high-grade metamorphic minerals (sillimanite, glaucophane, kya-.
nite, and atauro1it) indicate some sediment contributions from the
metamorphic rocks of the Iaamath Mountains, the Rocky Mounts ins,
and/or the northern Cascades.
St11ARY
Well-sorted, fine-grained subangular sand covers the continental
shelf between latitudes
£44°20' and 4448' north to a depth of 52
fathoms. Below this depth the sediments grade uniformly to silty
clays on the upper
continental slope.
Rock
outcrops, p,ravel, and
coarse sand are present in the vicinity of Stonewall Bank, a1on
the
shelf break, and on the shoals rising from the upper part of the
continental 8lope.
Mineralogical iAuaturity
characterizes the
nearaLtore sands and
the sand fraction of the If iner-grained offshore aeaiment.
nite, calcium carbonate, and organic matter are
Glauco-
essentially absent
from the sands, but may be abundant in the finer-grained sediment;
glauconite up to 91 percent of the sample; calcium carbonate, 1k
percent; and organic
matter, 6 percent.
Small quantities
of
organic
silica, mainly sponge spicules and radiolaria, are irregularly distrthuted in
the fine sediments.
Textural considerations suggest that the nearshore sands were
deposited in a high-energy littoral environment *ud may be a
Rolocene transgress ive deposit.
Wave action prevents deposition
82
of silt and clay and is probably reworking most of the sands.
although the glauconite-rich sediments on the
off shore
shoals and at
the edge of the continental shelf attest to little or no deposition,
the shallow depressions
and sea valleys of the upper
slope appear to be actively receiving sediment.
continental
83
SI DLI 0GAPIIY
1.
Alexander, A. E.
continental she]
2.
BeLly, Edgar U., ad RoUin E. 3tevena. Selective staining of
K-feldspar and plagioclase on rock slabs end thin sections.
American Mineralogist 45:1020-1025. 1960.
3.
Baldwin, Ewert N. Geology of Oregon. Distributed by University
of Oregon Cooperative Book Store, Eugene
1959.
136 p.
4.
Bouyoucoa, George John. Ditectioni for making mechanical
analyses of soils by the hydrometer method. Soil Science 42:
225-228. 1936.
5.
Burst 3. F. Mineral heterogeneity in "glauconite" pellets.
MmerLean UineraI.ogist 43:481-497. 1958.
6.
A petro6raptiic and petrologic study of acme
sediments. Journal of Sedimentary
Petrology '4:12.42. 1934.
Btx5hnell, David C.
Unpublished research on the sediments of
Corvallis. Department of Oceanography,
Oregon State University.
1961.
Msea Bay, Oregon.
7.
Byrne, John V. Geonorphology of the continental terxace of
the central coast of Oregon. Ore Bin 24:65-7k.
1962.
8.
Byrne, John V. Unpubliahed research on Pacific Northwest
drainage systems. Corvallis. Department of Oceanography,
Oregon State University. 1962.
9.
Byrne, John V. Personal coasunication. Corvallis.
of Oceanography, Oregon State University. 1963.
Department
10.
Cloud, Preston E., Jr. Physical limits of glauconite formation.
Bulletin of the American Association of Petroleum Geologists
42:484-492. 1955.
11.
Cuuininge, Jon C.
12.
Curl, Herbert, Jr. Analysis of carbon in marine plankton
organisms. Journal of Marine Research 20:181-188. 1962.
Recent eatuarian and marine sediments, Coos
Bay area, Oregon. Abstract. Bulletin of the American
Association of Petroleum Geologists 49263. 1962.
81
13.
Curray, Joseph R. Sediments and tistory of Holocene transgression, continental shelf, northwestern Gulf of Mexico.
1n
Recent sediments, northwest Gull! of Mexico.
Tulsa1
American A*sociation of Petroleum Geologists, 1960. p. 221266.
14.
Curray, Joseph R. Late Quaternary sea level: A discussion.
Geological Society of America Bulletin 72*1707-1712. 1961.
15.
Emery, K. 0.
iapid method of mechanical analysis of sanda.
Journal of Sedimentary Petrology 8:105-111. 1938.
16.
Emery, K. 0.
Wiley, 1960.
The sea off southern California.
New York,
366 p.
17.
Pennemen, Navin M. Physiography of the western United States.
14ev York, McGraw-Bill, 1931. 334 p.
18.
Friedman, Gerald fl.
19.
Galliher, N. Wayne.
20.
Gilluly, James, A. C. Waters, and A. 0. Woodford. Principles
of geology. 2d ad. San Francisco, Freeman, 1959. 534 p.
21.
lijuistrom, Pilip.
Transportation of detritus by moving water.
In:
ecent marine sediments: a symposium, ed. by Parker U.
Trask. Tulsa, Society of Economic Paleontologists and
Distinction between dune, beach, and
river sands from their textural characteristics. Journal of
Sedimentary Petrology 31:514-529.
1961.
Glauconite genesis. Bulletin of the
Geological Society of America 46:1351-1366. 1935.
Mineralogists, 1955.
22.
p. 5-31.
Inman, Douglas 1. Measures for describing the size distribution
of sediments. Journal of Sedimentary Petrology 22: 125-145.
1952.
23.
ipman, Douglas L., and C. S. Rusnak. Change in sand level on
the beach and shelf at La Jolla, California. 1956. 30 p.
(U. S. Department of the Army, Corps of Engineers
Erosion Board, Tech. Memo. 82.)
Beach
85
24.
Jarnan, Gary U. 'Recent Foraminifera sad associated sediments
of the continental shelf in the vicinity of Newport Oreon.
Master's thesis. Corvallis, Oregon State University, l962
Ill numb. leaves.
25. Krumbein, W. C., and F. J. Pettijohn.
petrogrnphy.
Manual of sedimentary
New York, Appleton-Century-Croft., 1938.
549 p.
26.
1ulm, Laverne U. Unpublished research on the sediments of
Yaquine Bay, Oregon. Corvallis. Department of Oceanography,
Oregon State University. 1963.
27.
Lamb, brace.
Uydrodynamics
6th ed.
New York, Dover, 1945.
738 p.
28.
Lewin, Joyce C. SiUcificstion, In: Physiology and biochemistry of algae, ed. by Ralph A. Lewin. New York, Academic,
1962. p. 445-455,
29,
Geologic map of the United States.
The Geographical Press, 1941. 1 sheet.
30.
ticAliater, W. Bruce.
3].
Naughan, Paul McAlpine *
Lobeck, A. IC.
Department of
New York,
Personal ccissunication. Corvallia.
Oceanography, Oregon State University. 1963.
Observations and analysis of ocean
currents above 250 meters off the Oregon coast. Master's
thesis. Corvallis, Oreon State University, 1951. 49 numb.
leaves.
32.
National Marine Consultants, Inc. Oceanographic study for
breakwater sites located at Yaquina Bay Siuslw River, Umpqua
River, and Coos Bay, Oregon. Santa Barbara, 1961.
14 numb.
(Prepared for U. S. Army Engineers
leaves, 5 maps, 6 tables.
District, Portland, Oregon).
33.
Pettijoha, F. J.
1957.
Sedimentary rocks.
Zd ed.
New York,
ILarper,
718 p.
34.
Powers, N. C. A new roundness scale for sedimentary particles.
Journal of Sedimentary Petrology 23:117-119. 1953.
35.
Pratt, Willis Layton. The origin and distribution of glauconite fran the sea floor off California and Baja, California.
Ph.D. thesis. Los Angeles, University of Southern California,
(Abstracted in Dissertation Abstracts
1962. 296 numb. leaves.
23:249 1-2492.
1963)
86
36.
Runge, Erwin S. Unpubliahed research on the sediments of
Sileta Bay, Oregon. Corvallis. Department of Oceanography,
Oregon State University
1962.
37.
Shrock, Robert ft., and William H. Twenhofel.
Principles of
invertebrate paleontology. 2d ed. New York, McGaw-flil1,
1953.
816 p.,
38.
Stump, Arthur Darrell. The uticroetructure of marine sediments.
Ph.D. thesis, Corvallis, Oregon State University, 1963. 130
numb. loaves.
39.
Sundborg, Ake. The river Klàralven, a study of fluvial pro-.
ceases. Geografiska Mutaler 38:127-316.
1956.
40.
Swrdrup, H. V., Mart in W. Johnson, and Richard B. Fleming.
The oceans, their physics, chemistry, and general biology.
Englewood Cliffs, New Jersey, Prentice-Rail, 1942. 1087 p.
41. Takatiashi, Juxi..Ichi. Synopsis of glauconitisaticn. In: Recent
marine sediments: A symposium, ed, by Parker 0. Trask. Tulsa,
Society of Economic Paleontologists and Mineralogists, 1955.
p. 503-512.
42.
Trask, Parker 0. Organic content of recent marine sediments.
In: Recent marine sediments: A symposium, ed. by Parker 0.
Trask. Tulsa, Okløhona, Society of Economic Paleontologists
and Mineralogists, 1955. p. 428-453.
43.
U. S. Coast and Geodetic SLrvey. Bathymetric chart 5702:
Trinidad Bead to Cape Blanco. Revised ed.
1962.
1 sheet.
44. U. S. Coast and Geodetic Survey. Bathymetric chart 5802:
Blanco to Yaqu ins Head Revised ed. 1960. 1 sheet.
Cape
45. U. S. Coast and Geodetic Survey. Bathymetric chart 5902:
Bathymetric chart 5902: Yaquina Head to Columbia River.
Revised ed. 1962. 1 sheet.
46. U. S. so1ogical Survey. Surface water supply of the United
States, 1960. Part 14. Pacific slope basins in Oregon and
lower Columbia River basin. l)6l. 305 p. (Geological Strvey
Water Supply Paper. 1718)
47.
Wakeiaan, Se].man A.
On the distribution of organic matter in the
sea bottom and the chemical nature and origin of marine humus.
Soil Science 36:125-147. 133 p.
87
48.
Williams, Uo*1, Prancis 3. Turner, and Char].ea i. Gilbert.
Petrography: an introduction to the study of rocks in thin
sections. San Francisco, Freeman, 1954. 406 p.
49.
Wyatt, Bruce, and Norman F. Kujala. Rydrographic data from
Oregon coastal waters; June, 1960, through Nay, 1961. CorvalUs, 1962. '7 p. (Oregon State niversity, Department of
Oceanography, Ref. 62-2, Data Report No. 1).
88
APPEIX
89
Table 4.
Sample locatione and depths.
Saup1e No.
Locatton
40' 45"
Depth
1
144°
2
44° 40' 145"
1214°
14.5'
41)
3
'411°
'40' 45"
12110
14.5'
39 fine.
4
1414°
40' '45"
1214°
18 6'
45
5
114° '40' '15"
12'4°
23 0'
46 fma
6
44° 110' 145"
1211'
27' 05"
53
7
44° 110' 145"
124° 31.5'
80 fins.
8
44° '40.8'
1211°
35.5'
1211 fine.
40.5'
1214°
140.0'
1714 fine.
'40.7'
1240 145.3'
117 fins.
9
44°
124° 07.0'
17 fins
fine.
fins
fine.
10
'440
11
414°
43.7'
124° 44.9'
200
fins.
12
4L° 43.5'
124° 140.0'
157
fine.
13
4140
1214°
36.1'
111.0
fine.
114
44° 43.3'
124° 31.6'
81 fins.
15
114°
43 3'
12110 27 14'
68 fms
16
411°
43.3'
124° 23 1'
59 fins.
17
44° 43.3'
1211°
18.6'
514
fins.
18
44° 43.3'
124° 14.6'
40
fins.
19
414°
43.3'
1240 10.5'
36 fins.
20
1440
43.3'
124°
6.3'
18 fins.
21
44° 47.6'
124°
5.1'
20
fins.
22
414' 147.6'
1214°
10.2'
314
fins.
43.3'
90
Sample No.
Location
Depth
23
L&4'
44.7'
1214'
24
411°
46.6'
124° 18.8'
62
25
144'
47.1'
124° 23.2'
70 fins.
26
L1#°
46.6'
1214°
28.4'
77 fins.
27
414° 146.8'
1214'
31.6'
100 fins.
28
411'
46.9'
1214°
35.8'
138
29
L1A4°
46.9'
124° 40.0'
165 fins.
30
44° 46.9'
124° 44.5'
192 fins.
31
144°
3144'
124° 05.8'
6
32
144°
34.9'
124° 10.1'
28
33
414°
34.6'
1211°
14.2'
39 fine.
34
414'
314.8'
1214'
18.5'
L15
fine.
35
44° 35.0'
124° 23.1'
38
fins.
36
44' 34.7'
124° 27.5'
245
fina.
37
44° 34.5'
124° 30.8'
63
fins.
38
11.4°
34.7'
1211'
35.0'
39
414°
314.7'
1211°
38.2'
160
fins.
40
144°
3147'
124' 41.3'
190
fins.
41
1114°
31.7'
1214' 141.3'
180
fine.
142
L4' 31.7'
1214°
38.2'
117 fine.
43
144°
31.7'
1214°
35.0'
73 fins.
414
'1.4°
31.7'
124° 30.8'
59 fins.
45
424°
31.8'
124° 27.5'
L44
fins.
46
414°
31.6'
124° 23.1'
27
fine.
14.5'
50 fins
fina.
fins.
fins.
81 fins.
Sample No.
Depth
Location
47
44° 31.6'
1240 18.2'
47
48
1140
31 8'
1240 14.4'
40 fz8.
49
414°
31 9'
12110
10.3'
29 fins.
50
'44°
31.7'
1240 07.1'
19 fins.
51
244°
28.6'
1240 06.5'
15 fins.
52
Z4°
287'
1214'
10.0'
25
53
144°
28.5'
12110
13.8'
35 fins.
54
44° 28 7'
1214'
18.4'
140
fins.
55
440 28.8'
124' 22.6'
34
fins..
56
414'
28.8'
124° 26.8'
40
fins.
57
440 28.8'
1240 31.2'
50 fins.
58
2124°
28.6'
124' 35.0'
67
fins.
59
LI4°
28.7'
1211'
39.2'
80
fine.
60
44° 28.8'
1240 43.6'
84
fins.
61
1i4°
25 8'
1211'
43.9'
72 fine.
62
244°
25.8'
12110
393*
69 fins.
63
1440
25.7'
1211°
35.2'
61
64
41i°
25.6'
1240 31.2'
65
244'
25.6'
1211'
26.8'
42
66
'44°
25.6'
1211'
22.6'
42
67
144°
25.6'
124' 18.4'
38 fine.
68
44° 25.6'
124' 14.1'
35
69
14°
124' 10.0'
27 fine.
70
44' 25.6'
12140
08
25.6'
06.2'
fins.
fins.
fina
49 fins.
fine.
fins.
fm.
92
Location
Sample No.
71
144°
22.6'
124° 06.0'
15 fma.
72
44° 26.8'
121° 10.2'
27
73
/44°
22.6'
124° 14.4'
37 fins.
74
Zj40
22.6'
1240 18.21
39 fins.
75
4/40
22.8'
1214°
22.7'
414 fins.
76
/44°
22.7'
1240 27.0'
'45
77
/44°
23 0'
12140
310'
58
78
4110
22.8'
12140
35,144
51 fins,
79
/4/1,0
22.7
1214°
39.3
60
80
4/4°
22.8'
124° 43.6'
74 fins.
SP Sample 1628
414
31.1'
1240 41.4'
120 fins.
SP Sample 2
4140
46.0'
124° '42.5'
190
fins.
SP Sample 3
44° 44.7'
124° 34.3'
120-145
fins.
81
1440
37.4'
12/4°
434'
117
fins.
82
/4/1'
37.6'
1240 39.3'
132
fins.
83
/44°
37.7'
1244
34.4'
94
fins.
144°
37.3'
1214°
30.7'
67
fins.
85
414°
37,5'
1214°
26.7'
50 fins.
86
'414°
37.7'
1214°
22.5'
49 fins.
87
44° 37 7'
1214°
18 2'
41
fins
88
114°
37.6'
124° 14.3'
40
fins.
89
'44°
37.8'
12/10
10.2'
26 fins.
90
114°
37.6'
124° 06.3'
18 fins.
91
'i4°
49.7'
124° 44.8'
239 fins.
fins.
fins.
finS
93
Sample No.
Location
Depth
92
45° 50.0'
124° 40.2'
200
fins..
92
45° '47.8'
1214°
38.6'
200
fins..
93
44° 49.7'
124
35.8'
172 fins.
44°
497*
124° 31.8'
120
fine.
411°
k.7'
12140
27.8'
119
fins.
96
44° 49 8'
12L1°
23.0'
75 fins
97
1111°
49.8'
124°
189'
68
fine.
98
114°
49.8'
1240 14.5'
53
fine.
99
440 '49.8'
124° 10.5'
35 fins.
100
44° 49.8'
124° 06.0'
23
103.
440 52.6'
124° 06.0'
26 fine.
102
44' 52.3'
124' 10.4'
45
fins.
103
44' 52.6'
124' 114.5'
60
fins.
1011.
144°
52.5'
124° 18 8'
76 fins
105
411°
52.6'
1240 23.1'
86 fins.
106
440 52.5'
107
4140
95
fine.
27.4'
100
fins.
52.1'
124° 31.6'
130
fins.
3.08
44° 52 8'
124° 35 7'
200
fins
109
144
53.1'
124° 39.8'
213 Ems.
110
114°
53 0'
124° 44.11'
200 Ems
111
114°
56.1'
124° 114 8'
250
112
44° 55.8'
124° 40.2'
207 fins.
113
114
55.8'
124° 35.6'
2214
3.24'
fins
fms
Depth
Location
Sample No.
35.7'
124' 31.5'
218 Ems.
1111
I1.40
115
44° 55.8'
116
'44°
55.7'
124° 23.3'
96 Ems.
117
4140
55.6'
1214
13.8'
81 Ems.
118
144°
5.5'
124° 14.5'
70 Ems,
119
144
55 6'
1214°
10.4'
53 Ems.
120
414°
55.8'
1214'
06.1'
30 fins.
12).
414°
55.8'
124° 03.0'
17 Ems.
1214'
27.4'
1147
Ems.
Table 5
11d
Textural parameters of tb
- Phi median diameter
sediments.
2'I - 2nd phi siceiineae measure
- Phi kurtosis measure
- Phi mean diameter
*
- Phi sorting measure
- An asterisk denotes gravelly sand
- Phi akenese measure
Sample
sand
c'
% silt
% clay
1
2.71
2.63
0.27
-0.29
-0.50
0.79
100
0
0
2
2.52
2.48
0.25
-0.15
_0.L11
0.65
100
0
0
3
2.48
2.42
0.26
-0.25
-0.61
0.83
100
0
0
4
2.46
2.34
0.32
-0.37
-1.02
1.04
100
0
0
5
2.80
2.85
0.21
0.24
0.16
0.68
100
0
0
6
2.47
5.80
3.58
0.93
63*
18
19
7
rock
8
3.66
4.94
1.93
0.66
69
17
14
9
2.70
4.55
2.33
0.79
79
7
14
0
t
L00
c.O
90
001
0
o
1it0
Si0
C90
001
0
o
0
OtiO
6i0
00!
0
0
8t0
L50
880
001
0
o
800
00
0S0
00!
0
O
150
6t0
00
Rt0
0O
1t10
00!
0
o
Z60
00!
0
o
oio
tco
090-
56
9Z
S
LZ
8!
9!
89
ot
1fly
981
8ii7
961
L9
LS
cro
691
Z1(
010
tro
EZ
181
t6t
080
1O
6O
7r0
ic
cro
t1i
8O
9L0
19'O
155
!!t
69
6t
St
8!
sc
t6
6C
c9
toc
9!
SI
t,t
tt
tdmee ou
11
PUB
me %
OL
S
0!
Pc
0c
Sanp1e
Md
25
3.51
'4.50
1.56
0.64
26
3.22
5.30
2.113
0.88
27
11.03
5.97
2.711
0.70
28
4.39
6.71
325
0.71
0.99
29
2.43
2.56
0.57
01k
'4.77
30
712
8.36
3.36
0.19
31
rock
32
1.98
1.81
0.35
-0.50
-0.92
33
2.68
2.53
0.26
-0.59
34
058
053
0.411
35
rock
36
gravel
37
1.90
2.119
38
3.17
3.35
sand
% ailt
S clay
711
8
18
69
16
15
50
31
19
0.39
11.0
35
25
5.31
92
2
6
5
50
45
0.77
100
0
0
-1.14
1.04
100
0
0
-0.11
-0.21
0.82
100
0
0
134
0.114
3.20
3.16
83
7
10
0.86
0.21
79
10
11
1.55
0.80
Sample
39
7.42
40
'4.62
41
no sample
42
'4.12
43
san4
% silt
% clay
6
49
45
3.14
0.59
39
36
25
259
320
0.77
47
28
25
2.89
3.24
0.54
0.65
87
6
7
'44
2.09
5.07
3.66
0.82
75
8
17
'45
1.64
1.42
0.30
-0.74
-1.45
1.02
100
0
0
2.49
2.141
0.23
-0.33
-0.63
0.75
100
0
0
11.7
2.70
2.51
0.26
-0.74
-i .26
1.04
100
0
0
48
1.69
1.79
0.50
0.21
0.34
0.48
100
0
0
49
2.110
2.32
0.3]
-0.28
-.0.70
0.74
100
0
0
50
2.36
2.28
0.28
-0.28
-0.44
0.74
1OC)
0
0
Si
2.52
2.46
0.26
-0.25
-0.38
0.58
100
0
0
52
2.57
2.47
0.314
-0.32
-0.69
0.62
100
C.)
0
53
2.73
2.68
0.24
-0.18
-0.54
0.90
100
0
0
6.49
6.96
6.55
c
6'O'
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001
0
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99'
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sand
Sample
silt
% clay
113
8.53
8.70
2.82
0.06
1
38
61
114
4.26
9.70
5.90
2.17
29
38
33
115
3.96
6.17
2.95
0.75
5].
28
21
116
3.25
4.49
1.64
0.75
75
12
13
117
343
5.33
2.2].
0.86
68
17
15
118
2.83
3.17
0.54
0.64
85
4
11
119
2.55
2.52
0.21
-0.10
0.88
1.78
95
0
5
120
2.00
1.90
0.55
-0.20
-0.31
0.40
100
0
0
121
rock
SP2
7.38
13
40
47
8P3
3.86
54
2].
25
1628
3.54
63
16
21
6.67
3.62
0.86
0
I-.
10L4.
Table 6.
Percent heavy uü.nerala in sand
and terrigenous sand fractions.
% heavies in
Sample
2
21
und fraction
% heavies in terrigenous
sand fraction
2.5
2.5
0.25
0.25
6.5
5.8
2:
30
2.8
3.5
32
1.2
1.2
£1.7
7.3
42
£4.2
5.4
62
3.8
6.1
66
4.0
4.0
69
3.8
38
84
7.2
8.2
92
3.8
6.2
111
1.2
11.1
io
Sample
% heavies in
sand fraction
heavies in terrigenous
sand fraction
11'4
5.9
71
115
514
63
116
10.1
13.6
117
7.1
7.7
118
414
147
119
8.4
8.4
120
1.6
1.6
8P2
3.7
4.6
106
Heavy minera1o,y of samples 22, 25, 27,
Table 7.
30, 62, 69, and 119.
Numbers are percents;
"r" denotes trace.
Sample
Mineral
22
25
27
30
82
69
119
Actinolite
--
0.3
1.3
1.4
1.6
--
0.3
Apatite
0.3
0.7
0.3
0.7
0.3
T
0.3
10.2
121
10.1
8.8
18.7
13.7
13.4
Basaltic Hornblende
1.2
0.3
0.3
4.9
1.6
4.5
1.1
Biotite
1.5
0.3
--
1.1
--
T
T
Chlorite
1.8
2.5
3.5
4.2
3.1
1.6
0.9
Diopside
5.14
3.9
3.8
53
*
2.5
3.1
Enstatite
1.2
1.6
2.5
4.2
0.3
1.3
1.4
Epidote
2.1
9.5
4.1
6.7
3.8
5.4
6.3
Garnet (pink)
3.9
0.7
0.3
0.3
0,3
3.2
1.4
Garnet (salmon)
0.3
--
-
--
--
0.6
--
Glaucophene
--
0.3
--
T
0.3
T
T
Hematite
--
0.7
13
--
0.6
0.3
1.1
Rornblende
6.9
9.5
114.6
24.0
20.2
8.9
10.0
flypersthene
6.6
3.9
0.9
0.3
2.8
5.14
5.2
T
0.7
T
--
--
0.3
--
Auite
Kyanite
* Included with au.ite
107
Sap1e
Mineral
22
25
27
30
62
69
11)
Leucoxene
3.9
2.3
0.6
1.1
1.2
3.2
1.7
Lionite
--
0.3
0.3
--
--
--
--
Nonazite
--
--
--
0.3
--
T
--
Muacevite
0.6
-
T
0.3
--
--
T
Olivine
1.5
0.7
1.9
1.8
--
1.0
0.3
12.0
12.1
2.8
3.7
22.3
18.3
Serpentine
0.9
--
i.l
-
1.4
0.9
--
0.3
Sillimenite
0.6
0.3
--
--
0.3
T
0.3
Sphene
--
-
0.3
0.9
0,6
--
-
0.6
Staurolite
-
--
T
T
Tourivaline
--
--
--
--
0.3
--
T
Tremolite
1.2
1.6
2.2
3.9
2.5
--
0.6
Zircon
0.3
--
0.6
0.3
--
1.3
0.6
Zoisite
0.3
0.3
0.6
2.5
--
--
0.9
Rock franents
22.7
20.3
28.8
11.6
26.1
8.6
19.7
Weathered ,rains
11.0
9.8
10.8
8.1
8.5
12.4
8.9
3.0
4.6
4.1
3.1
3.0
2.9
3.1
100.0
99.6
99.8
99.4 100.7
130.3
100.1
Opaque mineral8
Unknown
Total
A18o identified:
baaaltic laea
spinel
clinozoiaite
titanaugite
rutile
topa2
siderite