Chemical Geology 244 (2007) 507 – 519
www.elsevier.com/locate/chemgeo
40
Ar/ 39 Ar ages of hornblende grains and bulk Sm/Nd isotopes of
circum-Antarctic glacio-marine sediments: Implications for sediment
provenance in the southern ocean
Martin Roy a,⁎, Tina van de Flierdt a,b , Sidney R. Hemming a,b , Steven L. Goldstein a,b
a
Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, NY 10964 USA
b
Department of Earth and Environmental Sciences, Columbia University, USA
Received 31 May 2006; received in revised form 5 July 2007; accepted 6 July 2007
Editor: R.L. Rudnick
Abstract
The transfer of terrigenous sediments from Antarctica to the Southern Ocean results from glaciological processes and
subsequent transport by ocean currents. Establishing the link between the composition of circumpolar sediments and the geology of
Antarctica can provide important insights into past ice sheet and ocean current dynamics. Here we document the variability of
Antarctic sediment sources using 40Ar/39Ar ages of individual detrital hornblende grains and bulk (b 63 m) Sm/Nd isotope
systematics from glacio-marine sediments from 29 cores surrounding Antarctica. High 143Nd/144Nd ratios and associated young
Sm/Nd-model ages characterize sediments proximal to West Antarctica, while lower 143Nd/144Nd ratios and correspondingly older
Sm/Nd-model ages are found in samples nearby East Antarctica. Detrital hornblende grains in West Antarctic sediments typically
have 40Ar/39Ar ages younger than 200 Ma while East Antarctic hornblende grains yield 40Ar/39Ar ages that cluster in a
predominant population centered on ∼ 500 Ma, reflecting the widespread late Neoproterozoic–early Cambrian (Pan-African and
Ross) orogenies that affected East Antarctica. An exception comes from sediments adjacent to Wilkes Land, where abundant
Mesoproterozoic and Paleoproterozoic hornblende grains suggest that this portion of the East Antarctic craton was largely buffered
from Pan-African metamorphism. The geochemical characteristics of sediment sources are thus consistent with the geology of rock
outcrops around the Antarctic perimeter. The combined Sm–Nd data and 40Ar/39Ar ages of circum-Antarctic glacio-marine
sediments outline several geographic sectors with distinct provenance signals, thereby providing a base map for fingerprinting
sediment sources from the Antarctic margin.
© 2007 Elsevier B.V. All rights reserved.
Keywords: Sm–Nd isotopes;
40
Ar/39Ar ages; Sedimentary provenance; Glacio-marine sediments; Antarctic geology
1. Introduction
⁎ Corresponding author. Département des Sciences de la Terre et de
l'Atmosphère, Université du Québec à Montréal, C.P. 8888, Succ.
Centre-Ville, Montréal, QC, Canada H3C 3P8. Tel.: +1 514 987 3000
ext. 7619; fax: +1 514 987 7749.
0009-2541/$ - see front matter © 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.chemgeo.2007.07.017
The glacial conditions that prevail in Antarctica
promote active erosion of the underlying bedrock. The
resulting sediments are ultimately delivered to the ocean
through glacio-marine processes such as debris flow or
508
M. Roy et al. / Chemical Geology 244 (2007) 507–519
ice-rafting (e.g. Brachfeld et al., 2002; Evans et al.,
2005). Tracing the dispersal of glacially-derived sediments in the Southern Ocean has so far been inhibited by
the lack of information on sediment sources, and
specifically on the relationship between the composition
of sediments proximal to Antarctica and the geology of
this continent. Although the presence of extensive ice
sheets presents a considerable challenge to understand
the geology of Antarctica, detailed investigations of
limited rock exposures combined with large-scale
geophysical measurements provide an important geological framework against which the provenance characteristics of sediments can be compared.
The geology of Antarctica is naturally divided into
East and West Antarctic domains. East Antarctica is a
complex Precambrian craton that includes Archean
terrains separated by Proterozoic suture belts while West
Antarctica contains abundant late Mesozoic–Cenozoic
intrusive and volcanic rocks arranged around Paleozoic
and Mesozoic arc-related blocks (Fig. 1) (Anderson,
1999; Dalziel and Elliot, 1982; Storey and Garrett,
1985; Borg et al., 1987; Dalziel, 1992). The evolution of
the East Antarctic craton(s) (EAC) is marked by several
episodes of assembly and breakup of supercontinents. In
the Neoproterozoic, the EAC was attached to the
supercontinent Rodinia through Grenville-age sutures
zones (∼1 Ga). Following the breakup of Rodinia, the
EAC was part of the group of cratons that made up East
Gondwana and that collided with other land masses to
form Gondwana during the Pan-African orogeny at
∼ 500 Ma (Stern, 1994; Jacobs et al., 1998; Meert, 2003;
Goodge et al., 2004). The EAC was not directly affected
by the subsequent events that led to the final assembly of
Pangea at ∼ 250 Ma because Gondwana accreted to
Laurasia as a coherent block. West Antarctica was
mainly assembled during the Mesozoic and Cenozoic
through the juxtaposition of crustal blocks along the
paleo-Pacific margin of Gondwana (Dalziel and Elliot,
1982; Dalziel, 1992), a zone roughly parallel to the
Transantarctic Mountains, which had been formed
during the Ross Orogeny at ∼ 500 Ma (Storey et al.,
1996; Curtis et al., 2004).
In order to document the geochemical composition of
glacio-marine sediments and obtain the main geological
characteristics of the sediment sources, we used 40Ar/39Ar
ages of individual hornblende grains and bulk (b63 μm)
Sm/Nd isotope systematics of late Quaternary sediments
from 29 proximal cores located around the perimeter of
Fig. 1. Locations of marine cores studied (yellow dots) with corresponding ɛNd values and Nd model ages of the fine silicate fraction (b63 μm) of
core-top sediments. Cores are grouped under 7 sectors (labeled around the map) on the basis of geologic and geographic features. Figure shows a
schematic geological map of Antarctica and associated bedrock legend on the left (modified from Kirkham and Chorlton, 1995; outcrop limits based
on Dalziel, 1992). Light blue arrows in the ocean depict the major surface currents and the dark blue arrow represents the Antarctic Circumpolar
Current (from Colling, 2001).
M. Roy et al. / Chemical Geology 244 (2007) 507–519
Antarctica. The objective was to evaluate the coherence of
the regional provenance of glacio-marine sediments with
respect to the main known and inferred elements of the
geological evolution of Antarctica. The sediments are
mainly derived from glacial erosion by ice streams fed by
tributaries draining the deep interior of the continent
(Bamber et al., 2000). Accordingly, the sediments should
represent a mixture of the lithologies that were progressively incorporated during glacial transport, and thus their
provenance signal should reflect the composition of the
source regions.
Documenting the composition of sediments derived
from the erosion of the different sectors of the Antarctic
continent provides a basis for future studies seeking to
constrain the sectors of the Antarctic ice sheets that
contributed to iceberg discharges in the Southern
Ocean through time, and thereby allowing reconstruction of past ice sheet dynamics. Isotopic characterization of detrital sediments proximal to Antarctica
also provides a base map for studies of past dispersal
of terrigenous sediments in ocean currents around the
Antarctic continent.
2. Radiogenic isotopes of glacio-marine sediments as
provenance tools
Radiogenic isotopes, such as the Sm–Nd isotope
system in silicate detritus, are powerful tools for tracing
sediment provenance. As Sm and Nd are rare earth
elements, the Sm/Nd ratio is resistant to modification by
sedimentary and metamorphic processes, and thus the
Sm–Nd isotope system provides a means to estimate of
the average “mantle extraction” or “crustal residence”
age of the continental crustal sources (e.g., McCulloch
and Wasserburg, 1978; DePaolo, 1981; Goldstein et al.,
1984; Taylor and McLennan, 1985; McLennan and
Hemming, 1992).
40
Ar/39 Ar ages of individual K-bearing mineral
grains such as hornblende provide additional insights
on the geological history of the source rocks (e.g.
Hemming et al., 1998; Goldstein and Hemming, 2003;
Hemming, 2004). In contrast to the “hard” character of
the Sm–Nd system, meaning that the system is resistant to thermal resetting and weathering, and thus
useful for constraining crust formation ages, the K–Ar
chronometer in hornblende has a “soft” character. The
K–Ar clock of hornblende is subject to resetting during major metamorphism (N 450°C, Harrison, 1981),
and consequently, 40 Ar/39 Ar dating of individual amphibole grains can be used to gain information on
the last major thermal event that affected the source
terrains. In absence of complete metamorphic reset-
509
ting, the 40 Ar/ 39 Ar ages can also represent crystallization ages of hornblende-bearing igneous rocks.
The combined study of Sm–Nd and 40Ar/39 Ar
isotopic data from the fine and coarse fractions of
detrital marine sediments has proven to be a powerful
provenance tool to reconstruct the dynamics of ice
sheets in the North Atlantic region during the last glacial
cycle (e.g., Gwiazda et al., 1996; Hemming et al., 1998,
2000; Hemming and Hajdas, 2003). Similar information
on the radiogenic isotope composition of glacio-marine
sediments is currently inexistent in many locations
along the perimeter of Antarctica, and our data thus
provide a basis for studies that assess the variability in
the dynamics of the Antarctic ice sheets through time.
3. Methods and analytical procedures
We report data for near-modern sediment samples
from marine cores surrounding Antarctica. These coretop sediment samples consist predominantly of marine
clay with disseminated sand grains. Bulk-sediment
aliquots of 26 core-top samples were dispersed in
water and wet sieved at b63 μm. The b 63 μm fraction
was treated with buffered acetic acid to remove calcium
carbonate, and with buffered 0.02 M hydroxylamine
hydrochloride to remove Fe–Mn oxyhydroxides, following the procedure of Rutberg et al. (2000). The
residual sediment was digested on a hotplate using
HNO3–HF in screw-top Teflon beaker, dried, and redissolved in 1.6 N HNO3. Aliquots (10%) of the
solution were mixed with a Rare Earth Element (REE)
spike enriched in 145Nd and 149Sm for isotope dilution
(ID) measurement of the Sm and Nd abundances. REEs
were separated from the matrix using 30 microliter
columns of Eichrom TRU-spec® resin, cleaned with
1 M HCl and equilibrated with 1.6 M HNO3. Samples
were loaded in 1.6 M HNO3, and washed with
approximately 500 μm of 1.6 M HNO3. REEs were
eluted with approximately 750 μm of 1 M HCl. For Nd
isotope analysis of the 90% aliquot, Nd was separated
from the other REE using 0.15 M α-hydroxyisobutyric
acid (α-HIBA) at pH of 4.8 on 0.5 ml columns loaded
with cleaned and equilibrated AG50-X4 cation resin.
Nd isotopic ratios were analyzed on a VG Sector 54-30
thermal ionization mass spectrometer (TIMS) as NdO+,
using a 146Nd/144Nd ratio of 0.7219 to correct for mass
fractionation. Measurements of the La Jolla standard over
the time interval of the sample analyses gave values of
0.511858 ± 0.000017 (2σ external reproducibility, n = 21).
Isotope dilution analyses were made on an Axiom
multiple collector-inductively coupled plasma-mass spectrometer (MC-ICP-MS). Mass discrimination corrections
510
M. Roy et al. / Chemical Geology 244 (2007) 507–519
were based on assumed values of 149Sm/147Sm = 0.9200
and 145Nd/143Nd = 0.6814 for natural standards. The
estimated uncertainty on Sm and Nd concentration
measurements is better than 2% and the estimated
uncertainty on the 147Sm/144Nd ratio is better than 0.5%.
The N 63 μm aliquots were sieved at 150 μm and
hornblende grains were hand picked from the N150 μm
fraction. Coarse hornblende grains were absent in three
of the initial 26 core-top samples investigated. Three
additional cores were subsequently chosen to recover
hornblende grains. The number of grains dated in each
sample varies, and reflects the number of coarse
hornblende available in each sample. Samples and
monitor standards were irradiated in the Cd-lined incore facility (CLICIT) at the Oregon State reactor.
Normalization for neutron flux was based on J values
calculated from analyses of the Mmhb hornblende
standard with an age of 525 Ma (Samson and Alexander,
1987). Single-step laser fusion 40Ar/39Ar analyses for
individual grains were processed at the LDEO Ar
geochronology lab using a CO2 laser. Ages were
calculated from Ar isotope ratios corrected for mass
discrimination, interfering nuclear reactions, procedural
blanks, and atmospheric Ar contamination. Procedures
for irradiation, analysis, and corrections are similar to
those used by Hemming et al. (1998).
Table 1
Sm and Nd data for the b63 μm silicate fraction of circumpolar sediments
Site
Sample
Sector a
Latitude
(south)
Longitude
(east)
Water
depth
Nd
(ppm)
Sm
(ppm)
147
143
Nd/144Nd b
± 2σ S.E.
ɛNd c
Model age d
(Ma)
1
2
3
4
5
6
7
8
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
ELT05-22
ELT05-20
ELT42-09
ELT11-19
ELT11-18 e
ELT11-17
ELT33-12
ELT33-11
ELT27-20 e
ELT37-04 e
ELT37-06
ELT37-09 e
ELT37-10
ELT37-13
ELT50-18
ELT50-16
ELT50-13 e
ELT47-07 e
ELT47-14 e
RC17-51
RC17-56
IO1277-25
IO1277-41 e
IO1578-48 e
ELT07-11 e
NBP9802-2H
NBP9802-4H
NBP9802-3H
ODP188-1166 e
AP
AP
AP
WA
WA
WA
WA
WA
RS
WL
WL
WL
WL
WL
WL
WL
WL
PB
PB
PB
DL
DL
DL
WS
WS
RS
RS
RS
PB
65.95
67.18
69.99
70.42
70.14
70.17
70.00
70.10
71.96
64.83
66.08
65.55
65.22
64.67
64.43
61.04
60.00
66.66
61.12
65.65
65.40
68.61
70.00
62.00
66.50
73.54
64.20
66.14
67.41
289.75
285.22
279.60
260.75
257.18
253.36
239.83
237.74
178.60
150.49
145.02
141.10
137.88
132.98
119.98
114.81
105.00
77.90
71.27
60.68
36.72
10.97
354.92
339.99
314.38
176.96
170.08
169.45
74.47
373
2926
567
3808
3786
3456
2615
3639
2136
3274
201
1308
2249
1333
3120
4301
4208
1425
4166
3676
4794
2015
1873
4890
4197
600
2685
3154
480
40.7
38.1
55.1
55.1
47.1
38.1
66.1
58.1
46.1
46.7
34.1
37.7
42.8
74.6
47.8
48.3
n.d.
47.3
40.1
30.9
19.7
65.4
94.7
65.1
74.7
n.d.
n.d.
n.d.
n.d.
8.8
8.1
11.0
11.1
9.1
7.6
12.5
10.9
9.3
8.8
6.4
6.9
7.8
14.9
9.0
9.3
n.d.
8.3
7.1
6.1
3.5
12.3
18.1
12.1
14.0
n.d.
n.d.
n.d.
n.d.
0.1366
0.1341
0.1255
0.1271
0.1213
0.1257
0.1188
0.1187
0.1267
0.1188
0.1186
0.1147
0.1152
0.1255
0.1184
0.1216
n.d.
0.1104
0.1122
0.1237
0.1132
0.1188
0.1201
0.1175
0.1182
n.d.
n.d.
n.d.
n.d.
0.512685 ± 10
0.512469 ± 18
0.512420 ± 9
0.512470 ± 10
0.512399 ± 5
0.512400 ± 16
0.512358 ± 8
0.512502 ± 10
0.512283 ± 3
0.512003 ± 4
0.511765 ± 7
0.511817 ± 6
0.511815 ± 7
0.511876 ± 10
0.512006 ± 42
0.511927 ± 14
0.511881 ± 4
0.511544 ± 4
0.511681 ± 4
0.511655 ± 9
0.511749 ± 11
0.512074 ± 14
0.511867 ± 4
0.512201 ± 3
0.512147 ± 7
0.512262 ± 13
0.512498 ± 46
n.d.
0.511730 ± 8
0.9
− 3.3
− 4.3
− 3.3
− 4.7
− 4.6
− 5.5
− 2.7
− 6.9
− 12.4
− 17.0
− 20.4
− 16.1
− 14.9
− 12.3
− 13.9
− 14.8
− 21.3
− 18.7
− 19.2
− 17.3
− 11.0
− 15.0
− 8.5
− 9.6
− 7.3
− 2.7
n.d.
− 17.7
920
1304
1261
1197
1239
1299
1272
1040
1517
1838
2212
2387
2060
2194
1826
2018
1954 f
2360
2198
2529
2127
1725
2083
1502
1598
1370 f
1007 f
n.d.
2185 f
Sm/144Nd
n.d. — Not determined; sediment from site 29 was used only to obtain additional hornblende grains for 40Ar/39Ar dating.
a
AP — Antarctic Peninsula; WA — West Antarctica; RS — Ross Sea; WL — Wilkes Land; PB — Prydz Bay; DL — Dronning Maud Land;
WS — Weddel Sea.
b
La Jolla Nd standard that represents the TIMS data reported here was replicated with an averaged values of 0.511858 ± 0.000017 (2σ S.D.,
n = 21). All reported 143Nd/144Nd ratios of samples are corrected to a La Jolla value of 0.511858.
c
Calculations of ɛNd are based on the chondritic value of 143Nd/144Nd = 0.512638 (Jacobsen and Wasserburg, 1980) in parts per 10,000.
d
Nd model (“crustal residence”) ages calculated relative to the present depleted mantle (DM), assuming a one-stage/linear evolution:
147
Sm/144Nd = 0.2136; 143Nd/144Nd = 0.51315 (same as Goldstein et al., 1984).
e
Nd isotopic ratios from van de Flierdt et al. (2007).
f
Nd model age calculated using a 147Sm/144Nd ratio of 0.1150.
M. Roy et al. / Chemical Geology 244 (2007) 507–519
4. Results
4.1. Sm–Nd isotopic compositions and 40Ar/39Ar dating
of glacio-marine samples
Table 1 presents Nd isotope ratios and Sm−Nd
concentration data obtained from the silicate fractions of
the circumpolar sediment samples. The Nd isotope
ratios are discussed as ɛNd values, the deviation of the
measured 143Nd/144Nd from the chondritic value of
0.512638 (Jacobsen and Wasserburg, 1980) in parts per
104. Additional ɛNd values reported in Table 1 are from
van de Flierdt et al. (2007). Table 2 reports the results
from single-step laser fusion 40 Ar/ 39 Ar dating of
individual hornblende grains of the glacio-marine
511
sediments investigated. Overall, ɛNd values and Nd
model ages of the sediment samples vary according to
the main differences in the geology and “crustal
residence ages” of West and East Antarctica (Figs. 1
and 2), whereas 40Ar/39Ar ages characteristically cluster
into distinct populations (Fig. 3) that reflect the main
tectonic (thermal) events that affected the different
geographic sectors of Antarctica.
Taken together, the combined Nd crustal residence
ages and 40Ar/39Ar ages of hornblende grains delineate
seven sectors around Antarctica with distinctive isotopic
compositions and age distributions. The main characteristics of each sector are outlined below, beginning at the
eastern boundary of East Antarctica and moving
counterclockwise around the continent.
Table 2
Summary of 40Ar/39Ar ages of detritral hornblende grains (sediment fraction N 150 mm) of circumpolar sediments a
Site
Sample
Sector b
1
ELT05-22
AP
2
ELT05-20
AP
3
ELT42-09
AP
4
ELT11-19
WA
5
ELT11-18
WA
6
ELT11-17
WA
7
ELT33-12
WA
8
ELT33-11
WA
10
ELT27-20
RS
11
ELT37-04
WL
12
ELT37-06
WL
13
ELT37-09
WL
14
ELT37-10
WL
15
ELT37-13
WL
16
ELT50-18
WL
17
ELT50-16
WL
18
ELT50-13
WL
19
ELT47-07
PB
20
ELT47-14
PB
21
RC17-51
PB
22
RC17-56
DL
23
IO1277-25
DL
24
IO1277-41
DL
25
IO1578-48
WS
26
ELT07-11
WS
27
NBP9802-2H
RS
28
NBP9802-4H
RS
29
NBP9802-3H
RS
30
ODP188-1166
PB
Total number of grains dated:
Number of grains in the following age-groups (in Ga) c
Total
0–0.2
0.2–0.4
0.4–0.6
0.6–1.0
1.0–1.3
1.3–1.6
1.6–2.5
N2.5
Grains
44
9
23
39
11
3
10
9
3
∼
2
5
∼
1
∼
0
0
0
0
0
0
0
0
0
2
2
3
0
0
1
0
0
3
5
0
10
1
1
∼
0
0
∼
0
∼
0
0
0
0
0
0
0
0
0
0
0
1
0
0
1
0
0
0
1
0
0
0
7
∼
2
4
∼
0
∼
2
0
40
29
17
24
44
12
3
42
1
0
4
58
0
0
0
1
0
0
0
0
1
∼
1
1
∼
0
∼
0
0
9
5
9
1
0
0
2
5
0
0
1
1
0
0
0
2
0
0
0
0
0
∼
0
1
∼
7
∼
6
1
3
3
4
0
5
0
1
5
0
0
0
1
1
0
0
1
0
0
0
0
0
∼
0
14
∼
5
∼
1
1
0
1
1
2
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
∼
3
16
∼
1
∼
0
0
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2
0
2
∼
0
0
∼
1
∼
0
0
0
0
0
0
0
0
0
0
0
0
0
0
48
9
23
46
17
3
22
10
14
∼
8
41
∼
15
∼
9
2
53
39
32
27
49
12
6
54
3
4
5
61
612
∼ No data; detrital hornblende grains were absent in sediment samples from site 11, 14, and 16.
a
Complete data set is presented in Table B1 of Appendix B (online supplemental data).
b
AP — Antarctic Peninsula; WA — West Antarctica; RS — Ross Sea; WL — Wilkes Land; PB — Prydz Bay; DL — Dronning Maud Land;
WS — Weddel Sea.
c
Groups defined according to known tectonic events: built-up of West Antarctica 0–0.2 Ga; Pan-African/Ross orogenies 0.4–0.6 Ga Grenville
orogeny 1.0–1.3 Ga; unreset Archean rocks N2.5 Ga. See hornblende grain populations in histograms of Fig. 3.
512
M. Roy et al. / Chemical Geology 244 (2007) 507–519
Fig. 2. Diagram showing the ɛNd vs. 147Sm/144Nd ratio of sediment samples from the geographic sectors defined in Fig. 1. The difference in ɛNd
values between samples from West and East Antarctica is emphasized by the two horizontal gray lines with arrows. Thin black lines with slopes
represent 0.5, 1.0, 1.5, 2.0, and 2.5 Ga model ages. Square symbols are samples from East Antarctic sectors, circles are samples from West Antarctic
sectors, and triangles are samples from transitional sectors. WL — Wilkes Land, PB — Prydz Bay, DL — Dronning Maud Land, WS — Weddell
Sea, AP — Antarctic Peninsula, WA — West Antarctica, RS — Ross Sea.
4.2. Geographic variability of sediment provenance
characteristics around Antarctica
Wilkes Land sector (155°E–90°E) sediment samples
have crustal residence that average ∼2.1 Ga (Figs. 1 and 2).
This sector shows the widest range of 40Ar/39Ar ages, with
large peaks in the age spectrum at 1500–1800 Ma and
1100–1300 Ma, smaller peaks at ∼400–600 Ma and 0–
200 Ma, and two grains of ∼2.4 and 3.0 Ga (Fig. 3A).
Prydz Bay (90°E–55°E), Dronning Maud Land
(55°E–15°W), and Weddell Sea (15°W–55°W) sector
samples have crustal residence ages that become
progressively younger, averaging ∼2.4 Ga, ∼ 2.0 Ga,
and ∼ 1.5 Ga, respectively (Figs. 1 and 2). This contrasts
with the 40Ar/39Ar age spectrum, which is dominated by
400–600 Ma ages, with a small cluster of ages centered
on 1100–1300 Ma and two hornblende grains of
∼ 2.0 Ga in cores from Prydz Bay (Fig. 3B).
Antarctic Peninsula (55°W–85°W) and West Antarctica (85°W–140°W) sectors sediments have the youngest crustal residence ages, ranging from 0.9 to 1.3 Ga.
Hornblende grains with 40Ar/39Ar ages of around 0–
200 Ma largely predominate in this sector (Fig. 3C).
There are a few scattered grains with ages at 200–
400 Ma, 700 Ma, 1300 Ma, 1700 Ma, and 2500 Ma.
Finally, the Ross Sea sector (140°W–155°E) includes
contributions from West and East Antarctica, as reflected
by ɛNd values intermediate to the West Antarctica and
Wilkes Land sectors, and a large range in crustal
residence ages from 1.0 to 1.7 Ga (Figs. 1 and 2). The
40
Ar/39Ar age spectrum shows large peaks at 0–200 Ma
and 400–600 Ma, and a few grains at 1200 Ma, 2600 Ma,
and 2800 Ma (Fig. 3D).
5. Discussion
Approximately 98% of the Antarctic continent is
covered by ice. Therefore the geology of Antarctica has
been primarily revealed by a combination of detailed
studies of sparse rock outcrops and geophysical
mapping of distinctive structural boundaries. Although
the main elements of its geological history are well
defined, a large fraction of the continent's bedrock
remains inaccessible to further research. The glaciogenic heritage of the sediments investigated here is
particularly useful in documenting the integrated
geological characteristics of large source rock areas.
The processes of glacial erosion and transport typically
result in sediments having a composition representing
an average of the different lithologies eroded along the
length of a glacial flowline. Because the interior of the
Antarctic ice sheet is drained by a vast network of
flowlines (Bamber et al., 2000), we assume that the
samples represent an integrated compositional signal
M. Roy et al. / Chemical Geology 244 (2007) 507–519
513
Fig. 3. Stack histograms showing the distribution of 40Ar/39Ar ages of individual hornblende grains of the coarse sediment fraction (N150 μm) of
core-top samples. Note that the x-axis is divided in 100-Myr bins and the y-axis scale varies on each histogram. Histograms B and C regroup cores
from adjacent sectors and that show similarities in 40Ar/39Ar age distribution. A) Histogram for samples from Wilkes Land sector. B) Samples from
Prydz Bay (PB), Dronning Maud Land (DML), and Weddell Sea sectors. C) Samples from Antarctic Peninsula (AP) and West Antarctic (WA) sectors.
D) Samples from Ross Sea sector. The legend in each histogram gives the average Nd model age calculated for the associated sediment samples.
that reflects a significant fraction of the main
geological divisions of the continent. Although we
cannot precisely define the extent (surface area) of the
glacially eroded bedrock that is represented by
individual sediment samples, the Sm–Nd isotopic
compositions of bulk glacio-marine sediments and
40
Ar/39 Ar ages of associated individual detrital hornblende grains appear to capture the large-scale
variability in the crustal residence ages and major
tectono-thermal events that characterize the different
coastal regions of Antarctica (Fig. 1).
5.1. Comparisons of Sm–Nd isotope systematics between
glacio-marine sediments and Antarctic bedrock samples
Fig. 4 shows the isotopic compositions of the marine
core-top samples in the context of Sm/Nd ratios and Nd
isotopic values reported from Antarctic rock outcrops
(e.g. Black et al., 1986; Black and McCulloch, 1987;
Borg et al., 1987; Borg and DePaolo, 1991, 1994;
Wareham et al., 1998; Millar et al., 2001). Overall, the
Nd isotopic compositions of the glacio-marine samples
that characterize each Antarctic sector are consistent
514
M. Roy et al. / Chemical Geology 244 (2007) 507–519
Fig. 4. Graph showing ɛNd and 147Sm/144Nd ratios of circum-Antarctic glacio-marine sediments in the context of Antarctic outcrop data from the
literature (complete reference list in Appendix A). Color backgrounds without black borders display the fields for the outcrop data for the main
geological domains in Antarctica. Individual outcrop data points are shown by symbols corresponding to different geographic locations in Antarctica,
and include volcanic, plutonic, and metamorphic lithologies. The smaller fields with black borders show the range covered by the sediment samples
of each Antarctic sector (with the same color as the outcrop data). The depleted mantle field and dashed lines with slopes representing 1.1, 2.3, and
3.6 Ga model ages are shown for reference.
with the values reported for the associated bedrock
sectors on Antarctica. There are, however, some
differences with published results that can either be
related to the type of the sediments we investigated, or
attributed to the nature of detailed bedrock studies (e.g.
sampling a wide range of lithologies in order to
maximize the range of sample compositions, or focusing
on specific terrains). For example, the extreme low
bedrock ɛNd values from the Prydz Bay sector come
from studies that focused exclusively on old Archean
rocks of the Napier complex, which are unrepresentative
of this whole sector of Antarctica (Fig. 4).
Compared to our results, data from rock outcrops
also seem to have a bias toward more mafic compositions, with high Sm/Nd ratios. Our sediment data show
lower Sm/Nd ratios, closer to typical crustal Sm/Nd
ratios (e.g., Taylor and McLennan, 1985). This is likely
a result of the compositional “integration” that occur
during the processes of glacial erosion and transport,
which inevitably cause some loss of detailed informa-
tion compared to rock outcrop samples. Rock samples
generally display a wider array of Sm/Nd ratios that
reflect the wide variety of lithologies comprised in a
given sector. Such integration of multiple bedrock
lithologies over large areas by glacial erosion also
yields the much smaller isotopic variability observed in
the sediment data compared to the corresponding
geographic bedrock data. However, the fact that our
sediment data fall well within the range of the
corresponding published outcrop values is consistent
with the view that they are representative of the average
compositions of these Antarctic bedrock domains.
5.2. Interpretation of the Nd model ages and 40Ar/39Ar
ages of glacio-marine sediments within the geographic
sectors around Antarctica
The Sm/Nd and Nd isotope ratios of the bulksediment fraction show variations between the different
sectors that can be primarily associated with the
M. Roy et al. / Chemical Geology 244 (2007) 507–519
compositional characteristics of the Precambrian East
Antarctic craton and the Phanerozoic terrains of West
Antarctica (Figs. 1 and 2). The Nd isotope ratios of
West Antarctica are uniformly higher than East
Antarctica, representing younger crustal residence
ages, and there is a tendency toward higher Sm/Nd
ratios, especially in the Antarctic Peninsula, likely
representing more mafic compositions. The geological
events that assembled these two domains are also
reflected in the 40 Ar/39 Ar hornblende ages of the
glacio-marine sediment samples, which show age
clusters corresponding to the major tectono-thermal
events that affected the area of Antarctica from which
the sediments were derived (Fig. 3). Within each
geographic sector, compositional variability among the
core-top samples is generally small, except for Ross
Sea and Weddell Sea samples, which show variations
that likely reflect detrital inputs from East and West
Antarctica, as well as the Transantarctic Mountains that
separate these two geological entities (Fig. 2). The
following sections discuss the crust formation ages (Nd
crustal residence ages) and the latest metamorphic
overprint (40 Ar/39 Ar ages) that characterize the glaciomarine sediments of these sectors in the context of the
known geological elements of the associated continental source rocks.
515
5.2.1. West Antarctica
Samples from West Antarctica, here comprising the
Antarctic Peninsula and the West Antarctic Sector
(Fig. 1) have relatively young Nd model ages
(∼ 1.2 Ga) (Figs. 1 and 2) and a predominant young
(0–200 Ma) population of hornblende grains (approximately 95% and 75%, respectively) (Figs. 3C and 5).
These signatures are consistent with West Antarctica
being a mosaic of geologically young terrains formed
predominantly by Mesozoic–Cenozoic plutonic and
volcanic rocks that are underlain by older crystalline
basement rocks (Vaughan and Storey, 2000; Millar et al.,
2002). The Mesoproterozoic Nd model ages of
sediments adjacent to the Antarctic Peninsula likely
derive from the erosion of abundant Mesozoic and
Cenozoic magmatic rocks, which have Nd model ages
decreasing from ∼ 1.3 Ga to ∼ 0.5 Ga in progressively
younger granitoids (Millar et al., 2001). Erosion of
young mafic sources is also indicated by two samples
having high Sm/Nd and 143Nd/144Nd ratios (Fig. 2).
Overall, the dominance of detrital hornblende grains
with 40Ar/39Ar ages younger than 200 Ma in West
Antarctica samples (Fig. 3) is consistent with thermal
events related to the early Mesozoic amalgamation of
crustal blocks forming the core of this region (Dalziel
and Elliot, 1982; Dalziel, 1992), as well as the presence
Fig. 5. Average bulk detritus Sm–Nd “crustal residence age” vs. average 40Ar/39Ar age of the main populations of hornblende grains for sediment
samples from the seven geographic sectors defined in Fig. 1. Symbols for each sector are lined up with the average crustal age of the sediment samples
of the corresponding sector. The number of symbols in each sector represents the main 40Ar/39Ar age populations of hornblende grains in the samples
of the sector, and symbols are aligned with the average 40Ar/39Ar age of the population. The percentages above the symbols denote the number of
40
Ar/39Ar hornblende ages of the total grains dated in the samples that fall into these main populations. Grey bars delineate the Pan-African (P-A) and
Grenville (Gren.) metamorphism between 0.4–0.6 Ga and 1.0–1.3 Ga, respectively.
516
M. Roy et al. / Chemical Geology 244 (2007) 507–519
of Mesozoic–Cenozoic igneous rocks associated with
the development of the Antarctic Peninsula and part of
the Pacific margin of West Antarctica, which was
accompanied by abundant magmatism (Storey and
Garrett, 1985; Millar et al., 2001).
5.2.2. East Antarctica
Samples from East Antarctica yield relatively old
Sm–Nd model ages of 1.7 to 2.5 Ga, consistent with their
Archean and Paleoproterozoic heritage (Figs. 1 and 2).
The eastern Weddell Sea, Dronning Maud Land and
Prydz Bay sectors have a dominant hornblende population of ∼500 Ma 40Ar/39Ar ages (∼ 75%, ∼ 90%, and
∼ 80% respectively), and a subordinate ∼1.2 Ga population of 40Ar/39Ar ages (∼ 10%, ∼ 5%, and ∼ 5%
respectively) (Figs. 3B and 5). The subordinate ∼ 1.2 Ga
population is consistent with tectonic models stipulating
that a significant fraction of the EAC was involved in a
global Mesoproterozoic tectonic episode corresponding
to the Grenvillian orogenesis (Hoffman, 1991; Dalziel,
1991, 1992; Moores, 1991; Fitzsimons, 2000), while the
dominant ∼ 500 Ma population reflects extensive overprinting during the late Proterozoic–early Cambrian
Pan-African Orogeny (e.g. Boger et al., 2001; Veveers,
2004).
The Wilkes Land sector is characterized by substantially older populations of 1.8–1.4 Ga (∼ 50%) and
1.3–1.1 Ga (∼ 20%) grains (Figs. 3A and 5). These ages
show strong similarities with the timing of orogenic
events documented in the Gawler Craton, Australia
(Foster and Elhers, 1998) and are thus consistent with
published reconstructions suggesting that these two
cratons were contiguous since at least the Paleoproterozoic, and prior to the amalgamation of the Rodinia
supercontinent. Furthermore, Wilkes Land samples
show two secondary hornblende 40 Ar/ 39 Ar age populations centered at ∼ 500 Ma and ∼ 200 Ma. While the
first population likely reflects the extension of the Ross
Orogen into this sector of the EAC (e.g., Di Vincenzo
et al., 2007), the grains with 200 Ma ages may be
associated with detrital sediments derived from erosion
of West Antarctic rocks.
5.2.3. Ross Sea and Weddell Sea
Sediments from the Ross Sea yield Mesoproterozoic
Nd model ages (1.0–1.6 Ga) that likely reflect mixing of
the old East Antarctic basement terrains and young West
Antarctic rocks from both sides of this embayment
(Figs. 1 and 2). This mixing process is also suggested by
the bi-modal distribution of 40Ar/39Ar ages of hornblende grains in Ross Sea samples (Figs. 3d and 5).
Abundant ∼ 500 Ma grains likely reflect tectonic
resetting and igneous activity associated with the
formation of the Transantarctic Mountains during the
Ross Orogeny (Boger and Miller, 2004; Curtis et al.,
2004; Goodge et al., 2004). The population of ∼ 200 Ma
grains may be associated with thermal events and
igneous activity related to the edification of West
Antarctica described above, and the presence of Jurassic
flood basalts in the Transantarctic Mountains (Fleming
et al., 1995), if the given lava flows are rich in
hornblende. Weddell Sea sediments yield Mesoproterozoic Nd model ages (1.4–1.6 Ga) that likely reflect
detrital contributions from rocks of the Antarctic
Peninsula and East Antarctica that border this sector.
5.3. Implications for future provenance studies
The results of Sm–Nd systematics from the fine
fraction of marine bulk sediment and 40Ar/39Ar ages on
individual hornblende grains around Antarctica provide
the first large-scale characterization of detrital inputs
from the Antarctic continent to the Southern Ocean.
Glacio-marine sediments of core-top samples have a
geochemical composition that reflects the known
geological characteristics of Antarctica's main bedrock
divisions in the context of the present-day ice drainage
patterns (Bamber et al., 2000). Therefore this study
provides a base map for identifying the sectors of the ice
sheet that contributed to major iceberg discharges in the
past. Ice-rafted debris layers are abundant in the circumAntarctic sedimentary record, and allow a window into
past iceberg provenance and thereby ice sheet dynamics
(e.g., Kanfoush et al., 2000; Williams and Handwerger,
2005). Another potential use for this base map concerns
the study of sediment dispersal from Antarctica into the
Antarctic Circumpolar Current (ACC). Knowing the
source signature of Antarctic sediments delivered to the
Southern Ocean will allow the reconstruction of ocean
current patterns back in time, such as the vigor of the
ACC in the past (Hemming et al., 2007).
Future studies should focus on glacial deposits on the
coastal and marginal areas of the continent. This would
allow a better understanding of the provenance signal
recorded in glacially-transported sediments and add
further constraints on the compositional integration of
bedrock sources that takes place throughout the
processes of glacial erosion, transport, and deposition
in the marine environment. For instance, recent
provenance studies in Antarctica showed that the
geochemistry and radiogenic isotope composition of
onshore glacial deposits in the Ross Sea embayment
yield values that vary according to the age and isotopic
composition of the underlying bedrock (Licht et al.,
M. Roy et al. / Chemical Geology 244 (2007) 507–519
2005; Farmer et al., 2006). Similar investigations of
offshore glacial deposits from the bottom of Ross Sea
show variations that can be attributed to the erosional
input from the East and West Antarctic ice sheets
(Farmer et al., 2006), thereby further demonstrating the
potential of using the geochemical signature of
glaciogenic sediments to document ice sheet activity.
6. Conclusions
The provenance of glacio-marine sediments proximal to Antarctica can be traced by the combined
application of Sm–Nd isotopes in bulk terrigenous
sediments and 40 Ar/39 Ar ages of individual hornblende
grains. The results show a systematic geographic variability, in agreement with the major known geological
events that characterize Antarctica's bedrock. Sediments
derived from West Antarctica typically show younger
Nd crustal residence ages (0.9 to 1.3 Ga) and 40 Ar/ 39 Ar
ages (b 200 Ma) than those derived from East Antarctic
Precambrian terrains (1.7 to 2.5 Ga and N500 Ma,
respectively). Although sediments from the East Antarctic sectors show variable crustal residence ages,
limited ranges of 40 Ar/ 39 Ar ages of detrital hornblende
grains are documented along two thirds of the perimeter of the East Antarctic margin (Weddell Sea coast
to Prydz Bay), reflecting major thermal resetting at
∼ 500 Ma.
Because the investigated core-top sediments are
derived from glacial erosion of Antarctic bedrock, the
compositional data reflect a regional provenance signal
that integrates large source regions covered by the
catchment areas of ice streams that regulate the mass
balance of the Antarctic ice sheets. Although this prevents detailed determination of specific rock source
areas, the information obtained yields average bedrock
compositions that are particularly useful in the context of
an ice-covered continent. In addition to provide an
efficient means to derive continental-scale information
on Antarctic bedrock geology, radiogenic isotopes from
circum-Antarctic sediments also delineate geographic
sectors with distinct provenance characteristics. Our data
thus set the stage for fingerprinting regional source areas
back in time, thereby allowing the characterization of the
ice-rafting behavior of the Antarctic ice sheets, as well as
the study of the dispersal of terrigenous sediments in
currents of the Southern Ocean.
Acknowledgements
Millie Klas contributed to sample preparation, and
Jenna Cole and Allison Franzese assisted in data col-
517
lection. Gil Hanson (Stony Brook University) provided
the mixed REE spike and many stimulating discussions.
This research was funded by NSF grant OPP 00-88054
to SLG and SRH. LDEO contribution number 7070.
Appendix A. Supplementary data
Supplementary data associated with this article can
be found, in the online version, at doi:10.1016/j.chemgeo.
2007.07.017.
References
Anderson, J.B., 1999. Antarctic Marine Geology. Cambridge University Press, p. 289.
Bamber, J.L., Vaughan, D.G., Joughin, I., 2000. Widespread complex
flow in the interior of the Antarctic ice sheet. Science 287,
1248–1250.
Black, L.P., McCulloch, M.T., 1987. Evidence for isotopic equilibration of Sm–Nd whole-rock systems in early Archaean crust of
Enderby Land, Antarctica. Earth Planet. Sci. Lett. 82, 15–24.
Black, L.P., Sheraton, J.W., James, P.R., 1986. Late Archean granites
of the Napier Complex, Enderby Land, Antarctica; a comparison
of Rb–Sr, Sm–Nd and U–Pb isotopic systematics in a complex
terrain. Precambrian Res. 32, 343–368.
Boger, S.D., Wilson, C.J.L., Fanning, C.M., 2001. Early Paleozoic
tectonism within the East Antarctic craton: the final suture between
east and west Gondwana? Geology 29, 463–466.
Boger, S.D., Miller, J.M., 2004. Terminal suturing of Gondwana and
the onset of the Ross–Delamerian Orogeny: the cause and effect of
an Early Cambrian reconfiguration of plate motions. Earth Planet.
Sci. Lett. 219, 35–48.
Borg, S.G., DePaolo, D.J., 1991. A tectonic model of the Antarctic
Gondwana margin with implications for southeastern Australia —
isotopic and geochemical evidence. Tectonophysics 196, 339–358.
Borg, S.G., DePaolo, D.J., 1994. Laurentia, Australia, and Antarctica
as a Late Proterozoic Supercontinent—constraints from isotopic
mapping. Geology 22, 307–310.
Borg, S.G., Stump, E., Chappell, B.W., McCulloch, M.T., Wyborn, D.,
Armstrong, R.L., Holloway, J.R., 1987. Granitoids of northern
Victoria Land, Antarctica: implications of chemical and isotopic
variations to regional crustal structure and tectonics. Amer. J. Sci.
287, 127–169.
Brachfeld, S.A., Banerjee, S.K., Guyodo, Y., Acton, G.D., 2002. A
13 200 year history of century to millennial-scale paleoenvironmental change magnetically recorded in the Palmer Deep, western
Antarctic Peninsula. Earth Planet. Sci. Lett. 194, 311–326.
Colling, A., 2001. Ocean Circulation. Boston–Johannesburg–Melbourne–New Delhi–Oxford, The Open University, 2nd edition.
286pp.
Curtis, M.L., Millar, I.L., Storey, B.C., Fanning, M., 2004. Structural
and geochronological constraints of early Ross orogenic deformation in the Pensacola Mountains, Antarctica. Geol. Soc. Amer.
Bull. 116, 619–636.
Dalziel, I.W.D., 1991. Pacific margins of Laurentia and East
Antarctica–Australia as a conjugate rift pair: evidence and
implications for an Eocambrian supercontinent. Geology 19,
598–601.
Dalziel, I.W.D., 1992. Antarctica: a tale of two supercontinents? Ann.
Rev. Earth Planet. Sci. 20, 501–526.
518
M. Roy et al. / Chemical Geology 244 (2007) 507–519
Dalziel, I.W.D., Elliot, D.H., 1982. West Antarctica: problem child of
Gondwanaland. Tectonics 1, 3–19.
DePaolo, D.J., 1981. A neodymium and strontium isotopic study of
Mesozoic calc-alkaline granitic batholiths of the Sierra Nevada
and Peninsular Ranges, California. J. Geophys. Res. 86,
10470–10488.
Evans, J., Pudsey, C.J., O'Cofaigh, C., Morris, P., Domack, E., 2005.
Late Quaternary glacial history, flow dynamics and sedimentation
along the eastern margin of the Antarctic Peninsula ice sheet.
Quat. Sci. Rev. 24, 741–777.
Farmer, G.L., Licht, K.J., Swope, Andrews, J.T., 2006. Isotopic
constraints on the provenance of fine-grained sediment in LGM
tills from the Ross Embayment, Antarctica. Earth Planet. Sci. Lett.
249, 90–107.
Fleming, T.H., Foland, K.A., Elliot, D.H., 1995. Isotopic and chemical
constraints on the crustal evolution and source signature of Ferrar
magmas. Contrib. Mineral. Petrol. 121, 217–236.
Fitzsimons, I.C.W., 2000. Grenville-age basement provinces in East
Antarctica: evidence for three separate collisional orogens.
Geology 28, 879–882.
Foster, D.A., Elhers, K., 1998. 40Ar/39Ar thermochronology of the
southern Gawler Craton, Australia: implications for Mesoproterozoic and Neoproterozoic tectonics of East Gondwana and
Rodinia. J. Geophys. Res. 103, 10177–10193.
Goldstein, S.L., Hemming, S.R., 2003. Long-lived isotopic tracers in
oceanography, paleoceanography, and ice-sheet dynamics. In:
Elderfield, H. (Ed.), Treatise on Geochemistry. Elsevier, Oxford,
pp. 453–489.
Goldstein, S.L., O'Nions, R.K., Hamilton, P.J., 1984. A Sm–Nd
isotopic study of atmospheric dusts and particulates from major
river system. Earth Planet. Sci. Lett. 70, 221–236.
Goodge, J.W., Williams, I.S., Myrow, P., 2004. Provenance of
Neoproterozoic and lower Paleozoic siliciclastic rocks of the
central Ross orogen, Antarctica: detrital record of rift-, passive-,
and active-margin sedimentation. Geol. Soc. Amer. Bull. 116,
1253–1279.
Gwiazda, R.H., Hemming, S.R., Broecker, W.S., Onsttot, T., Mueller,
C., 1996. Evidence from 40Ar/39Ar ages for a Churchill Province
source of ice-rafted amphiboles in Heinrich layer 2. J. Glaciol. 42,
440–446.
Harrison, T.M., 1981. Diffusion of 40Ar in hornblende. Contrib.
Mineral. Petr. 78, 324–331.
Hemming, S.R., 2004. Heinrich events: massive late Pleistocene
detritus layers of the North Atlantic and their global climate
imprint. Rev. Geophys. 42 (1). doi:10.1029/2003RG000128.
Hemming, S.R., Hajdas, I., 2003. Ice rafted detritus evidence from
40
Ar/39Ar of individual hornblende grains for evolution of the
southeastern Laurentide ice sheet since 43 14C ky. Quat. Int. 99,
29–43.
Hemming, S.R., Broecker, W.S., Sharp, W.D., Bond, G.C., Gwiazda,
R.H., McManus, J.F., Klas, M., Hajdas, I., 1998. Provenance of
Heinrich layers in core V28-82, northeastern Atlantic: 40Ar/39Ar
ages of ice-rafted hornblende, Pb isotopes in feldspar grains, and
Nd–Sr–Pb isotopes in the fine sediment fraction. Earth Planet. Sci.
Lett. 164, 317–333.
Hemming, S.R., Bond, G.C., Broecker, W.S., Sharp, W.D., KlasMendelson, M., 2000. Evidence from 40Ar/39Ar ages of individual
hornblende grains for varying Laurentide sources of iceberg
discharges 22,000 to 10,500 yr B.P. Quat. Res. 54, 372–383.
Hemming, S.R., van de Flierdt, T., Goldstein, S.L., Franzese, A.M.,
Roy, M., Gastineau, G., Landrot, G., 2007. Strontium isotope
tracing of terrigenous sediment dispersal in the Antarctic
Circumpolar Current: implications for constraining frontal positions. Geochem. Geophy. Geos. 8, Q06N13. doi:10.1029/
2006GC001441.
Hoffman, P.F., 1991. Did the breakout of Laurentia turn Gondwanaland inside-out. Science 252, 1409–1412.
Jacobs, J., Fanning, C.M., Henjes-Kunst, F., Olesch, M., Paech, H.J.,
1998. Continuation of the Mozambique Belt into East Antarctica:
Grenville-Age metamorphism and Polyphase Pan-African highgrade events in Central Dronning Maud Land. J. Geol. 106,
385–406.
Jacobsen, S.B., Wasserburg, G.J., 1980. Sm–Nd isotopic evolution of
chondrites. Earth Planet. Sci. Lett. 50, 139–155.
Kanfoush, S.L., Hodell, D.A., Charles, C.D., Guilderson, T.P., Mortyn,
P.G., Ninnemann, U.S., 2000. Millennial-scale instability of the
Antarctic ice sheet during the last glaciation. Science 288,
1815–1818.
Kirkham, R.V., Chorlton, J.J., 1995. Generalized map of the world and
linked databases, Geol. Surv. Can. Open-File Report no. 2915d
(CD-ROM).
Licht, K.J., Lederer, J.R., Swope, J.R., 2005. Provenance of LGM
glacial till (sand fraction) across the Ross Embayment, Antarctica,
Quat. Sci. Rev. 24, 1499–1520.
McCulloch, M.T., Wasserburg, G.J., 1978. Sm–Nd and Rb–Sr
chronology of continental crust formation. Science 200, 1003–1011.
McLennan, S.M., Hemming, S.R., 1992. Samarium/neodymium
elemental and isotopic systematics in sedimentary rocks. Geochim.
Cosmochim. Acta 56, 887–898.
Meert, J.G., 2003. A synopsis of events related to the assembly of
eastern Gondwana. Tectonophysics 362, 1–40.
Millar, I.L., Willan, R.C.R., Wareham, C.D., Boyce, A.J., 2001. The
role of crustal and mantle sources in the genesis of granitoids of the
Antarctic Peninsula and adjacent crustal blocks. J. Geol. Soc.
London 158, 855–867.
Millar, I.L., Pankhurst, R.J., Fanning, C.M., 2002. Basement
chronology and the Antarctic Peninsula: recurrent magmatism
and anatexis on the Palaeozoic Gondwana margin. J. Geol. Soc.
London 159, 145–158.
Moores, E.M., 1991. Southwest U.S.–East Antarctic (SWEAT)
connection: a hypothesis. Geology 19, 425–428.
Rutberg, R.L., Hemming, S.R., Goldstein, S.L., 2000. Reduced North
Atlantic deep water flux to the glacial Southern Ocean inferred
from Nd isotope ratios. Nature 405, 935–938.
Samson, S.D., Alexander Jr., E.C., 1987. Calibration of the
interlaboratory 40Ar–39Ar dating standard, MMhb-1. Chem.
Geol. 66, 27–34.
Stern, R.J., 1994. Arc assembly and continental collision in the
Neoproterozoic East African Orogen: implications for the
consolidation of Gondwanaland. Ann. Rev. Earth Planet. Sci. 22,
319–351.
Storey, B.C., Garrett, S.W., 1985. Crustal growth of the Antarctic
Peninsula by accretion, magmatism and extention. Geol. Mag. 122,
5–14.
Storey, B.C., Macdonald, D.L.M., Dalziel, I.W.D., Isbell, J.L., Millar,
I.L., 1996. Early Paleozoic sedimentation, magmatism, and
deformation in the Pensacola Mountains, Antarctica: the significance of the Ross orogeny. Geol. Soc. Amer. Bull. 108,
685–707.
Taylor, R.S., McLennan, S.M., 1985. The Continental Crust: its
Composition and Evolution. Blackwell, Oxford, p. 312.
van de Flierdt, T., Goldstein, S.L., Hemming, S.R., Roy, M., Frank,
M., Halliday, A.N., 2007. Global neodymium–hafnium isotope
systematics — revisited. Earth Planet. Sci. Lett. 259, 432–441.
M. Roy et al. / Chemical Geology 244 (2007) 507–519
Vaughan, A.P.M., Storey, B.C., 2000. The eastern Palmer Land shear
zone: a new terrane accretion model for the Mesozoic development
of the Antarctic Peninsula. J. Geol. Soc. London 157, 1243–1256.
Veveers, J.J., 2004. Gondwanaland from 650–500 Ma assembly
through 320 Ma merger in Pangea to 185–100 Ma breakup:
supercontinental tectonics via stratigraphy and radiometric dating.
Earth-Sci. Rev. 8, 1–132.
Di Vincenzo, G., Talarico, F., Kleinschmidt, G., 2007. An 40Ar–39Ar
investigation of the Mertz Glacier area (George V Land,
519
Antarctica): implications for the Ross Orogen–East Antarctic
Craton relationship and Gondwana reconstructions. Precambrian
Res. 152, 93–118.
Wareham, C.D., Pankhurst, R.J., Thomas Storey, B.C., Grantham, G.H.,
Jacobs, J., 1998. Pb, Nd, and Sr isotope mapping of Grenville-age
crustal provinces in Rodinia. J. Geol. 106, 647–659.
Williams, T., Handwerger, D., 2005. A high-resolution record of early
Miocene Antarctic glacial history from ODP site 1165, Prydz Bay.
Paleoceanography 20 (2) Art. No. PA2017.