Preliminary results from the USCGC Glacier 1985 cruise
(3) John Anderson, Chief Scientist of this cruise with whom we shared ship time, went out of his way to assist our program and to act in our behalf; and (4) we had very good luck in that we had calm weather, much of the eastern Amundsen Sea was ice free, and the ice we did encounter was not beyond the capabilities of Glacier. This work is supported by National Science Foundation grant DPP 80-20000. References Anderson, J.B., and N.C. Myers. 1981. USCGC Glacier Deep Freeze 81 expedition to the Amundsen Sea and Bransfield Strait. Antarctic Journal of the U.S., 16(5), 118 - 119. Anonymous. 1968. Antarctic sketch map: Thurston Island-Jones Mountains. (U.S. Geological Survey.) Washington, D.C.: U.S. Government Print-
ing Office.
Preliminary results from the USCGC Glacier 1985 cruise
Crabtree, R.D., and C.S.M. Doake. 1982. Pine Island Glacier and its drainage basin: Results from radio-echo sounding. Annals of Glaciology, 3, 65 - 70. Kellogg, T.B., D.E. Kellogg, and J.B. Anderson. 1982. Preliminary results of microfossil analyses of Amundsen Sea sediment cores. Antarctic Journal of the U.S., 17(5), 125 - 126. Lindstrom, D. 1985. A study of Pine Island and Thwaites Glaciers. (Masters Thesis, University of Maine, Orono, Maine.) Lindstrom, D., and D.A. Tyler. 1984. Preliminary results of Pine Island and Thwaites Glaciers study. Antarctic Journal of the U. S., 19(5), 53-55. Lindstrom, D., and T.J. Hughes. 1984. Downdraw of the Pine Island Bay drainage basins of the west antarctic ice sheet. Antarctic Journal of the U. S., 19(5), 56-58. Stauffer, B., and J . Schwander. 1984. Core processing and first analysis of ice cores from Siple and South Pole Stations. Antarctic Journal of the U. S., 19(5), 59-60.
Iceberg drift tracks were also measured, using the ship's radar, to assess potential threats to drilling operations. Preliminary micropaleontologic age determinations of cores were conducted by Davida Kellogg.
J . B. ANDERSON Department of Geology Rice University Houston, Texas 77251
On 18 December 1984 the U.S. Coast Guard icebreaker Glacier departed from Punta Arenas, Chile, to begin marine geologic work on the antarctic continental margin. Four areas were surveyed as part of this cruise. These included the western margin of the South Orkney Plateau, portions of the Bransfield Strait and the adjacent continental shelf of the South Shetland Islands, Marguerite Bay, and Pine Island Bay (figure). In all, some 761 kilometers of seismic data and approximately 5,000 kilometers of bottom profiler data were obtained. In addition, 115 piston coring stations and 15 grab sample stations were occupied (table). The scientific party consisted of geologists from Rice University and the University of Maine at Orono. This report provides an account of samples and data obtained and a ummary of preliminary findings. South Orkney Plateau. The first phase of the cruise was conucted on the western margin of the South Orkney Plateau. ur objectives were to investigate the possibility that an ice cap as once grounded on the plateau, to investigate the seismic tratigraphy of the western margin of the plateau using singlehannel sparker data and piston cores taken in outcrops, and to i vestigate sedimentation at various depths on the plateau in elation to different water masses which impinge on it, and to 1 ok for sedimentologic evidence of paleoceanographic c anges. The latter is the primary objective of proposed Ocean rril1ing Project drill sites in the area, and our study, which focuses on the Quaternary record, is intended as an initial test of this objective. A total of 320 kilometers of single channel (sparker) seismic profiles and 36 piston cores were collected in the area (figure). 1985 REVIEW
Cruise track for USCGC Glacier. Heavy lines with "s" indicate seismic lines.
Previous marine geophysical work in the region includes single-channel (airgun) seismic surveys by Peter Barker (University of Birmingham, England); these data, along with a bathymetric base map for the area, were kindly made available to us by Peter Barker for planning of our cruise. Other prior studies include seismic refraction work (Harrington, Barker, and Griffiths 1972) and a single multichannel profile collected by West German scientists during a recent (1983) cruise (ANTARKTIS-II) of the research vessel Polarstern (Haase 1984). Prior to this cruise, only a few sediment samples had been collected on the plateau. The seismic reflection profiles collected during the Glacier cruise show a relatively thick (0.7 seconds), laminated sequence resting on folded(?) strata. Large normal (down to the basin) faults occur on the slope and form modern seafloor scarps. Two 81
piston cores (cores 11 and 16, table) penetrated outcrops on the lower slope, and preliminary micropaleontologic analyses yielded Miocene and Pliocene ages for these deposits. Piston cores from the upper laminated seismic sequence contain diatoms of Pleistocene and Recent age. Two seismic lines were collected across the platform for the purpose of recording possible glacial erosional surfaces and/or moraines. No moraines were noted, but a trough-like feature does occur just south of the main island, and a widespread erosional surface extends across the northern portion of the platform to its edge. Thirteen piston cores were collected on the platform, and at least one of these cores penetrated an overcompacted diamicton, which could be a basal till. South Shetland Shelf and Bransfield Basin. After completing the survey of the South Orkney Plateau, the Glacier steamed west to the continental shelf north of the South Shetland Islands. Work there was intended to establish whether an ice sheet had once been grounded on the continental shelf, as previously inferred by Sugden and John (1973) and Denton and Hughes (1981). Two seismic lines were obtained on the shelf (figure) and seven piston cores. The seismic data show northwestwardly dipping reflectors that have been truncated by a widespread erosional unconformity and probable moraines situated near the edge of the continental shelf. These features are presently situated at a water depth of 370 meters. Piston cores penetrated volcaniclastic sands, which indicates that strong bottom currents occur on the shelf, and diamictons of either glacial or glacialmarine origin. Additional seismic data were collected in the Bransfield Strait region as part of an ongoing investigation into the Quaternary glacial history of this region. Two of these lines were acquired in fjords of King George Island, Admiralty Bay, and Maxwell Bay. In addition, three piston cores were collected in Admiralty Bay. Seismic data from Admiralty Bay and Maxwell Bay show that both fjords are silled at their seaward terminus, and both contain relatively thick (up to 200 milliseconds) sediment layers. Large terminal moraines occur in both bays, and meltwater deltas are notably absent, which provides a striking contrast to most arctic fjords. A helicopter survey of the region was also conducted, and the glacial setting of the coast was mapped. Meltwater plumes were observed in both Admiralty Bay and Maxwell Bay. A seismic profile across the Bransfield Strait (figure) was obtained to determine the origin of platforms and associated channel-like features there. These data indicate that the shallow platform has been eroded and that channel-like features on this platform have U-shaped, erosional profiles, and were therefore probably eroded by glacial ice rather than by streams. These data will help in the interpretation of piston cores collected from this area during austral summers 1980 - 1981 and 1981 - 1982. After completing our seismic survey of the Bransfield Strait, the Glacier steamed west to the vicinity of Anvers Island where seismic and coring operations were conducted on the shelf and in two fjords in the area. A widespread erosional surface and possible moraines were mapped on the shelf north of Daliman Bay. Three piston cores were collected on the shelf to see if basal tills exist in the area. Two fjords, Fournier Bay and Flanders Bay, were surveyed for purposes of investigating the Quaternary glacial history of the region and fjord sedimentation. In addition, seismic profiling and piston coring were conducted in a deep, enclosed basin situation west of Anvers Island. A 12-meter-long piston core
82
Station information 1985
Station -1
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Core (length)
Trigger core (IC) !grab
Latitude! longitude
Water depth (meters)
61"34.3'S 47"29.9'W 61°32.9'S 47"l 4.4W 61029.7'S 47"02.5'W 61031.6'S 47001.7'W 61027.6'S 46"45.6'W
2,504
450
TC
988
108"
TC
576
41"
Grab
553
51/4"
None
411
23"
Grab
61042.2'S 47"35.9'W 61043.9'S 47031.1'W 61043.7'S 47028.1'W 61042.6'S 47021.9'W 61042.3'S 47016.3'W
2,196
4,5"
Grab
1,573
NR"
Grab
1,235
310"
Grab
1,243
5'l.5"
None
1,364
5,7"
Grab
61"40.1 'S 47"07.6'W 61040.6'S 46°57.8'W 61039.6'S 46"54.O'W 61042.0'S 46"46.O'W 61055.6'S 47014.3'W
1,360
16"
None
962
91.25"
None
732
4,4"
None
512
4"
None
2,397
3,4"
TC
61055.3'S 47"04.7'W 61"54.7'S 47"05.6'W 61051.9'S 47"03.3'W 61052.6'S 46"57.3'W 61045.5'S 46"50.6'W
2,004
2'3"
IC
1,482
8'7"
None
1,261
410"
TC
1,151
Bagged
IC
768
1 '4"
TC
60"49.5'S 45"36.2'W 60"SO.O'S 45041.3'W 60049.1'S 45"44.7'W 60"50.6'S 45°53.9'W 60051.5'S 46"06.7'W
256
Bagged
TC
348
96"
None
304
9,7"
TC
133
Bagged
Grab
155
9"
Grab
61000.3'S 46"18.1 'W 61"09.2'S 46"22.2'W 61°18.9'S 46"28.3'W 61029.1'S 46031.5'W 61038.2'S 46021.4'W
220
14"
Grab
249
6'9"
Grab
295
2'6"
None
357
2"/2"
Grab
311
8.5"
Grab
ANTARCTIC JOURNAL
Station information 1985 (Continued)
Station information 1985 (Continued)
Latitude! Water depth Core Trigger core (TC) Latitude/ Water depth Core Trigger core (TC) Station longitude (meters) (length) !grab Station longitude (meters) (length) /grab 31 61046.4'S 416 311" None 46011.6'W 32 6155.7'S 448 Bagged Grab 4558.9'W 33 62°20.4'S 2,843 310" TC 46°29.5'W 34 62012.1'S 1,794 91111, 462O.8'W 35 62010.6'S 1,054 99" None 46°1 2.2W TC 36 62011.8'S 1,684 9' 46019.7'W 37 61032.2'S 408 NA None 58015.0'W Grab 38 61033.5'S 388 Bagged 58°11.9'W NA 39 6137.4'S 302 Grab 5808.0'W 40 61040.8'S 302 NA Grab 5805.9'W Grab NA 41 61044.8'S 238 5801.7'W 10" Grab 42 61054.8'S 304 59°54.5'W None 43 61058.6'S 210 63" 59°52.8'W Grab 44 62004.8'S 106 NA 5950.5'W Grab 45 6204.8'S 101 26" 59°50.5'W 46 61047.3'S 229 NA Grab 58°00.3'W 47 6207.4'S 415 NA Grab 58°25.8'W 48 62008.9'S 439 89" TC 58°25.7'W 49 6208.4'S 363 TC 139" 58°26.6'W 50 63027.2'S 201 Bagged Grab 64°06.9'W 51 63°35.1'S 144 3½" None 6348.6'W 52 63046.6'S 522 810" TC 63°22.9'W 53 64033.5'S 201 5'2.7" TC 6309.3'W 54 64c31.9S 311 96" TC 63°08.O'W 55 6430.3'S 462 175" TC 63°06.6'W 56 64026.6'S 294 NA Grab 6302.4'W 57 65005.8'S 650 TC 8' 63010.2'W 58 65004.7'S 439 TC 5,9" 63010.7'W 59 6503.1'S 384 TC 1310" 63011.4'W 60 6501.4'S 448 87.5" None 63016.4'W
185 REVIEW
61 64057.7'S 1,190 811.25" Grab 64017.3'W 62 64°58.7'S 772 99" Grab 64019.7'W 63 64056.9'S 1,373 365.25" TC 64°19,O'W 64 67046.6'S 399 NA Grab 68015.1'W 65 67°46.1'S 358 4' TC 68°16.1 'W 66 67048.3'S 859 199" Grab 68°06.3'W 67 6755.9'S 412 62.5" Grab 68°32.8'W 68 67057.6'S 576 2' Grab 68"25.1'W + Bagged 69 67°59.9'S 256 8" None 68°24.8'W 70 68000.1'S 207 NA Grab 6828.5'W 71 67059.2'S 607 7' Grab 68°34.O'W 72 67054.9'S 808 227" TC 68°26.9'W 73 68006.1'S 275 NA Grab 68©33.5'W 74 68006.1'S 338 3'1" Grab 68034.1'W 75 68°05.5'S 366 87" None 68°26.6'W 76 68005.4'S 594 19½" None 6807.5'W 77 68005.1'S 316 110" Grab 67°52.5'W 78 6808.7'S 470 24" None [email protected] 79 68011.7'S 485 1611" Grab 68015.2'W 80 6814.3'S 275 NR Grab 6823.0'W 81 68014.6'S 421 169" Grab 67°04.2'W 82 68014.4'S 275 43.6" None 67°30.2'W 83 68°17.9'S 155 NA Grab 67°42.O'W 84 6816.8'S 329 63" Grab 67°54.5'W 85 6816.3'S 406 Bagged None 68002.1'W 86 68015.7'S 448 811.8" Grab 68°1 1.0W 87 6815.2'S 622 196" Grab 68'19.9'W 88 68017.5'S 220 35.4" None 6831.5'W + Bagged 89 68017.5'S 201 NA Grab 68°54.9'W 90 6819.9'S 302 5.25' Grab 69°32.2'W
83
Station information 1985
Station 91 92 93 94 95 96 97 98 99 100
Latitude! longitude 68°20.9'S 69°40.7'W 68°26.7'S 69°46.2'W 72°50.6'S 105°12.4'W 73013.1'S 103°59.2'W 73018.3'S 103038.4'W
Water depth (meters)
Core (length)
Trigger core (TC) !grab
NA
Grab
153 348
42"
Grab
550
22"
Grab
584
9"
Grab
777
8'10.5"
TC
786
3,4"
IC
728
48"
TC
329
Bagged
IC
307
3.5"
None
915
NR
TC
73°44.4'S 103°43.1 'W 730320'S 103033.6'W 73°56.2'S 103007.2'W 74°23.5'S 102054.9'W 74°38.9'S 102033.7'W
924
7,5.4"
TC
329
111.5"
IC
586
6'
None
316
Bagged
IC
650
9'6"
TC
74°45.8'S 102025.1'W 74058.1'S 101032.9'W 74°39.1 'S 102057.8'W 72°29.5'S 104028.6'W 71038.5'S 101 027.8'W
1,052
18'3.5"
TC
933
17'0.5"
None
615
91"
TC
567
23.25"
TC
463
5,4"
Grab
71°20.2'S 100°59.1 'W 71014.2'S 100051.3'W 71°06.6'S 100037.4'W 68°19.9'S 70049.5'W 68'26.6'S 70°45.8'W
417
6'8.5"
Grab
412
75.7"
Grab
403
411.5"
Grab
713
1'5/t
None
726
611"
None
68°29.O'S 70°36.O'W 68°29.7'S 70012.5'W 68018.9'S 70°27.5'W 68°20.6'S 70°22.8'W 68017.6'S 69°49.4'W
650
4,9.5"
None
503
61"
None
489
1510"
None
787
96"
None
933
Bagged
None
73°17.9'S 103037.1'W 73023.1'S 103045.7'W 7305975 104°30.3'W 73°53.8'S 103046.7'W 7304395
Station information 1985 (Continued) Latitude! Water depth Core Trigger core Station longitude (meters) (length) !grab 121 680 14.2'S 412 Bagged None 69°49.1 'W 122 680 15.9'S 676 94" None 69°33.2'W 123 680 15.1'S 538 815" None 69021.0'W 124 680 12.7'S 215 Bagged None 69°29.O'W 125 680 13.9'S 558 4'8" None 69°40.7'W TC 126 680 10.3'S 860 4' 69°41.O'W 127 68008.5'S 247 NA Grab 69°36.3'W 128 68002.5'S 774 99" None 69°37.3'W 129 67049.9'S 256 5'2" Grab 67°34.9'W 130 67054.3'S 137 NA Grab 67°39.6'W
103044.7'W 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120
131 67050.7'S 247 Bagged Grab 67°32.2'W a
"NA" denotes "no recovery?'
b
"NA" denotes "none attempted?'
collected within this feature will be investigated for its Quaternary glacial record. Marguerite Bay area. Marguerite Bay is the terminus of the George VI Ice Shelf, which drains a large segment of Palmer Land. British scientists have already done careful glacial geology studies of the region (Sugden and John 1973), and it was our intention to gather marine geologic information to complement their work. The complex morphology of the seafloor in this area provided an indication that this would be a key region in which to investigate Antarctica's Quaternary glacial record and to study glacial marine sedimentation. Rough seas prevented completion of the survey; however, most of our objectives were completed, and we gathered some 90 ki1ometer, of seismic data and 42 geologic samples before having to leav the area. The primary objective in the Pine Island Bay survey was to examine the Quaternary glacial history of the area. Our surve' took us to 75°00'S 101°30'W, the deepest recorded penetratioi of the bay (figure). Two short seismic lines and 12 piston core were obtained. Other activities included recovering a damagei weather station from Lindsey Island, taking a hydrocast ner the terminus of Pine Island Glacier, sampling a raised moraire (situated approximately 300 meters above the present gladil surface) near the base of the Hudson Mountains, and geologc sampling of previously unmapped islands (Lindsey Island, Sterrett Islands, Edwards Islands, and Brownson Islands). Tie passage out of Pine Island Bay required extensive backing aid ramming, and on one occasion, progress was slowed to abcit 500 meters in 15 hours. ANTARCTIC JOURNL
This scientific party consisted of John B. Anderson (chief scientist), Lou Bartek, Tom Griffith, Margaret Herron, Doug Kennedy, Jill Singer, and Mike Smith of Rice University, and Tom Kellogg, Davida Kellogg, and Terry Hughes of the University of Maine at Orono. We are indebted to the men and women of the U.S. Coast Guard icebreaker Glacier for their enthusiastic support during our cruise. We could not have expected any greater support than we received. Peter Barker kindly provided seismic data from the South Orkney Plateau, which proved invaluable in the planning of our cruise. John West of the U.S. Geological Survey, Corpus Christie, assisted us in preparing for our seismic work. Steve Montgomery also helped in this regard. This reasearch is funded by National Science Foundation grants DPP 83-15555 (to John B. Anderson) and DPP 80-20000 (to Thomas B. Kellogg).
Marine geology of the northwestern Weddell Sea and adjacent coastal fjords and bays: Implications for glacial history M.J. SMITH*
References
Denton, G.H., and T.J. Hughes. 1981. The last great ice sheets. New York: John Wiley and Sons. Haase, H. 1984. Marine geology, Sea Beam and 3.5 kHz measurements during the German Antarktis II expedition. Berichte zur Polarforschung, 129 - 136. Harrington, P.K., P.F. Barker, and D.H. Griffiths. 1972. Crustal structure of the South Orkney Islands area from seismic refraction and magnetic measurements. In R.J. Adie (Ed.), Antarctic geology and geophysics. Oslo: Universitetsforlaget. Sugden, D.E., and B.S. John. 1973. The ages of glacier fluctuations in the South Shetland Islands, Antarctica. [Reprinted from E.M. van Zinderen Bakker, Sr. (Ed.), Paleoecology of Africa and the Surrounding Islands and Antarctica. VIII Balkema, Cape Town, pp. 141 - 159.1
tional glacial marine units, which suggests that a floating ice shelf was not present in this region (figure 3). Surface sediments on the shelf show that marine currents are redistributing terrigenous material derived mainly from local islands, because there is textural grading in an offshore direction. 56W
57W
63S
635-
Department of Geology Rice University Houston, Texas 77251
During austral summer 1981 - 1982, scientists on board the U.S. Coast Guard icebreaker Glacier collected 53 piston cores and grab samples from the northwest Weddell Sea continental shelf and from fjords and bays of the James Ross Island area (figure 1). The purpose of this study was to examine these cores n light of the postulated expansion of the late Pleistocene Antrctic Peninsula ice sheet into this region. Detailed sedimentologic, compositional, and clast-shape nalyses reveal that piston cores penetrated compound glacial anne sediments north of 64°30'S, residual glacial marine sedients adjacent to Seymour Island, and transitional glacial marne sediments south of 64°30'S (figure 2). Basal tills are not resent in these cores. If the deposits penetrated in these cores a e of late Wisconsin age, these data are inconsistent with prevously proposed models for the late Wisconsin extent of g ounded ice in the Antarctic Peninsula region (Stuiver et al. 1 81). The presence of transitional glacial marine sediments on t continental shelf does, however, imply expansion of a floatirg ice shelf over this area at some time during the past. Petrologic analyses of pebbles and coarse sand from the transitional glacial marine units has led to the identification of disti petrologic provinces and indicates eastward expansion of th Larsen Ice Shelf over the continental shelf. Compound glicial marine sediments are located to the north of the transi* Fresent address: Pecten International Company, Houston, Texas 77001.
195 REVIEW
HHOPE BAY JOINVILLE ISLAND
\CHAN
750 177
EGA ISLAN
2n
RO T B
0
1,a
0167 1
184
64S0173 clog
'AMES IS ROSS 174 02 (0 ISLAND 17 171
20 019
0 S-
Is
HILL
00
Ik
0 -65S
655 OPISTON CORE AND GRAB SAMPLE 010 PISTON CORE ONLY OGRAB SAMPLE ONLY ii
SOW
5W
57W
12
WEDDELL SEA
56W
Figure 1. Locations of piston cores and grab samples.
Sediments obtained in fjords and bays of the northeastern Antarctic Peninsula were examined to characterize sedimentary processes active in these areas and to relate sedimentation to land-based studies of local glacial history. Sediments obtained in the Prince Gustav Channel consist of sand and gravel, suggesting deposition by floating ice under the influence of rela85
ing Office.
Preliminary results from the USCGC Glacier 1985 cruise
Crabtree, R.D., and C.S.M. Doake. 1982. Pine Island Glacier and its drainage basin: Results from radio-echo sounding. Annals of Glaciology, 3, 65 - 70. Kellogg, T.B., D.E. Kellogg, and J.B. Anderson. 1982. Preliminary results of microfossil analyses of Amundsen Sea sediment cores. Antarctic Journal of the U.S., 17(5), 125 - 126. Lindstrom, D. 1985. A study of Pine Island and Thwaites Glaciers. (Masters Thesis, University of Maine, Orono, Maine.) Lindstrom, D., and D.A. Tyler. 1984. Preliminary results of Pine Island and Thwaites Glaciers study. Antarctic Journal of the U. S., 19(5), 53-55. Lindstrom, D., and T.J. Hughes. 1984. Downdraw of the Pine Island Bay drainage basins of the west antarctic ice sheet. Antarctic Journal of the U. S., 19(5), 56-58. Stauffer, B., and J . Schwander. 1984. Core processing and first analysis of ice cores from Siple and South Pole Stations. Antarctic Journal of the U. S., 19(5), 59-60.
Iceberg drift tracks were also measured, using the ship's radar, to assess potential threats to drilling operations. Preliminary micropaleontologic age determinations of cores were conducted by Davida Kellogg.
J . B. ANDERSON Department of Geology Rice University Houston, Texas 77251
On 18 December 1984 the U.S. Coast Guard icebreaker Glacier departed from Punta Arenas, Chile, to begin marine geologic work on the antarctic continental margin. Four areas were surveyed as part of this cruise. These included the western margin of the South Orkney Plateau, portions of the Bransfield Strait and the adjacent continental shelf of the South Shetland Islands, Marguerite Bay, and Pine Island Bay (figure). In all, some 761 kilometers of seismic data and approximately 5,000 kilometers of bottom profiler data were obtained. In addition, 115 piston coring stations and 15 grab sample stations were occupied (table). The scientific party consisted of geologists from Rice University and the University of Maine at Orono. This report provides an account of samples and data obtained and a ummary of preliminary findings. South Orkney Plateau. The first phase of the cruise was conucted on the western margin of the South Orkney Plateau. ur objectives were to investigate the possibility that an ice cap as once grounded on the plateau, to investigate the seismic tratigraphy of the western margin of the plateau using singlehannel sparker data and piston cores taken in outcrops, and to i vestigate sedimentation at various depths on the plateau in elation to different water masses which impinge on it, and to 1 ok for sedimentologic evidence of paleoceanographic c anges. The latter is the primary objective of proposed Ocean rril1ing Project drill sites in the area, and our study, which focuses on the Quaternary record, is intended as an initial test of this objective. A total of 320 kilometers of single channel (sparker) seismic profiles and 36 piston cores were collected in the area (figure). 1985 REVIEW
Cruise track for USCGC Glacier. Heavy lines with "s" indicate seismic lines.
Previous marine geophysical work in the region includes single-channel (airgun) seismic surveys by Peter Barker (University of Birmingham, England); these data, along with a bathymetric base map for the area, were kindly made available to us by Peter Barker for planning of our cruise. Other prior studies include seismic refraction work (Harrington, Barker, and Griffiths 1972) and a single multichannel profile collected by West German scientists during a recent (1983) cruise (ANTARKTIS-II) of the research vessel Polarstern (Haase 1984). Prior to this cruise, only a few sediment samples had been collected on the plateau. The seismic reflection profiles collected during the Glacier cruise show a relatively thick (0.7 seconds), laminated sequence resting on folded(?) strata. Large normal (down to the basin) faults occur on the slope and form modern seafloor scarps. Two 81
piston cores (cores 11 and 16, table) penetrated outcrops on the lower slope, and preliminary micropaleontologic analyses yielded Miocene and Pliocene ages for these deposits. Piston cores from the upper laminated seismic sequence contain diatoms of Pleistocene and Recent age. Two seismic lines were collected across the platform for the purpose of recording possible glacial erosional surfaces and/or moraines. No moraines were noted, but a trough-like feature does occur just south of the main island, and a widespread erosional surface extends across the northern portion of the platform to its edge. Thirteen piston cores were collected on the platform, and at least one of these cores penetrated an overcompacted diamicton, which could be a basal till. South Shetland Shelf and Bransfield Basin. After completing the survey of the South Orkney Plateau, the Glacier steamed west to the continental shelf north of the South Shetland Islands. Work there was intended to establish whether an ice sheet had once been grounded on the continental shelf, as previously inferred by Sugden and John (1973) and Denton and Hughes (1981). Two seismic lines were obtained on the shelf (figure) and seven piston cores. The seismic data show northwestwardly dipping reflectors that have been truncated by a widespread erosional unconformity and probable moraines situated near the edge of the continental shelf. These features are presently situated at a water depth of 370 meters. Piston cores penetrated volcaniclastic sands, which indicates that strong bottom currents occur on the shelf, and diamictons of either glacial or glacialmarine origin. Additional seismic data were collected in the Bransfield Strait region as part of an ongoing investigation into the Quaternary glacial history of this region. Two of these lines were acquired in fjords of King George Island, Admiralty Bay, and Maxwell Bay. In addition, three piston cores were collected in Admiralty Bay. Seismic data from Admiralty Bay and Maxwell Bay show that both fjords are silled at their seaward terminus, and both contain relatively thick (up to 200 milliseconds) sediment layers. Large terminal moraines occur in both bays, and meltwater deltas are notably absent, which provides a striking contrast to most arctic fjords. A helicopter survey of the region was also conducted, and the glacial setting of the coast was mapped. Meltwater plumes were observed in both Admiralty Bay and Maxwell Bay. A seismic profile across the Bransfield Strait (figure) was obtained to determine the origin of platforms and associated channel-like features there. These data indicate that the shallow platform has been eroded and that channel-like features on this platform have U-shaped, erosional profiles, and were therefore probably eroded by glacial ice rather than by streams. These data will help in the interpretation of piston cores collected from this area during austral summers 1980 - 1981 and 1981 - 1982. After completing our seismic survey of the Bransfield Strait, the Glacier steamed west to the vicinity of Anvers Island where seismic and coring operations were conducted on the shelf and in two fjords in the area. A widespread erosional surface and possible moraines were mapped on the shelf north of Daliman Bay. Three piston cores were collected on the shelf to see if basal tills exist in the area. Two fjords, Fournier Bay and Flanders Bay, were surveyed for purposes of investigating the Quaternary glacial history of the region and fjord sedimentation. In addition, seismic profiling and piston coring were conducted in a deep, enclosed basin situation west of Anvers Island. A 12-meter-long piston core
82
Station information 1985
Station -1
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Core (length)
Trigger core (IC) !grab
Latitude! longitude
Water depth (meters)
61"34.3'S 47"29.9'W 61°32.9'S 47"l 4.4W 61029.7'S 47"02.5'W 61031.6'S 47001.7'W 61027.6'S 46"45.6'W
2,504
450
TC
988
108"
TC
576
41"
Grab
553
51/4"
None
411
23"
Grab
61042.2'S 47"35.9'W 61043.9'S 47031.1'W 61043.7'S 47028.1'W 61042.6'S 47021.9'W 61042.3'S 47016.3'W
2,196
4,5"
Grab
1,573
NR"
Grab
1,235
310"
Grab
1,243
5'l.5"
None
1,364
5,7"
Grab
61"40.1 'S 47"07.6'W 61040.6'S 46°57.8'W 61039.6'S 46"54.O'W 61042.0'S 46"46.O'W 61055.6'S 47014.3'W
1,360
16"
None
962
91.25"
None
732
4,4"
None
512
4"
None
2,397
3,4"
TC
61055.3'S 47"04.7'W 61"54.7'S 47"05.6'W 61051.9'S 47"03.3'W 61052.6'S 46"57.3'W 61045.5'S 46"50.6'W
2,004
2'3"
IC
1,482
8'7"
None
1,261
410"
TC
1,151
Bagged
IC
768
1 '4"
TC
60"49.5'S 45"36.2'W 60"SO.O'S 45041.3'W 60049.1'S 45"44.7'W 60"50.6'S 45°53.9'W 60051.5'S 46"06.7'W
256
Bagged
TC
348
96"
None
304
9,7"
TC
133
Bagged
Grab
155
9"
Grab
61000.3'S 46"18.1 'W 61"09.2'S 46"22.2'W 61°18.9'S 46"28.3'W 61029.1'S 46031.5'W 61038.2'S 46021.4'W
220
14"
Grab
249
6'9"
Grab
295
2'6"
None
357
2"/2"
Grab
311
8.5"
Grab
ANTARCTIC JOURNAL
Station information 1985 (Continued)
Station information 1985 (Continued)
Latitude! Water depth Core Trigger core (TC) Latitude/ Water depth Core Trigger core (TC) Station longitude (meters) (length) !grab Station longitude (meters) (length) /grab 31 61046.4'S 416 311" None 46011.6'W 32 6155.7'S 448 Bagged Grab 4558.9'W 33 62°20.4'S 2,843 310" TC 46°29.5'W 34 62012.1'S 1,794 91111, 462O.8'W 35 62010.6'S 1,054 99" None 46°1 2.2W TC 36 62011.8'S 1,684 9' 46019.7'W 37 61032.2'S 408 NA None 58015.0'W Grab 38 61033.5'S 388 Bagged 58°11.9'W NA 39 6137.4'S 302 Grab 5808.0'W 40 61040.8'S 302 NA Grab 5805.9'W Grab NA 41 61044.8'S 238 5801.7'W 10" Grab 42 61054.8'S 304 59°54.5'W None 43 61058.6'S 210 63" 59°52.8'W Grab 44 62004.8'S 106 NA 5950.5'W Grab 45 6204.8'S 101 26" 59°50.5'W 46 61047.3'S 229 NA Grab 58°00.3'W 47 6207.4'S 415 NA Grab 58°25.8'W 48 62008.9'S 439 89" TC 58°25.7'W 49 6208.4'S 363 TC 139" 58°26.6'W 50 63027.2'S 201 Bagged Grab 64°06.9'W 51 63°35.1'S 144 3½" None 6348.6'W 52 63046.6'S 522 810" TC 63°22.9'W 53 64033.5'S 201 5'2.7" TC 6309.3'W 54 64c31.9S 311 96" TC 63°08.O'W 55 6430.3'S 462 175" TC 63°06.6'W 56 64026.6'S 294 NA Grab 6302.4'W 57 65005.8'S 650 TC 8' 63010.2'W 58 65004.7'S 439 TC 5,9" 63010.7'W 59 6503.1'S 384 TC 1310" 63011.4'W 60 6501.4'S 448 87.5" None 63016.4'W
185 REVIEW
61 64057.7'S 1,190 811.25" Grab 64017.3'W 62 64°58.7'S 772 99" Grab 64019.7'W 63 64056.9'S 1,373 365.25" TC 64°19,O'W 64 67046.6'S 399 NA Grab 68015.1'W 65 67°46.1'S 358 4' TC 68°16.1 'W 66 67048.3'S 859 199" Grab 68°06.3'W 67 6755.9'S 412 62.5" Grab 68°32.8'W 68 67057.6'S 576 2' Grab 68"25.1'W + Bagged 69 67°59.9'S 256 8" None 68°24.8'W 70 68000.1'S 207 NA Grab 6828.5'W 71 67059.2'S 607 7' Grab 68°34.O'W 72 67054.9'S 808 227" TC 68°26.9'W 73 68006.1'S 275 NA Grab 68©33.5'W 74 68006.1'S 338 3'1" Grab 68034.1'W 75 68°05.5'S 366 87" None 68°26.6'W 76 68005.4'S 594 19½" None 6807.5'W 77 68005.1'S 316 110" Grab 67°52.5'W 78 6808.7'S 470 24" None [email protected] 79 68011.7'S 485 1611" Grab 68015.2'W 80 6814.3'S 275 NR Grab 6823.0'W 81 68014.6'S 421 169" Grab 67°04.2'W 82 68014.4'S 275 43.6" None 67°30.2'W 83 68°17.9'S 155 NA Grab 67°42.O'W 84 6816.8'S 329 63" Grab 67°54.5'W 85 6816.3'S 406 Bagged None 68002.1'W 86 68015.7'S 448 811.8" Grab 68°1 1.0W 87 6815.2'S 622 196" Grab 68'19.9'W 88 68017.5'S 220 35.4" None 6831.5'W + Bagged 89 68017.5'S 201 NA Grab 68°54.9'W 90 6819.9'S 302 5.25' Grab 69°32.2'W
83
Station information 1985
Station 91 92 93 94 95 96 97 98 99 100
Latitude! longitude 68°20.9'S 69°40.7'W 68°26.7'S 69°46.2'W 72°50.6'S 105°12.4'W 73013.1'S 103°59.2'W 73018.3'S 103038.4'W
Water depth (meters)
Core (length)
Trigger core (TC) !grab
NA
Grab
153 348
42"
Grab
550
22"
Grab
584
9"
Grab
777
8'10.5"
TC
786
3,4"
IC
728
48"
TC
329
Bagged
IC
307
3.5"
None
915
NR
TC
73°44.4'S 103°43.1 'W 730320'S 103033.6'W 73°56.2'S 103007.2'W 74°23.5'S 102054.9'W 74°38.9'S 102033.7'W
924
7,5.4"
TC
329
111.5"
IC
586
6'
None
316
Bagged
IC
650
9'6"
TC
74°45.8'S 102025.1'W 74058.1'S 101032.9'W 74°39.1 'S 102057.8'W 72°29.5'S 104028.6'W 71038.5'S 101 027.8'W
1,052
18'3.5"
TC
933
17'0.5"
None
615
91"
TC
567
23.25"
TC
463
5,4"
Grab
71°20.2'S 100°59.1 'W 71014.2'S 100051.3'W 71°06.6'S 100037.4'W 68°19.9'S 70049.5'W 68'26.6'S 70°45.8'W
417
6'8.5"
Grab
412
75.7"
Grab
403
411.5"
Grab
713
1'5/t
None
726
611"
None
68°29.O'S 70°36.O'W 68°29.7'S 70012.5'W 68018.9'S 70°27.5'W 68°20.6'S 70°22.8'W 68017.6'S 69°49.4'W
650
4,9.5"
None
503
61"
None
489
1510"
None
787
96"
None
933
Bagged
None
73°17.9'S 103037.1'W 73023.1'S 103045.7'W 7305975 104°30.3'W 73°53.8'S 103046.7'W 7304395
Station information 1985 (Continued) Latitude! Water depth Core Trigger core Station longitude (meters) (length) !grab 121 680 14.2'S 412 Bagged None 69°49.1 'W 122 680 15.9'S 676 94" None 69°33.2'W 123 680 15.1'S 538 815" None 69021.0'W 124 680 12.7'S 215 Bagged None 69°29.O'W 125 680 13.9'S 558 4'8" None 69°40.7'W TC 126 680 10.3'S 860 4' 69°41.O'W 127 68008.5'S 247 NA Grab 69°36.3'W 128 68002.5'S 774 99" None 69°37.3'W 129 67049.9'S 256 5'2" Grab 67°34.9'W 130 67054.3'S 137 NA Grab 67°39.6'W
103044.7'W 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120
131 67050.7'S 247 Bagged Grab 67°32.2'W a
"NA" denotes "no recovery?'
b
"NA" denotes "none attempted?'
collected within this feature will be investigated for its Quaternary glacial record. Marguerite Bay area. Marguerite Bay is the terminus of the George VI Ice Shelf, which drains a large segment of Palmer Land. British scientists have already done careful glacial geology studies of the region (Sugden and John 1973), and it was our intention to gather marine geologic information to complement their work. The complex morphology of the seafloor in this area provided an indication that this would be a key region in which to investigate Antarctica's Quaternary glacial record and to study glacial marine sedimentation. Rough seas prevented completion of the survey; however, most of our objectives were completed, and we gathered some 90 ki1ometer, of seismic data and 42 geologic samples before having to leav the area. The primary objective in the Pine Island Bay survey was to examine the Quaternary glacial history of the area. Our surve' took us to 75°00'S 101°30'W, the deepest recorded penetratioi of the bay (figure). Two short seismic lines and 12 piston core were obtained. Other activities included recovering a damagei weather station from Lindsey Island, taking a hydrocast ner the terminus of Pine Island Glacier, sampling a raised moraire (situated approximately 300 meters above the present gladil surface) near the base of the Hudson Mountains, and geologc sampling of previously unmapped islands (Lindsey Island, Sterrett Islands, Edwards Islands, and Brownson Islands). Tie passage out of Pine Island Bay required extensive backing aid ramming, and on one occasion, progress was slowed to abcit 500 meters in 15 hours. ANTARCTIC JOURNL
This scientific party consisted of John B. Anderson (chief scientist), Lou Bartek, Tom Griffith, Margaret Herron, Doug Kennedy, Jill Singer, and Mike Smith of Rice University, and Tom Kellogg, Davida Kellogg, and Terry Hughes of the University of Maine at Orono. We are indebted to the men and women of the U.S. Coast Guard icebreaker Glacier for their enthusiastic support during our cruise. We could not have expected any greater support than we received. Peter Barker kindly provided seismic data from the South Orkney Plateau, which proved invaluable in the planning of our cruise. John West of the U.S. Geological Survey, Corpus Christie, assisted us in preparing for our seismic work. Steve Montgomery also helped in this regard. This reasearch is funded by National Science Foundation grants DPP 83-15555 (to John B. Anderson) and DPP 80-20000 (to Thomas B. Kellogg).
Marine geology of the northwestern Weddell Sea and adjacent coastal fjords and bays: Implications for glacial history M.J. SMITH*
References
Denton, G.H., and T.J. Hughes. 1981. The last great ice sheets. New York: John Wiley and Sons. Haase, H. 1984. Marine geology, Sea Beam and 3.5 kHz measurements during the German Antarktis II expedition. Berichte zur Polarforschung, 129 - 136. Harrington, P.K., P.F. Barker, and D.H. Griffiths. 1972. Crustal structure of the South Orkney Islands area from seismic refraction and magnetic measurements. In R.J. Adie (Ed.), Antarctic geology and geophysics. Oslo: Universitetsforlaget. Sugden, D.E., and B.S. John. 1973. The ages of glacier fluctuations in the South Shetland Islands, Antarctica. [Reprinted from E.M. van Zinderen Bakker, Sr. (Ed.), Paleoecology of Africa and the Surrounding Islands and Antarctica. VIII Balkema, Cape Town, pp. 141 - 159.1
tional glacial marine units, which suggests that a floating ice shelf was not present in this region (figure 3). Surface sediments on the shelf show that marine currents are redistributing terrigenous material derived mainly from local islands, because there is textural grading in an offshore direction. 56W
57W
63S
635-
Department of Geology Rice University Houston, Texas 77251
During austral summer 1981 - 1982, scientists on board the U.S. Coast Guard icebreaker Glacier collected 53 piston cores and grab samples from the northwest Weddell Sea continental shelf and from fjords and bays of the James Ross Island area (figure 1). The purpose of this study was to examine these cores n light of the postulated expansion of the late Pleistocene Antrctic Peninsula ice sheet into this region. Detailed sedimentologic, compositional, and clast-shape nalyses reveal that piston cores penetrated compound glacial anne sediments north of 64°30'S, residual glacial marine sedients adjacent to Seymour Island, and transitional glacial marne sediments south of 64°30'S (figure 2). Basal tills are not resent in these cores. If the deposits penetrated in these cores a e of late Wisconsin age, these data are inconsistent with prevously proposed models for the late Wisconsin extent of g ounded ice in the Antarctic Peninsula region (Stuiver et al. 1 81). The presence of transitional glacial marine sediments on t continental shelf does, however, imply expansion of a floatirg ice shelf over this area at some time during the past. Petrologic analyses of pebbles and coarse sand from the transitional glacial marine units has led to the identification of disti petrologic provinces and indicates eastward expansion of th Larsen Ice Shelf over the continental shelf. Compound glicial marine sediments are located to the north of the transi* Fresent address: Pecten International Company, Houston, Texas 77001.
195 REVIEW
HHOPE BAY JOINVILLE ISLAND
\CHAN
750 177
EGA ISLAN
2n
RO T B
0
1,a
0167 1
184
64S0173 clog
'AMES IS ROSS 174 02 (0 ISLAND 17 171
20 019
0 S-
Is
HILL
00
Ik
0 -65S
655 OPISTON CORE AND GRAB SAMPLE 010 PISTON CORE ONLY OGRAB SAMPLE ONLY ii
SOW
5W
57W
12
WEDDELL SEA
56W
Figure 1. Locations of piston cores and grab samples.
Sediments obtained in fjords and bays of the northeastern Antarctic Peninsula were examined to characterize sedimentary processes active in these areas and to relate sedimentation to land-based studies of local glacial history. Sediments obtained in the Prince Gustav Channel consist of sand and gravel, suggesting deposition by floating ice under the influence of rela85
