Preliminary diatom results from eastern Taylor Valley drill ...
D.E. Hayes, L.A. Frakes et al. (Eds.), Initial Reports of the Deep Sea Drilling Project, Vol. 28. Washington, D.C.: U.S. Government Printing Office. Schrader, H.-J. 1976. Cenozoic planktonic diatom biostratigraphy of the southern Pacific Ocean. In C.D. Hollister, C. Craddock et al., Initial
Preliminary diatom results from eastern Taylor Valley drill cores
Institute for Quaternary Studies and Department of Geological Sciences University of Maine Orono, Maine 04469
In conjunction with the drilling project in eastern Taylor Valley under the joint direction of Donald Elston of the U.S. Geological Survey and Paul Robinson of the New Zealand Geological Survey, we made diatom analyses of ice-cemented sediments from cores drilled during the 1982-1983 field season. These analyses provide micropaleontologic age support for interpretation of paleomagnetic results, as well as information on the depositional environments represented by these sediments. Analyses of additional cores drilled in 1983-1984 will be completed this summer. We analyzed 20 samples from five of the six cores drilled in 1982-1983, but gave priority (12 samples) to ETV-3, a 58.5meter core from a depression just east of the crest of Coral Ridge (approximately 1.5 kilometers west of Explorers Cove) (see figure). Additional effort was concentrated on analyses of the upper portions of ETV-5 and ETV-6, collected from sites lo-
ci
Government Printing Office. Webb, P.N., D.M. Harwood, B.C. McKelvey, J.H. Mercer, and L.D. Stott. 1984. Cenozoic marine sedimentation and ice-volume variation on the East Antarctic craton. Geology, 12, 287-291.
cated within 50 meters of DVDP-11. Our purpose here was to
D. E. KELLOGG and T. B. KELLOGG
TAYLOR VALLEY
Reports of the Deep Sea Drilling Project, Vol. 35. Washington, D.C.: U.S.
km
evaluate the reversed magnetic polarity reported from about 2 to 4 meters in DVDP-11 (Elston and Bressler 1981; Elston, Robinson, and Bressler 1981; Purucker, Elston, and Bressler 1981). Our findings may be summarized for all the ETV samples analyzed as follows: (1) Non-marine species predominate in all samples (table 1). (2) Fragments of marine species are present in most samples. (3) Non-marine specimens are in a much better state of preservation than the marine specimens. (4) Some marine species with known stratigraphic ranges are present; ages represented include Miocene, Pliocene, and Quaternary (samples with Brunhes indicators are listed in table 2). We conclude that considerable reworking was involved in the deposition of all unconsolidated deposits penetrated by the ETV drill cores. This conclusion is based on the facts that (1) marine specimens are highly fragmented, and (2) marine indicator species present represent mixed ages in the Miocene to Recent. The most recent reworking can be no older than Brunhes in age (0-730,000 years' old, Mankinen and Dalrymple 1979) because all samples containing older stratigraphic indicators also contain species with ranges restricted to the Brunhes. The better preserved non-marine diatom species provide the key to understanding depositional environments represented in the ETV drill cores. Non-marine diatoms present (table 1) are commonly found living today in lakes and small melt ponds in the dry valleys and on the McMurdo Ice Shelf (Kellogg and Kellogg, Antarctic Journal, this issue) and were found in late Quaternary-perched deltas in Taylor Valley, which formed
•.:./':''
:•./..
J(oM:o:w::LrH :Y GLACIER C2
) CANADA GLACIER
\
•
EXPLORERS
• -.1
LAKE FRYXELL
• TV8
in
COVE
DP 11 . ..DVDP 10 & ETV5 ETV3 I
'-
DV^D P Ii 2
ETV
I.',
'0
Map of eastern Taylor Valley showing locations of eastern Taylor Valley (ETV) and Dry Valley Drilling Project (DvDP) cores mentioned In text. ("km" denotes kilometer.)
1984 REVIEW
45
age in the Ross Sea (Kellogg and Truesdale 1979; Kellogg and Kellogg 1981). Marine stratigraphic indicator species from ETV-5 and ETV-6 are not consistent with a pre-Brunhes (more than 730,000 years old) age. The sample at 1.71 meters in ETV-5 contained the Miocene indicator species Denticulopsis antarctica, but it also contained the Brunhes species Nitzschia curta and Thalassionema bacteriastrum and possibly (badly broken and thus not positively identified) Rouxia antarctica. The sample at 2.01 meters in ETV-5 also contained a possible specimen of N. curta but none of the older indicators. Other levels in ETV-5 analyzed (4.05 and 5.06 meters) contained 100 percent non-marine diatoms. In ETV-6 at
along the margin of Glacial Lake Washburn during retreat of the late Wisconsin west antarctic ice sheet (Kellogg et al. 1980). For this reason, and because of the sedimentology of the eastern Taylor Valley deposits (Robinson, unpublished data), we suggest that these deposits formed in a glacial-proximal, possibly deltaic, environment. Marine diatoms present in ETV cores are thought to have been derived from glacial drift deposited in Taylor Valley by advances of west antarctic ice, entering the valley from McMurdo Sound (Stuiver et al. 1981). Drift from the most recent Ross Sea glaciation contains reworked marine diatoms (D. Kellogg, unpublished), as do marine sediments of presumed late Wisconsin
Table 1. Complete list of non-marine diatoms and census data for selected Taxa
Core depth in meters
Achnanthes sp. Amphora sp. Cyclotella comta Cyclotella comta v. oligactis Cyclotella glomerata Cyclotella stelligera Cyclotella spp. Diploneis sp. Fragillaria sp. Hantzschia amphioxys Melosira distans Melosira italica v. subarctica Navicula contenta Navicula contenta v. parallela Navicula deltaica Navicula gaussi Navicula gibbula Navicula cf. kerguelensis Navicula mutica Navicula mutica v. capitata Navicula mutica v. cohni Navicula muticopsis Navicula muticopsis v. evoluta Navicula muticopsis v. murrayi Navicula muticopsis v. reducta Navicula aft. pseudoscuteformis Navicula quaternaria Navicula aft. scuteformis Navicula shackletoni Navicula sp. Nitzschia westii Pinnularia cymatopleura Pinnularia Cf. kerguelensis Stauroneis anceps Stauroneis spp. Synedra ? sp. Tabellaria fenestrata Tabellaria flocculosa Tabellaria quadriseptata
ETV samples
ETV-3 ETV-3 ETV-4 ETV-5 ETV-6 ETV-7 33.99
38.59
5.33
1.71
1.58
9.88
2 2
5
6
1
6
13
14
2
3
10 27 5 211 18 2 3
3 30 2
46
26 9
32
3 7
2 3
2
4
2 3
1
31 5 6
1
2
3 1
3 12
4
5
4
16 15 3
1
2
12 8
1 -
4
2
1
2
2 5 5
Other (Unidentified) Totals
25 178 54 66
109
301
U-,, denotes no species found in sample.
46
ANTARCTIC JOURNAL
Table 2. Census data for marine Brunhes indicator diatoms in Taxa
ETV
cores
ETV-3 ETV-3 ETV-3 ETV-4 ETV-5 ETV-5 ETV-6 ETV-7
Core depth in meters
33.99
38.59 38.62 5.33 1.71 2.01 1.58
7.07
Actinocyc/us actinochilus Coscinodiscus lentigenosus Coscinodiscus stel/aris v. symbolophorus Nitzschia curta Rouxia antarctica Thalassionema bacteriastrum
_a 1++ -
2++b 1- - - 2+ d - - - - 1++ - - - - - - - 2++ 1- 6- - 3- 1- - 11- - 2- 1++ - 3-
U 1-
a ""
denotes no species found in sample. b " " denotes positive identification. denotes possible identification, but specimen badly broken. "+" denotes probable identification.
1.58 meters, possible specimens of T bacteriastrum and R. ant- Journal of the U.S., 18(5), 29-31. arctica were encountered, supporting a Brunhes age. This age Kellogg, D.E., and T.B. Kellogg. 1984. Diatoms from the McMurdo Ice supports the paleomagnetic results from ETV-5 and ETV-6 Shelf, Antarctica. Antarctic Journal of the U.S., 19(5). which are all of normal magnetic polarity (Elston, Robinson, Kellogg, TB., and D.E. Kellogg. 1981. Pleistocene sediments beneath the Ross Ice Shelf. Nature, 293, 130-133. and Rieck 1983). Kellogg, D.E., M. Stuiver, T.B. Kellogg, and G.H. Denton. 1980. Non This work was supported by National Science Foundation marine diatoms from late Wisconsin perched deltas in Taylor Valley, grant DPP 80-20000. Coring was supported by National Science Antarctica. Palaeogeography, Palaeoclimatology, Palaeoecology, 30, Foundation grant DPP 81-20877 and the Antarctic Division of the 157-189. Department of Scientific and Industrial Research, New Kellogg, TB., and R.S. Truesdale. 1979. Late Quaternary paleoecology Zealand. and paleoclimatology of the Ross Sea: The diatom record. Marine References
Micropaleontology, 4, 137-158.
Mankinen, E.A., and G.B. Dalrymple. 1979. Revised geomagnetic time Elston, D.P., and S. L. Bressler. 1981. Magnetic stratigraphy of DVDP drill scale for interval 0-5 m.y.B.P. Journal of Geophysical Research, 84, cores and late Cenozoic history of Taylor Valley, Transantarctic Moun- 615-626. Purucker, M.E., D.P. Elston, and S.L. Bressler. 1981. Magnetic stratigratains, Antarctica. Antarctic Research Series, 33, 413-426. Elston, D.P., P.H. Robinson, and S.L. Bressler. 1981. Stratigraphy, sedi- phy of late Cenozoic glaciogenic sediments from drill cores, Taylor mentology and paleomagnetism of the Coral Ridge sand body, east- Valley, Transantarctic Mountains, Antarctica. Antarctic Research Series, ern Taylor Valley, Antarctica. United States Geological Survey Open-File 33, 109-129. Report, No. 81-1303. Washington, D.C.: U.S. Government Printing Stuiver, M., G.H. Denton, T.J. Hughes, and J.L. Fastook. 1981. History of the marine ice sheet in West Antarctica during the last glaciation: A Office. Elston, D.P., H.J. Rieck, and P.H. Robinson. 1983. Dry valleys/ working hypothesis. In G. H. Denton and T.J. Hughes (Eds.), The last McMurdo Sound magnetostratigraphy and sedimentology. Antarctic great ice sheets. New York: Wiley-Interscience.
The antarctic ice sheet exhibited two forms of late Cenozoic
Ice-sheet overriding of the ice-free expansion. During the last two (and probably three) late valleys of southern Victoria Land Quaternary glaciations, ice grounded in the Ross and Weddell C. H. DENTON and R. P. ACKERT Department of Geological Sciences and Institute of Quaternary Studies University of Maine Orono, Maine 04469 M.
L. PRENTICE
Department of Geological Sciences Brown University Providence, Rhode island 02912 N. POTTER, JR.
Department of Geology Dickinson College Carlisle, Pennsylvania 17013
1984 REVIEW
embayments and on the narrow east antarctic continental shelf. However, the Transantarctic Mountains remained exposed to separate the east and west antarctic ice sheets. A surprising discovery from recent field work (Denton et al. 1984) is that several earlier expansions involved a massive ice sheet that flowed northeastward over the dry valleys and the central Transantarctic Mountains. We infer a unified ice sheet (figure 4 in Denton et al. 1984) with a volume substantially greater than in the latest Quaternary glaciations. It has been widely speculated that eustatic sea-level fluctuations were the primary cause of antarctic ice-volume changes (Hollin 1962; Thomas and Bentley 1978; Stuiver et al. 1981). However, additional factors such as changes in temperature and precipitation are probably important in driving the older, more massive ice budget changes. It is important to understand in detail this history of antarctic ice dynamics, because it bears on the coeval history of other climate-system components as well as on the long-term mechanics of global climate. To reconstruct and date overriding glaciations, we are examining strategic field areas along an overriding ice flowband in 47
Preliminary diatom results from eastern Taylor Valley drill cores
Institute for Quaternary Studies and Department of Geological Sciences University of Maine Orono, Maine 04469
In conjunction with the drilling project in eastern Taylor Valley under the joint direction of Donald Elston of the U.S. Geological Survey and Paul Robinson of the New Zealand Geological Survey, we made diatom analyses of ice-cemented sediments from cores drilled during the 1982-1983 field season. These analyses provide micropaleontologic age support for interpretation of paleomagnetic results, as well as information on the depositional environments represented by these sediments. Analyses of additional cores drilled in 1983-1984 will be completed this summer. We analyzed 20 samples from five of the six cores drilled in 1982-1983, but gave priority (12 samples) to ETV-3, a 58.5meter core from a depression just east of the crest of Coral Ridge (approximately 1.5 kilometers west of Explorers Cove) (see figure). Additional effort was concentrated on analyses of the upper portions of ETV-5 and ETV-6, collected from sites lo-
ci
Government Printing Office. Webb, P.N., D.M. Harwood, B.C. McKelvey, J.H. Mercer, and L.D. Stott. 1984. Cenozoic marine sedimentation and ice-volume variation on the East Antarctic craton. Geology, 12, 287-291.
cated within 50 meters of DVDP-11. Our purpose here was to
D. E. KELLOGG and T. B. KELLOGG
TAYLOR VALLEY
Reports of the Deep Sea Drilling Project, Vol. 35. Washington, D.C.: U.S.
km
evaluate the reversed magnetic polarity reported from about 2 to 4 meters in DVDP-11 (Elston and Bressler 1981; Elston, Robinson, and Bressler 1981; Purucker, Elston, and Bressler 1981). Our findings may be summarized for all the ETV samples analyzed as follows: (1) Non-marine species predominate in all samples (table 1). (2) Fragments of marine species are present in most samples. (3) Non-marine specimens are in a much better state of preservation than the marine specimens. (4) Some marine species with known stratigraphic ranges are present; ages represented include Miocene, Pliocene, and Quaternary (samples with Brunhes indicators are listed in table 2). We conclude that considerable reworking was involved in the deposition of all unconsolidated deposits penetrated by the ETV drill cores. This conclusion is based on the facts that (1) marine specimens are highly fragmented, and (2) marine indicator species present represent mixed ages in the Miocene to Recent. The most recent reworking can be no older than Brunhes in age (0-730,000 years' old, Mankinen and Dalrymple 1979) because all samples containing older stratigraphic indicators also contain species with ranges restricted to the Brunhes. The better preserved non-marine diatom species provide the key to understanding depositional environments represented in the ETV drill cores. Non-marine diatoms present (table 1) are commonly found living today in lakes and small melt ponds in the dry valleys and on the McMurdo Ice Shelf (Kellogg and Kellogg, Antarctic Journal, this issue) and were found in late Quaternary-perched deltas in Taylor Valley, which formed
•.:./':''
:•./..
J(oM:o:w::LrH :Y GLACIER C2
) CANADA GLACIER
\
•
EXPLORERS
• -.1
LAKE FRYXELL
• TV8
in
COVE
DP 11 . ..DVDP 10 & ETV5 ETV3 I
'-
DV^D P Ii 2
ETV
I.',
'0
Map of eastern Taylor Valley showing locations of eastern Taylor Valley (ETV) and Dry Valley Drilling Project (DvDP) cores mentioned In text. ("km" denotes kilometer.)
1984 REVIEW
45
age in the Ross Sea (Kellogg and Truesdale 1979; Kellogg and Kellogg 1981). Marine stratigraphic indicator species from ETV-5 and ETV-6 are not consistent with a pre-Brunhes (more than 730,000 years old) age. The sample at 1.71 meters in ETV-5 contained the Miocene indicator species Denticulopsis antarctica, but it also contained the Brunhes species Nitzschia curta and Thalassionema bacteriastrum and possibly (badly broken and thus not positively identified) Rouxia antarctica. The sample at 2.01 meters in ETV-5 also contained a possible specimen of N. curta but none of the older indicators. Other levels in ETV-5 analyzed (4.05 and 5.06 meters) contained 100 percent non-marine diatoms. In ETV-6 at
along the margin of Glacial Lake Washburn during retreat of the late Wisconsin west antarctic ice sheet (Kellogg et al. 1980). For this reason, and because of the sedimentology of the eastern Taylor Valley deposits (Robinson, unpublished data), we suggest that these deposits formed in a glacial-proximal, possibly deltaic, environment. Marine diatoms present in ETV cores are thought to have been derived from glacial drift deposited in Taylor Valley by advances of west antarctic ice, entering the valley from McMurdo Sound (Stuiver et al. 1981). Drift from the most recent Ross Sea glaciation contains reworked marine diatoms (D. Kellogg, unpublished), as do marine sediments of presumed late Wisconsin
Table 1. Complete list of non-marine diatoms and census data for selected Taxa
Core depth in meters
Achnanthes sp. Amphora sp. Cyclotella comta Cyclotella comta v. oligactis Cyclotella glomerata Cyclotella stelligera Cyclotella spp. Diploneis sp. Fragillaria sp. Hantzschia amphioxys Melosira distans Melosira italica v. subarctica Navicula contenta Navicula contenta v. parallela Navicula deltaica Navicula gaussi Navicula gibbula Navicula cf. kerguelensis Navicula mutica Navicula mutica v. capitata Navicula mutica v. cohni Navicula muticopsis Navicula muticopsis v. evoluta Navicula muticopsis v. murrayi Navicula muticopsis v. reducta Navicula aft. pseudoscuteformis Navicula quaternaria Navicula aft. scuteformis Navicula shackletoni Navicula sp. Nitzschia westii Pinnularia cymatopleura Pinnularia Cf. kerguelensis Stauroneis anceps Stauroneis spp. Synedra ? sp. Tabellaria fenestrata Tabellaria flocculosa Tabellaria quadriseptata
ETV samples
ETV-3 ETV-3 ETV-4 ETV-5 ETV-6 ETV-7 33.99
38.59
5.33
1.71
1.58
9.88
2 2
5
6
1
6
13
14
2
3
10 27 5 211 18 2 3
3 30 2
46
26 9
32
3 7
2 3
2
4
2 3
1
31 5 6
1
2
3 1
3 12
4
5
4
16 15 3
1
2
12 8
1 -
4
2
1
2
2 5 5
Other (Unidentified) Totals
25 178 54 66
109
301
U-,, denotes no species found in sample.
46
ANTARCTIC JOURNAL
Table 2. Census data for marine Brunhes indicator diatoms in Taxa
ETV
cores
ETV-3 ETV-3 ETV-3 ETV-4 ETV-5 ETV-5 ETV-6 ETV-7
Core depth in meters
33.99
38.59 38.62 5.33 1.71 2.01 1.58
7.07
Actinocyc/us actinochilus Coscinodiscus lentigenosus Coscinodiscus stel/aris v. symbolophorus Nitzschia curta Rouxia antarctica Thalassionema bacteriastrum
_a 1++ -
2++b 1- - - 2+ d - - - - 1++ - - - - - - - 2++ 1- 6- - 3- 1- - 11- - 2- 1++ - 3-
U 1-
a ""
denotes no species found in sample. b " " denotes positive identification. denotes possible identification, but specimen badly broken. "+" denotes probable identification.
1.58 meters, possible specimens of T bacteriastrum and R. ant- Journal of the U.S., 18(5), 29-31. arctica were encountered, supporting a Brunhes age. This age Kellogg, D.E., and T.B. Kellogg. 1984. Diatoms from the McMurdo Ice supports the paleomagnetic results from ETV-5 and ETV-6 Shelf, Antarctica. Antarctic Journal of the U.S., 19(5). which are all of normal magnetic polarity (Elston, Robinson, Kellogg, TB., and D.E. Kellogg. 1981. Pleistocene sediments beneath the Ross Ice Shelf. Nature, 293, 130-133. and Rieck 1983). Kellogg, D.E., M. Stuiver, T.B. Kellogg, and G.H. Denton. 1980. Non This work was supported by National Science Foundation marine diatoms from late Wisconsin perched deltas in Taylor Valley, grant DPP 80-20000. Coring was supported by National Science Antarctica. Palaeogeography, Palaeoclimatology, Palaeoecology, 30, Foundation grant DPP 81-20877 and the Antarctic Division of the 157-189. Department of Scientific and Industrial Research, New Kellogg, TB., and R.S. Truesdale. 1979. Late Quaternary paleoecology Zealand. and paleoclimatology of the Ross Sea: The diatom record. Marine References
Micropaleontology, 4, 137-158.
Mankinen, E.A., and G.B. Dalrymple. 1979. Revised geomagnetic time Elston, D.P., and S. L. Bressler. 1981. Magnetic stratigraphy of DVDP drill scale for interval 0-5 m.y.B.P. Journal of Geophysical Research, 84, cores and late Cenozoic history of Taylor Valley, Transantarctic Moun- 615-626. Purucker, M.E., D.P. Elston, and S.L. Bressler. 1981. Magnetic stratigratains, Antarctica. Antarctic Research Series, 33, 413-426. Elston, D.P., P.H. Robinson, and S.L. Bressler. 1981. Stratigraphy, sedi- phy of late Cenozoic glaciogenic sediments from drill cores, Taylor mentology and paleomagnetism of the Coral Ridge sand body, east- Valley, Transantarctic Mountains, Antarctica. Antarctic Research Series, ern Taylor Valley, Antarctica. United States Geological Survey Open-File 33, 109-129. Report, No. 81-1303. Washington, D.C.: U.S. Government Printing Stuiver, M., G.H. Denton, T.J. Hughes, and J.L. Fastook. 1981. History of the marine ice sheet in West Antarctica during the last glaciation: A Office. Elston, D.P., H.J. Rieck, and P.H. Robinson. 1983. Dry valleys/ working hypothesis. In G. H. Denton and T.J. Hughes (Eds.), The last McMurdo Sound magnetostratigraphy and sedimentology. Antarctic great ice sheets. New York: Wiley-Interscience.
The antarctic ice sheet exhibited two forms of late Cenozoic
Ice-sheet overriding of the ice-free expansion. During the last two (and probably three) late valleys of southern Victoria Land Quaternary glaciations, ice grounded in the Ross and Weddell C. H. DENTON and R. P. ACKERT Department of Geological Sciences and Institute of Quaternary Studies University of Maine Orono, Maine 04469 M.
L. PRENTICE
Department of Geological Sciences Brown University Providence, Rhode island 02912 N. POTTER, JR.
Department of Geology Dickinson College Carlisle, Pennsylvania 17013
1984 REVIEW
embayments and on the narrow east antarctic continental shelf. However, the Transantarctic Mountains remained exposed to separate the east and west antarctic ice sheets. A surprising discovery from recent field work (Denton et al. 1984) is that several earlier expansions involved a massive ice sheet that flowed northeastward over the dry valleys and the central Transantarctic Mountains. We infer a unified ice sheet (figure 4 in Denton et al. 1984) with a volume substantially greater than in the latest Quaternary glaciations. It has been widely speculated that eustatic sea-level fluctuations were the primary cause of antarctic ice-volume changes (Hollin 1962; Thomas and Bentley 1978; Stuiver et al. 1981). However, additional factors such as changes in temperature and precipitation are probably important in driving the older, more massive ice budget changes. It is important to understand in detail this history of antarctic ice dynamics, because it bears on the coeval history of other climate-system components as well as on the long-term mechanics of global climate. To reconstruct and date overriding glaciations, we are examining strategic field areas along an overriding ice flowband in 47
