Geological studies in southern Victoria Land, on Black Island, and on ...
References
Figure 2. Mount Flora, Hope Bay. (The Trinity Peninsula Formation crops out on the low ground at the base of Mount Flora. The conglomeratic rocks form the lower north-facing cliffs (right-hand side of the photo) of Mount Flora below the prominent pale band located in the middle part of that face. The volcanic rocks form the upper part of that face and the rest of the mountain.)
the early Mesozoic Gondwanian Orogeny, is seen to be unconformably overlain by what probably are Jurassic sedimentary rocks. The conglomerates probably resulted from the erosion of the uplifted Gondwanian Orogen; however, these rocks, together with the overlying plant-bearing beds, have intercalated volcanic rocks representing the initiation of the Andean cycle. Nowhere else in the northern Antarctic Peninsula is this transition from Gondwanian to Andean events so well displayed. Paleomagnetic studies. An extensive paleomagnetic investigation of Mesozoic rocks in the northern Antarctic Peninsula was initiated with the collection of 234 oriented samples from the vicinity ofJoinville Island and Hope Bay. Wherever possible, oriented cores were collected using a commercially available, portable drilling apparatus; otherwise, oriented block samples were taken. The samples were oriented by clinometer and magnetic compass. Magnetic bearings were checked by a direct-reading solar compass (Stone, 1967) when possible. Samples were collected from intrusive rocks at King Point, Fitzroy Point, and the offshore islands to the north and east ofJoinville Island. Most of the units sampled in the area consist of gabbro, though a few have intermediate compositions. Intrusive rocks of granitic and intermediate composition were sampled at Hope Bay. The Antarctic Peninsula Volcanic Group was sampled in detail at Hope Bay. Volcanic rocks above and below the plant-bearing horizons were collected. Because normal faulting has tilted some of the volcanic rocks up to 50°, the fold test of Graham (1949) may be applied to establish the stability of the magnetization of these rocks. It is hoped that laboratory analysis of the samples collected will yield a well-dated Mesozoic pole position for the northern Antarctic Peninsula. We appreciate the excellent support of Captain Lenie and the crew of iJv Hero. This work was supported by National Science Foundation grant DPP 77-23427. ANTARCTIC JOURNAL
Bibby,J. S. 1966. The stratigraphy of part of north-east Graham Land and the James Ross Island group. British Antarctic Survey, Scientific Report 53. Dalziel, I. W. D., D. H. Elliot, J. W. Thomson, M. R. A. Thomson, N. A. Wells, and W. J. Zinsmeister. 1977. Geologic studies in the South Orkney Islands: it/v Hero cruise 77-1,January 1977. AntarcticJournal of the US., 12(4): 98-101. Elliot, D. H. 1967. The geology of Joinville Island. British Antarctic Survey Bulletin, 12: 23-40. Elliot, D. H., C. Rinaldi, W. J . Zinsmeister, T. A. Trautman, W. A. Bryant, and R. del Valle. 1975. Geological Investigations on Seymour Island, Antarctic Peninsula. Antarctic Journal of the US., 10(4): 182-188. Elliot, D. H., and T. A. Trautman. In press. Lower Tertiary strata on Seymour Island. In: Antarctic Geoscience ( C. Craddock, ed.). The University of Wisconsin Press, Madison, Wisconsin. Elliot, D. H., and N. A. Wells. In press. Mesozoic alluvial fans of the South Orkney Islands. In: Antarctic Geoscience ( C. Craddock, ed.). The University of Wisconsin Press, Madison, Wisconsin. Graham,J. W. 1949. The stability and significance of magnetism in sedimentary rocks.Journal of Geophysical Research, 59: 131-137. Stone, D. B. 1967. A sun compass for the direct determination of geographical north. Journal of Scientific Instruments, 49: 661-667. Watts, D. R. In press. Potassium-argon and paleomagnetic results from King George Island, South Shetland Islands. In: Antarctic Geoscience ( C. Craddock, ed.). The University of Wisconsin Press, Madison, Wisconsin.
Geological studies in southern Victoria Land, on Black Island, and on the McMurdo Ice Shelf HOWARD THOMAS BRADY
School of Biological Sciences Macquarie University, North Ryde Sydney. 2113 Australia
Earlier dry valley glaciations (H.T. Brady and B. McKelvey, Armidale University, N.S.W.). Brady and McKelvey (in preparation) describe an ancient tillite at 2,750 meters on Mt. Feather overlooking the Skelton Nevé, the Ferrar Glacier, and Beacon Valley. The deposit has many features in common with the Sirius tillites described by Mercer (1972), Mayewski (1972, 1975) and Barrett (in press). Brady and McKelvey mapped 57 directions on striated clasts and exposed two sections of striated pavement showing a glacial direction to the south-southeast towards and parallel to the Skelton Glacier. Brady and McKelvey's paleocurrent readings do not agree with those of Mayewski's thesis diagram, which shows a direction at Mt. Feather parallel to the Ferrar Glacier. No descriptions of the site are given in his text. Brady and McKelvey consider the tillite to be a remnant of an uplifted 13
paleoglacial valley which predates Beacon Valley and the present day Taylor Glacier system. It was not a small tributary glacier (like the glaciers that cut Beacon and Arena Valley) because the tillite rock types cannot be derived from the surrounding Mt. Feather complex. The age of the tillite is unknown, but it predates the glaciations that cut the Taylor Valley fjord and presumably the Wright Valley fjord which are at least early late Miocene or middle Miocene (Brady 1977). The Mt. Feather glaciation suggests that glacial drainage patterns have been modified substantially during a long history of uplift in southern Victoria Land that is consistent with uplift along continental rift zones. This uplift has continued for at least 50 million years (Stuckless 1975). Marine fossils on the shore of Lake Vanda (G. Denton, University of Maine, and H. T. Brady). A gully section in one of the low terraces along the northeastern shore of Lake Vanda was discovered to contain rich marine diatom and silicoflagellate floras. Shells also were recovered by Denton from the section. The diatom floras contain late Miocene diatoms. Studies are in progress to see if a younger flora is also present. Initial studies suggest that these floras are similar to those described by Brady (1977) from the lowermost section of the Lake Vanda drill core (DVDP 4A). The relationship between the shells in this section and the Prospect Mesa pectens is being studied. Mirabilite deposit on the McMurdo Ice Shelf (Brady and B. Koci, University of Wisconsin). Brady and Koci sampled 30 sites on the McMurdo Ice Shelf near Black Island for living algae. Living cultures were brought to Australia and are being maintained in a cold room at Macquarie University, Sydney. Samples from the Scallop Hill Formation were collected so that a diatom investigation can be made. A bed of mirabilite was discovered on the McMurdo Ice Shelf along a 1-kilometer line parallel to the eastern shore of Black Island. The mirabilite, is resting on ice, and the upper surface of the 1-meter bed is covered with a compressed algal mat. Carbon-14 dates for the algal mat are being determined by Sydney University. Brady (in press) suggests the mirabilite has been injected from beneath the McMurdo Ice Shelf when grounding forced saline solutions through crevasses to the surface. This deposit suggests that mirabilite can be concen-
Japanese scientific activities in Victoria Land 1977-1978 TAKES! NAGATA National Institute of Polar Research Tokyo,Japan
Two Japanese scientists visited McMurdo Station and Victoria Land during the austral summer field season of 14
trated in a manner suggested by Dort and Dort (1972) but the deposition is unrelated to sea level heights. Brady (1977) suggested that nonmarine moats can occur between marine ice sheets and land forming an environment in which marine material can be reworked and rebedded. Brady (in press) suggests that these moats are also possible sites for mirabilite deposition. George Denton encouraged me to study the relationships between Dry Valley Drilling Project cores and his surface glaciological studies. The Victoria University, Wellington, welcomed me to their camp at Mt. Feather enabling Dr. Barrie McKelvey (Armidale University, Australia) and myself to reevaluate the Mt. Feather tillite. Bruce Koci was my field assistant at Black Island. The continual help of vxE-6 helicopter pilots made such a diverse field season possible. This research was supported by National Science Foundation grant DPP 76-20657 to Northern Illinois University (Peter Noel Webb).
References
Brady, H. T. In press. Late Neogene history of Taylor and Wright Valleys and McMurdo Sound, derived from diatom biostratigra phy and paleoecology of DVDP cores. SCAR symposium, Madison, Wisconsin. Brady, H. T. In press. A diatom report on DVDP cores 3, 4A, 12, 14, 15 and other related surface sections. DVDP symposium, Tokyo, 1978. Brady, H., and B. McKelvey. In preparation. The interpretation of a Tertiary tillite at Mt. Feather, southern Victoria Land. Dort, W., and D. Dort. 1972. Marine origin of sodium sulphate deposits in Antarctica. In: Antarctic Geology and Geophysics (R. J. Adie, ed.). Universitetforlaget, Oslo. pp. 659-661. Mayewski, P. A. 1972. Glacial geology near McMurdo Sound and comparison with the central Transantarctic Mountains. Antarctic Journal of the Us., 7(4): 103-106. Mayewski, P. A. 1975. Glacial Geology and Late Cenozoic History of the Transantarctjc Mountains, Antarctica, Report 56, Institute of Polar Studies. The Ohio State University, Columbus, Ohio. Mercer,J. H. 1972. Some observations on the glacial geology of the Beardmore Glacier area. In: Antarctic Geology and Geophysics (R. J. Adie, ed.). Universitetforlaget, Oslo. pp. 427-433.
1977-78. K. Yanai (geologist and meteoriticist) and M. Funaki (geophysicist), National Institute of Polar Research, stayed at McMurdo Station for their research from 16 November 1977 to 2 February 1978. Three research programs were carried out during this seaon. Geological survey of dike rocks in Dry Valley area (K. Yanai). As part of a comparative study of geological structure in East Antarctica, geological survey of dike rocks was conducted in the Dry Valley area. Many dikes and their mutual relationship were determined in the field near Vanda Station of Wright Valley. The succession of intrusion is as follows in order of time: black-colored lamprophyre A and B; grey-colored lamprophyre, porphyry A, B, and C; granite porphyry A ANTARCTIC JOURNAL
Figure 2. Mount Flora, Hope Bay. (The Trinity Peninsula Formation crops out on the low ground at the base of Mount Flora. The conglomeratic rocks form the lower north-facing cliffs (right-hand side of the photo) of Mount Flora below the prominent pale band located in the middle part of that face. The volcanic rocks form the upper part of that face and the rest of the mountain.)
the early Mesozoic Gondwanian Orogeny, is seen to be unconformably overlain by what probably are Jurassic sedimentary rocks. The conglomerates probably resulted from the erosion of the uplifted Gondwanian Orogen; however, these rocks, together with the overlying plant-bearing beds, have intercalated volcanic rocks representing the initiation of the Andean cycle. Nowhere else in the northern Antarctic Peninsula is this transition from Gondwanian to Andean events so well displayed. Paleomagnetic studies. An extensive paleomagnetic investigation of Mesozoic rocks in the northern Antarctic Peninsula was initiated with the collection of 234 oriented samples from the vicinity ofJoinville Island and Hope Bay. Wherever possible, oriented cores were collected using a commercially available, portable drilling apparatus; otherwise, oriented block samples were taken. The samples were oriented by clinometer and magnetic compass. Magnetic bearings were checked by a direct-reading solar compass (Stone, 1967) when possible. Samples were collected from intrusive rocks at King Point, Fitzroy Point, and the offshore islands to the north and east ofJoinville Island. Most of the units sampled in the area consist of gabbro, though a few have intermediate compositions. Intrusive rocks of granitic and intermediate composition were sampled at Hope Bay. The Antarctic Peninsula Volcanic Group was sampled in detail at Hope Bay. Volcanic rocks above and below the plant-bearing horizons were collected. Because normal faulting has tilted some of the volcanic rocks up to 50°, the fold test of Graham (1949) may be applied to establish the stability of the magnetization of these rocks. It is hoped that laboratory analysis of the samples collected will yield a well-dated Mesozoic pole position for the northern Antarctic Peninsula. We appreciate the excellent support of Captain Lenie and the crew of iJv Hero. This work was supported by National Science Foundation grant DPP 77-23427. ANTARCTIC JOURNAL
Bibby,J. S. 1966. The stratigraphy of part of north-east Graham Land and the James Ross Island group. British Antarctic Survey, Scientific Report 53. Dalziel, I. W. D., D. H. Elliot, J. W. Thomson, M. R. A. Thomson, N. A. Wells, and W. J. Zinsmeister. 1977. Geologic studies in the South Orkney Islands: it/v Hero cruise 77-1,January 1977. AntarcticJournal of the US., 12(4): 98-101. Elliot, D. H. 1967. The geology of Joinville Island. British Antarctic Survey Bulletin, 12: 23-40. Elliot, D. H., C. Rinaldi, W. J . Zinsmeister, T. A. Trautman, W. A. Bryant, and R. del Valle. 1975. Geological Investigations on Seymour Island, Antarctic Peninsula. Antarctic Journal of the US., 10(4): 182-188. Elliot, D. H., and T. A. Trautman. In press. Lower Tertiary strata on Seymour Island. In: Antarctic Geoscience ( C. Craddock, ed.). The University of Wisconsin Press, Madison, Wisconsin. Elliot, D. H., and N. A. Wells. In press. Mesozoic alluvial fans of the South Orkney Islands. In: Antarctic Geoscience ( C. Craddock, ed.). The University of Wisconsin Press, Madison, Wisconsin. Graham,J. W. 1949. The stability and significance of magnetism in sedimentary rocks.Journal of Geophysical Research, 59: 131-137. Stone, D. B. 1967. A sun compass for the direct determination of geographical north. Journal of Scientific Instruments, 49: 661-667. Watts, D. R. In press. Potassium-argon and paleomagnetic results from King George Island, South Shetland Islands. In: Antarctic Geoscience ( C. Craddock, ed.). The University of Wisconsin Press, Madison, Wisconsin.
Geological studies in southern Victoria Land, on Black Island, and on the McMurdo Ice Shelf HOWARD THOMAS BRADY
School of Biological Sciences Macquarie University, North Ryde Sydney. 2113 Australia
Earlier dry valley glaciations (H.T. Brady and B. McKelvey, Armidale University, N.S.W.). Brady and McKelvey (in preparation) describe an ancient tillite at 2,750 meters on Mt. Feather overlooking the Skelton Nevé, the Ferrar Glacier, and Beacon Valley. The deposit has many features in common with the Sirius tillites described by Mercer (1972), Mayewski (1972, 1975) and Barrett (in press). Brady and McKelvey mapped 57 directions on striated clasts and exposed two sections of striated pavement showing a glacial direction to the south-southeast towards and parallel to the Skelton Glacier. Brady and McKelvey's paleocurrent readings do not agree with those of Mayewski's thesis diagram, which shows a direction at Mt. Feather parallel to the Ferrar Glacier. No descriptions of the site are given in his text. Brady and McKelvey consider the tillite to be a remnant of an uplifted 13
paleoglacial valley which predates Beacon Valley and the present day Taylor Glacier system. It was not a small tributary glacier (like the glaciers that cut Beacon and Arena Valley) because the tillite rock types cannot be derived from the surrounding Mt. Feather complex. The age of the tillite is unknown, but it predates the glaciations that cut the Taylor Valley fjord and presumably the Wright Valley fjord which are at least early late Miocene or middle Miocene (Brady 1977). The Mt. Feather glaciation suggests that glacial drainage patterns have been modified substantially during a long history of uplift in southern Victoria Land that is consistent with uplift along continental rift zones. This uplift has continued for at least 50 million years (Stuckless 1975). Marine fossils on the shore of Lake Vanda (G. Denton, University of Maine, and H. T. Brady). A gully section in one of the low terraces along the northeastern shore of Lake Vanda was discovered to contain rich marine diatom and silicoflagellate floras. Shells also were recovered by Denton from the section. The diatom floras contain late Miocene diatoms. Studies are in progress to see if a younger flora is also present. Initial studies suggest that these floras are similar to those described by Brady (1977) from the lowermost section of the Lake Vanda drill core (DVDP 4A). The relationship between the shells in this section and the Prospect Mesa pectens is being studied. Mirabilite deposit on the McMurdo Ice Shelf (Brady and B. Koci, University of Wisconsin). Brady and Koci sampled 30 sites on the McMurdo Ice Shelf near Black Island for living algae. Living cultures were brought to Australia and are being maintained in a cold room at Macquarie University, Sydney. Samples from the Scallop Hill Formation were collected so that a diatom investigation can be made. A bed of mirabilite was discovered on the McMurdo Ice Shelf along a 1-kilometer line parallel to the eastern shore of Black Island. The mirabilite, is resting on ice, and the upper surface of the 1-meter bed is covered with a compressed algal mat. Carbon-14 dates for the algal mat are being determined by Sydney University. Brady (in press) suggests the mirabilite has been injected from beneath the McMurdo Ice Shelf when grounding forced saline solutions through crevasses to the surface. This deposit suggests that mirabilite can be concen-
Japanese scientific activities in Victoria Land 1977-1978 TAKES! NAGATA National Institute of Polar Research Tokyo,Japan
Two Japanese scientists visited McMurdo Station and Victoria Land during the austral summer field season of 14
trated in a manner suggested by Dort and Dort (1972) but the deposition is unrelated to sea level heights. Brady (1977) suggested that nonmarine moats can occur between marine ice sheets and land forming an environment in which marine material can be reworked and rebedded. Brady (in press) suggests that these moats are also possible sites for mirabilite deposition. George Denton encouraged me to study the relationships between Dry Valley Drilling Project cores and his surface glaciological studies. The Victoria University, Wellington, welcomed me to their camp at Mt. Feather enabling Dr. Barrie McKelvey (Armidale University, Australia) and myself to reevaluate the Mt. Feather tillite. Bruce Koci was my field assistant at Black Island. The continual help of vxE-6 helicopter pilots made such a diverse field season possible. This research was supported by National Science Foundation grant DPP 76-20657 to Northern Illinois University (Peter Noel Webb).
References
Brady, H. T. In press. Late Neogene history of Taylor and Wright Valleys and McMurdo Sound, derived from diatom biostratigra phy and paleoecology of DVDP cores. SCAR symposium, Madison, Wisconsin. Brady, H. T. In press. A diatom report on DVDP cores 3, 4A, 12, 14, 15 and other related surface sections. DVDP symposium, Tokyo, 1978. Brady, H., and B. McKelvey. In preparation. The interpretation of a Tertiary tillite at Mt. Feather, southern Victoria Land. Dort, W., and D. Dort. 1972. Marine origin of sodium sulphate deposits in Antarctica. In: Antarctic Geology and Geophysics (R. J. Adie, ed.). Universitetforlaget, Oslo. pp. 659-661. Mayewski, P. A. 1972. Glacial geology near McMurdo Sound and comparison with the central Transantarctic Mountains. Antarctic Journal of the Us., 7(4): 103-106. Mayewski, P. A. 1975. Glacial Geology and Late Cenozoic History of the Transantarctjc Mountains, Antarctica, Report 56, Institute of Polar Studies. The Ohio State University, Columbus, Ohio. Mercer,J. H. 1972. Some observations on the glacial geology of the Beardmore Glacier area. In: Antarctic Geology and Geophysics (R. J. Adie, ed.). Universitetforlaget, Oslo. pp. 427-433.
1977-78. K. Yanai (geologist and meteoriticist) and M. Funaki (geophysicist), National Institute of Polar Research, stayed at McMurdo Station for their research from 16 November 1977 to 2 February 1978. Three research programs were carried out during this seaon. Geological survey of dike rocks in Dry Valley area (K. Yanai). As part of a comparative study of geological structure in East Antarctica, geological survey of dike rocks was conducted in the Dry Valley area. Many dikes and their mutual relationship were determined in the field near Vanda Station of Wright Valley. The succession of intrusion is as follows in order of time: black-colored lamprophyre A and B; grey-colored lamprophyre, porphyry A, B, and C; granite porphyry A ANTARCTIC JOURNAL
