Ellsworth Mountains studies, 1980-1981
In conclusion, the present study may alter earlier under-
standing of the geologic development of the Ellsworth Mountains (Craddock 1969; Craddock, Anderson, and Webers 1964; Hjelle, Ohta, and Winsnes 1978). It is possible to assume that some metamorphic and folding episodes (e.g., Ross and/or Borchgrevink and related orogenies of Craddock 1972; Bradshaw, Laird, and Wodzicki in press) had affected the Ellsworth Mountains before the early Mesozoic Ellsworth orogeny of Craddock (1972). There is a possibility that considerable portions of the sequence of superposed deformations are comparable to those of the Pensacola Mountains ( Schmidt and Ford 1969). The view of the "autochthonous" origin of the crust of the Ellsworth Mountains (e.g., Ford 1972; Grikurov et al. 1980) appears to be receiving more support than the "exotic" origin view (Clarkson 1977; Schopf 1969). This work was partly supported by the National Institute of Polar Research, Japan, the National Science Foundation, and the Department of Scientific and Industrial Research, New Zealand. My hearty thanks are extended to the scientists, Navy, and Holmes and Narver personnel who guided and supported my field activities. References Bradshaw, J. D., Laird, M. C., and Wodzicki, A. In press. Structural style and tectonic history in northern Victoria Land, Antarctica. In C. Craddock (Ed.), Antarctic geosciences. Madison: University of Wisconsin Press. Clarkson, P. D. 1977. Age and position of the Ellsworth Mountains crustal fragment, Antarctica. Nature, 265, 615-616. Craddock, C. 1969. Geology of the Ellsworth Mountains (Folio 12). In V. C. Bushnell and C. Craddock (Eds.), Geologic maps of Antarctica,
Ellsworth Mountains studies, 1980-1981 GERALD
F. WEBERS
Macalester College St. Paul, Minnesota 55105 Following the 1979-80 field season in the Ellsworth Mountains (Splettstoesser and Webers 1980), thf, 1980-81 year has been one of intensive study of the field data and of the more than 3,000 kilograms of rocks, minerals, and fossils collected. A list of 16 articles that have been published or accepted for publication during the last year is included (see table). Seven fossil faunas are presently under study by a number of investigators. The 7,000-meter-thick Heritage Group has been subdivided into formations, and the stratigraphy of the Crashsite Quartzite, developed in the Sentinel Range, has been extended and modified to the Heritage Range. Two geologic maps of the Ellsworth Mountains are in preparation. A meeting was held in Madison, Wisconsin, 22-24 April 1981,
18
Antarctic map folio series. New York: American Geographical Society. Craddock, C. 1972. Tectonics of Antarctica. In R. J. Adie (Ed.), Antarctic geology and geophysics. Oslo: Universitetsforlaget. Craddock, C., Anderson, J . J . , and Webers, C. F. 1964. Geological outline of the Ellsworth Mountains. In R. J . Adie (Ed.), Antarctic geology. Amsterdam: North-Holland Publishing. Ford, A. B. 1972. Weddell orogeny—Latest Permian to early Mesozoic deformation at the Weddell Sea margin of the Transantarctic Mountains. In R. J . Adie (Ed.), Antarctic geology and geophysics. Oslo: Universitetsforlaget. Grikurov, C. E., Znachko-Yavorsky, G. A., Kamemev, E. N., and Kurinin, R. G. 1980. Explanatory notes to the tectonic map of Antarctica (scale 1:10,000,000). Leningrad: Research Institute of the Geology of the Arctic. Hjelle, A., Ohta, Y., and Winsnes, T. S. 1978. Stratigraphy and igneous petrology of southern Heritage Range, Ellsworth Mountains, Antarctica. In Results from Norwegian antarctic research 1974 -1977 (see Vol. 15, No. 5, p. 32). Oslo: Norsk Polarinstitutt. Schmidt, D. L., and Ford, A. B. 1969. Geology of the Pensacola and Thiel Mountains (Folio 12). In V. C. Bushnell and C. Craddock (Eds.), Geologic maps of Antarctica, Antarctic map folio series. New York: American Geographical Society. Schopf, J . M. 1969. Ellsworth Mountains: Position in West Antarctica due to sea-floor spreading. Science, 164(3875), 63-66. Winkler, H. G. F. 1974. Petrogenesis of metamorphic rocks (3rd ed.). Berlin: Springer-Verlag. - Yoshida, M. 1980. Nishinankyoku erusuwasu sanchi ni okeru dgufuku henkei [Superposed deformation in the Ellsworth Mountains, West Antarctica]. In Second symposium on antarctic geosciences. Tokyo: National Institute of Polar Research. (Abstract) Yoshida, M. 1981. Participation in the U.S. Ellsworth Mountains operation of the 1979-1980 austral summer, Antarctica. Antarctic Record, 72,101-107. Yoshida, M. In preparation. Superposition of foldings and its implication to the geologic history of the Ellsworth Mountains.
to further coordinate research on Ellsworth Mountains geology. It was attended by 10 investigators, including representatives from New Zealand and West Germany. All segments of the geology were discussed, with emphasis on problematic areas. I can provide notes on this meeting, on request. A symposium on the geology of the Ellsworth Mountains has been organized and will take place as a special session of the annual meeting of the Geological Society of America, to be held in New Orleans in 1982. Plans for a volume on the geology of the Ellsworth Mountains are nearly complete. Application will be made shortly to the American Geophysical Union's Board of Associate Editors for a volume in the Antarctic Research Series. Twenty-two papers have been organized for the volume. This project was supported by National Science Foundation grant DPP 78-21720 to Macalester College, St. Paul, Minnesota; John Splettstoesser critically read the manuscript.
Reference Splettstoesser, J . F., and Webers, C. F. 1980. Geological investigations and logistics in the Ellsworth Mountains, 1979-80. Antarctic Journal of the U. S., 15(5), 36-37.
ANTARCnc JOURNAL
Recent Ellsworth Mountains papers Bockheim, James, and Leide, James. 1980. Soil development and rock weathering in the Ellsworth Mountains, Antarctica. Antarctic Journal of the U.S., 15(5), 33-34. Collinson, James, Vavra, Charles L., and Zawiske, John M. 1980. Sedimentology of the Polarstar Formation (Permian), Ellsworth Mountains. Antarctic Journal of the U.S., 15(5), 30-32. Craddock, John, and Webers, Gerald. In press. Probable cave deposits in the Ellsworth Mountains of West Antarctica. Proceedings of the Eighth International Congress of Speleology.
Dreschhoff, Gisela A. M., Zeller, Edward J., Thoste, Volker, and Bulla, Klaus. 1980. Resource and radioactivity survey in the Ellsworth Mountains. Antarctic Journal of the U.S., 15(5), 32. Ojakangas, Richard, and Matsch, Charles. 1980. Sedimentation of the Late Paleozoic Whiteout Conglomerate: A glacial and glaciomarine sequence in the Ellsworth Mountains, West Antarctica. In B. Harland and M. Hambrey (Eds.), Pre-Pleistocene tillites. Cambridge, Eng.: Cambridge University Press. Pojeta, John, Yochelson, Ellis, and Webers, Gerald. In press. Upper Cambrian mollusks from the Ellsworth Mountains, West Antarctica. Proceedings, Second International Symposium on the Cambrian System. U.S. Geological Survey, Open File Report.
Rutford, Robert H., Denton, George H., and Andersen, BjOrn G. 1980. Glacial history of the Ellsworth Mountains. Antarctic Journal of the U.S., 15(5), 56-57. Splettstoesser, John F. 1981. Bird sightings in the Ellsworth Moun-
tains in 1979-80, and other inland areas. Antarctic Journal of the U.S., 16(5).
Splettstoesser, John F., and Webers, Gerald F. 1980. Geological investigations and logistics in the Ellsworth Mountains, 1979-80. Antarctic Journal of the U.S., 15(5), 36-39. Splettstoesser, John F., Webers, Gerald F., and Waldrip, David B. In press. Logistical aspects of geological investigations in the Ellsworth Mountains, 1979-80. Polar Record. Splettstoesser, John F., and Whitney, Marion. Comparison of states of ventifaction in various polar environments. Abstract submitted to International Association of Sedimentologists, 11th Annual Meeting, McMaster University, Hamilton, Ontario, August 1982. Watts, Doyle R., and Bramall, Andrew M. 1980. Paleomagnetic investigation in the Ellsworth Mountains. Antarctic Journal of the U.S., 15(5)34-36. Webers, Gerald F. In press. Cambrian rocks of the Ellsworth Mountains, West Antarctica. Proceedings, Second International Symposium on the Cambrian System. U.S. Geological Survey, Open
File Report. Yoshida, Masaru. 1981. Participation in the U.S. Ellsworth Mountains operation of the 1979-80 austral summer, Antarctica. Antarctic Record, 72, 103-109. Yoshida, Masaru. 1981. U.S. Ellsworth Mountains operation in 1979-80. Kyokuchi (Polar News), 32,16-23. Yoshida, Masaru. In press. Stay in the U.S. Ellsworth Mountains camp in 1979-80. Kyokuchi (Polar News).
Mid-Tertiary glacial history recorded at Mount Petras, Marie Byrd Land WESLEY E. LEMASURIER Natural and Physical Sciences-Geology University of Colorado-Denver Denver, Colorado 80202 WILLIAM C. MCINTOSH Department of Geology University of Colorado Boulder, Colorado 80303 DAVID C. REX Department of Earth Sciences University of Leeds Leeds LS2 9JT England
Among the major topographic features of coastal Marie Byrd Land are isolated nunataks and mountain ranges composed of granitic and metamorphic rocks and surmounted by a very flat early Tertiary erosion surface. The erosion surface is of regional extent (e.g., see Laudon 1972; LeMasurier and Rex in press; Rutford, Craddock, and Bastien 1968) and clearly represents a large region of very low topographic relief in early Tertiary
1981 REVIEw
time. It has subsequently been disrupted by block faulting, and the highest block-faulted remnant of the surface is now found at Mount Petras (figure), 120 kilometers from the coast; here it is coincidentally overlain by the thickest and most extensive outcrop of late Oligocene-early Miocene palagonitetuff-breccia (hyaloclastite) in Marie Byrd Land. Hyaloclastite is essentially a deposit composed of chips of volcanic glass produced when lava is erupted beneath water or ice. The Mount Petras hyaloclastite is elieved to have been produced by volcanic eruptions beneath the antarctic ice sheet; together with the underlying erosion surface, it provides an unusually valuable record of the geologic environment of this region in middle Tertiary time, roughly 25 million years ago. A reexamination of Mount Petras was begun during the 1977-78 field season, and the major results are summarized here. Mount Petras stands 800 meters above the level of the continental ice sheet at an elevation of 2,867 meters. The entire range from Peter Nunatak and Wallace Rock to Putzke Peak is composed mainly of deeply eroded late Mesozoic volcanic and plutonic rocks. Cataclastic gneisses crop out at Navarrette Peak and Wallace Rock (figure). The most common composition of the igneous rocks is rhyodacite, and their potassium-argon (KAr) age is roughly 80 million years (LeMasurier and Wade 1976). The erosion surface is preserved on the rhyodacite at the 2,700-meter level of the range, from Schwob Peak to the north end of Mount Petras. Hyaloclastite rests on the surface at Mount Petras proper. The contact was first visited by LeMasurier during the 1967-68 season at a location where the configuration of the erosion surface was not very clear. The relief on the surface was estimated at that time to be roughly 400 meters (LeMasurier and Wade 1976). A more thorough
19
standing of the geologic development of the Ellsworth Mountains (Craddock 1969; Craddock, Anderson, and Webers 1964; Hjelle, Ohta, and Winsnes 1978). It is possible to assume that some metamorphic and folding episodes (e.g., Ross and/or Borchgrevink and related orogenies of Craddock 1972; Bradshaw, Laird, and Wodzicki in press) had affected the Ellsworth Mountains before the early Mesozoic Ellsworth orogeny of Craddock (1972). There is a possibility that considerable portions of the sequence of superposed deformations are comparable to those of the Pensacola Mountains ( Schmidt and Ford 1969). The view of the "autochthonous" origin of the crust of the Ellsworth Mountains (e.g., Ford 1972; Grikurov et al. 1980) appears to be receiving more support than the "exotic" origin view (Clarkson 1977; Schopf 1969). This work was partly supported by the National Institute of Polar Research, Japan, the National Science Foundation, and the Department of Scientific and Industrial Research, New Zealand. My hearty thanks are extended to the scientists, Navy, and Holmes and Narver personnel who guided and supported my field activities. References Bradshaw, J. D., Laird, M. C., and Wodzicki, A. In press. Structural style and tectonic history in northern Victoria Land, Antarctica. In C. Craddock (Ed.), Antarctic geosciences. Madison: University of Wisconsin Press. Clarkson, P. D. 1977. Age and position of the Ellsworth Mountains crustal fragment, Antarctica. Nature, 265, 615-616. Craddock, C. 1969. Geology of the Ellsworth Mountains (Folio 12). In V. C. Bushnell and C. Craddock (Eds.), Geologic maps of Antarctica,
Ellsworth Mountains studies, 1980-1981 GERALD
F. WEBERS
Macalester College St. Paul, Minnesota 55105 Following the 1979-80 field season in the Ellsworth Mountains (Splettstoesser and Webers 1980), thf, 1980-81 year has been one of intensive study of the field data and of the more than 3,000 kilograms of rocks, minerals, and fossils collected. A list of 16 articles that have been published or accepted for publication during the last year is included (see table). Seven fossil faunas are presently under study by a number of investigators. The 7,000-meter-thick Heritage Group has been subdivided into formations, and the stratigraphy of the Crashsite Quartzite, developed in the Sentinel Range, has been extended and modified to the Heritage Range. Two geologic maps of the Ellsworth Mountains are in preparation. A meeting was held in Madison, Wisconsin, 22-24 April 1981,
18
Antarctic map folio series. New York: American Geographical Society. Craddock, C. 1972. Tectonics of Antarctica. In R. J. Adie (Ed.), Antarctic geology and geophysics. Oslo: Universitetsforlaget. Craddock, C., Anderson, J . J . , and Webers, C. F. 1964. Geological outline of the Ellsworth Mountains. In R. J . Adie (Ed.), Antarctic geology. Amsterdam: North-Holland Publishing. Ford, A. B. 1972. Weddell orogeny—Latest Permian to early Mesozoic deformation at the Weddell Sea margin of the Transantarctic Mountains. In R. J . Adie (Ed.), Antarctic geology and geophysics. Oslo: Universitetsforlaget. Grikurov, C. E., Znachko-Yavorsky, G. A., Kamemev, E. N., and Kurinin, R. G. 1980. Explanatory notes to the tectonic map of Antarctica (scale 1:10,000,000). Leningrad: Research Institute of the Geology of the Arctic. Hjelle, A., Ohta, Y., and Winsnes, T. S. 1978. Stratigraphy and igneous petrology of southern Heritage Range, Ellsworth Mountains, Antarctica. In Results from Norwegian antarctic research 1974 -1977 (see Vol. 15, No. 5, p. 32). Oslo: Norsk Polarinstitutt. Schmidt, D. L., and Ford, A. B. 1969. Geology of the Pensacola and Thiel Mountains (Folio 12). In V. C. Bushnell and C. Craddock (Eds.), Geologic maps of Antarctica, Antarctic map folio series. New York: American Geographical Society. Schopf, J . M. 1969. Ellsworth Mountains: Position in West Antarctica due to sea-floor spreading. Science, 164(3875), 63-66. Winkler, H. G. F. 1974. Petrogenesis of metamorphic rocks (3rd ed.). Berlin: Springer-Verlag. - Yoshida, M. 1980. Nishinankyoku erusuwasu sanchi ni okeru dgufuku henkei [Superposed deformation in the Ellsworth Mountains, West Antarctica]. In Second symposium on antarctic geosciences. Tokyo: National Institute of Polar Research. (Abstract) Yoshida, M. 1981. Participation in the U.S. Ellsworth Mountains operation of the 1979-1980 austral summer, Antarctica. Antarctic Record, 72,101-107. Yoshida, M. In preparation. Superposition of foldings and its implication to the geologic history of the Ellsworth Mountains.
to further coordinate research on Ellsworth Mountains geology. It was attended by 10 investigators, including representatives from New Zealand and West Germany. All segments of the geology were discussed, with emphasis on problematic areas. I can provide notes on this meeting, on request. A symposium on the geology of the Ellsworth Mountains has been organized and will take place as a special session of the annual meeting of the Geological Society of America, to be held in New Orleans in 1982. Plans for a volume on the geology of the Ellsworth Mountains are nearly complete. Application will be made shortly to the American Geophysical Union's Board of Associate Editors for a volume in the Antarctic Research Series. Twenty-two papers have been organized for the volume. This project was supported by National Science Foundation grant DPP 78-21720 to Macalester College, St. Paul, Minnesota; John Splettstoesser critically read the manuscript.
Reference Splettstoesser, J . F., and Webers, C. F. 1980. Geological investigations and logistics in the Ellsworth Mountains, 1979-80. Antarctic Journal of the U. S., 15(5), 36-37.
ANTARCnc JOURNAL
Recent Ellsworth Mountains papers Bockheim, James, and Leide, James. 1980. Soil development and rock weathering in the Ellsworth Mountains, Antarctica. Antarctic Journal of the U.S., 15(5), 33-34. Collinson, James, Vavra, Charles L., and Zawiske, John M. 1980. Sedimentology of the Polarstar Formation (Permian), Ellsworth Mountains. Antarctic Journal of the U.S., 15(5), 30-32. Craddock, John, and Webers, Gerald. In press. Probable cave deposits in the Ellsworth Mountains of West Antarctica. Proceedings of the Eighth International Congress of Speleology.
Dreschhoff, Gisela A. M., Zeller, Edward J., Thoste, Volker, and Bulla, Klaus. 1980. Resource and radioactivity survey in the Ellsworth Mountains. Antarctic Journal of the U.S., 15(5), 32. Ojakangas, Richard, and Matsch, Charles. 1980. Sedimentation of the Late Paleozoic Whiteout Conglomerate: A glacial and glaciomarine sequence in the Ellsworth Mountains, West Antarctica. In B. Harland and M. Hambrey (Eds.), Pre-Pleistocene tillites. Cambridge, Eng.: Cambridge University Press. Pojeta, John, Yochelson, Ellis, and Webers, Gerald. In press. Upper Cambrian mollusks from the Ellsworth Mountains, West Antarctica. Proceedings, Second International Symposium on the Cambrian System. U.S. Geological Survey, Open File Report.
Rutford, Robert H., Denton, George H., and Andersen, BjOrn G. 1980. Glacial history of the Ellsworth Mountains. Antarctic Journal of the U.S., 15(5), 56-57. Splettstoesser, John F. 1981. Bird sightings in the Ellsworth Moun-
tains in 1979-80, and other inland areas. Antarctic Journal of the U.S., 16(5).
Splettstoesser, John F., and Webers, Gerald F. 1980. Geological investigations and logistics in the Ellsworth Mountains, 1979-80. Antarctic Journal of the U.S., 15(5), 36-39. Splettstoesser, John F., Webers, Gerald F., and Waldrip, David B. In press. Logistical aspects of geological investigations in the Ellsworth Mountains, 1979-80. Polar Record. Splettstoesser, John F., and Whitney, Marion. Comparison of states of ventifaction in various polar environments. Abstract submitted to International Association of Sedimentologists, 11th Annual Meeting, McMaster University, Hamilton, Ontario, August 1982. Watts, Doyle R., and Bramall, Andrew M. 1980. Paleomagnetic investigation in the Ellsworth Mountains. Antarctic Journal of the U.S., 15(5)34-36. Webers, Gerald F. In press. Cambrian rocks of the Ellsworth Mountains, West Antarctica. Proceedings, Second International Symposium on the Cambrian System. U.S. Geological Survey, Open
File Report. Yoshida, Masaru. 1981. Participation in the U.S. Ellsworth Mountains operation of the 1979-80 austral summer, Antarctica. Antarctic Record, 72, 103-109. Yoshida, Masaru. 1981. U.S. Ellsworth Mountains operation in 1979-80. Kyokuchi (Polar News), 32,16-23. Yoshida, Masaru. In press. Stay in the U.S. Ellsworth Mountains camp in 1979-80. Kyokuchi (Polar News).
Mid-Tertiary glacial history recorded at Mount Petras, Marie Byrd Land WESLEY E. LEMASURIER Natural and Physical Sciences-Geology University of Colorado-Denver Denver, Colorado 80202 WILLIAM C. MCINTOSH Department of Geology University of Colorado Boulder, Colorado 80303 DAVID C. REX Department of Earth Sciences University of Leeds Leeds LS2 9JT England
Among the major topographic features of coastal Marie Byrd Land are isolated nunataks and mountain ranges composed of granitic and metamorphic rocks and surmounted by a very flat early Tertiary erosion surface. The erosion surface is of regional extent (e.g., see Laudon 1972; LeMasurier and Rex in press; Rutford, Craddock, and Bastien 1968) and clearly represents a large region of very low topographic relief in early Tertiary
1981 REVIEw
time. It has subsequently been disrupted by block faulting, and the highest block-faulted remnant of the surface is now found at Mount Petras (figure), 120 kilometers from the coast; here it is coincidentally overlain by the thickest and most extensive outcrop of late Oligocene-early Miocene palagonitetuff-breccia (hyaloclastite) in Marie Byrd Land. Hyaloclastite is essentially a deposit composed of chips of volcanic glass produced when lava is erupted beneath water or ice. The Mount Petras hyaloclastite is elieved to have been produced by volcanic eruptions beneath the antarctic ice sheet; together with the underlying erosion surface, it provides an unusually valuable record of the geologic environment of this region in middle Tertiary time, roughly 25 million years ago. A reexamination of Mount Petras was begun during the 1977-78 field season, and the major results are summarized here. Mount Petras stands 800 meters above the level of the continental ice sheet at an elevation of 2,867 meters. The entire range from Peter Nunatak and Wallace Rock to Putzke Peak is composed mainly of deeply eroded late Mesozoic volcanic and plutonic rocks. Cataclastic gneisses crop out at Navarrette Peak and Wallace Rock (figure). The most common composition of the igneous rocks is rhyodacite, and their potassium-argon (KAr) age is roughly 80 million years (LeMasurier and Wade 1976). The erosion surface is preserved on the rhyodacite at the 2,700-meter level of the range, from Schwob Peak to the north end of Mount Petras. Hyaloclastite rests on the surface at Mount Petras proper. The contact was first visited by LeMasurier during the 1967-68 season at a location where the configuration of the erosion surface was not very clear. The relief on the surface was estimated at that time to be roughly 400 meters (LeMasurier and Wade 1976). A more thorough
19
