Geologic survey of Marie Byrd Land
References Faure, G., C. H. Shultz, and R. H. Carwile. 1971. Isotope composition of strontium in volcanic rocks from Deception Island. Antarctic Journal of the U.S., VI(5): 197-198. Gast, P. W. 1967. Isotope geochemistry of volcanic rocks. In: Basaltc: the Poldervaart Treatise on Rocks of Basaltic Composition, Vol. 1. New York, Interscience Publishers, 325-358.
Geologic survey of Marie Byrd Land F. ALTON WADE
The Museum Texas Tech University Detailed studies and analyses of the rock specimens from Marie Byrd Land and of the field data recorded during the field seasons 1966-1967 and 1967-1968 are still in progress. These are being supplemented by studies of rock specimens and field data obtained during the 1934 Byrd Antarctic Expedition II and the U.S. Antarctic Service Expedition, 1940. A complex and rather unique geologic history of Marie Byrd Land is being unravelled. Based on available data, it appears that the sequence of events is as follows: 1. A thick sequence of marine sediments, mostly quartz sands, argillaceous quartz sands, subgraywackes, and thin shale beds was deposited in a subsiding basin during late Precambrian-early Paleozoic time. Ages of these sediments are based on the assemblages of microfossils in specimens from the Ford Ranges (litchenko, in press) and from Drummond Peak, Edward VII Peninsula (unpublished report, this laboratory). 2. Intense folding and metamorphism of the sequence of sediments occurred in late Ordovician time (Lopatin and Lorenko, in press). This is the time of the Ross orogeny in East Antarctica. 3. Intrusion of large granodioritic plutons in midPaleozoic time in the northern Ford Ranges: Mount June, 352 million years (Halpern, in press); Mount June, 328 million years; Saunders Mountain, 348 million years; Radford Islands, 355 million years; Mount Swan, 334 million years (table). This igneous activity was probably late synkinematic. 4. Farther to the east in the Kohler Mountains, Bakutis Coast sector, intrusive igneous activity occurred during late-Paleozoic time: Mount Strange, 265 million years (Halpern, in press), and Mount Isherwood, 283 million years (table). 5. No record has been noted of any geologic processes other than erosion during the Triassic and Jurassic Periods. 144
6. There were widespread intrusions of granitic plutons during the entire Cretaceous period with activity at a maximum in mid-Cretaceous time. These plutons are exposed in Edward VII Peninsula, Ford Ranges, Kohler Mountains, and Bear Island. New potassium-argon age determinations that supplement those already published (Boudette et al., 1966; Wade, 1969; Halpern, 1968, in press) are listed in the table. 7. The Cenozoic period is characterized by periodic eruptions of alkali basalt and pyroclastics. This volcanic activity has continued for approximately 50 million years. The advent of glaciation was early in the period and, according to LeMasurier (1972), has continued without significant deglaciation since Eocene time. The insular units that comprise this portion of Antarctica are of continental crustal material. It is believed that they were at one time united with the East Antarctic craton. The basement rocks of Oates Land appear to resemble most closely those of Marie Byrd Land. Too little is known, however, of the early geologic history of Oates Land for a reliable correlation to be made. There is some indirect evidence for block faulting in Marie Byrd Land. The islands may have been formed by such a process, and the block segments may have moved into their present positions prior to the Cretaceous orogeny. The formation and intrusion of the Cretaceous granite-like plutons with no apparent preliminary processes other than subsidence present somewhat of a problem. It is hoped that detailed microtextural studies of the older rocks will provide pertinent data. Potassium-argon ages of granitoid rocks from Marie Byrd Land. Latitude Longitude Age Locality (deg., mm., (deg., (million Mineral sec. S.) min. W.) years) Webster Bluff 76 06 30 14508 88 ± 3.4 whole rock Mount Franklin 7805 30 15448 95.9-4--3.5 biotite Chester Mountains 7640 14530 98.4±3.6 biotite McKinley Peak 7752 148 10 101 ±4 biotite The Billboard 7704 14538 101 ±4 biotite Wunneburger Rock 7442 11302 101 ± 4 biotite Early Bluff 75 11 20 11349 101±4 biotite Prezbecheski Island 77 02 14836 107 ± 4 biotite Phillips Mountains (west nun.) 76 15 14542 134 ± 5 biotite Jeffrey Head 74 33 45 11145 143 ± 11 biotite Mount Isherwood 7459 11336 283 ± 10 biotite Wiener Peaks 7649 14426 299 ± 11 biotite Mount June 76 16 145 02 328-L5 biotite Mount Swan 7658 14348 334 ± 12 biotite Saunders Mountain 7651 14548 348±12 biotite Radford Island 7654 14645 355±12 biotite
ANTARCTIC JOURNAL
It is estimated that reports on Marie Byrd Land and Ellsworth Land will be completed on or before September 1, 1973. This work is supported by National Science Foundation grant GV-22901. References Boudette, E. L., R. F. Marvin, and C. E. Hedge. 1966. Biotite, potassium-feldspar, and whole rock ages of adamellite, Clark Mountains, West Antarctica. U.S. Geological Survey. Professional Paper, 550-D: 190-194. Halpern, M. 1968. Ages of Antarctic and Argentine rocks bearing on continental drift. Earth and Planetary Science Letters, 5(3): 159-167. Halpern, M. In press. Rubidium-strontium total-rock and mineral ages from the Marguerite Bay area, Kohler Range and Fosdick Mountains, West Antarctica. In: Antarctic Geology and Geophysics (R. J . Adie, ed.). Oslo, Universitetsforlaget. Jitchenko, L. N. In press. Late Precambrian acritarcha of Antarctica. In: Antarctic Geology and Geophysics (R. J. Adie, ed.). Oslo, Universitetsforlaget. Lopatin, B. G., and E. M. Lorenko. In press. Outlines of the geology of Marie Byrd Land and Eights Coast. In: Antarctic Geology and Geophysics (R. J . Adie, ed.). Oslo, Universitetsforlaget. LeMasurier, W. E. 1972. Volcanic record of antarctic glacial history: implications with regard to Cenozoic sea levels. In: Polar Geomorphology (C. Embleton, ed.). Institute of British Geographers. Special Publication, 4. Wade, F. A. 1969. Geology of Marie Byrd Land. Antarctic Map Folio Series, 12; plate XVII.
present in lesser proportions are basalt, andesite, shale, sandstone, and siltstone. The sandstones, with few exception, are lithic sandstones, or litharenites (fig.) according to the classification of Folk (1968). The sandstones of the Trinity Peninsula Series of Carboniferous(?) age (Adie, 1957) are markedly different from those of the Latady Formation. Elliot (1965) has shown that the Trinity Peninsula series sandstones are arkoses. Feldspar, dominantly plagioclase, and quartz are much more abundant than rock fragments, which are mostly particles derived from rhyolite and granite, but include subordinate sedimentary and metamorphic rocks. A fine-grained matrix comprising half the rock is typical of Trinity Peninsula Series sandstones. Rocks of both the Latady Formation and the Trinity Peninsula Series are commonly poorly exposed. The two units are similar in appearance; both are dark colored, are tightly folded, and have well developed slaty cleavage. Fossils are rare and poorly preserved in all known exposures of the Trinity Peninsula Series and in many exposures of the Latady Formation. Comparison of sandstone composition is the most useful method for distinguishing between the two formations. This work was supported by National Science Foundation grant AG-187. References
Composition of Jurassic sandstones, Lassiter Coast P. L. WILLIAMS and P. D. ROWLEY
Adie, R. J . 1957. The petrology of Graham Land, III. Metamorphic rocks of the Trinity Peninsula Series. Falk-
land Island Dependencies Surveys. Scientific Reports, 20.
26 p. Elliot, D. H. 1965. Geology of North-west Trinity Peninsula, Graham Land. British Antarctic Survey. Bulletin, 7. 24 p.
U.S. Geological Survey Denver, Colorado Sandstone comprises 10-60 percent of measured stratigraphic sections of the Latady Formation of Late Jurassic age in the Lassiter Coast and adjacent areas of southern Palmer Land. Other rock types present are carbonaceous siltstone, shale, and mudstone; conglomerate is absent (Williams, 1970; Williams and Rowley, 1971; Williams et al., in press). Major components of the sandstones are, on the average, quartz, 20 percent; feldspar, 17 percent; rock fragments, 33 percent; and quartz-sericite matrix, commonly with minor amounts of carbonate, 30 percent. Plagioclase feldspar (An 20-30) is slightly more abundant than potassium feldspar, which is almost entirely orthoclase with rare grains of microcine. Rock fragments are dominantly felsic volcanic rocks; Publication authorized by the Director, U. S. Geological Survey.
September-October 1972
Quartz
Feldspar
Rock fragments
Composition of clastic particles of sandstones of the Trinity Peninsula Series (0) (after Elliot, 1965) and the Latady Formation (i). Generalized from Folk (1968).
145
Geologic survey of Marie Byrd Land F. ALTON WADE
The Museum Texas Tech University Detailed studies and analyses of the rock specimens from Marie Byrd Land and of the field data recorded during the field seasons 1966-1967 and 1967-1968 are still in progress. These are being supplemented by studies of rock specimens and field data obtained during the 1934 Byrd Antarctic Expedition II and the U.S. Antarctic Service Expedition, 1940. A complex and rather unique geologic history of Marie Byrd Land is being unravelled. Based on available data, it appears that the sequence of events is as follows: 1. A thick sequence of marine sediments, mostly quartz sands, argillaceous quartz sands, subgraywackes, and thin shale beds was deposited in a subsiding basin during late Precambrian-early Paleozoic time. Ages of these sediments are based on the assemblages of microfossils in specimens from the Ford Ranges (litchenko, in press) and from Drummond Peak, Edward VII Peninsula (unpublished report, this laboratory). 2. Intense folding and metamorphism of the sequence of sediments occurred in late Ordovician time (Lopatin and Lorenko, in press). This is the time of the Ross orogeny in East Antarctica. 3. Intrusion of large granodioritic plutons in midPaleozoic time in the northern Ford Ranges: Mount June, 352 million years (Halpern, in press); Mount June, 328 million years; Saunders Mountain, 348 million years; Radford Islands, 355 million years; Mount Swan, 334 million years (table). This igneous activity was probably late synkinematic. 4. Farther to the east in the Kohler Mountains, Bakutis Coast sector, intrusive igneous activity occurred during late-Paleozoic time: Mount Strange, 265 million years (Halpern, in press), and Mount Isherwood, 283 million years (table). 5. No record has been noted of any geologic processes other than erosion during the Triassic and Jurassic Periods. 144
6. There were widespread intrusions of granitic plutons during the entire Cretaceous period with activity at a maximum in mid-Cretaceous time. These plutons are exposed in Edward VII Peninsula, Ford Ranges, Kohler Mountains, and Bear Island. New potassium-argon age determinations that supplement those already published (Boudette et al., 1966; Wade, 1969; Halpern, 1968, in press) are listed in the table. 7. The Cenozoic period is characterized by periodic eruptions of alkali basalt and pyroclastics. This volcanic activity has continued for approximately 50 million years. The advent of glaciation was early in the period and, according to LeMasurier (1972), has continued without significant deglaciation since Eocene time. The insular units that comprise this portion of Antarctica are of continental crustal material. It is believed that they were at one time united with the East Antarctic craton. The basement rocks of Oates Land appear to resemble most closely those of Marie Byrd Land. Too little is known, however, of the early geologic history of Oates Land for a reliable correlation to be made. There is some indirect evidence for block faulting in Marie Byrd Land. The islands may have been formed by such a process, and the block segments may have moved into their present positions prior to the Cretaceous orogeny. The formation and intrusion of the Cretaceous granite-like plutons with no apparent preliminary processes other than subsidence present somewhat of a problem. It is hoped that detailed microtextural studies of the older rocks will provide pertinent data. Potassium-argon ages of granitoid rocks from Marie Byrd Land. Latitude Longitude Age Locality (deg., mm., (deg., (million Mineral sec. S.) min. W.) years) Webster Bluff 76 06 30 14508 88 ± 3.4 whole rock Mount Franklin 7805 30 15448 95.9-4--3.5 biotite Chester Mountains 7640 14530 98.4±3.6 biotite McKinley Peak 7752 148 10 101 ±4 biotite The Billboard 7704 14538 101 ±4 biotite Wunneburger Rock 7442 11302 101 ± 4 biotite Early Bluff 75 11 20 11349 101±4 biotite Prezbecheski Island 77 02 14836 107 ± 4 biotite Phillips Mountains (west nun.) 76 15 14542 134 ± 5 biotite Jeffrey Head 74 33 45 11145 143 ± 11 biotite Mount Isherwood 7459 11336 283 ± 10 biotite Wiener Peaks 7649 14426 299 ± 11 biotite Mount June 76 16 145 02 328-L5 biotite Mount Swan 7658 14348 334 ± 12 biotite Saunders Mountain 7651 14548 348±12 biotite Radford Island 7654 14645 355±12 biotite
ANTARCTIC JOURNAL
It is estimated that reports on Marie Byrd Land and Ellsworth Land will be completed on or before September 1, 1973. This work is supported by National Science Foundation grant GV-22901. References Boudette, E. L., R. F. Marvin, and C. E. Hedge. 1966. Biotite, potassium-feldspar, and whole rock ages of adamellite, Clark Mountains, West Antarctica. U.S. Geological Survey. Professional Paper, 550-D: 190-194. Halpern, M. 1968. Ages of Antarctic and Argentine rocks bearing on continental drift. Earth and Planetary Science Letters, 5(3): 159-167. Halpern, M. In press. Rubidium-strontium total-rock and mineral ages from the Marguerite Bay area, Kohler Range and Fosdick Mountains, West Antarctica. In: Antarctic Geology and Geophysics (R. J . Adie, ed.). Oslo, Universitetsforlaget. Jitchenko, L. N. In press. Late Precambrian acritarcha of Antarctica. In: Antarctic Geology and Geophysics (R. J. Adie, ed.). Oslo, Universitetsforlaget. Lopatin, B. G., and E. M. Lorenko. In press. Outlines of the geology of Marie Byrd Land and Eights Coast. In: Antarctic Geology and Geophysics (R. J . Adie, ed.). Oslo, Universitetsforlaget. LeMasurier, W. E. 1972. Volcanic record of antarctic glacial history: implications with regard to Cenozoic sea levels. In: Polar Geomorphology (C. Embleton, ed.). Institute of British Geographers. Special Publication, 4. Wade, F. A. 1969. Geology of Marie Byrd Land. Antarctic Map Folio Series, 12; plate XVII.
present in lesser proportions are basalt, andesite, shale, sandstone, and siltstone. The sandstones, with few exception, are lithic sandstones, or litharenites (fig.) according to the classification of Folk (1968). The sandstones of the Trinity Peninsula Series of Carboniferous(?) age (Adie, 1957) are markedly different from those of the Latady Formation. Elliot (1965) has shown that the Trinity Peninsula series sandstones are arkoses. Feldspar, dominantly plagioclase, and quartz are much more abundant than rock fragments, which are mostly particles derived from rhyolite and granite, but include subordinate sedimentary and metamorphic rocks. A fine-grained matrix comprising half the rock is typical of Trinity Peninsula Series sandstones. Rocks of both the Latady Formation and the Trinity Peninsula Series are commonly poorly exposed. The two units are similar in appearance; both are dark colored, are tightly folded, and have well developed slaty cleavage. Fossils are rare and poorly preserved in all known exposures of the Trinity Peninsula Series and in many exposures of the Latady Formation. Comparison of sandstone composition is the most useful method for distinguishing between the two formations. This work was supported by National Science Foundation grant AG-187. References
Composition of Jurassic sandstones, Lassiter Coast P. L. WILLIAMS and P. D. ROWLEY
Adie, R. J . 1957. The petrology of Graham Land, III. Metamorphic rocks of the Trinity Peninsula Series. Falk-
land Island Dependencies Surveys. Scientific Reports, 20.
26 p. Elliot, D. H. 1965. Geology of North-west Trinity Peninsula, Graham Land. British Antarctic Survey. Bulletin, 7. 24 p.
U.S. Geological Survey Denver, Colorado Sandstone comprises 10-60 percent of measured stratigraphic sections of the Latady Formation of Late Jurassic age in the Lassiter Coast and adjacent areas of southern Palmer Land. Other rock types present are carbonaceous siltstone, shale, and mudstone; conglomerate is absent (Williams, 1970; Williams and Rowley, 1971; Williams et al., in press). Major components of the sandstones are, on the average, quartz, 20 percent; feldspar, 17 percent; rock fragments, 33 percent; and quartz-sericite matrix, commonly with minor amounts of carbonate, 30 percent. Plagioclase feldspar (An 20-30) is slightly more abundant than potassium feldspar, which is almost entirely orthoclase with rare grains of microcine. Rock fragments are dominantly felsic volcanic rocks; Publication authorized by the Director, U. S. Geological Survey.
September-October 1972
Quartz
Feldspar
Rock fragments
Composition of clastic particles of sandstones of the Trinity Peninsula Series (0) (after Elliot, 1965) and the Latady Formation (i). Generalized from Folk (1968).
145
