Geological investigations in the Scott Glacier and Byrd ...
much lower levels than the outcrops along Touchdown Glacier. As the survey was extended south of the head of Byrd Glacier into the area of the Sefton and Zeller glaciers, a complex series of low-grade metamorphic rocks was encountered overlain by Beacon Supergroup sediments. Contorted white dolomitic marbles interbedded with high-purity talc occur above steeply dipping dark shales. The entire sequence is probably Cambrian in age. Relief .on the Kukri Erosion Surface exceeds 100 meters, and the Brown Hills conglomerate is more than 30 meters thick and made up of coarse cobbles of dolomite. Some of the beds in the Windy Gully sandstone are anomalously radioactive, but here the radioactivity results from uranium rather than thorium. The uranium is disseminated, however, and no localized concentrations could be found during a brief ground survey. Near the conclusion of airborne survey operations, a flight was made to Butcher Ridge in the northwestern corner of the survey area. A layered intrusive body was discovered that outcrops for nearly 10 kilometers along the east face of the ridge. This body differs from the larger layered intrusion of the Dufek Massif in several ways. Although the layering is very well developed, it varies from essentially horizontal to nearly vertical. Unconformable contacts between steeply dipping and horizontal layered sequences are well exposed at several localities. It appears that the body may represent a portion of a magma chamber that served as an intrusive center for some of the Ferrar Group dolorites. The contorted
Geological investigations in the Scott Glacier and Byrd Glacier areas EDMUND STUMP, MICHAEL F. SHERIDAN, SCOTT G. BORG, PATRICK H. LOWRY, and PHILIP V. COLBERT Department of Geology Arizona State Unzverszty Tempe, Arizona 85281
Our 1978-79 field season was divided into two principal efforts, one in the Scott Glacier area and the other in the Byrd Glacier area (with some additional work in the McMurdo Sound area). From 19 November until 8 December 1978, we were involved in geological mapping and collection activities on the west side of the upper Scott Glacier. We occupied two base camps and used snowmobiles for transportation to the surrounding areas. The primary objective of this effort was to examine
-. JI •
:.
4t '' Figure 2. Contorted bed of dolomitic marble and talc in the metamorphic sequence that underlies the Kukri Erosion Surface. Fiat lying Beacon Supergroup elements are clearly visible in the upper right. The outcrop is located at the fork in Zeller Glacier.
layering may have developed as a result of turbulence in the magma chamber. The AIRS Project is a joint research effort of the University of Kansas and the Federal Institute for Geosciences and Resources (Bundesanstalt für Geowissenschaften und Rohstoffe) of the Federal Republic of Germany. It is supported in part by National Science Foundation grant DPP 77-21504.
the late Precambrian Wyatt Formation and to determine its mode of emplacement. Previous mapping had been conducted by Minshew (1967), who had suggested that the Wyatt Formation was composed of volcanic rocks of pyroclastic origin. We have confirmed this interpretation in part, but also have noted important differences. For instance, the rocks at Mount Wyatt (the type locality of the Wyatt Formation) appear to be intrusive rather than extrusive. Also, a new locality of Beacon rocks was found at the summit of Mount Farley and at the unnamed peak to the northwest. In addition, we determined that a fairly large area in the vicinity of Lee Peak and Mount Denauro, previously mapped as Wyatt Formation (Mmshew, 1967), is, in fact, underlain by metasedimentary rocks of the LaGorce Formation. This is in fault contact with Wyatt Formation west of Lee Peak. Furthermore, we found that granitic rocks occur at several localities previously mapped as Wyatt Formation. Petrographic and chemical analysis of all the igneous rocks encountered in the Scott Glacier area is now in progress. We also examined the Tertiary volcanic rocks cropping out at Mount Early and "Sheridan Bluff"* (Doumani and Minshew, 1965; Treves, 1967), and discovered *Unofficial name pending approval by the Advisory Committee on Antarctic Names of the U.S. Board on Geographic Names. 39
156° 66°1SS
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152°
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-
-
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Figure 2. Survey area south of Byrd Glacier.
0
Sheridan Bluff
87°
i
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Figure 1. Survey area on west side of upper Scott Glacier.
that they were erupted subglacially. Isotopic dating of these rocks is now in progress. Following our return from Scott Glacier, we investigated volcanic rocks in the McMurdo Sound area at Minna Bluff, Castle Rock, Turks Head, Cape Barne, and the summit of Mount Erebus, putting emphasis on the hyaloclastite deposits at several of these localities. During the second half of the season, from 19 December 1978 to 14 January 1979, we worked as a satellite party of the helicopter-supported Darwin Glacier camp investigating Cambrian sequences south of Byrd Glacier. We occupied tent camps at Mounts Madison, Tuatara, Hamilton, Durnford, and Ubique, with three additional days of close support by helicopter. Highlights of this phase of our work included measurement of a 1,940-meter-long section of Shackleton Limestone at Mount Tuatara, recognition of two generations of folding at Mount Madison, and examination 40
of the type localities of Douglas Conglomerate and Dick Formation at Nunatak 841 and of Starshot Formation at Mount Ubique (Skinner, 1965; Laird, 1963). Silicic volcanic rocks collected from the Starshot Formation at Mount Ubique will be chemically analyzed for comparison with volcanic rocks in the Taylor and Fairweather formations farther to the south (Stump, 1976). This work has been supported by National Science Foundation grant DPP 76-82040 AOl. References Doumani, George A., and Velon H. Minshew, 1965. General Geology of the Mount Weaver Area, Queen Maud Mountains, Antarctica. Antarctic Research Series, 6: 127-39. Washington, D.C.: American Geophysical Union. Laird, M. G., 1963. Geomorphology and stratigraphy of the Nimrod Glacier-Beaumont Bay Region, Southern Victoria Land, Antarctica. New Zealand Journal of Geology and Geophysics, 6: 465-84. Minshew, V. H. 1967. Geology of the Scott Glacier and Wisconsin Range areas, central Transantarctic Mountains, Antarctica. Ph.D. dissertation, Department of Geology, The Ohio State University. Skinner, D. N. B. 1964. A summary of the geology of the region between Byrd and Starshot glaciers, South Victoria Land. In Antarctic Geology, ed. R. J . Adie, pp. 284-92. Amsterdam, Netherlands: North-Holland. Stump, E. 1976. On the late Precambrian-early Paleozoic metavolcanic and metasedimentary rocks of the Queen Maud Mountains, Antarctica, and a comparison with rocks of similar age from southern Africa. Institute of Polar Studies Report, 62: 212. Treves, S. B. 1967. Volcanic rocks from the Ross Island, Marguerite Bay and Mt. Weaver areas, Antarctica. Japanese Antarctic Research Expedition, Scientific Reports, special issue no. 1, pp. 136-49.
Geological investigations in the Scott Glacier and Byrd Glacier areas EDMUND STUMP, MICHAEL F. SHERIDAN, SCOTT G. BORG, PATRICK H. LOWRY, and PHILIP V. COLBERT Department of Geology Arizona State Unzverszty Tempe, Arizona 85281
Our 1978-79 field season was divided into two principal efforts, one in the Scott Glacier area and the other in the Byrd Glacier area (with some additional work in the McMurdo Sound area). From 19 November until 8 December 1978, we were involved in geological mapping and collection activities on the west side of the upper Scott Glacier. We occupied two base camps and used snowmobiles for transportation to the surrounding areas. The primary objective of this effort was to examine
-. JI •
:.
4t '' Figure 2. Contorted bed of dolomitic marble and talc in the metamorphic sequence that underlies the Kukri Erosion Surface. Fiat lying Beacon Supergroup elements are clearly visible in the upper right. The outcrop is located at the fork in Zeller Glacier.
layering may have developed as a result of turbulence in the magma chamber. The AIRS Project is a joint research effort of the University of Kansas and the Federal Institute for Geosciences and Resources (Bundesanstalt für Geowissenschaften und Rohstoffe) of the Federal Republic of Germany. It is supported in part by National Science Foundation grant DPP 77-21504.
the late Precambrian Wyatt Formation and to determine its mode of emplacement. Previous mapping had been conducted by Minshew (1967), who had suggested that the Wyatt Formation was composed of volcanic rocks of pyroclastic origin. We have confirmed this interpretation in part, but also have noted important differences. For instance, the rocks at Mount Wyatt (the type locality of the Wyatt Formation) appear to be intrusive rather than extrusive. Also, a new locality of Beacon rocks was found at the summit of Mount Farley and at the unnamed peak to the northwest. In addition, we determined that a fairly large area in the vicinity of Lee Peak and Mount Denauro, previously mapped as Wyatt Formation (Mmshew, 1967), is, in fact, underlain by metasedimentary rocks of the LaGorce Formation. This is in fault contact with Wyatt Formation west of Lee Peak. Furthermore, we found that granitic rocks occur at several localities previously mapped as Wyatt Formation. Petrographic and chemical analysis of all the igneous rocks encountered in the Scott Glacier area is now in progress. We also examined the Tertiary volcanic rocks cropping out at Mount Early and "Sheridan Bluff"* (Doumani and Minshew, 1965; Treves, 1967), and discovered *Unofficial name pending approval by the Advisory Committee on Antarctic Names of the U.S. Board on Geographic Names. 39
156° 66°1SS
154°
152°
I / I
lbO°
160°W
177 - 77 \J 86°15's 0 10 20 30Km I- I I —I
5 10 15Krn Qmt. Gardiner
0 Cl) Cl)
Lee rf Peak w , 0
///o
Mt Camp Denauro 0 / () //
(7
4 -J
2
)
Mt. Farley
C) M Cl) I rTi I-Ti
81°S
ojj
N
81°S
10
-
-
/0 Ubique Mt.Wy
I
/ (
{
86045'
160°W
Figure 2. Survey area south of Byrd Glacier.
0
Sheridan Bluff
87°
i
£?t.oariy I 156 0 154° 1520 150°
Figure 1. Survey area on west side of upper Scott Glacier.
that they were erupted subglacially. Isotopic dating of these rocks is now in progress. Following our return from Scott Glacier, we investigated volcanic rocks in the McMurdo Sound area at Minna Bluff, Castle Rock, Turks Head, Cape Barne, and the summit of Mount Erebus, putting emphasis on the hyaloclastite deposits at several of these localities. During the second half of the season, from 19 December 1978 to 14 January 1979, we worked as a satellite party of the helicopter-supported Darwin Glacier camp investigating Cambrian sequences south of Byrd Glacier. We occupied tent camps at Mounts Madison, Tuatara, Hamilton, Durnford, and Ubique, with three additional days of close support by helicopter. Highlights of this phase of our work included measurement of a 1,940-meter-long section of Shackleton Limestone at Mount Tuatara, recognition of two generations of folding at Mount Madison, and examination 40
of the type localities of Douglas Conglomerate and Dick Formation at Nunatak 841 and of Starshot Formation at Mount Ubique (Skinner, 1965; Laird, 1963). Silicic volcanic rocks collected from the Starshot Formation at Mount Ubique will be chemically analyzed for comparison with volcanic rocks in the Taylor and Fairweather formations farther to the south (Stump, 1976). This work has been supported by National Science Foundation grant DPP 76-82040 AOl. References Doumani, George A., and Velon H. Minshew, 1965. General Geology of the Mount Weaver Area, Queen Maud Mountains, Antarctica. Antarctic Research Series, 6: 127-39. Washington, D.C.: American Geophysical Union. Laird, M. G., 1963. Geomorphology and stratigraphy of the Nimrod Glacier-Beaumont Bay Region, Southern Victoria Land, Antarctica. New Zealand Journal of Geology and Geophysics, 6: 465-84. Minshew, V. H. 1967. Geology of the Scott Glacier and Wisconsin Range areas, central Transantarctic Mountains, Antarctica. Ph.D. dissertation, Department of Geology, The Ohio State University. Skinner, D. N. B. 1964. A summary of the geology of the region between Byrd and Starshot glaciers, South Victoria Land. In Antarctic Geology, ed. R. J . Adie, pp. 284-92. Amsterdam, Netherlands: North-Holland. Stump, E. 1976. On the late Precambrian-early Paleozoic metavolcanic and metasedimentary rocks of the Queen Maud Mountains, Antarctica, and a comparison with rocks of similar age from southern Africa. Institute of Polar Studies Report, 62: 212. Treves, S. B. 1967. Volcanic rocks from the Ross Island, Marguerite Bay and Mt. Weaver areas, Antarctica. Japanese Antarctic Research Expedition, Scientific Reports, special issue no. 1, pp. 136-49.
