Early Tertiary coal bed on Seymour Island, Antarctic Peninsula
Early Tertiary coal bed on Seymour Island, Antarctic Peninsula S
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R. FARLEY FLEMING
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Department of Geological Sciences University of Colorado Boulder, Colorado 80309
ROSEMARY A. ASKIN Geology Department Colorado School of Mines Golden, Colorado 80401 L
Taut", A coal seam was discovered on Seymour Island, Antarctic Peninsula, during the course of geological fieldwork in March 1982. The seam is tentatively assigned to the early Tertiary Cross Valley Formation and is apparently the first discovery of a Tertiary coal bed in Antarctica. The coal seam is exposed on a precipitous, scree-covered seacliff (see figure) just south of Cross Valley on the eastern coast of Seymour Island. Field relationships suggest that the coal-bearing sediments are equivalent to the upper, finegrained portion of the Cross Valley Formation, but because of the inaccessibility of the exposure we were unable to measure the section containing the seam. The exposed seam is approximately 1 meter thick and 6 meters long and contains coalified logs. Several thin, discontinuous, clay partings occur within the seam, and the sediments overlying and underlying the coal consist of fine to medium sands. In the examined (southern) portion, an apparently discontinuous layer of dark gray clay (2 centimeters thick) occurs at the base of the coal. Fourteen channel samples from the coal seam were collected for palynological, petrographic, and other analyses. Vitrinite reflectance averages of 0.28 percent Ro and 0.30 percent Ro suggest that the coal is a lignite (American Society for Testing Materials scale; see table 4, Stach et al. 1975). Palynomorphs recovered are light yellow, exhibiting a low level of thermal alteration which also suggests a low rank for the coal. Initial palynological processing of two channel samples yielded abundant, well-preserved pollen grains, rare fern spores, and no marine palynomorphs. The assemblage is dominated by podocarpaceous pollen, mainly Phyllocladidites spp., and also contains angiosperm pollen, including Not hofagidites spp., proteaceous species, and a tricolpate species (see F in figure, Askin and Fleming, Antarctic Journal, this issue) which apparently is restricted to the Sobral and Cross Valley Formations. Cranwell (1969) suggests a Maestrichtian to Paleocene age for palynomorphs from the Cross Valley Formation. Wrenn (1982),
1982 REVIEW
View of coal seam in upper seaclift south of Cross Valley.
on the basis of dinoflagellates, suggests that the Cross Valley Formation is Paleocene-Eocene in age. Elliot and Trautman (1982) interpreted the upper, fine-grained part of the Cross Valley Formation as deposited in low-energy interdistributary areas of a delta. Future studies of this coal seam could provide valuable information on the floral components and climatic factors of the early Tertiary in the Antarctic Peninsula area and could aid in the interpretation of the depositional environment of the Cross Valley Formation. We thank other members of the expedition, particularly William J . Zinsmeister, for locating the coal seam, the captain and crew of USCGC Glacier for logistic support, and Tom Hemler (Amoco Production, Denver) and Mel Thompson (Chevron U.S.A., Denver) for vitrinite reflectance data. This work was supported by National Science Foundation grant DPP 80-20095.
References Askin, R. A., and Fleming, R. F. 1982. Palynological investigations of Campanian to lower Oligocene sediments on Seymour Island, Antarctic Peninsula. Antarctic Journal of the U.S., 17(5). Cranwell, L. M. 1969. Antarctic and circum-Antarctic palynological contributions. Antarctic Journal of the U.S., 4(5), 197-198. Elliot, D. H., and Trautman, T. A. 1982. Lower Tertiary strata on Seymour Island, Antarctic Peninsula. In C. Craddock (Ed.), Antarctic geoscience. Madison: University of Wisconsin Press. Stach, E., Mackowski, M.-Th., Teichmuller, M., Taylor, C. H., Chandra, D., and Teichmuller, R. 1975. Stach's textbook of coal petrology (2nd ed.). Berlin: Cebruder Borntraeger. Wrenn, J. H. 1982. Dinocyst hiostratigraphy of Seymour Island, Palmer Peninsula, Antarctica. Unpublished doctoral thesis, Louisiana State University.
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. .
R. FARLEY FLEMING
. -
-
Department of Geological Sciences University of Colorado Boulder, Colorado 80309
ROSEMARY A. ASKIN Geology Department Colorado School of Mines Golden, Colorado 80401 L
Taut", A coal seam was discovered on Seymour Island, Antarctic Peninsula, during the course of geological fieldwork in March 1982. The seam is tentatively assigned to the early Tertiary Cross Valley Formation and is apparently the first discovery of a Tertiary coal bed in Antarctica. The coal seam is exposed on a precipitous, scree-covered seacliff (see figure) just south of Cross Valley on the eastern coast of Seymour Island. Field relationships suggest that the coal-bearing sediments are equivalent to the upper, finegrained portion of the Cross Valley Formation, but because of the inaccessibility of the exposure we were unable to measure the section containing the seam. The exposed seam is approximately 1 meter thick and 6 meters long and contains coalified logs. Several thin, discontinuous, clay partings occur within the seam, and the sediments overlying and underlying the coal consist of fine to medium sands. In the examined (southern) portion, an apparently discontinuous layer of dark gray clay (2 centimeters thick) occurs at the base of the coal. Fourteen channel samples from the coal seam were collected for palynological, petrographic, and other analyses. Vitrinite reflectance averages of 0.28 percent Ro and 0.30 percent Ro suggest that the coal is a lignite (American Society for Testing Materials scale; see table 4, Stach et al. 1975). Palynomorphs recovered are light yellow, exhibiting a low level of thermal alteration which also suggests a low rank for the coal. Initial palynological processing of two channel samples yielded abundant, well-preserved pollen grains, rare fern spores, and no marine palynomorphs. The assemblage is dominated by podocarpaceous pollen, mainly Phyllocladidites spp., and also contains angiosperm pollen, including Not hofagidites spp., proteaceous species, and a tricolpate species (see F in figure, Askin and Fleming, Antarctic Journal, this issue) which apparently is restricted to the Sobral and Cross Valley Formations. Cranwell (1969) suggests a Maestrichtian to Paleocene age for palynomorphs from the Cross Valley Formation. Wrenn (1982),
1982 REVIEW
View of coal seam in upper seaclift south of Cross Valley.
on the basis of dinoflagellates, suggests that the Cross Valley Formation is Paleocene-Eocene in age. Elliot and Trautman (1982) interpreted the upper, fine-grained part of the Cross Valley Formation as deposited in low-energy interdistributary areas of a delta. Future studies of this coal seam could provide valuable information on the floral components and climatic factors of the early Tertiary in the Antarctic Peninsula area and could aid in the interpretation of the depositional environment of the Cross Valley Formation. We thank other members of the expedition, particularly William J . Zinsmeister, for locating the coal seam, the captain and crew of USCGC Glacier for logistic support, and Tom Hemler (Amoco Production, Denver) and Mel Thompson (Chevron U.S.A., Denver) for vitrinite reflectance data. This work was supported by National Science Foundation grant DPP 80-20095.
References Askin, R. A., and Fleming, R. F. 1982. Palynological investigations of Campanian to lower Oligocene sediments on Seymour Island, Antarctic Peninsula. Antarctic Journal of the U.S., 17(5). Cranwell, L. M. 1969. Antarctic and circum-Antarctic palynological contributions. Antarctic Journal of the U.S., 4(5), 197-198. Elliot, D. H., and Trautman, T. A. 1982. Lower Tertiary strata on Seymour Island, Antarctic Peninsula. In C. Craddock (Ed.), Antarctic geoscience. Madison: University of Wisconsin Press. Stach, E., Mackowski, M.-Th., Teichmuller, M., Taylor, C. H., Chandra, D., and Teichmuller, R. 1975. Stach's textbook of coal petrology (2nd ed.). Berlin: Cebruder Borntraeger. Wrenn, J. H. 1982. Dinocyst hiostratigraphy of Seymour Island, Palmer Peninsula, Antarctica. Unpublished doctoral thesis, Louisiana State University.
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