Paleogene Strata, Seymour Island, Antarctic Peninsula

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9508089 Elliot Abstract This award supports a geologic research project that will take advantage of an opportunity to participate in the 1994-95 geology field program of the Argentine Antarctic Institute. Participation will provide the opportunity to address important problems in the stratigraphic relations and dating of the Paleogene strata on Seymour Island and to field check the new 1:20,000 topographic map that is being prepared by the USGS. The sedimentary strata on Seymour Island are part of the only exposed Upper Cretaceous to Lower Tertiary marine sequence in Antarctica. The Cretaceous-Tertiary succession was deposited in an ensialic back-arc basin related to the development of the mid-Mesozoic to mid-Cenozoic active plate margin of the Antarctic Peninsula. Seymour Island strata range in age between Late Campanian and middle(?) Eocene to earliest(?) Oligocene. These poorly consolidated sedimentary rocks contain a diverse and exceptionally preserved invertebrate fauna, a diverse microflora, and a variety of vertebrates, including marsupials. Fieldwork (to be supported by the Argentine Antarctic Institute in the 1994-95 season) will be directed toward: resolving the complex stratigraphic relations of the Paleogene units on Seymour Island; collection of tuff beds for radiometric dating, and petrologic and geochemical analysis; and sequence analysis of the Paleogene succession. This award is to support travel to Buenos Aires to join the Argentine Antarctic Institute's geology project, travel to confer with the USGS about the results of field checking of the topographic map, and laboratory studies on samples collected in the course of the field season. Specifically, the lab objectives are to: 1) date the ash beds in order to provide absolute age control for sequences that lack calcareous and siliceous microfossil assemblages; and 2) establish the geochemistry of the ash beds to assess contemporaneous volcanic activity and magmatic evol ution of the source region. The results will provide the stratigraphic framework for on-going paleontological projects on Paleogene strata, radiometric data in support of paleontological ages and sequence analysis, and characteristics of the magmatic activity in the source region of the sediments.