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Grand Teton National Park Report

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The crystalline rocks that form the core of the Teton Range are part of the Wyoming Province, which is one of the oldest portions of North America. Study of the basement of the Tetons, coupled with the results of ongoing research in similar aged rocks exposed elsewhere in Wyoming, will provide information on how the crust evolved in the early Earth in general and in the Wyoming province in particular. In 1998 the project involved one week of fieldwork in Teton National Park to collect samples of key units for geochemical studies. This field work involved four faculty members from UW and a graduate student, who is doing the study as part of her MS thesis. The field work has been followed by several months of laboratory analysis at UW. We have characterized the rocks through thin section, stained slabs, and whole rock geochemical and Nd, Sr, and Pb isotopic methods. Geochronology is in progress: datable minerals have been isolated from samples of four different units and precise ages with uncertainties on the order of ± 5 million years are forthcoming.