CONTINENTAL EVOLUTION OF THE NORTHERN ARCHEAN WYOMING PROVINCE: INTEGRATING GEOLOGY AND GEOPHYSICS ACROSS 4.0 GA OF EARTH HISTORY

The northern Archean Wyoming Province contains a mosaic of continental crustal components that span 4 Ga of Earth history. Archean igneous components include: a) ancient detrital zircons from quartzites from across the province (~3.2-4.0 Ga); b) older gneisses (3.5-3.6 Ga); c) a major crust-forming event at ~3.3-3.2 Ga (younger gneisses); d) calc-alkaline TTG magmatism at ~2.8 Ga (Beartooth-Bighorn magmatic terrane); and e) minor leucogranites at 2.55 Ga. Regional reworking along the northwestern margin of the Wyoming Province occurred through granulite facies metamorphism and partial crustal melting at ~2.4 Ga . Major reworking (Great Falls Tectonic Zone) and the only post-Archean crustal growth occurred at 1.76-1.86 Ga; hydrothermal alteration at 1.4 Ga (talc deposits) developed in areas marginal to the Belt basin. Low-grade metasedimentary units of unknown depositional age occur in the Gravelly Range and Jardine areas. The distribution of Precambrian rocks and structures has strongly influenced Phanerozoic geology through reactivation of structures, formation of basins, and metallogenesis. For example, major zones of tectonic discontinuities occur in the present-day Yellowstone, Madison and Jefferson River valleys and along structures such as the Madison mylonite zone that initially developed in the Precambrian. To fully understand the fragmented record of crustal evolution of the northern Wyoming Province, spatial and temporal relations must be integrated with available geologic, geochronological, and geophysical data (e.g. aeromagnetic, gravity, and forthcoming seismic and geodetic data from EarthScope). We have begun this process by providing a web-based database of USGS geologic maps: http://serc.carleton.edu/research_education/mtgeodata/index.html. This poster will present a compilation showing the distribution of major crustal components, structures and geophysical anomalies produced by this interactive database.