1:24000-SCALE MAPPING OF THE NORTH TETON VALLEY, TETON COUNTY, IDAHO

The Drummond 7.5’ Quadrangle (estimated release May 2014), Lamont 7.5’ Quadrangle (estimated relsease May 2014), Tetonia 7.5’ Quadrangle (2013) Packsaddle 7.5’ Quadrangle (2013) were mapped at 1:24,000-scale by the Idaho Geological Survey and its affiliates as part of the USGS STATEMAP program. As a smaller part of the larger 30’x60’ Rexburg Mapping project, these four quads give an idea of the geology and structure of the northern Teton Valley. Exposure in the area is limited by loess deposits which blankets most of the region. However, the excision of the Teton River, Badger Creek and Bitch Creek, reveal much about the relationships between 2.1 Ma Huckleberry Ridge Tuff and younger regional basalt flows. XRF and paleomagnetic analysis reveals that at least three basalts are found in the mapping area: Badger Creek, Aard Farms, and Bailey’s Reset. Determining the lateral extent of these basalts is difficult due to the thick loess, though it appears that in the basalt of Bailey’s Reset is confined by a graben.

The northern Teton Valley appears to be the farthest northern extent of the West Tetonia Fault system, a horst and graben extensional basin, likely associated with larger normal faults to the south. The faults in the Teton basin are trending northwest to southeast which is similar in orientation to surrounding the faults of the thrust belt. Further mapping the area will help constrain the relationship of the West Tetonia Fault System and the larger scale thrust belt to the south and east.