TRACKING EROSION AND SEDIMENT TRANSPORT IN THE BEAR RIVER, UT, WY, AND ID USING DETRITAL ZIRCON AND OPTICALLY STIMULATED LUMINESCENCE PROVENANCE

How sediment erodes, transports, and deposits across internally drained extensional basin systems remains unresolved. To create a sedimentological framework for how extensional sedimentary systems function, we investigate the Bear River in the N. Basin and Range, the largest endorheic river in North America, constrain the sediment source areas, and compare them with sediment provenance tracers along the Bear River’s path. To understand the bedrock source area contributions, DEM analysis was integrated with georeferenced geologic maps, providing preliminary data on channel slope and variable catchment geomorphology. We sampled modern river sediments from the Uinta Mountains headwaters, tributaries along the main stem (Porneuf, Smith Fork, Logan, Genes Creek), and the terminal basin sink at Great Salt Lake to acquire detrital zircon (DZ) as well as optically and infrared stimulated luminescence (OSL/IRSL) quartz and feldspar data over the course of the watershed. The DZ and OSL/IRSL data serve as sediment provenance tracers and characterize source regions, sediment mixing, and establish a modern baseline to compare with the depositional record. Constraining sediment signal propagation through a modern extensional system provides a framework for modeling tectonic, paleogeographic, and paleodrainage histories.