Pennsylvanian and Permian Sun Valley Group, Wood River Basin, South-Central Idaho

Abstract

We define the Sun Valley Group of south-central Idaho to include the Desmoinesian to Leonardian Wood River, Dollarhide, and Grand Prize Formations, which consist of 2000 to 3400 m of mixed carbonate-siliciclastic strata deposited in the epicratonic Wood River basin. In the Woo d River Formation we revise the basal Hailey Member to make it more easily mappable, and define overlying Eagle Creek and Wilson Creek Members. The Middle Pennsylvanian part of the Sun Valley Group contains proximallyderived conglomerate and interbedded biostromal limestone deposited on a braiddelta and adjacent slope. The Late Pennsylvanian to Early Permian part of the group comprises a south-sloping finegrained mixed carbonate-siliciclastic rampapron system. This system received cratonal quartz sand from a northern source and comminuted bioclastic debris and micrite from the coeval Snaky Canyon Formation to the east.