Structural evolution and tectonic significance of the Jurassic (?) Talbot fault zone in the Northern Sierra terrane, California

Abstract

The Northern Sierra terrane in California contains a ~20-km-thick section of crust tilted nearly vertically. This study examines the rocks ~25 km west of Lake Tahoe. Here, the Talbot fault zone, which is suggested to be part of the main breakaway fault responsible for tilting, is exposed. Rare kinematic indicators in the Picayune Valley Formation are concordant with a west-down sense of motion for the Talbot fault zone which could have caused the map relations seen in the tilted section. Folds and fabrics in the study area suggest two deformational events following slip on the Talbot fault zone. Following deformation the emplacement of a post-tectonic granodioritic pluton occurred at ~101 Ma, which is based on a 40Ar/39Ar hornblende-biotite cooling age.