Transtensional Deformation of the Brittle Crust: Field Observations and Theoretical Applications in the Coso-China Lake Region, Eastern Margin of the Sierra Nevada Microplate, Southeastern California

The focus of this work is the description of non-plane strain brittle deformation through field observations and theoretical applications. The seismically and volcanically active Coso—China Lake region in the transtensional Eastern California shear zone is an exemplary location for field observation of brittle structure. The region deforms in a constrictional strain field, well-described by earthquake focal mechanisms and GPS measurements, and further demonstrated by our field observations and outcrop-scale mapping. Fundamental geometric relationships in transtensional zones and tectonic reconstruction allows practical applications of theory using real transtension zone parameters, and expands our ability to describe triaxial strain in three dimensions. Theoretical instantaneous strain axes are constrictional and oriented xi WNW, yi NNE, zi vertical, similar to seismogenic and GPS derived instantaneous strain axes, and kinematic analysis of field data. Orientations of brittle structures in the field corre...