An axial view of a metamorphic core complex: crustal structure of the Whipple and Chemehuevi Mountains, southeastern California

A 135-km-long, NW-SE trending, seismic refraction/wide-angle reflection profile provides a unique along-strike view of the crustal structure of a belt of metamorphic core complexes in southeastern California: the Whipple, Chemehuevi, and Sacramento mountains metamorphic core complexes. Observations support greater uplift and a slightly deeper midcrustal origin for the rocks now exposed in the core of the Whipple Mountains compared to rocks in the Chemehuevi and Sacramento mountains. Despite the enhanced uplift and extension in the Whipple Mountains, the crust is thicker here (30 km) than anywhere else along the Colorado River extensional corridor. Inflation of the crust during Tertiary extension is suggested as the dominant mechanism. Both mantle derived magmatism and lateral ductile inflow in the crust are proposed. -from Authors