Geology of the Sacramento and Chemehuevi Mountains

The Sacramento and Chemehuevi Mountains lie within the Colorado River extensional corridor (CREC), and expose rocks ranging in age from Proterozoic to Tertiary, which have been extended by low-angle normal faulting during the Miocene. Extension at this latitude has been dated between ~23-12 Ma with various different pulses of extension. The Sacramento and Chemeheuvi Mountains both represent midcrustal intrusive rocks of Proterozoic, Cretaceous, and Miocene age. Hanging wall rocks to the detachment fault system include a broad range of rock types including upper crustal Proterozoic rocks and Miocene volcanic and sedimentary rocks. Exposures within both ranges provide and excellent opportunity to analyze the dynamics of low-angle normal faults.

The participants spent five days along the Colorado River analyzing fault contacts and tectonic relationships in the region. The goal of the trip was for students investigating highly extended regimes in both continental and oceanic environments to observe extensional core complexes in the field. More details on the features studied on our geologic expedition are summarized below.

Chemehuevi Detachment 1

On the River, Topock Gorge

Chemehuevi Detachment 2

The Devil's Elbow Fault

Eagle Wash

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