Sierra Nevada

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Research: Convergent Systems

The Mount Tallac roof pendant is the largest and best exposed body of metavolcanic rocks in the Sierra Nevada, contains rocks that predate the intrusion of the Jurassic-Cretaceous granitic batholith, and is cut by the Sierra Nevada boundary fault. Thus, these rocks record a comprehensive record of the pre-, syn- and post geologic history of the Sierra Nevada. While the petrology of both the metavolcanic rocks and the plutons have been widely studied, relatively little is known regarding the structural fabrics in the roof pendant. Reconnaissance mapping within the Mount Tallac pendant in the eastern portion of the Desolation Wilderness Area in the summer of 2012 documented an interesting array of structural fabrics. Here strata of the Tuttle Lake Formation are penetratively deformed, involved in open folds, and are cut by an array of fractures that have accommodated varying degrees of sinistral offset. A detailed interpretation of these fabrics will undoubtably provide new insights into the modes of pluton emplacement within the pendant and deformation associated with uplift of the Sierra Nevada.

In collaboration with

Scott Giorgis, SUNY New Paltz

Anthony Pivarunas, USGS

Bob Miller, California State University, San Jose