Significance of Ductile Shear Zones in the Implacement of Batholiths: Part I: Central Sierra Nevada, California

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The central Sierra Nevada batholith, an Andean-type magmatic arc, was emplaced in an overriding continental plate during the Cretaceous. Modern Andean studies imply the plate should be under compressional stress produced by subduction, however in the batholith only magmatic foliation is present and there is a virtual absence of regionally developed solid-state foliation. Given the compressional field thought to be active, these observations raise questions concerning the dynamic field attending emplacement of the batholith. This project will examine the geometry, kinematics and strain features of ductile shear zones in the batholith and wall rocks to establish their role in the dynamic and deformational history of batholith emplacement. Results are expected to shed light on upper crustal stress fields accompanying plutonism and in the fabrics developed in collisional tectonic environments.