--> Internal Architecture Of The Proto-Kern Canyon Fault At Engineer's Point, Lake Isabella Dam Site, Kern County, California
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Pacific Section AAPG Convention

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Internal Architecture Of The Proto-Kern Canyon Previous HitFaultNext Hit At Engineer's Point, Lake Isabella Dam Site, Kern County, California

Zachary Martindale1, Graham Andrews1, Sarah Brown1 and Junhua Guo1

1California State University, Bakersfield

May 5, 2015 Tuesday 8:00 A.M. Pacific Section AAPG Convention, Oxnard, California

Abstract

The core of the Cretaceous (?) proto-Kern Canyon Previous HitFaultNext Hit (KCF) is exposed continuously for 1.25 km along Engineers Point at Lake Isabella, Kern County, California. The proto-KCF is notable for (1) its long and complex history within, and perhaps preceding the Sierra Nevada batholith, and (2) hosting the Quaternary Kern Canyon Previous HitFaultNext Hit, an active Previous HitfaultNext Hit that threatens the integrity of the Lake Isabella auxiliary dam and surrounding communities. We are investigating the internal architecture of the proto-KCF to explore its control on the likely behavior of the modern KCF. The proto-KCF is developed in the Alta Sierra biotite-granodiorite pluton. A traverse across Engineers Point, perpendicular to the proto-KCF trace, reveals gradational increases in fracture density, fracture length, bulk alteration, and decreases in fracture spacing and grain size toward the Previous HitfaultNext Hit core. Mapping of the Previous HitfaultNext Hit core reveals two prominent and laterally extensive zones: (1) continuous foliated blastomylonitic granodiorite with steeply-dipping, anastomosing shear bands and minor mylonite Previous HitplanesNext Hit, and (2) foliated orange and green Previous HitfaultNext Hit breccia with intergranular gouge, strong C/S fabric, and a central gouge plane. The Previous HitfaultNext Hit breccia zone is intruded by a lensoidal, post-deformation dacite dike, probably ca. 105 - 102 Ma (Nadin & Saleeby, 2008) and is weakly overprinted by a set of cross-cutting spaced, short, brittle fractures, often coated in calcite, which we infer to be genetically related to the modern KCF. We present our structural and lithological data that will be supported by mineralogical and geochemical analyses. Nadin & Saleeby (2008) Disruption of regional primary structure of the Sierra Nevada batholith by the Kern Canyon Previous HitfaultTop system, California: Geological Society of America Special Paper 438, p. 429-454.

AAPG Datapages/Search and Discovery Article #90215 © 2015 Pacific Section AAPG Convention, Oxnard, California, May 3-6, 2015