Age and Tectonic Significance of Metamorphic Rocks Along the Axis of the Sierra Nevada Batholith: A Critical Reappraisal

SCHWEICKERT, R. A., and M. M. LAHREN, University of Nevada-Reno, Reno, NV

Metamorphic rocks in many roof pendants along the axis of the Sierra Nevada batholith (SNB) between 36 and 38 degrees N lat. have been considered part of the Kings sequence, of probable Mesozoic age. However, most of the pendants are in fact undated by fossils and may contain Paleozoic or Precambrian strata. Our critical reappraisal of new and existing data on these pendants has led to the following hypotheses: (1) A continental crustal sliver referred to as the Snow Lake block, with the approximate dimensions of the Salinian block, and represented by metamorphosed Proterozoic and Cambrian miogeoclinal rocks, extends 120 mi (200 km) southeastward from northern YNP to the Kaweah River drainage, and includes rocks in the following pendants: Snow Lake, Piute Mountain, Glen Aulin, May Lak , Iron Mountain, Shuteye Peak, Dinkey Creek, Patterson Mountain, Boyden Cave, and Sequoia Park. Probable stratigraphic units in this block include the Proterozoic Stirling Quartzite, Lower Cambrian Wood Canyon Formation and Zabriskie Quartzite, Lower to Middle Cambrian Carrara Formation, Middle Cambrian Bonanza King Formation, and Lower Triassic Fairview Valley Formation. This sliver was displaced about 400 km northward along an intrabatholithic dextral strike-slip fault during the Early Cretaceous time. (2) Based on reconnaissance studies, we propose that the Shoo Fly Complex, which lies west of the Snow Lake block, continues southeastward to 36 degrees N lat., and includes parts of the following pendants: Oakhurst, Lower Kings River, Kaweah River, Tule River, and Kern Canyon.

The apparent juxtaposition of the Shoo Fly Complex with the Snow Lake block requires the presence of a major tectonic break between them. This structure, now largely obliterated by Cretaceous plutons of the SNB, may be the equivalent of the Golconda thrust in north-central Nevada.

AAPG Search and Discovery Article #91009©1991 AAPG-SEPM-SEG-SPWLA Pacific Section Annual Meeting, Bakersfield, California, March 6-8, 1991 (2009)