Metagraywacke in the Salinian Block, central Coast Ranges, California: And a possible correlative across the San Andreas Fault

Donald C. Ross

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USGS · 70233430

Metagraywacke in the Salinian Block, central Coast Ranges, California: And a possible correlative across the San Andreas Fault

Donald C. Ross

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Abstract

The schist of Sierra de Salinas is a monotonously homogeneous biotite quartzofeldspathic schist with minor amounts of quartzite, amphibolite, and marble that forms a northwest-trending outcrop belt that strikes across parts of the Santa Lucia and Gabilan Ranges and is traceable further south in the subsurface to where it is presumably cut off by the San Andreas fault zone. Chemical composition of the schist is similar to that of "average" graywackes. This large and monotonous terrane of metagraywacke is anomalous in the Salinian block, where a great variety of metamorphic rocks is the general rule. The age of the schist is not known, but it has been intruded by granitic rocks of presumably mid-Cretaceous age. Although it contains somewhat greater amounts of admixed quartzite, amphibolite, and marble, the schist of Portal-Bitter Ridge (Pelona Schist?), on the east side of the San Andreas fault and west of Palmdale, is nevertheless modally and chemically similar to the schist (metagraywacke) of Sierra de Salinas, and I suggest that the two terranes are correlative and once were contiguous.

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Journal of Research of the U.S. Geological Survey Article

Source-reported bounding extent: 36° to 36.45° latitude; -122° to -120.75° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Donald C. Ross. 1976. Metagraywacke in the Salinian Block, central Coast Ranges, California: And a possible correlative across the San Andreas Fault. https://pubs.usgs.gov/publication/70233430

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