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Mineral resources and resource potential map of the Pyramid Peak Roadless Area, Riverside County, California

Miscellaneous Field Studies Map 1999

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Abstract

The Pyramid Peak Roadless Area is underlain by mid-Cretaceous plutonic rocks (granite, granodiorite, and tonalite) that intrude metasedimentary rocks of the Desert Divide Group. The granodiorite grades eastward into strongly deformed mylonitic rocks mapped as part of the Santa Rosa mylonite zone. Metasedimentary rocks, orthogneiss, and anatexites of the Palm Canyon Complex were displaced westward over the Santa Rosa mylonite zone along low-angle thrust faults that are nearly synchronous with the mylonite zone. The Pliocene and (or) Pleistocene Bautista Formation unconformably overlies the mid-Cretaceous plutonic rocks.

Geologic and geochemical data indicate that the study area has high resource potential for marble, and moderate resource potential for epithermal gold deposits and tungsten skarns. The Desert Divide Group and the Palm Canyon Complex contain large resources of marble quarried for Portland cement and for construction applications. Gold occurs in quartz veins and pegmatites in the Desert Divide Group and the Penrod Quartz Monzonite. Skarns in the Desert Divide Group contain scheelite and anomalous concentrations of arsenic and beryllium. Thin layers of tremolite asbestos along low-angle thrust faults occur outside of the study area.

Study Area

Additional publication details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Mineral resources and resource potential map of the Pyramid Peak Roadless Area, Riverside County, California
Series title:
Miscellaneous Field Studies Map
Series number:
1999
Year Published:
1988
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Description:
Plate: 28.18 x 25.27 inches
Country:
United States
State:
California
County:
Riverside County
Other Geospatial:
Pyramid Peak Roadless Area
Scale:
0
Online Only (Y/N):
N
Additional Online Files (Y/N):
N