Description
Seventy-three square miles of dominantly cataclastic augen gneisses and schists were investigated in the Rawhide Mountains. Structural analysis indicates that these possible Precambrian supracrustal rocks were cataclastically deformed under amphibolite facies conditions during the generation of Precambrian northeast-trending flexural flow folds, with the cataclastic lineations formed parallel to the fold axes. After a period of metamorphism to the epidote-chlorite assemblage conditions the Precambrian structures were broken by Basin and Range transverse northwest-trending faulting. Both periods of metamorphism were associated with a period of intrusion. During the Tertiary, tectonic slices slid off the adjacent higher portions of the block-faulted mountains, and formed the stack of gravity-slide blocks that form the Rawhide Mountains. This movement was responsible for the formation of a thin band of secondary cataclastic rocks during the Eocene. The Paleozoic(?) and Tertiary sedimentary sections, which were rafted along on the top of the first generation gravity-slide blocks, slid onto the more resistant second generation cataclastic rocks from the erosion remnants of the slide blocks. The Rawhide Mountains are on the northern boundary of a band of northeast-trending mountains. The discontinuities that separate these mountains from the rest of the Basin and Range province appear to be part of a major crustal feature that extends from Tucson, Arizona to Death Valley, California.
