Interdependency of Mechanical and Chemical Processes During the Evolution of Chloritic Breccia, Sacramento Mountains, SE California

Abstract

Complex interaction between brittle deformation and mineralizing fluids resulted in the formation of the chloritic breccia zone that is found in crystalline footwall rocks of the Sacramento Mountains detachment fault (SMDF). The Sacramento Mountains, located in southeastern California, is one of a line of metamorphic core complexes in western North America that extends from Canada into Mexico. Similar to other core complexes, the Sacramento Mountains is characterized by upper plate Tertiary sedimentary and volcanic rocks separated from lower plate intrusive rocks (predominantly granite and granodiorite) by a low angle extensional fault. Chloritic breccia is found in the crystalline footwall rocks in most metamorphic core complexes and is characterized by 1) the disruption of preexisting rock textures due to brittle deformation and 2) a green color due to secondary chlorite and epidote.