Interrelationships of cataclasite, mylonite, and leucocratic bodies associated with the Catalina detachment fault, dual wash area, Saguaro National Park east, Rincon Mountains

Abstract

The Dual Wash area is comprised of two west-northwest-trending washes (Deer Valley and Carillo), which provide excellent cross-section exposures of metamorphic core complex fault rock units. The structural components of metamorphic core complexes consist of upper plate rocks, a detachment fault, cataclasite and chlorite breccia, subdetachment fault, and mylonites. Within the Carillo Wash, the Catalina detachment fault dips ~13° NW, which is consistent with its overall dip in this part of the Rincon Mountains. However, exposed along the Deer Valley Wash, the Catalina detachment fault dips more steeply at ~60° NW. Beneath the detachment fault, in the lower plate, the structurally highest rock is a highly-fractured chlorite cataclasite which lies above two different units of mylonites. Embedded in these unit is leucocratic granitic unit which floods the cataclasite and mylonites. Evidence of brittle faulting and fracturing show evidence of this being a late-stage intrusion. The structural geology of the Dual Wash area proves to be somewhat structurally anomalous. The cause for much of these anomalies within the lower plate may be credited to the presence of this abundant leucogranite unit. This may be because it is a late-stage intrusion as well as a potential driver of core complex development.