The geology of the Canada del Oro headwaters, Santa Catalina Mountains, Arizona

Abstract

Geologic mapping, with an emphasis on structure, was carried out in the region of the headwaters of the Canada del Oro. Major intrusive rock types delineated in the study area include the Oracle Granite, Leatherwood quartz diorite, granodiorite porphyry, Catalina granite, and Reef of Rock granite. Sedimentary rock types mapped in the area include the Younger Precambrian Apache Group, Cambrian Boisa Quartzite and Abrigo Formation, Devonian Martin Formation, and the Mississippian Escabrosa Limestone. Large wavelength synclines deform the Apache Group sedimentary rocks in the north and metamorphosed Paleozoic sedimentary rocks of Marble Peak in the south. The northwest-trending Geeseman Fault cuts across Oracle Granite, Leatherwood quartz diorite, and Catalina and Reef of Rock granites. Structural analysis indicates a Cretaceous(?) component of sinistral strike-slip displacement and a Tertiary component of dip-slip displacement, south block down. The Older Precambrian Oracle Granite is the oldest rock in the area. Tectonic quiescence is marked by the deposition of the Younger Precambrian and Paleozoic sediments. Subsequent intrusive events began in the Late Mesozoic ending with the Reef of Rock granite. Movements on the Geeseman Fault and other northwest-trending faults during Basin and Range time resulted in the formation of the down-dropped graben of the Canada del Oro valley.