Metamorphic core complexs are characteristically areas of exposed mylonitic rocks that were exhumed by large displacement on gently to moderately dipping normal faults. Arizona hosts a number of core complexes that formed during Olig-Miocene extension associated with early Basin and Range development.
Online Resources authored by Jon Spencer: A geologist's guide to the core complex geology along the Catalina Highway, Tucson Area, Arizona; https://library.azgs.arizona.edu/item/AOFR-1552429673312-319
Graphics for core-complex morphology and geologic continuous casting; https://library.azgs.arizona.edu/item/AOFR-1552427048153-178
Photographer: Jon Spencer
Photo Date: 2009