UCLA

The North American Cordilleran metamorphic core-complex belt provides insight into the tectonometamorphic evolution of North America. Specifically, the Whipple Mountains metamorphic core complex, or the birthplace of the modern concept of low-angle detachment faulting, has been a target of research for decades. Each project presented in this dissertation addresses scientific questions regarding the deformation history of the Whipple Mountains shear zone which build on each other to provide a holistic view of the geologic history. First, new pressure, temperature, and timing (P-T-t) of deformation constraints were determined for shear zone rocks. The high P-T conditions and the structural relations in the rocks allow for different styles of deformation to be present in the brittle-ductile transition zone at 15-20 km depth where the pore-fluid pressure ratios may be calculated. Finally, a new model is proposed to further explain the formation of the Whipple detachment fault which suggests it may have been active since Mesozoic time. The advancement of analytical tools continues to help bridge the gap between what is known and what can be further discovered, and these projects may help further understand the evolution of the metamorphic core complexes in North America.