MANTLE XENOLITH MICROSTRUCTURES, TI-IN-QUARTZ IN MYLONITES, AND NON-STEADY STATE RECRYSTALLIZED GRAIN SIZE: ONGOING STRUCTURE PROJECTS AT CCNY

We present three ongoing projects at City College of New York involving a microstructural approach to rock deformation history and rheology. Lubicich presents microstructures from a suite of xenoliths from near the Alpine Fault, New Zealand. The xenoliths, some mylonitic and very fine grained (~28 μm), were deformed during early stages of development of the Alpine Fault. The xenoliths provide insight into the rheological development and physical processes associated with the formation of plate boundary faults. Kidder presents Ti-in-qtz data from two transects through the Alpine Fault Mylonite in order to constrain rock deformation temperatures (TitaniQ) associated with mylonitization. Hyperspectral cathodoluminescence (CL) images are presented from two of the mylonite samples. Soleymani presents the results of Griggs-rig deformation experiments involving ramped stress increases. The experiments are aimed at simulating the gradual increase in stress that rocks experience as they approach the brittle-ductile transition during exhumation.