Lithospheric Processes

High-grade metamorphic terranes, in which multiple geospeedometry, thermochronological, thermobarometric and other geochemical and/or petrological techniques can be combined with detailed numerical diffusion and thermal models, can be used to place tight constraints on the conditions and timescales of tectonic metamorphism. In collaboration with Mauricio Ibañez-Mejia at the University of Arizona, we have successfully combined U-Pb, Sm-Nd and Lu-Hf dating techniques with P-T conditions and cooling rates determined independently from garnet-pyroxene thermobarometry and garnet-biotite diffusion chronometry to produce a quantitative temperature-time path of collisional orogenesis seen by a Proterozoic metasediment from the Putumayo orogenic belt. We have implemented a similar approach in collaboration with Hao Cheng at Tongji University, in which we combined U-Pb, Lu-Hf, Sm-Nd, Ar-Ar and U-Th/He dating techniques with garnet-clinopyroxene thermobarometry and garnet diffusion chronometry on an amphibolite from the Cathaysia Block in southern China. We found that all of the data collected in this study are consistent with a single thermal history in which late-stage reheating reset the different thermochronological systems to different degrees. The approach implemented in these studies highlights the potential that combining such a variety of techniques offers for studying lithospheric processes, as well as the challenges and complexities of interpreting high-temperature thermochronological systems.