Much or our research is centered around developing comprehensive P-T-t paths and metamorphic spatial and temporal domains, which allow us to test a range of orogenic models and scenarios. To do this, we use the laser ablation split-stream (LASS) technique for REE minerals, which allows for the coupling of geochronologic “dates” with trace element data such as Y and REE to discriminate diagnostic chemical processes in petrogenetic assemblages. In practice, this allows for direct association of REE-mineral dates with specific metamorphic reactions and melting events, thereby allowing us to distinguish the timing and conditions of complex metamorphic and deformational overprinting. By integrating LASS analyses with isochemical metamorphic analyses and multiple thermochronologic systems, we establish comprehensive P-T-t paths that document particle evolution from early prograde burial to exhumation. A secondary yet “critically” important component is the development of comprehensive inventories of bedrock REE-bearing phases where we work. In the southern Appalachians, our LASS geochronology campaign, aimed initially at answering tectonic process questions, has allowed us to initiate new studies focused on the interplay between spatial genesis of REE phases, paleo-Appalachian landscape evolution, and the present accumulation of these “critical” minerals in placer deposits through Cenozoic-Mesozoic time.
REE-PETROCHRONOLOGY AND THE “FOOTPRINTS” OF PALEOZOIC METAMORPHISM IN THE SOUTHERN APPALACHIANS
Under construction……
Regional tectonic map of the southern Appalachians. The areal extent of the metamorphic and geo-/thermochronology maps below are indicated by the dark blue outline. Modified from Merschat et al. (2017) and Thigpen et al. (2022).
Geologic map of the southern Appalachian Blue Ridge and Inner Piedmont in parts of TN, NC, SC, and GA. Data highlights our ongoing campaign style of geochronology and thermochronology to resolve the spatial and temporal “footprints” of Paleozoic metamorphism, deformation, and exhumation in the complex southern Appalachian system. This new data, when synthesized with our developing isochemical psuedosection models, quartz fabric analyses, and pre-existing geo- and thermochronology data in the region is giving us the ability to unravel multiple phases of Paleozoic orogeneis and in doing so, evaluate and/or reinterpret complex tectonic models of the region.
COUPLING REE-PETROCHRONOLOGY AND MULTI-SYSTEM THERMOCHRONOLOGY TO DEVELOP DIAGNOSTIC P-T-t PATHS IN OROGENS
Under construction….