Anatexis and crustal differentiation: Insights from the Fosdick migmatite-granite complex, West Antarctica ...

• Main Author: Yakymchuk, Christopher
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Digital Repository at the University of Maryland 2014
• Subjects: Geology; FOS Earth and related environmental sciences; Petrology; Geochemistry; geochronology; granite; isotope; migmatite; partial melting; phase equilibria modeling; West Antarctica; Antarc*; Antarctica
• Online Access: https://dx.doi.org/10.13016/m2501k; http://hdl.handle.net/1903/15755

In the Fosdick migmatite-granite complex of West Antarctica, U-Pb geochronology of monazite in migmatites and zircon in granites records two episodes of high-temperature metamorphism, one in the Devonian-Carboniferous and another in the Cretaceous. For the older lower-grade event, whole-rock and zircon isotope geochemistry of granites within the Fosdick complex are interpreted to record crustal reworking during metamorphism associated with continental arc magmatism along the East Gondwana convergent plate margin. By contrast, the geochemistry of correlative granites suites from along and across the same margin indicates a greater proportion of crustal growth. This suggests prominent arc-parallel and arc-normal variations in the mechanisms of crustal reworking versus growth in continental arc systems. Based on garnet Lu-Hf ages, the timing of peak metamorphism in the younger higher-grade event has been determined as c. 116-111 Ma. U-Pb ages of monazite from migmatites and zircon from anatectic granites ...