Entwicklung der Mineralchemie und Einschlussparagenesenen von Zirkonen aus I- bis S-Typ Granitoiden des Wilson Terranes von Nord Viktoria Land (Antarktika): Zirkon als Monitor einer dynamischen Entstehung kontinentaler Kruste

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The only pristine remnants of early continental crust are zircons in highly reworked gneisses, and detrital zircon grains. Therefore, our knowledge about the evolution of early continental crust mainly relies on the chemical composition and geochronological data obtained from these extremely resistant and robust minerals. The central aim of this project is to investigate the reliability of zircon populations as record of continental crust formation. Regional focus is the Wilson Terrane (WT) in northern Victoria Land, where a unique mid-crustal profile across a former continental arc is exposed from the convergent plate margin into the cratonic basement. There, I-type granitoids, which presumably were formed by differentiation or by partial melting of mantle derived arc rocks and assimilated crustal material, can be found close to the former margin. Craton-wards, they transition to S-type granitoids, which result from partial melting of sedimentary to felsic crystalline rocks. We will use U-Pb ages, O and Hf isotopes, U-Hf-Yb-Y trace-element systematics, and inclusion assemblages of the granitoid zircons and correlate these with the petrology of the host rock. In addition to their evaluation as reliable records of host rock history, zircons from the WT granitoid also offer insight to granitoid evolution across continental margins and island arcs. Regionally, this project will estimate how much Precambrian crust, if any, underlies WT rocks, or whether the WT instead is composed exclusively of paragneiss derived from a deep continental margin basin.