Pre-survey: Magmatic evolution of the Tiger gabbroic complex (Northern Victoria Land, Antarctica): insights into the lower crust of a Cambrian immature Island Arc

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Subduction-zone related mafic/ultramafic complexes marking the suture between the Wilson Terrane and the Bowers Terrane in Northern Victoria Land (Antarctica) are wellsuited for evaluating the magmatic and structural evolution at the active paleo-Pacific continent margin of Gondwana during the Cambrian. One of these intrusions is the Tiger Gabbro Complex (TGC), a Cambrian arc-related, layered mafic complex which is characterized by extraordinary fresh rock sequences including ultramafic and evolved lithologies and by the presence of spectacular high-temperature shear zones. It is our overall goal to establish the petrogenesis of the TGC in order to evaluate the magmatic/ structural/geological evolution of deep crustal sequences active during the Cambrian at the margin of Gondwana. The second 12-month project will focus on microanalytical and bulk rock geochemical studies on samples which will be collected during the GANOVEX X expedition by one of the applicants (F. Henjes-Kunst). Additional sampling and scientific investigations on the new samples should help to clarify important new aspects concerning the magmatic evolution of the complex, which emerged during the first three months of research in the ongoing project KO 1723/11-1 (see below). Together with the work performed during the first period of this project these investigations will serve to better plan our far-reaching goal which will include a comprehensive experimental study as well as detailed geochronological and isotope geochemical work. A very close petrographic similarity with the Chilas Complex in Kohistan (Pakistan), a world site for deep, juvenile arc crust, opens interesting perspectives for the global understanding of crustal accretion beneath young island arcs.