Thursday, 30 August 2007 - 2:50 PM
4.P1.C-5
Lamproite-hosted xenoliths of Vestfjella: implications for lithospheric architecture in western Dronning Maud Land, Antarctica
I. Romu and A.V. Luttinen. Department of Geology, University of Helsinki, P.O.Box 64, Helsinki, 00014, Finland
Lamproite-hosted xenoliths from Kjakebeinet (73º47’ S, 14º53’ W), southern Vestfjella, represent unique samples of the unexposed continental crust at the rifted margin of western Dronning Maud Land. The exposed bedrock of the study area comprises Jurassic tholeiites and minor Permian sedimentary rocks. The xenoliths comprise mainly granulite facies metamorphosed igneous and sedimentary rock types; sediments of shallower origin and cognate phlogopitite and silicocarbonatite inclusions are also found. Two leucocratic gneissic tonalites, which probably represent middle crustal levels, yielded U-Pb SHRIMP zircon ages of ~1.0–1.3 Ga. The granoblastic mafic granulites probably represent lower parts of the continental crust: Mineral–whole-rock Sm-Nd isotope results imply compositional affinity to Proterozoic lower crustal xenoliths from Lesotho , South Africa, and equilibration of the Sm-Nd system during Grenvillean and Jurassic magmatic events. Highest pressures, 11-17 kbars, were recorded by mafic garnet granulites. Overall, these lamproite-hosted crustal xenoliths indicate extension of the Proterozoic Maud Belt crust to Vestfjella.
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See more of The 10th International Symposium on Antarctic Earth Sciences (Aug. 26 to Sept 1, 2007)
See more of General Submissions
See more of The 10th International Symposium on Antarctic Earth Sciences (Aug. 26 to Sept 1, 2007)