Shrimp zircon ages and petrology of lower crustal granulite xenoliths from the Letseng-la-Terae kimberlite, Lesotho: further evidence for a Namaqua - natal connection

Sommer, Holger and Wan, Y. and Kröner, A. and Xie, H. and Jacob, D.E. (2013) Shrimp zircon ages and petrology of lower crustal granulite xenoliths from the Letseng-la-Terae kimberlite, Lesotho: further evidence for a Namaqua - natal connection. South African Journal of Geology, 116 (2). pp. 183-198. ISSN 1012-0750

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Abstract

Recrystallized zircons extracted from intermediate granulites of the Letseng-la-Terae Diamond Mine in northeastern Lesotho provide evidence that the Tugela Terrane of the Mesoproterozoic high-grade Namaqua-Natal mobile belt may extend ~200 km farther west than previously thought. The rock-forming minerals in the investigated lower crustal granulites contain garnet, clinopyroxene, plagioclase and quartz or garnet, wollastonite, plagioclase and quartz. Calculated values for peak granulite-facies metamorphism are ~13 kbar and ~850°C. Thermal overprint and therein granulite-facies metamorphism occurred during the late Mesoproterozoic and is documented by SHRIMP metamorphic zircon ages of 1018 ± 18, 1126 ± 10 and 1127 ± 6 Ma. These ages are in good agreement with the timing of other events in the Namaqua-Natal belt. High-grade metamorphism was probably caused by crustal thickening resulting from continent-arc collision, followed by underplating of hot mantle melts.

Item Type:	Journal Article
Subjects:	Q Science > QE Geology
Divisions:	Faculty of Science, Technology and Environment (FSTE) > School of Geography, Earth Science and Environment
Depositing User:	Holger Sommer
Date Deposited:	15 Sep 2014 23:35
Last Modified:	06 Jul 2016 23:56
URI:	http://repository.usp.ac.fj/id/eprint/7625

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