Original paper

Sedimentology, geochemistry and tectonic setting of the Neoproterozoic Malmesbury Group (Tygerberg Terrane) and its relation to neighbouring terranes, Saldania Fold Belt, South Africa

Buggisch, Werner; Kleinschmidt, Georg; Krumm, Stefan

Abstract

The metamorphic grade and the facies of the Neoproterozoic Malmesbury Group of the Saldania Fold Belt changes abruptly across major fault zones. Therefore three different tectonostratigraphic domains were assumed: The Tygerberg Terrane, the Swartland Terrane and the Boland Terrane. Additionally, a small block with volcanic greenstones and carbonates (Bridgetown Formation) is squeezed between the Swartland and Boland terranes. Based on the investigations of sedimentray and tectonic structures, geochemistry and data from literature, a geodynamic model of the Saldania Belt is proposed including: (1) An ocean between South America with the attached Tygerberg Terrane and the Swartland Terrane, (2) rifting between the Swartland Terrane and South Africa with the attached Boland Terrane, subduction ot the ocean (1) towards west, followed by subduction of the ocean (2) underneath the Swartland Terrane.

Keywords

south africamalmesburysaldania fold beltneoproterozoicsedimentology structure