Abstract

Evidence is provided for Neoproterozoic sinistral displacement along the Darling Mobile Belt between Greater India and Precambrian terranes of Western Australia. A dilatational bend in the shear zone is thought to have controlled emplacement of alkali granites, anorthosite and mafic intrusives of the Leeuwin Complex which was deformed during progressive deformation. Faults formed in this event extend across the Albany Mobile Belt, and control the formation of the Stirling Basin on the southern margin of the Yilgarn Craton. The regional extent of this event and the rotation of Mesoproterozoic trends in the Albany Mobile Belt through 90° suggests that the Darling Mobile Belt may be part of a shear system of regional importance during assembly of proto-East Gondwanaland.

Much attention is being focused on the assembly of Gondwanaland and the relative displacements between Archaean cratons along Proterozoic mobile belts (e.g. Powell 1993; Unrug 1994; Yoshida 1994). Southwestern Australia is a key area within proto-East Gondwanaland as, in reconstructions such as de Witt et al. 1988 and Powell et al. 1988, it constitutes the junction between the Archaean Yilgarn Craton of Western Australia, India/Greater India, and the East Antarctic Shield (Fig. 1). This paper examines the timing and nature of displacements along the Darling Mobile Belt (Glikson & Lambert 1973; Mathur & Shaw 1982) on the western margin of the Yilgarn Craton and contemporaneous structures within the Albany Mobile Belt and southern Yilgarn Craton (Fig. 2).

The Darling Mobile Belt. The Darling Mobile Belt, referred to by Myers (1990) as the

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