Recognition of ancient rift systems: Examples from the proterozoic of South Australia

Abstract

Rifting is a dynamic process which can lead to crustal separation. An essential feature in the development of rifts is the progressive intrusion of dykes of basic and ultrabasic magma along the rift axis. Different stages in the development of these dykes are reflected by gravity and magnetic anomalies and an understanding of these can facilitate the recognition of ancient rift systems and continental margins. An examination of gravity and magnetic data covering the Proterozoic Adelaide Geosyncline of South Australia has allowed the identification of an Atlantic type passive margin. Sinuous, extensive coincident gravity and magnetic anomalies from the west of South Australia appear to represent an ancient Proterozoic rift system which did not develop to crustal separation.