The Perth Basin: a Possible Framework For its Formation and Evolution

Abstract

The Perth Basin of Western Australia is a linear structure of sedimentary rock extending north?south for some 1000 km (Fig. 1). Phanerozoic sedimentary material may exceed 15 km in thickness. The basin is bound on the east by the north-trending Darling Fault which separates the basin from the Archaean Yilgarn Block. Its western boundary is less well defined but appears to coincide mostly with the base of the continental slope. Questions to which preliminary answers are suggested in this paper are (i) what is the crustal and upper mantle structure associated with this basin, (ii) how did this basin evolve through time, and (iii) how has this basin structure been preserved. A number of relevant geophysical, geological and geomorphological observations (Playford et al. 1976) are summarized below. The proposed model should be viewed only as a possible framework for discussing the observational evidence from both the basin and the adjacent Yilgarn Block and as providing a hypothesis to be tested with further geophysical and geological observations.