Abstract

The subdivision of the sedimentary succession into the rift-related depositional sequences (pre-rift, syn-rift and post-rift) has enabled clear identification and understanding of the separate influence of the Tasman rift and the Otway rift in the evolution of the Bass Basin. Tasman rifting had a much more prominent role in shaping the basin history than the earlier Otway rifting both in terms of structural style and stratigraphic development. The structural style in the Bass Basin has been shaped through three major extensional phases that are reflected in distinctly different fault trends. The initial response to extensional forces during Otway rifting was the development of discrete fault segments all across the basin. The present day fault pattern subsequently developed through progressive propagation and linkages of the initial fault segments. The extension direction (E-W) during Tasman rift was oblique to the basement grain (NW-SE) already created during Otway rifting, and this obliquity of Tasman rifting to the earlier trend had a profound influence on the sequential development of the regional fault trend associated with extensional tectonics