WESTERN OTWAY CRAYFISH GROUP TROUGHS

Abstract

Commercial volumes of hydrocarbons have been discovered in Early Cretaceous synrift sediments of the Crayfish Group of the Penola Trough, western Otway Basin. Four other such depocentres are recognised using available seismic and drilling data. A standard nomenclature is proposed for the major structural elements observed in this part of the Otway Basin.

Various tectonic models proposed for the Early Cretaceous rift history of the Otway Basin are reviewed and tested using true dip analysis of seismic events and sandbox modelling experiments. Results support a generally north-south direction for rift extension in the Tithonian-Barremian. This implies that the ENE trending Robe Trough is the headwall rift compartment (although with 20°obliquity), whereas the NW trending Penola Trough is a more oblique or transtensional rift compartment.