STRUCTURING AND CONTROLS ON DEVONIAN REEF DEVELOPMENT ON THE NORTH-WEST BARBWIRE AND ADJACENT TERRACES, CANNING BASIN

Abstract

The major terraces flanking the southern margin of the Fitzroy Trough have had a complex history of development involving at least four major episodes of structuring with varying degrees of intensity from the Mid-Late Ordovician Rodingan Movement through to the Latest Triassic-Early Jurassic Fitzroy Movement. Extensive salt tectonism associated with the massive evaporite deposits of the Silurian Carribuddy Formation has also had a profound effect on structuring in these areas.

Despite sparse well control, seismic recognition of the resultant structural styles has provided the basis for more comprehensive modelling of the main controls on sedimentation than has previously been possible.

In particular, a complex sub-surface distribution of stacked Devonian carbonate platform and reef complexes can now be recognised, having similar morphologies to the spectacular outcrop on the northern side of the Fitzroy Trough. In addition to broad platform areas, individual peninsula developments, isolated atolls and extensive inter-reef seaways were present at both Pillara and Nullara cycle levels, largely controlled by faulting initiated in the Mid-Devonian and influenced in some cases by salt diapirism.

Identification of the carbonate and associated palaeogeographic trends will provide direction for future exploration efforts in this wildcat area.