PLAYFORD, PHILLIP, ROGER HOCKING, and IAIN COPP
Geological Survey of Western Australia, Perth, Australia

Abstract: New Insights into Devonian Reef Complexes of the Canning Basin, Western Australia:

New insights have been gained into the lithostratigraphy, sequence stratigraphy, structure, and sedimentology of the Devonian reef complexes of the Canning Basin, and the controls on oil accumulation and mineralization. Detailed biostratigraphic studies, using conodonts and ammonoids, provide precise controls on the timing of significant events.

A new series of geological maps has been released by the Geological Survey of Western Australia, at scales of 1:250,000 (the whole reef belt), 1:100,000 (four maps), 1:50,000, and 1:25,000. They integrate mapping and other research by the Survey and its many co-workers. Accompanying cross sections, incorporating subsurface data, illustrate the subsurface stratigraphy and structure.

Huge masses of terrigenous conglomerate and sandstone, representing alluvial-cone, fan-delta, and submarine-fan deposition, interfinger with carbonate facies of the reef complexes, and range from mid Givetian to late Famennian in age. They were shed from active fault scarps in the adjoining Precambrian rocks of the Kimberley Block, the maximum inflow of terrigenous clastics being linked with periods of strongest tectonism. Many conglomerates were deposited in deep water (more than 200 m deep).

Karstification of the Devonian limestones occurred during the earliest Famennian, late Famennian, Late Carboniferous, and Cenozoic. Modern karst development has rejuvenated some of the Paleozoic paleokarst, and the most spectacular modern cave systems can be shown to have first developed in the Late Carboniferous.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas