Publication Name: The Sedimentary Basins of WA
Authors: Robert P. Iasky, Arthur J. Mory and Sergey I. Shevchenko
Publication Volume: 2
Date Published: December 1998
Number of Pages: 21
Reference Type: Book Section
Abstract:
The Gascoyne Platform is a sub-basin with relatively shallow basement in the Southern Carnarvon Basin, extending for 600 km between the Northampton Complex to the south and the Exmouth Sub-basin to the north. The platform contains mainly ?Ordovician-Devonian strata up to 5000 m thick, and is adjacent to prominent Permian depocentres in the Merlinleigh, Byro and Coolcalalaya sub-basins to the east; there is little evidence of Permian deposition on the platform. The platform has been poorly explored with limited seismic coverage, regional low-resolution gravity and aeromagnetics, and only eleven wells deeper than 1000 m.The platform is relatively undeformed, although the degree of deformation increases northward. Extensional, northerly-trending normal faults related to the breakup of Australia from Greater India dominate; Miocene compression is evident mostly in the northern platform. Depth to basement calculations largely from gravity data, indicate two depocentres, and show that the platform is shallowest along the Wandagee Ridge. The northern depocentre is probably Late Devonian in age; the southern, appears to be ?Ordovician to Early Devonian.
Mature source rocks in the Upper Devonian Gneudna Formation are present in the northern Gascoyne Platform, but absent in the south. The Upper Silurian in that area contains thin shales with good source rock characteristics but is at an early maturation stage. The northern Gascoyne Platform has greater hydrocarbon potential than the southern part because it is more mature and has greater potential for entrapment because of more extensive structuring.