Permian-Carboniferous tectono-stratigraphic evolution and petroleum potential of the northern Canning basin, Western Australia

摘要

The Canning basin (400,000 kin2) of Western Australia is one of the largest intracratonic basins to have been affected by cold cli-mates as Gondwana drifted across the south polar regions during the Permian—Carboniferous. This article describes the tectono-stratigraphic setting and evolution of the Permian—Carboniferous Reeves Formation and Grant Group of the northern part of the basin. We employ seismic facies analysis, downhole well-log re-sponses, palynostratigraphy, and sedimentary facies logs from 25 continuously cored wells. The succession rests on a widespread ero-sional unconformity of middle Carboniferous age. This surface may have been modified by glacial erosion when a late Carboniferous ice sheet expanded across the entire basin, but no primary glacial deposits can be identified; if present, such sediments were likely reworked during subsequent basin faulting. Reeves Formation and Grant Group strata are dominated by massive and deformed sand-stones, diamictites, and conglomerates deposited subaqueously as sediment gravity flows close to active faults. Initial strata of Late Carboniferous age (Reeves Formation) are preserved in the deeper troughs (Fitzroy trough) and in salt collapse subbasins on high-standing structural blocks (Barbwire, Betty, and Balgo terraces; Crossland platform). These areas later subsided and were blanketed by gravity flow deposits of Early Permian age (Hoya Formation). In turn, a regional flooding surface and overlying bioturbated siltstone unit (Calytrix Formation) records an increase in relative water depths across the northern Canning basin. Siltstones coarsen up-ward into lower shoreface storm-influenced sandstones (Clianthus Formation) and the fluvial Poole Sandstone. Potential petroleum play types are principally associated with faults and channels.