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Permian Cyclothem Development within the Onshore Canning Basin, Western Australia

R. M. Adkins
James Cook University, School of Earth Sciences, Townsville, QLD, Australia

This investigation will test for glacially-influenced cyclothem development during the mid-Permian. Historically, cyclothems occur in sediments deposited during periods of widespread glaciation, such as the Plio-Pleistocene and the Permo-Carboniferous. Although there is evidence of Gondwanan glaciation throughout the Permian, few studies exist on cyclothem development past the earliest stages of this era. Understanding cyclothem development during this period is important because the mid-to Late Permian spans a transition from icehouse to greenhouse conditions, and is analogous to the modern climatic setting.

The mid-Permian Tuckfield Member outcrops in the St. George Ranges of the onshore Canning Basin, Western Australia, as a 50 to 100 meter package of mudstone, siltstone, sandstone, and conglomerate. Preliminary investigations indicate that the Tuckfield consists of multiple coarsening-upward cycles, ranging in thickness from 5 to 15 meters.

Outcrops will be evaluated on a bed by bed basis. Gamma-ray data will be collected from the outcrops and used as a proxy for grain size. Time-series spectral analyses will be conducted to detect cyclicities that can be matched with Milankovitch periodicities.Well-log data will be used to determine the lateral extent of these cycles.

AAPG Search and Discovery Article #90902©2001 AAPG Foundation Grants-in-Aid