Mesozoic stratigraphy and history of the Canning Desert and Fitzroy Valley,Western Australia

Abstract

Large outcrop areas in the Canning Desert and the Fitzroy Valley of northwestern Australia consist of marine Jurassic and Upper Triassic rocks, not of Permian as formerly believed. On present knowledge, outcrops of the Triassic formations are restricted to parts of the Fitzroy and Bonaparte Gulf Basins, whereas the distribution of Jurassic (Kimmeridgian to Tithonian) rocks provides evidence for a major marine invasion that affected the Canning Desert area and may have advanced into the centre of the Australian continent and beyond. The late Jurassic transgression did not enter the Fitzroy Basin area.

From the distribution and nature of the Mesozoic formations it is concluded that the main phase of post-Permian folding in the Fitzroy Basin is early Triassic. Later movements affected minor northern parts of the Canning Desert area in early Jurassic and in early Cretaceous time.

As an alternative working hypothesis to the traditional basin concept it is suggested that during the Mesozoic the Canning Desert area was an epicontinental shelf platform.