Glacial incursion on a Neoproterozoic carbonate platform in the Kimberley region, Australia

The 80-m-thick Egan Formation preserves sediment deposited during the young er of two episodes of glaciation recorded in the Neoproterozoic. succession of the Kimberley region, northwestern Australia. Like many terminal Proter ozoic glaciations recorded in Australia and elsewhere, the glacial strata o f the Egan Formation are associated with carbonate rocks of likely warm-wat er affinity, but they are sedimentologically distinct from the marker "cap carbonate" horizons that overlie glacial strata in other Neoproterozoic suc cessions. The carbonate strata comprise a wide range of facies indicative o f shallow-water patch reef, shoal, and lagoonal deposition. Detailed facies analysis of the Egan Formation indicates interruption of the carbonate sys tem by glaciation and subsequent resumption of warm-water conditions. This sedimentological analysis allows a reassessment of the regional stratigraph ic correlations proposed for the Egan Formation, which is here considered t o record a glacial event younger than the widespread Marinoan glaciation of central and South Australia and, therefore, a speculated third global glac iation in terminal Proterozoic time.