Glacially grooved surfaces in the Grant Group, Grant Range, Canning Basin and the extent of Late Palaeozoic Pilbara ice sheets

Updated: 2018-04-20

Grooved surfaces in Late Palaeozoic Grant Group rocks in the central Grant Range were cut by glacial ice. The orientation of the grooves and small step-like sedimentary structures on the surfaces indicate ice motion from the south-southeast. Pebbles of banded iron formation in marine diamictites associated with the surfaces suggest that the ice originated in the Pilbara Block and extended 400 km into the Canning Basin. The geometry of facies associated with the grooves indicates that they were cut at or near the grounding line of an ice shelf in a marine embayment occupying the Fitzroy Trough. These surfaces confirm the existence of large continental ice sheets in Western Australia during the Late Palaeozoic g laciation .