ABSTRACT: Upper Cretaceous and Paleocene Marine Sand Fairways, Browse Basin

CONOLLY, JOHN R, J. R. Conolly & Associates Pty Ltd, Rose Bay, New South Wales, Australia, and VIRGINIA L. PASSMORE, Bureau of Mineral Resources, Canberra, Australian Capital Territory, Australia

Two quartzose sand fairways were deposited in the Browse basin: one in the Upper Cretaceous, the other in the Paleocene. They both represent important potential reservoirs that are characterized by well-sorted quartzose sands that were derived from the Precambrian Kimberley hinterlands to the east. The Cretaceous Campanian age fairway has two distinct turbidite sand systems that can be mapped seismically. Both systems were derived from the Leveque and Yampi Shelves: one progrades northwards through the Yampi area, and the other through the Caswell area. The more westerly system, intersected by the Caswell and Bassett wells, have sandstones that are 100 to 200 m thick. These sands consist of well-sorted, fine- to coarse-grained quartz grains, many of which have been rounded and frosted in a nearshore beach-dune environment. The authors postulate that the sands in the Late Cretaceous fairways were derived from an extensive coastal plain-beach barrier-dune system that developed on the Leveque and Yampi Shelves during the Late Cretaceous. Long shore currents moved the sand along the northwest-southeast trending shelves into canyon heads that fed the sediment northwards up the central Browse basin into the Ashmore-Cartier region over a distance of 500 km. Features associated with this prograding wedge include north-dipping foresets, channels, and mounds. In contrast, the Paleocene fairway consists of mainly fluvial, deltaic and shallow marine quartzose sands that prograde generally westwards across the Browse basin. The coal-bearing sequences in the east change westward to outer deltaic plain and eventually to marine shelf sands.

AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)