Seismic geomorphology of continental margin evolution in the late Cretaceous to Neogene of the Browse Basin, northwest Australia

Abstract

Recent discoveries in the Browse Basin of Northwest offshore Australia provide the impetus for data abundance and interest in evaluating the temporal and spatial changes in slope morphology and sediment movements from shelf to slope. Northwest Shelf of Australia was characterized by clastic margin development from the end of Cretaceous to the end of the Oligocene. The margin became carbonate dominated post Oligocene. These differences are reflected in the margins clinoform morphology. Carbonate margin of Browse Basin has a concave profile, reflecting its development as a rimmed margin basin. Water depths of siliciclastic margin from topset to toesets are more than 1000 m, the clinoform show a low progradation rate and a relatively high aggradation rate. Very little difference in toeset slopes can be seen in between these two margin types, the majority of difference is seen in the clinoform foresets. Slope gullies are well developed during Eocene-Oligocene time, showing both spatial and temporal variability across the margin. The gullies migrate northwestward through time, and slightly lateral migrate from southwest to northeast along seismic cross-section line profiles. They reveal a bi-model distribution of gully morphometrics, gullies on western and central slope exhibit larger dimensions than the gullies on the eastern slope. This change in gully morphologies corresponds to the thickness change of Tpal-Tolig interval which two thicks located in the western and central region of the study area, respectively. The spatial and temporal variability of the gully morphologies indicates two sources located to the southern region of the study area.