Syn-sedimentary deformation as a mechanism for the initiation of submarine gullies on a carbonate platform to slope transition, Browse Basin, Australian North West Shelf

Syn-sedimentary deformation and submarine channel initiation are both important processes influencing the stratigraphic development and reservoir properties of carbonate platforms. Based on a high-resolution 3D seismic dataset our study shows that platform-margin parallel syn-sedimentary faulting in the vicinity of the clinoform breakpoint can lead to the indention of channel heads that subsequently grow and expand in headward and downslope direction. The carbonate-dominated Miocene succession of the Browse Basin on the Australian North West Shelf reveals a distinct submarine channel system during a time of overall platform progradation. The progradation occurs over a drowned Eocene to Lower Miocene carbonate ramp, which formed a large scale inflection. Previous studies investigated the architecture of the carbonate platform, containing a large Neogene barrier reef system. We present a high-resolution 3D seismic study of the contemporaneous platform to slope transition. Landward of first significant gullies, a distinct network of margin parallel, small scale arcuate faults is observed. Active faulting during appearance of the first gullies is exhibited by growth strata, which are located directly basinward of the faults. These steep (65°–85°), small-scale faults are characterized by throws of 5–25 ms TWT and show a tendency to merge laterally and vertically with adjacent faults. Syn-sedimentary deformation associated with these faults likely triggered slope failure and the generation of turbidity currents finally leading to the growth of the gullies by headward and downslope erosion.