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Carbonate Channel-Levee Systems Influenced by Mass-Transport Complexes, Browse Basin, Western Australia


Submarine channels are primary conduits for sediment transport to deep-water basins, thereby controlling the location of marine depocenters and sediment bypass. The evolution and depositional character of submarine channels have implications for sediment dispersal, sediment quality, and hydrocarbon reservoir potential. Siliciclastic channel systems have been extensively studied in modern environments, seismic-reflection data, and outcrop; however, carbonate channel-levee deposits have only recently been explored.

Here, we utilize newly released high-resolution (90 Hz) seismic-reflection data from the Australian Browse Basin to document the influence of mass-transport complex (MTC) deposition on the stratigraphic architecture of carbonate channel-levee systems. The 2014 vintage seismic-reflection survey is 2500 km2 and hosts numerous Miocene-age carbonate channel-levee complexes basinward of the shelf edge. Regional horizons and individual channel forms were mapped. Channels range from ~200-300 m wide and are bounded by high-relief levee-overbank wedges (>100 ms TWTT). These channels extend across the survey area >70 km. The leveed channels were sourced from middle and late Miocene slope gullies linked to platform carbonates. Slope-attached and locally derived MTC’s are evident throughout the Miocene section likely related to periods of basin inversion and shelf-edge gully incision. We interpret that regionally extensive (>30 km) slope-attached MTC’s can shut down a channel-levee system and trigger the initiation of a new system, whereas more locally derived (<30 km) MTC’s can promote changes in channel map-view pattern, including avulsion in some cases. The stratigraphic architectures of the carbonate channel-levee systems and their interactions with MTC’s are similar to siliciclastic analogs. The similarity in stratigraphic patterns between siliciclastic and carbonate depositional systems suggests similar formative processes related to submarine mass wasting and turbidity currents. These interpretations inform depositional models of carbonate slope systems and call for re-evaluation of the controls on stratigraphic patterns in mixed siliciclastic-carbonate deep-water basins.