Over the last 140 kyr, the composition and accumulation of sediment shed from the Gulf of Papua margin to surrounding slopes and basins have changed dramatically. Carbonate input to the basin reached maximum values during sea-level rise and highstand, decreased during early sea-level fall, and reached minimum values during late sea-level fall and lowstand. Siliciclastic input was greatest during early sea-level fall and late sea-level rise, abundant only on the proximal slope during late sea-level fall, and decreased during lowstand and highstand. Carbonate accumulation in Ashmore Trough was accurately predicted by reciprocal sedimentation, however, the siliciclastic record contains complexities not accounted for by this concept. The proposed depositional model demonstrates how sea level, climate change, and margin physiography all contribute to the complexity of siliciclastic accumulation. Overall, reciprocal sedimentation can be used to predict carbonate accumulation in tropical mixed siliciclastic-carbonate systems, however, a firm understanding of sea level, sedimentary processes, climate, and regional physiography is required to accurately predict the siliciclastic component.
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