MASS TRANSPORT ON THE GULF OF PAPUA CONTINENTAL SLOPE: PHYSIOGRAPHIC CONTROLS ON DEPOSITION

The Gulf of Papua (GoP), part of an extensive mixed siliciclastic-carbonate system that rims the Coral Sea from northeast Australia to Papua New Guinea, has become a focal point for understanding the deposition of terrigenous and biogenous material along and across a low latitude continental margin. However, prior to this study GoP continental slope geomorphologic features were poorly documented. This study presents and interprets results from approximately 13,000 line-km of multi-beam bathymetry, in conjunction with 3.5 kHz 2D seismic and sediment cores collected from the GoP shelf edge, slope, and intra-slope troughs. Scalloped morphology, slump scars, canyons, channels, and mass transport deposits (MTDs) indicate that mass wasting and other gravity-driven processes are important mechanisms for sediment delivery across the slope system, and in shaping the evolution of the GoP. MTDs, in particular, are pervasive across the GoP and can be traced to shelf-edge sources marked by slump scars or by wholesale shelf-edge failure. In many cases, complex preexisting slope physiography has greatly influenced mass transport processes, confining and redirecting flows during transport. The resulting MTDs have well-developed pressure ridges, used to indicate flow direction. Oblique pressure ridge orientations within the deposits also reveal stacked and shingled MTDs. These data provide an important understanding of recent deep-water processes in the GoP and act as an analog for continental margin evolution in complex physiographic settings.