SOURCE-TO-SINK ANALYSIS OF NORTHERN PAPUA NEW GUINEA RIVER SEDIMENT DISCHARGE

Approximately 501 million tons/yr. of sediment is delivered to the Bismarck Sea and dispersed on a narrow continental shelf off the coast of Northern Papua New Guinea (NPNG) (Milliman, 1995). Thirty NPNG watersheds are analyzed for their slope, relief, lithology, and rainfall to determine prominent source regions of the load carried offshore. Terrestrial sediments in this region are rich in iron, manganese, and aluminum and are carried from the narrow continental shelf offshore into the deep sea, where sediments are then carried by the New Guinea Coastal Undercurrent (NGCU).The NGCU and the New Ireland Coastal Undercurrent are primary sources of nutrients to the Eastern Pacific, which are carried by the Equatorial Undercurrent (EUC) (Slemons et. al 2010, Qin et. al 2016). Elemental compositions and grain size of core top sediments (n=25) derived from IODP Expedition 363 and RR1313 reveal where the sediment is mobilized within watersheds and how sediment is dispersed along the ocean floor in recent years (<300yrs). Samples are prepared with a flux fusion method (derived from Murray et. al 2000) and elemental concentrations are measured via ICP-OES. A multivariate statistical analysis of the geochemistry of samples determines if endmembers can be determined to identify source regions of sediment from the contributing watersheds. Elevation of delivery of modern sediments to the Bismarck Sea provides supplemental information on the efficacy of terrestrial proxies like titanium variations used to develop long term paleoclimate records (Tachikawa et. al 2011).