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Role of Paleoclimate and Paleoceanography in Sediment Delivery to the Gulf of Papua over the Last ~300kyrs Based on Foraminiferal and Organic Matter Stable Isotope Records

Melany A. McFadden1, Larry C. Peterson1, Samuel J. Bentley2, Gerald Dickens3, Andre Droxler3, and Bradley Opdyke4
1 University of Miami, Rosenstiel School of Marine and Atmospheric Science, Miami, FL
2 Louisiana State University
3 Rice University, Houston, TX
4 Australian National University, Canberra, Australia

The goal of the MARGINS Source-to-Sink (S2S) study in the Papua New Guinea (PNG) focus area is to develop an understanding of sediment production, transport, and accumulation in the mixed siliciclastic-carbonate system of the Gulf of Papua. The PNG study area is centrally located in the Western Pacific Warm Pool and experiences strong seasonal changes in rainfall associated with the Monsoon which affects sediment delivery to the Gulf. The PNG region is also affected by the ENSO phenomenon. We report here geochemical results from a piston core (MV25-0403-63JPC) collected from the Eastern Plateau region of the basin. This topographically elevated feature was targeted to sample carbonate-rich hemipelagic sediments for purposes of generating continuous isotope-based records of climate change. The carbonate content of the core rarely exceeds 40%, attesting to the huge input of terrestrial siliciclastic sediments over the last several glacial-interglacial cycles. Foraminiferal oxygen isotope stratigraphies indicate variable sedimentation rates that average 6 cm/kyrs at the plateau site. Isotope records from the planktic foraminifer Globigerinoides ruber and the benthic taxon Cibicides wuellerstorfi are used to assess changes in nutrient concentrations, productivity, and water column structure. Carbon and nitrogen organic isotope values, %TOC, C/N ratio, and biogenic silica records are used to identify changes in productivity and relative amounts and sources of marine and terrigenous-derived organic matter. We will discuss the influence of variations in productivity, climate, sea level, and oceanography on sediment accumulation in the Gulf of Papua over the last ~300kyrs based on this combination of measured indices.