Differentiating the Geochemical Signature of Northern Papua New Guinea Margin Sediments from 20 kyr ago to Present
Hannah Carney – MS Candidate
Advisor: Dr. Samantha Bova
May 6, 2022 @ 1:15 pm
CSL 422 or via zoom
Abstract
Mountainous islands belonging to the Indonesian Archipelago account for approximately 25% of the sediment entering the world’s ocean (Kao & Milliman, 2008; Walsh et al., 2004). The coastline of northern Papua New Guinea (NPNG) contains many mountainous watersheds that in total, deliver approximately 501 million tons/yr. of sediment into the Pacific Ocean. Riverine sediments of NPNG are delivered offshore through a divergent sediment plume, carrying sediments to the surface and dispersing along the continental shelf, and to the deep ocean (Kineke et al., 2000). Paleo-erosion records from this region are derived from variations in Fe, Ti, and Al in deep sea sediment cores and are frequently used as proxies for past changes in hydroclimate (Aiello et al., 2019; Dang et al., 2020; Tachikawa et al., 2014). However, there are many other factors in addition to climate that may mobilize and transport sediment, and it is not clear if these records can be interpreted as direct evidence for variations in rainfall or changes in source materials delivered offshore. In this study, sediment core top samples collected in the upper 10 cm (n = 17) and two downcore records (20 kya) collected on IODP Expedition 363 and RR-1313 are analyzed for their geochemical signatures via ICP-OES and XRF to assess the impact of variations in source material on the geochemistry of sediments. We identify endmembers through a multivariate statistical analysis known as Q-mode factor analysis that could complicate paleo-erosion records. Analyzing the geochemistry of NPNG sediments through space and time will better constrain the geologic signature of sediment mobilized off the coast of NPNG and further assess the possible impact of variations in sediment supply vs hydroclimate over the Holocene.