Geochemistry and mineralogy of the sediments in the New Britain shelf-trench continuum, offshore Papua New Guinea: Insights into sediment provenance and burial in hadal trenches. (November 2021)

• Record Type: Journal Article
• Authors: Lin, Gang; Luo, Min; Chen, Linying; Chen, Yilun; Chen, Duofu
• Is Part Of: Deep sea research. Volume 177(2021)
• Publication Date: 2021-11
• Subjects: New britain trench -- Sediment provenance -- Elemental composition -- Mineralogy -- Sr–Nd isotopes -- Palynomorph; Oceanography -- Periodicals; Océanographie -- Périodiques; 551.4605
• DOI: 10.1016/j.dsr.2021.103621
• Languages: English
• ISSNs: 0967-0637

Abstract

Abstract: Seven short cores collected along two transects from the shelf to trench bottom in the New Britain Trench (NBT) area, Papua New Guinea (PNG), were studied to illuminate the provenance and burial of sediments across the shelf-trench continuum. Here, we present geochemical data, including major, minor and rare earth elements, bulk and clay mineralogy, grain size, and Sr–Nd isotopes. The results indicate that sediments in the NBT area were mainly derived from intermediate volcanogenic materials of the surrounding islands with the contribution of volcanogenic materials up to 90%. Volcanogenic materials from Rabaul Volcano had a significant influence on the western NBT (Transect 1), whereas the eastern NBT (Transect 2) was more strongly affected by the Tabar-Lihir-Tanga-Feni (TLTF) volcanic chain. In addition, pollen and spores analyses showed a decreasing trend in their concentrations in the order of the landward site, the trench axis site, and the abyssal site on the Transect 1 and the dominance of Cyperaceae in the herb fraction at the trench axis site NBT01. This observation, accompanied by the significant differences in the major and minor elements as well as Sr–Nd isotopes between upper 4 cm sediments and those below at NBT01, suggests that the upper 4 cm sediments were probably sourced from river sediments. Together with low chemical index of alteration (CIA) values, we suggest that terrigenous riverine materials are rapidly transported and buried at the trench axis. Our findings highlight the important role of hadal trenches in trapping terrigenous materials and have implication for understanding the fate of terrigenous materials in the deep ocean. Highlights: Intermediate volcanogenic materials have significant contribution to the sediments in the NBT area. The upper 4 cm sediments at the trench axis site NBT01 are likely sourced from riverine materials. Rapid transport and burial of terrigenous sediments to the trench bottom is likely associated with mass-wasting events.