The impact of precipitation changes on terrigenous sediment export to the Indian Ocean

• Applicants: Professorin Dr. Anne Bernhardt, since 8/2019; Dr. Hella Wittmann-Oelze
• Subject Area: Palaeontology
• Term: from 2018 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 399568093

Terrigenous and marine sediment archives are often used to reconstruct past environmental conditions such as climatic changes, tectonic and seismic activity as well as past geohazards. However, our ability to quantitatively assess how climate changes influence terrestrial erosion and how these changes are mirrored in terrestrial and marine sedimentary archives is very limited. Hence, we need to gain quantitative insights into sedimentary signal propagation to be able to correctly interpret sedimentary archives and ultimately invert them to the upland control factors that shaped these sedimentary successions. The high-relief, tectonically active islands in the Indo-Pacific are efficient sediment suppliers, contributing ~20 to 25% of the global annual sediment to the worlds’ oceans from only ~2% of the global land area. West Sumatra and the adjacent enclosed marine Mentawai Basin form an ideal natural laboratory to trace onshore changes in precipitation and erosion from the continental watersheds into the deep ocean.In this proposed study, we will quantify changes in Holocene erosional history of watersheds in West Sumatra that drain into the marine Mentawai Basin to address potential cause-and-effect relationships of erosion with e.g. precipitation, vegetation, fires and volcanic activity. The erosional record will be established from Holocene sediment budgets derived from radiocarbon-dated, river-floodplain sediment cores and from geophysical ground imaging of river-floodplain sediment in conjunction with the determination of denudation and paleodenudation rates using cosmogenic nuclides. Holocene precipitation changes will be assessed using the stable hydrogen isotopic composition of higher-plant leaf waxes, working on terrestrial archives close to the source to avoid proxy modification by extensive sediment transport. We will compare the terrestrial records to the marine sediment fill and the variations of sediment budgets and grain-sizes of sediment in the Mentawai Basin obtained from already retrieved sediment cores and sediment-echosounding profiles. This study will enhance our understanding of sedimentary signal generation and propagation along sediment-routing systems on high-relief tropical islands in response to climate change, one of the most efficient sediment producers and sediment contributors to the world’s ocean. Moreover, this study tackles the preservation of these sedimentary signals in the marine sedimentary archives. Therefore, we strive towards the detailed understanding and, ultimately, the inversion of these sediment archives into their original upland forcings. Moreover, this study will help to better predict future changes in sediment supply to the ocean in response to climate change.

• DFG Programme: Research Grants
• International Connection: Indonesia
• Cooperation Partners: Professorin Dr. Wiebke Bebermeier; Dr. Gayatri Indah Marliyani
• Ehemalige Antragstellerin: Dr. Eva M. Niedermeyer, until 8/2019