This project is a cooperation between the FU Berlin and the GFZ Potsdam

DFG project:BE 5070/4-1

PIs: Anne Bernhardt, Hella Wittmann-Oelze, Alexander Rohrmann

Cooperation partners: Gayatri Indah Marliyani, Stefanie Tofelde

PhD student: Sarah Mosser

 

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. Paleo-precipitation records retrieved from marine successions show that precipitation periodically varied over the Holocene.

In this study, periodic Holocene precipitation changes will be established using terrestrial archives close to the source to avoid proxy modification by extensive sediment transport. We will quantify changes in Holocene erosional history of watersheds West Sumatra that drain into the Mentawai basin. This erosional record will be established from Holocene sediment budgets derived from radiocarbon-dated, river-floodplain sediment cores and geophysical ground imaging of river-floodplain sediment in conjunction with the determination of denudation and paleodenudation rates using cosmogenic nuclides. We will compare the terrestrial record to the marine sediment fill and the variations of sediment budgets 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.

Sediment plume in the Indian Ocean offshore the Padang River after heavy rainfall.

 

Outcrop of volcanic tuff deposits which are currently being eroded and incorporated into river sediment.

 

Describing Auger sediment cores of river floodplain deposits that are cultivated as rice paddies.