Lake Towuti (2.5°S, 121.5°E) is a long-lived, tectonic lake located on the Island of Sulawesi, Indonesia, and in the center of the Indo-Pacific warm pool (IPWP). Lake Towuti is connected with upstream lakes Matano and Mahalona through the Mahalona River, which constitutes the largest inlet to the lake. The Mahalona River Delta is prograding into Lake Towuti’s deep northern basin thus exerting significant control on depositional processes in the basin. We combine high-resolution seismic reflection and sedimentological datasets from a 19.8-m-long sediment piston core from the distal edge of this delta to characterize fluctuations in deltaic sedimentation during the past ~29 kyr BP and their relation to climatic change. Our datasets reveal that, in the present, sedimentation is strongly influenced by deposition of laterally transported sediments sourced from the Mahalona River Delta. Variations in the amount of laterally transported sediments, as expressed by coarse fraction amounts in pelagic muds and turbidite recurrence rates and cumulative thicknesses, are primarily a function of lake-level induced delta slope instability and delta progradation into the basin. We infer lowest lake-levels between ~29 and 16, a gradual lake level rise between ~16 and 11, and high lake-levels between ~11 and 0 kyr BP. Periods of highest turbidite deposition, ~26 to 24 and ~18 to 16 kyr BP coincide with Heinrich events 2 and 1, respectively. Our lake-level reconstruction therefore supports previous observations based on geochemical hydroclimate proxies of a very dry last glacial and a wet Holocene in the region, and provides new evidence of millennial-scale variations in moisture balance in the IPWP.
Bibliographical noteFunding Information:
This research was partially supported by grants from the US National Science Foundation (NSF), the German Research Foundation (DFG, VO 1591/2-1), the German Ministry for Education and Research (BMBF, IDN 10/006) and the Swiss National Science Foundation (SNSF, 200021_153053/1). PT Vale Indonesia and the Indonesian Institute of Sciences (LIPI, Geotechnology branch) are acknowledged for logistical support during fieldwork. We would like to thank Ludvig Löwemark, an anonymous reviewer, and editors Thomas J. Whitmore and Steffen Mischke for helpful comments and suggestions, which helped improve a previous version of our manuscript. Fauzi Izmaya, Arne Kesseler, and Alexander Francke are acknowledged for help during fieldwork and Florian Boxberg, Nicole Mantke, and Valentin Nigg are acknowledged for help in the laboratory. This research was carried out with permission from the Ministry of Research and Techonology (RISTEK) of the government of Indonesia.
© 2015, Springer Science+Business Media Dordrecht.
- Depositional processes
- Indo-Pacific warm pool
- Lake Towuti