Climatic and tectonic controls on source-to-sink processes in the tropical, ultramafic catchment of Lake Towuti, Indonesia

Morlock, Marina Alexandra; Vogel, Hendrik; Nigg, Valentin; Ordoñez, Luis; Hasberg, Ascelina K.M.; Melles, Martin; Russell, James M.; Bijaksana, Satria (2018). Climatic and tectonic controls on source-to-sink processes in the tropical, ultramafic catchment of Lake Towuti, Indonesia. Journal of Paleolimnology, 61(3), pp. 279-295. Springer 10.1007/s10933-018-0059-3

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Humid tropical landscapes are subject to intense weathering and erosion, which strongly influence sediment mobilisation and deposition. In this setting, we aimed to understand how geomorphology and hydroclimate altered the style and intensity of erosion and sediment composition in a tropical lake and its tectonically active catchment. Lake Towuti (2.75°S, 121.5°E) is one of the oldest and deepest lakes in Indonesia, with uninterrupted lacustrine sedimentation over several glacial-interglacial cycles. Here we present results from a novel set of Lake Towuti surface sediment, bedrock and soil samples from the catchment, and two existing sediment cores that extend to 30,000 and 60,000 years before present. We studied the catchment morphology, soil properties, geochemistry, and clay and bulk mineralogy. Results from several river long profiles show clear signs of tectonic activity, which enhances river incision, favours mass movement processes, and together with remobilisation of fluvial deposits, strongly influences modern sedimentation in the lake. Material from the Mahalona River, the lake’s largest inflow, dominates modern sediment composition in Towuti’s northern basin. The river transports Al-poor and Mg-rich sediments (mainly serpentines) to the lake, indicating river incision into the Mg-rich serpentinised peridotite bedrock. Relatively small, but important additional contributions of material, come from direct laterite-derived input and the Loeha River, which both provide Al-rich and Mg-poor sediment to the lake. Over time, the Al/Mg and kaolinite-to-serpentine ratios varied strongly, primarily in response to lake-level fluctuations driven by hydroclimatic changes. In the past 60,000 years, both the Al/Mg and kaolinite-to-serpentine ratios showed variations sensitive to changes in climate boundary conditions across glacial-interglacial cycles, while tectonic activity had less influence on changes in sediment composition on these short time-scales.

Item Type:

Journal Article (Original Article)

Division/Institute:

10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)
08 Faculty of Science > Institute of Geological Sciences

Graduate School:

Graduate School of Climate Sciences

UniBE Contributor:

Morlock, Marina Alexandra; Vogel, Hendrik and Nigg, Valentin

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

1573-0417

Publisher:

Springer

Funders:

[42] Schweizerischer Nationalfonds
[UNSPECIFIED] International Continental Scientific Drilling Program
[UNSPECIFIED] US National Science Foundation
[UNSPECIFIED] Deutsche Forschungsgemeinschaft
[UNSPECIFIED] Brown University
[UNSPECIFIED] Genome British Columbia
[UNSPECIFIED] Indonesian Ministry of Research, Technology, and Higher Education (RISTEK)

Projects:

[1214] Climate history of the Indo-Pacific region and subsurface biosphere of Lake Towuti: The Swiss contribution to the ICDP Towuti Drilling Project (research part)
[1215] Climate history of the Indo-Pacific region and subsurface biosphere of Lake Towuti: The Swiss contribution to the ICDP Towuti Drilling Project (drilling part)

Language:

English

Submitter:

Marina Alexandra Morlock

Date Deposited:

09 Oct 2018 14:51

Last Modified:

24 Oct 2019 02:24

Publisher DOI:

10.1007/s10933-018-0059-3

BORIS DOI:

10.7892/boris.120383

URI:

https://boris.unibe.ch/id/eprint/120383

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