Lake Towuti (2.5°S, 121°E) is a, 560 km2, 200-m deep tectonic lake at the downstream end of the Malili lake system, a set of five, ancient (1-2 MYr) tectonic lakes in central Sulawesi, Indonesia. Lake Towuti’s location in central Indonesia provides a unique opportunity to reconstruct long-term paleoclimate change in a crucially important yet understudied region- the tropical Western Pacific Warm Pool (IPWP), centre of the El Niño-Southern Oscillation. The Malili Lakes have extraordinarily high rates of floral and faunal endemism, and the lakes are surrounded by one of the most diverse tropical forests on Earth. Drilling in Lake Towuti will identify the age and origin of the lake and the environmental and climatic context that shaped the evolution of this unique lacustrine and terrestrial ecosystem. The ultramafic (ophiolitic) rocks and lateritic soils surrounding Lake Towuti provide metal substrates that feed a diverse, exotic microbial community, analogous to the microbial ecosystems that operated in the Archean Oceans. The drill cores will provide unique insights into long-term changes in this ecosystem as well as microbial processes operating at depth in the sediment column.
High-resolution seismic reflection data (CHIRP and airgun) combined with numerous long sediment piston cores collected from 2007-2010 demonstrate the potential of Lake Towuti as a valuable archive. Well-stratified sequences of up to 150 m thickness, uninterrupted by unconformities or erosional truncation, are present in multiple sub-basins within Towuti, providing ideal sites for long-term environmental, climatic, evolutionary, and limnological reconstructions. Multiproxy analyses of our piston cores document a continuous and detailed record of moisture balance variations in Lake Towuti during the past 60 kyr BP, highlighted by arid conditions during northern hemisphere stadials and the last glacial maximum, followed by a dry early and wet late Holocene. This history suggests that climate in central Indonesia responds most strongly to high-latitude climate forcing, despite Indonesia’s remote location, and secondarily to southern hemisphere insolation forcing, a hypothesis we aim to test across multiple glacial-interglacial cycles through scientific drilling within the framework of the International Continental Scientific Drilling Program (ICDP). The principal objectives of our TOWUTI initiative are to:
International collaborators (PI’s) within the framework of this project are: J.M. Russell (lead-PI, U. Brown, USA), S. Bijaksana (ITB, Bandung, Indonesia), S.Y. Cahyarini (LIPI, Bandung, Indonesia), D. Fowle (U. Kansas, USA), D. Haffner (GLIER, Canada), Y. Huang (U. Brown, USA), S. Idriyanti (U. Indonesia, Bandung, Indonesia), J. King (U. Rhode Island, USA), A. Noren (U. Minnesota, USA), D. Oppo (WHOI, USA), T. von Rintelen (Museum f. Naturkunde Berlin, Germany), N. Wattrus (U. Minnesota, USA)