Project

Discipline

Indonesia; lake sediments; Subsurface biosphere; Int. Continental Scientific Drilling Program; Paleoenvironment; Paleoclimate

Lead
Die Tropen spielen eine entscheidende Rolle im Klimasystem der Erde. Die klimawirksamen Prozesse und Mechanismen dieser Regionen sind aufgrund ihrer Komplexität allerdings noch nicht hinreichend verstanden. Für ein besseres Verständnis sind lange, mehrere Klimazyklen umfassende, Klimazeitreihen notwendig. Seesedimente eignen sich, aufgrund der Kontinuität ihrer Ablagerung und der oftmals hohen zeitlichen Auflösung, hervorragend als natürliche Klimaarchive. Der Towutisee (2.5°S, 121°E) auf der Insel Sulawesi in Zentralindonesien stellt ein solches hervorragendes natürliches Klimaarchiv für die letzten ~800,000 Jahre dar. Die Entschlüsselung dieses einzigartigen Klimaarchivs ist der Kern dieses Arbeit.
Lay summary
Inhalt und Ziel des Forschungsprojekts  Die übergeordneten Ziele unserer Arbeit sind: Abteufung einer Tiefbohrung am Towutisee, Indonesien; Rekonstruktion der Hydroklimageschichte der letzten ~800,000 Jahre mit Hilfe von sedimentologischen, geochemischen und mineralogischen Analysemethoden; Exploration der lakustrinen Biosphäre in tiefen Sedimentschichten; Charakterisierung der Frühstadien des Sees, die Ursuppe für die heutige Biodiversität und der einzigartigen Artenvergesellschaftung in dem See. Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojekts Unsere Arbeit wird Aufschluss über wichtige Prozesse und Mechanismen im globalen Klimasystem und damit eine wichtige Grundlage für verbesserte Vorhersagen des zukünftigen Klimas liefern. Damit leistet die Arbeit einen wichtigen Beitrag für die Entscheidungsfindung von Politikerinnen und Politikern für die Definition von Klimaschutzzielen und Klimaadaptionsstrategien. Darüberhinaus wird das Projekt wichtige Erkenntnisse über mikrobiell induzierte Stoffkreisläufe in einem schwefelarmen und eisendominierten System liefern und damit Aufschluss geben über mögliche Prozesse, welche während der Frühstadien unseres Planeten und dem Mars auftraten.

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Last update: 10.04.2014

Active participation

Self-organised

Active participation

Communication	Title	Media	Place	Year

Number	Title	Start	Funding scheme

Two interlinked proposals seek funds for the Swiss contribution to the Lake Towuti Drilling Project (TDP) that is already partially sponsored and will be executed by the International Continental Scientific Drilling Program (ICDP). One proposal seeks funds for the Swiss share of costs related to drilling operations that will recover several hundred meters of sediment from Lake Towuti’s subsurface. Another proposal seeks funds for scientific staff and scientific activities of the involved Swiss research groups. Lake Towuti (2.5°S, 121°E) is a 560 km2-large and 200-m deep tectonic lake at the downstream end of the Malili lake system, a set of five ancient (1-2 Ma) tectonic lakes located in central Sulawesi, Indonesia. Lake Towuti’s location in central Indonesia provides an important opportunity to reconstruct long-term terrestrial paleoclimate change in a crucially important yet understudied region- the Western Pacific warm pool, heart of the El Niño-Southern Oscillation. Lake Towuti has high rates of floral and faunal endemism and is surrounded by one of the most diverse tropical forests on Earth, making it a hotspot of Southeast Asian biodiversity. The ultramafic (ophiolitic) rocks and lateritic soils surrounding Lake Towuti provide ferruginous metal substrates that feed a diverse, exotic microbial community in the lake and its sediments, potentially analogous to the microbial ecosystems that operated in the Archean Oceans and on Mars. Therefore, Lake Towuti is a key site for ICDP activities and the TDP will provide valuable new information to understand the climate, biological, and geomicrobiological evolution of this unique system. This Swiss initiative embedded in the overarching ICDP Towuti Drilling Project encompasses two interlinked research modules: Module (A): Climate history: Detailed sedimentology, geochemistry, and mineralogy of drill core from Site 1 (PI’s: Hendrik Vogel & Flavio Anselmetti, U. Bern). This module will provide the temporal succession of lithological variations and contribute the stratigraphic backbone for the main site of the TDP. Detailed lithofacies characterization, paired with high-resolution major element chemistry (XRF core-scanning), and detailed granulometric and mineralogical analysis on the sediment succession, will produce datasets crucial for the reconstruction of climatic and environmental variability and limnological change at unprecedented temporal resolutions. Information on sediment geochemistry and mineralogy as well as on climate-induced changes of past limnological conditions will also be beneficial for the geomicrobiological research of Module (B). The sedimentological and geochemical analysis of fluviolacustrine sediments will help characterizing the style and nature of Towuti’s early lake stages, the primordial ooze for today biodiversity and endemism. Module (B): Exploring the lacustrine subsurface biosphere (PI’s: Daniel Ariztegui & Massimo Chiaradia, U. Geneva). Microbial activity decreases dramatically below the sediment water interface, yet over long time-scales this activity has an appreciable impact on sediment composition and on extant biogeochemical cycles. In this module we will examine the activity of the microbial community throughout the sediments. We will provide first hand information on microbial activity measuring in situ ATP activity immediately after the cores will be retrieved. This bulk data will be compared and blended with more detailed analyses that will be performed by other members of the ICDP project. Laboratory analyses will include Rock-Eval pyrolysis to characterize the bulk nature of the organic matter that is the main support for microbial development. Lake Towuti’s sediments are Fe-rich and thus stand out as an end member microbial habitat. Thus, Fe-isotope analyses will be also performed by the Ph.D. student of this module. These data are anticipated to capture signals of strong water column stratification and anoxia as well as to record information about catchment weathering. Additionally, Zn isotopes will be measured in the same samples providing an independent proxy for productivity changes. This information will be amalgamated with that coming out from Module A to provide a solid picture of the nature of the lithological variations and its relationship with environmental changes.