The Towuti Drilling Project: paleoenvironments, biological evolution, and geomicrobiology of a tropical Pacific lake

Abstract

Abstract. The Towuti Drilling Project (TDP) is an international research program, whose goal is to understand long-term environmental and climatic change in the tropical western Pacific, the impacts of geological andPublished by Copernicus Publications on behalf of the IODP and the ICDP. The Towuti Drilling Project environmental changes on the biological evolution of aquatic taxa, and the geomicrobiology and biogeochemistry of metal-rich, ultramafic-hosted lake sediments through the scientific drilling of Lake Towuti, southern Sulawesi, Indonesia. Lake Towuti is a large tectonic lake at the downstream end of the Malili lake system, a chain of five highly biodiverse lakes that are among the oldest lakes in Southeast Asia. In 2015 we carried out a scientific drilling program on Lake Towuti using the International Continental Scientific Drilling Program (ICDP) Deep Lakes Drilling System (DLDS). We recovered a total of ∼ 1018 m of core from 11 drilling sites with water depths ranging from 156 to 200 m. Recovery averaged 91.7 %, and the maximum drilling depth was 175 m below the lake floor, penetrating the entire sedimentary infill of the basin. Initial data from core and borehole logging indicate that these cores record the evolution of a highly dynamic tectonic and limnological system, with clear indications of orbital-scale climate variability during the mid-to late Pleistocene.

Modern sedimentation processes in Lake Towuti, Indonesia, revealed by the composition of surface sediments

“…Lake Towuti is roughly separated into a northern and a southern basin by a large island and a series of subaquatic ridges ascending to ca 125 m water depth ( Fig. 1; Russell et al, 2016). The largest tributary is the Mahalona River, which forms a large delta in the northern part of the lake (the Mahalona Delta) and exerts a strong influence on sedimentation in the northern basin (Costa et al, 2015;Vogel et al, 2015;Weber et al, 2015;Goudge et al, 2017).…”

Metabolic potential of microbial communities from ferruginous sediments

“…Unlike upstream Lake Matano, which is permanently stratified and anoxic below 110 m water depth (Katsev et al, 2010), Lake Towuti (2.5 S, 121 E), has been inferred to mix at least occasionally (Costa et al, 2015). Sporadic mixing could affect the distribution of phosphate in the water column (Katsev et al, 2010) and potentially influence its productivity (Bramburger et al, 2008;Russell et al, 2016). Lake Towuti has a maximum water depth of ca.…”

A simple and inexpensive technique for assessing contamination during drilling operations

“…Lake Towuti: In June/July 2015, a 114 m long sediment core was retrieved for geomicrobiological investigations from Lake Towuti, located in Sulawesi, Indonesia (Russell et al 2016). DOSECC Exploration Services carried out drilling operations using the ICDP Deep Lakes Drilling System (DLDS 2010).…”

“…The borehole was drilled with specialized lake drilling tools. Cores were collected in standard IODP-style butyrate liners (66 mm core diameter) in 3 m intervals using P size drill rods (122.6 mm borehole diameter) (Russell et al 2016). Hydraulic piston coring (HPC) was applied for soft unconsolidated sediment, and the rotating Alien corer (ALN) was used for more resistant layers such as lithified tephras.…”

“…7. Simplified stratigraphy of the drilled Lake Towuti core (Russell et al 2016) and amount of drilling fluid (lL) that has infiltrated into one cm 3 of sediment during drilling. Intervals in which the Alien tool (ALN) was used are marked in light grey.…”