NOAA/WDS Paleoclimatology - Lake Towuti, Indonesia 60KYr Geochemical Data

STUDY NOTES: Major and trace element data are reported from river sediments and from sediment core TOW9 in Lake Towuti. For age model and calibration of XRF data, please see Russell et al. 2014. Data are organized according to their presentation in the figures: Figure 3 Downcore profiles of major ion concentrations: Al, Mg, K, and Ti (data file towuti2014ions.txt). Figure 4 Downcore profiles of redox-sensitive elements: Fe, Cr, Co, V, and U (data file towuti2014xrf.txt). Figure 5 K, Mg, Al, and STE concentrations for the rivers. Al and STE concentrations TOW9 lake sediment (below). Figure 6 Average major ion concentrations for the three river groups (below). Figure 7 Lakewater dissolved Fe concentrations (below). Figure 4b. Downcore profiles of redox-sensitive elements: Co, V, and U Age (ka) Co (ppm) V (ppm) U (ppm) 1.17 148 130 0.79 2.40 155 132 0.81 4.58 198 118 0.60 7.17 146 126 0.66 10.00 169 144 0.84 11.39 174 132 0.82 16.92 229 123 0.53 18.47 223 126 0.58 19.83 225 130 0.56 22.68 241 129 0.44 25.92 181 101 0.35 27.49 235 136 0.48 30.92 195 143 0.67 34.04 199 135 0.60 36.74 207 157 0.67 39.52 135 146 1.05 44.44 142 144 0.93 47.74 123 138 0.96 52.64 183 143 0.96 59.18 189 110 0.42 Figure 5a. K, Mg, Al, and STE concentrations for the rivers. Sediment Type Sample K (wt%) Mg (wt%) Al (wt%) STE (ppm) River Bantilang 1.57 5.77 6.05 369 River Lantibu 0.00 10.49 4.99 16.6 River Lelebiu 0.09 6.36 5.93 91.3 River Lemo Lemo 0.03 15.36 3.34 31.9 River Loeha 1.52 2.76 7.24 483 River Mahalona 0.14 21.32 3.22 100 River Taora 1.14 10.57 4.67 90.2 River Tokolalo 0.00 14.80 4.01 22.1 River Tomerakah 0.00 14.69 4.08 14.5 Figure 5b. Al and STE concentrations TOW9 lake sediment Age (ka) Al (wt%) STE (ppm) 1.17 4.79 271 2.40 5.12 272 4.58 4.17 193 7.17 4.53 231 10.00 5.11 292 11.39 5.43 313 16.92 3.53 189 18.47 4.03 202 19.83 4.28 199 22.68 3.89 147 25.92 3.31 131 27.49 5.26 172 30.92 5.02 248 34.04 4.83 237 36.74 5.29 247 39.52 6.00 387 44.44 5.92 363 47.74 5.73 358 52.64 5.05 336 59.18 3.54 145 Figure 6. Average major ion concentrations for the three river groups Mahalona River Mahalona (1s) Metasedimentary River Average Metasedimentary (1s) Peridotite River Average Peridotite (1s) Al (wt%) 3.22 0.31 6.65 0.84 4.18 1.08 Ca (wt%) 1.31 0.05 4.82 2.48 0.80 0.41 K (wt%) 0.14 0.04 1.55 0.03 0.02 0.03 Ti (wt%) 0.15 0.01 0.51 0.04 0.08 0.09 Na (wt%) 0.09 0.01 0.32 0.15 0.01 0.01 Mg (wt%) 21.32 2.16 4.27 2.12 12.16 3.54 Sr (ppm) 14.72 1.74 71.20 2.78 1.93 1.72 Figure 7. Lakewater dissolved Fe concentrations Month-Year Water Depth (m) Fe (ppm) March-13 10 0.01 March-13 80 0.00 March-13 150 0.08 April-13 10 0.00 April-13 80 0.00 April-13 150 0.13 May-13 10 0.00 May-13 80 0.00 May-13 150 0.01 July-13 10 0.01 July-13 80 0.00 July-13 150 0.10
ABSTRACT SUPPLIED BY ORIGINATOR: The Indo-Pacific Warm Pool (IPWP) is an important driver of global climate, but its response to and involvement in paleoclimate change is poorly constrained. We generated a new record of sediment geochemistry from Lake Towuti (2.5S, 121.5E), Indonesia, located in the heart of the IPWP, to investigate changes in hydrological connectivity with upstream lakes and the extent of lake mixing and oxygenation during paleoclimate changes over the last 60,000 years BP (60 ka). Lake Towuti is located at the downstream end of the Malili Lakes, a chain of large, ancient, and biologically diverse tectonic lakes occupying a geologically heterogeneous terrain in central Sulawesi, Indonesia. Major and trace element data from river and lake sediments suggest no changes in sediment provenance during the Last Glacial Maximum (LGM), indicating that some of the Malili Lakes remained hydrologically open despite a regionally drier climate. However, samples from the LGM are uniformly less enriched in trace elements than samples from the Holocene and Marine Isotope Stage 3 (MIS3), which suggests a decrease in weathering intensity during the LGM, likely in response to decreased precipitation and temperature. Changes in Fe and other redox-sensitive trace element concentrations indicate changes in water column oxygenation, with the highest oxygen availability occurring during the LGM (15-35 ka) likely due to more frequent and/or deeper mixing of Lake Towuti's water column. The glacial-interglacial trend in lake oxygenation corresponds with changes in regional precipitation and associated changes in the seasonal cycle. The high degree of faunal endemism in these lakes may be related to changes in the lake geochemistry associated with glacial-interglacial environmental variability driven by changing inputs and redox variability.