DOI: 10.25921/r4gm-te09
title: NOAA/WDS Paleoclimatology - Lake Towuti, Indonesia 60KYr Geochemical Data

description: 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.
description: 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