Publication Date:
2023-12-12
Description:
〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉This study provides a descriptive characterization of the modern sedimentary processes in Lake Issyk Kul, Kyrgyzstan, important for the selection of a suitable coring or deep‐drilling site, interpretation of future core data and applicability of proxies. The quasi‐equidistant sampling grid of 66 sediment surface samples covers the entirety of the lake basin and is complemented by 10 samples from the major inflows. The methodological approach includes geochemical, granulometric, lipid biomarker, diatom, and statistical analyses. The quantitative and qualitative changes in sediment composition yield information on its generic origin and prevailing transport and depositional environments. The composition of the surface sediments in Issyk Kul is highly heterogenous. Nearshore deposition is mainly controlled by wave action and by fluvial sediment supply with highest quantities of detrital input coming from the high‐energetic, eastern tributaries. Sediments in the deep central basin are mainly produced in situ and dominated by authigenic calcite. Biogenic accumulation is overall low, except for the western extremity of the lake, where the nearshore, shallow‐water, and low‐energetic environment favors aquatic productivity and subsequent preservation of organic material and diatoms. Redeposition of sediments is a dominant process along the slopes across the southern and western basin floor, where run‐out distances of mass movement deposits are up to 5 km. Directional sediment transport by lake currents appears to be less important, except for the transport of very fine‐grained organic matter. Biomarker‐inferred temperature reconstructions suggest lake surface temperatures of ∼15°C in the western littoral zone and in Tyup Bay and a decrease to ∼13°C basinward.〈/p〉
Description:
Plain Language Summary: Intensive research on the natural component of climate variability on geological time scales is needed to better understand and validate current and future climate change. Lakes can provide continuous sediment successions that allow us to reconstruct regional trends in climate and environment dynamics far beyond the industrial age. In continental Eurasia, Lake Issyk Kul, one of the deepest and largest mountain lakes in the world, has long been targeted for a deep‐drilling campaign, because its sediment succession potentially holds information of the past ∼10 million years. Prerequisite for future drilling is a better understanding of prevailing transport and (re)deposition mechanisms in Lake Issyk Kul. The overarching aim of this study is to test the applicability of different proxies, vital for the interpretation of future sediment core data. Therefore, a quasi‐equidistant sampling grid of up to 66 sediment surface (and 10 river) samples spanning the entire lake basin of Lake Issyk Kul was examined by means of sedimentological, geochemical, biological, and statistical analyses. The interpretation provides insights into spatial differences in, for example, clastic input from major rivers, biogenic sedimentation, and endogenic precipitation of calcium carbonates.〈/p〉
Description:
Key Points:
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〈list-item〉
〈p xml:lang="en"〉The study provides information on the prevailing transport and (re)deposition mechanisms in Lake Issyk Kul today〈/p〉〈/list-item〉
〈list-item〉
〈p xml:lang="en"〉Geochemical, granulometric, lipid biomarker, diatom, and statistical analyses were performed on surface sediment and inlet stream samples〈/p〉〈/list-item〉
〈list-item〉
〈p xml:lang="en"〉The results are prerequisite to interpret longer sediment successions from the lake〈/p〉〈/list-item〉
〈/list〉
〈/p〉
Description:
Deutsche Forschungsgemeinschaft
http://dx.doi.org/10.13039/501100001659
Description:
https://doi.org/10.5281/zenodo.8059855
Keywords:
ddc:551.3
;
Issyk Kul
;
modern sedimentary processes
;
climate
;
geochemistry
;
grain‐size
;
XRF
;
lipid biomarker
;
diatoms
Language:
English
Type:
doc-type:article
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