81-9 Spatial-temporal Patterns of the Holocene Climate over Arid Central Asia: Insights from the Lacustrine Records of Eastern Lake Issyk-Kul

Session: Investigating Earth’s History With Continental Scientific Drilling

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Abstract:

Lake Issyk-Kul, located in the center of the Tien Shan glacial mountain ranges in mid-latitude arid Central Asia (ACA), is one of the world’s largest and deepest lakes. This region is characterized by a strong west-to-east moisture gradient and is dominated by the westerlies. The lake’s hydrology depends on glacial meltwater, and it is especially sensitive to climatic fluctuations. Additionally, the ACA is at risk of a faster-than-average temperature rise. However, the Holocene climate history of ACA remains poorly understood due to a lack of high-resolution records and the complex interplay of competing forcing mechanisms. This research reconstructs the Holocene climate variability of ACA based on organic geochemical proxies from eastern Lake Issyk-Kul sediments. We analyzed lacustrine alkenones (%C_37:4 and total C₃₇) to examine changes in salinity and primary productivity, and glycerol dialkyl glycerol tetraethers (GDGTs) to generate temperature reconstructions based on TEX₈₆ and the Ring Index of isoprenoid Hydroxylated (RI-OH). These records provide new insights into long-term hydroclimatic changes in ACA. Preliminary results indicate significant climate shifts during the Bølling-Allerød and Younger Dryas (YD) periods. Notably, the TEX₈₆ and RI-OH records display an anti-phase relationship over the past ~13,600 years, which is an unexpected pattern that may reflect salinity change or depth sensitivities of the proxies. To place our findings in a broader context, we compare Issyk-Kul’s biomarker records with the proxy records from other Asian lakes and/or westerlies-dominated regions to examine regional dynamics in a large lake system. Our new organic geochemical analyses contribute to addressing a gap in our understanding of past temperature and hydroclimate change in mid-latitude ACA, supporting the value of using lacustrine sediments as paleoclimate archives. Additional work on analyzing primary productivity biomarkers and the carbon and deuterium isotopic composition of leaf waxes, as well as examining another core from the western lake basin, will enhance our understanding of the lake’s full hydroclimate evolution.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-7202

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