High-amplitude lake-level changes in tectonically active Lake Issyk-Kul (Kyrgyzstan) revealed by high-resolution seismic reflection data

Abstract

Abstract.A total of 84 seismic profiles, mainly from the western and eastern deltas of Lake Issyk-Kul, were used to identify lake-level changes. Seven stratigraphic sequences were reconstructed, each containing a series of delta lobes that were formed during former lake-level stillstands or during slow lake-level increase or decrease. The lake level has experienced at least four cycles of stepwise rise and fall of 400 m or more. These fluctuations were mainly caused by past changes in the atmospheric circulation pattern. During periods of low lake levels, the Siberian High was likely to be strong, bringing dry air masses from the Mongolian steppe blocking the midlatitude Westerlies. During periods of high lake levels, the Siberian High must have been weaker or displaced, and the midlatitude Westerlies could bring moister air masses from the Mediterranean and North Atlantic regions.

Seismic stratigraphical record of Lake Levinson‐Lessing, Taymyr Peninsula: evidence for ice‐sheet dynamics and lake‐level fluctuations since the Early Weichselian

“…This is confirmed by the predominance of fine-grained laminae of silt and clay in the respective sediments of core PG1228 . Following other seismic-stratigraphical studies in fluctuating lakes Moernaut et al 2010;Cukur et al 2014;Gebhardt et al 2017), these features and the sediment draping of Unit I are characteristic of a highstand level. 5), appear to be inherited from the underlying basement topography as captured on the multi-channel seismic data (Fig.…”

“…6). Following other seismic-stratigraphical studies in fluctuating lakes Moernaut et al 2010;Cukur et al 2014;Gebhardt et al 2017), these features and the sediment draping of Unit I are characteristic of a highstand level.…”

Shortening Accommodated by Thrust and Strike‐Slip Faults in the Ili Basin, Northern Tien Shan

“…Lake Issyk Kul also shows relatively weak seismicity compared with the surrounding ranges. The bathymetry and the topography along its edges further indicate a fundamental difference in the crustal material, although recent seismic surveys have shown that the lake floor is deforming (Buslov et al, ; de Batist et al, ; Gebhardt et al, ). Issyk Kul may be the relict of a stronger block trapped between weaker units (e.g., Buslov et al, ) that have recently entered a stage where it is easier to deform the interior rather than further uplift the surrounding mountains which reach over 5,000 m above sea level.…”

Dinocyst records from deep cores reveal a reversed salinity gradient in the Caspian Sea at 8.5–4.0 cal ka BP

“…The long-term water-level histories of ancient lakes are fingerprinted in their sediments, and both biological and non-biological proxies may be used to unravel long-term environmental changes. In fact, numerous examples of long-term rapid water-level changes with large vertical amplitudes (>500 m) have been exposed for large lakes, such as Tanganyika, Victoria, Malawi (Cohen et al, 2007), Baikal (Colman et al, 1993), and Issyk-Kul (Gebhardt et al, 2017). The annual to decadal amplitudes observed with the instrumental record are in the order of 10-50 times smaller than the centennial to millennial ones , as they only capture the short-term variability.…”