Climate Evolution in Central Asia during the Past Few Million Years: A Case Study from Issyk Kul

Abstract

The lake Issyk Kul occupies a deep basin within the Earth’s most active intracontinental mountain belt, the Tien Shan, far from any oceanic influence. It offers a record of continental climate spanning millions of years that is likely unmatched by any other source.A three-day workshop, with the same title as this report and sponsored by the International Continental Drilling Project and German Science Foundation, was held on 12–17 June 2011 on the shore of Issyk Kul to discuss the scientific justification for and the logistical aspects of scientific drilling of the lake. A two-day geological field trip followed the workshop. Forty-five scientists from twelve countries discussed three obvious targets for paleoclimatic study, a related study of erosion, and a study of how microbial life has evolved within the basin. The conclusion was that these research topics justify further consideration of deep continental drilling at Issyk Kul

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

“…In 2001, 40 additional profiles (∼ 600 km) were acquired with the same source, and another 12 profiles using a SIG sparker (200-800 Hz, operated at 500 J). During both surveys, a single-channel streamer (2.7 m length, 10 hydrophones at 0.3 m spacing) was used as seismic receiver (Naudts, 2002). Recording time and shot interval were chosen depending on the water depth of the specific area.…”

“…Drilling of sediment cores from the different sediment lobes would be required in order to reliably date the lake-level stillstands. Lake Issyk-Kul with its long sedimentary archive therefore provides an ideal drill site to study the history of the interplay between the Siberian High, the midlatitude Westerlies and the Asian summer monsoon through time (Oberhänsli and Molnar, 2012). The lake is located in an area with high relief, implying different climate conditions over short distances.…”

Rapid Late Quaternary Slip, Repeated Prehistoric Earthquake Rupture, and Widespread Landsliding Associated With the Karakudzhur Thrust, Central Kyrgyz Tien Shan

“…The Issyk‐Kul Basin is underlain by strong, granitic basement (De Grave et al, ) and extends 250 km E‐W, coinciding with the E‐W extent of the central Tien Shan region (e.g., Figure ). Folds are present in the Cenozoic sediments of the Issyk‐Kul basin, and in the lake floor (Oberhänsli & Molnar, ), but these folds appear to be restricted to the sediment fill, and hence thin‐skinned splays from the basin‐bounding faults. If the pre‐Cenozoic basement of the Issyk‐Kul Basin does not deform, it may act to concentrate stress onto the major basin margin faults north and south of the main Issyk‐Kul Basin boundaries, which, in turn, may have helped to generate the present‐day configuration of high‐relief, high‐elevation intramontane basins observed today.…”

An extended history of high-amplitude lake-level changes in tectonically active Lake Issyk-Kul (Kyrgyzstan), as revealed by high-resolution seismic reflection data

“…Drilling of sediment cores from the different sediment lobes would be required in order to reliably date the lake-level stillstands. Lake Issyk-Kul with its long 15 sedimentary archive therefore provides an ideal drill site to study the history of the interplay between the Siberian Anticyclone, the mid-latitude Westerlies and the Asian summer monsoon through time (Oberhänsli and Molnar, 2012). The lake is located in an area with high relief, implying different climate conditions over short distance.…”