Late Pleistocene–Holocene records from Lake Ulaan, southern Mongolia: implications for east Asian palaeomonsoonal climate changes

Abstract

ABSTRACTA 5.88‐m‐long core taken from Lake Ulaan was studied for high‐resolution paleoclimatic changes during the last 17 000 years. The core sediments are divided into three units based on grain‐size distribution: unit 1 (top to 392 cm depth, covering the last 11 200 years), unit 2 (392–530 cm, 11.2–15 ka) and unit 3 (530–588 cm, 15.0–16.7 ka). These sediments were transported by local westerly winds (units 1 and 3) and fluvial processes (unit 2). Based on major element compositions and geological setting of adjacent areas, provenance of unit 1 sediments was interpreted to be the Lake terrane, and that of unit 2 to be the Idermeg terrane. Unit 3 sediments were derived from the Gobi Altai terrane. The records of total organic carbon, C/N ratio and weathering intensity suggest that paleoclimate in the source area of Lake Ulaan sediment was most humid during the Early Holocene, humid during the mid‐Holocene and dry in the Late Holocene. The decrease of humidity through the Holocene is a typical characteristic of the East Asian monsoon region. Comparison with lacustrine records of other Mongolia regions suggests that the northern boundary of East Asian summer‐monsoon influence could have been located further north than previously assumed. Copyright © 2013 John Wiley & Sons, Ltd.