A 7-ka climatic variability record inferred from peat bog sediments in the north of Bayan Har Mountains, northeastern Tibetan Plateau

Abstract

Reconstructions of the Holocene (especially the mid-Holocene) climatic and environmental changes may serve as an analogue for future scenarios. About 7 ka of Holocene climatic variability in the north of Bayan Har Mountains on the northeastern Tibetan Plateau is reconstructed, using grain size, magnetic susceptibility, geochemical parameters, and accelerator mass spectrometry 14C chronology from peat bog sediments. The peat’s source is found to be aeolian sediments. Climatic variability from the peat bog sediments during the last 7.3 ka can be divided into four stages: warm and wet from 7.3 to 5.7 cal ka BP; cool and dry (semi-wet) from 5.7 to 2.5 cal ka BP; relatively cool and wet from 2.5 to 1.1 cal ka BP; and cold and dry from 1.1 cal ka BP to present. Mid-late Holocene climate in the north of Bayan Har Mountains was significantly unstable during the last 7.3 ka and characterized by five centennial-scale oscillations: 6.2‒6.0, 4.3‒3.9, 2.5‒2.1, 1.7‒1.4, and 0.7‒0.2 cal ka BP. This mid-late Holocene climate recorded by peat bog deposits is consistent with most lacustrine sediment records in the north of Bayan Har Mountains and its adjacent areas. These lacustrine sediments indicated that the climate on the northeastern Tibetan Plateau was warm and humid in the early Holocene, cold and dry after the mid-Holocene (ca. 7.5‒6.0 cal ka BP), and relatively cool and wet in the late Holocene.