Quaternary glaciations and glacial landform evolution in the Tailan River valley, Tianshan Range, China

Abstract

The Tailan River originates on the southern slope of Tumur Peak, the largest center of modern glaciation in the Tianshan Range. Five moraine complexes and associated fluvioglacial deposits in this valley record a complex history of Quaternary glacial cycles and landform evolution. Electron spin resonance (ESR) dating of glacial sediments was carried out using germanium (Ge) centers in quartz grains, which are sensitive to both sunlight and grinding. Based on the dating results as well as geomorphic and stratigraphic data, the Piyazilike end moraines (the second moraine complex) were deposited during Neoglaciation (the largest glacial advances during the last 3–4 ka in western China) and an early Holocene glacial advance, the third set of moraines was deposited in marine isotope stage (MIS) 2–4, and the glacial landforms of the Tailan glaciation (the fourth moraine complex), which include hummocky moraines on the piedmont, were formed in MIS 6 (penultimate glaciation). The end moraines of the innermost moraine complex (the first moraine complex) are inferred to have been deposited during the Little Ice Age (LIA). Thus the landforms and dates indicate compound valley glaciers from the LIA to MIS 2–4, and piedmont glaciers during MIS 6. The oldest tills studied belong to the “Kokdepsang Glacial Stage”, and occur on a high plateau. Based on similar glacial landforms (glacial deposits on a high plateau and a high glacial terrace) and their ESR ages in adjacent valleys on the southern slope of Tumur Peak, the Kokdepsang Glacial Stage is assigned to MIS 12.