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Glacial geomorphology and ice ages in Tibet and the surrounding mountains
Author(s) -
Kuhle Matthias
Publication year - 2005
Publication title -
island arc
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.554
H-Index - 58
eISSN - 1440-1738
pISSN - 1038-4871
DOI - 10.1111/j.1440-1738.2005.00501.x
Subject(s) - glacial period , geology , moraine , snow line , glacier , ice sheet , marine isotope stage , stadial , physical geography , snow , geomorphology , interglacial , snow cover , geography
Since 1973 new data have been obtained on the maximum extent of glaciation in High Asia. Evidence for an ice sheet covering Tibet during the last glacial period means a radical rethinking about glaciation in the northern hemisphere. The ice sheet's subtropical latitude, vast size (2.4 million km 2 ) and high elevation (6000 m a.s.l.) are supposed to have resulted in a substantial, albedo‐induced cooling of the Earth's atmosphere and the disruption of summer monsoon circulation. Moraines were found to reach down to 460 m a.s.l. on the southern flank of the Himalayas and to 2300 m a.s.l. on the northern slope of the Tibetan Plateau, in the Qilian Shan region. On the northern slopes of the Karakoram, Aghil and Kuen‐Lun Mountains, moraines occur as far down as 1900 m a.s.l. In southern Tibet, radiographic analyses of erratics suggest a former ice thickness of at least 1200 m. Glacial polish and roches moutonnées in the Himalayas and Karakoram suggest former glaciers as thick as 1200–2700 m. On the basis of this evidence, a 1100–1600‐m lower equilibrium line has been reconstructed, resulting in an ice sheet of 2.4 million km 2 , covering almost all of Tibet. Radiometric ages, obtained by different methods, classify this glaciation as isotope stage 3–2 in age (Würmian, the last glacial period, ca 60 000–18 000 years ago).