Palaeoglaciology of the northeastern Tibetan Plateau
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
This study concerns the palaeoglaciation of the northeastern Tibetan Plateau, with emphasis on the Bayan Har Shan (Shan = Mountain) in the headwaters of Huang He (Yellow River). To reconstruct past glacier development multiple techniques, including remote sensing, field investigations, cosmogenic exposure dating, and numerical modelling have been employed. Analysis of the large-scale geomorphology indicates that glacial erosion has been dominant in the elevated mountain areas on the low-relief plateau, whereas fluvial erosion outpaces glacial erosion along the plateau margin. Landform and sediment records yield evidence for multiple local glaciations, restricted to the highest mountain areas, and a maximum glaciation beyond the mountain front. Absence of data supporting the former presence of proposed ice sheets, plateau-wide or regional, tentatively indicates that no ice sheet glaciation occurred on the northeastern Tibetan Plateau. Cosmogenic exposure dating of boulders, surface pebbles, and sediment sections in central Bayan Har Shan indicates that its record of past glaciations predates the global Last Glacial Maximum (LGM). Based on a world-wide analysis, yielding that wide age disparity within apparent exposure age datasets is most likely caused by post-glacial shielding processes, the Bayan Har Shan exposure ages constrain four periods of glaciation with minimum ages of 40-65 ka, 60-100 ka, 95-165 ka, and undetermined oldest stage. Similar to Bayan Har Shan, the plateau-wide distribution of boulders with pre-LGM exposure ages close to present-day glaciers shows that its LGM glaciers were generally not much larger than today. The results of a high resolution glacier model applied to nine regions across the plateau indicates that temperature depressions of 2-4 K are enough to expand glaciers beyond their global LGM extent, implying that during periods of Northern Hemisphere glaciation the Tibetan Plateau was not much colder than today or became exceedingly dry.
Place, publisher, year, edition, pages
Stockholm: Department of Physical Geography and Quaternary Geology, Stockholm University , 2010. , 15 p.
Dissertations from the Department of Physical Geography and Quaternary Geology, ISSN 1653-7211 ; 21
Tibetan Plateau, palaeoglaciology
Physical Geography Geology
Research subject Physical Geography
IdentifiersURN: urn:nbn:se:su:diva-38689ISBN: 978-91-7447-074-1OAI: oai:DiVA.org:su-38689DiVA: diva2:312664
2010-06-02, De Geersalen, Geovetenskapens hus, Svante Arrhenius väg 14, Stockholm, 13:00 (English)
Lehmkuhl, Frank, Professor
Stroeven, Arjen PHättestrand, ClasAlexanderson, Helena
At the time of doctoral defence the following publications were unpublished and had a status as follows: Paper 4: Manuscript. Paper 5: Manuscript.2010-05-112010-04-262010-05-13Bibliographically approved
List of papers