Late Quaternary Lake-System Dynamics on the northern Tibetan Plateau

• Main Authors: Diekmann, Bernhard, Ramisch, A., Lockot, G., Haberzettl, T., Hartmann, K., Lehmkuhl, F., Stauch, G., Wünnemann, B., Zahng, Y.
• Format: Conference Object
• Language: unknown
• Published: 2015
• Subjects: Fossil Lake; Low Lake; Ice; permafrost
• Online Access: https://epic.awi.de/id/eprint/44726/; https://hdl.handle.net/10013/epic.50977

Lake systems on the Tibetan Plateau reveal complex responses to late Quaternary climate variations, driven by monsoon dynamics and the influence of the westerlies regime. A limnogeological case study from Lake Heihai, situated at 4440 m a.s.l. on the northern Tibetan Plateau, gives evidence for marked changes in the depositional environment related to climatic and orographic effects. The 10 km long, 4 km wide, and 22 m deep lake is situated in a basin north of the Kunlun Mountain Range. Sub-bottom profiling revealed the presence of subaquatic terraces and ancient fan systems from a former low lake stand, draped by younger sediments. Sediment cores above basal sands comprise lacustrine sediments of late glacial to Holocene age. A prominent lake terrace about 6 m above modern level gives evidence of a higher lake level in the early Holocene. The terrace structure includes fossil lake sediments, which include ground ice and are distorted by permafrost structures. Proxy records document marked changes in allogenic sediment provenance and endogenic carbonate precipitation during the last 12 ka. Thus dominant detrital sediment and water supply from proximal alluvial fans appeared only during times, when precipiation was not blocked by the Kunlun Mountains. After a prolonged dry and cold phase during the Late Glacial, this situation of enhanced precipitation-generated sediment supply ocurred between 10.7 cal. ka BP and 7.9 cal. ka BP and decreased afterwards. This Holocene trend is in phase with known variations in atmospheric circulation systems over monsoonal Asia.