Palaeoclimatology of Central Asia and the northeastern Tibetan Plateau on basis of compound-specific isotope analysis of biomarkers.

该项目最初阶段的目的是建立中亚干旱地区和青藏高原东北部(NE-TP)的水文气候记录，这些记录至少可以追溯到最后一次冰川高峰期，方法主要是应用有机地球化学指标。在提出本建议时，已在三个湖泊(中亚帕米尔的卡拉库尔湖；东北-TP的东吉科纳湖；东北-TP的哈拉湖)取得了成功的进展。陆地生物标志物的氢同位素数据表明，两个研究区在晚冰期季风的加强是不同步的。与所研究的两个湖泊相比，北半球快速气候事件对东北-总磷的影响在中亚显得更强。整合来自同位素全球环流模型的数据，证明降水季节性的变化是在晚期冰川期间观察到的中亚卡拉库尔湖流域大规模水文和生态变化背后的主要驱动因素。在项目的扩展阶段，我计划对已经处理的样品中的其他水生来源的化合物(烷烃、不饱和脂肪族化合物)进行额外的DD测量。其目标是破译过去湖水同位素和盐度的变化，根据已经分析的有机和无机替代品，这一点尚不清楚。此外，我的目标是分析更多的样品，以提高哈拉湖沉积物岩芯全新世段的时间分辨率，以及c)指示生物质燃烧(左旋葡聚糖)和温度(长链二醇)的更多化合物。这种多指标方法结合了几种温度敏感指标(烯烃、长链二醇)和火灾指示剂，旨在促进正在进行的关于东北-总磷地区的社会文化行为，特别是较高海拔的定居是否受到全新世冷事件影响的讨论。(A部)。此外，我建议对中亚卡拉库尔湖及其集水区至少6个选定的样品进行化合物特定放射性碳分析(CSRA)，以更好地了解陆地有机化合物在极端干旱环境中进入沉积物的命运和潜在的滞后时间(B部分)。

The aim of the initial phase of this project was to establish hydroclimatic records from both arid Central Asia and the northeaster Tibetan Plateau (NE-TP) which reach back at least to the last glacial maximum, by applying mainly organic geochemical proxies. At the timing of this proposal this has been progressed successfully at three lakes (Lake Karakul, Pamir, Central Asia; Lake Donggi Cona, NE-TP; Lake Hala Hu, NE-TP). Hydrogen isotopic data of terrestrial biomarkers show an asynchronous intensification of monsoons during the late glacial in the two study areas. Impacts of Northern Hemispheric rapid climate events appear stronger in Central Asia compared to the two studied lakes on the NE-TP. Integration of data derived from isotope enabled global circulation models give evidence for changes in precipitation seasonality as a major driving factor behind the observed large scale hydrological and ecological changes in the catchment of central Asian Lake Karakul during the late glacial.Within the extension phase of the project, I´m planning to do a) additional dD measurements on additional compounds of aquatic origin in already processed samples (alkenones, unsaturated aliphatic compounds). The goal is to decipher past changes of lake water isotopes and salinities, which is yet unclear based on already analysed organic and inorganic proxies. Further I aim to analyse b) more samples to increase time-resolution in the Holocene section of the lake Hala Hu sediment core and c) additional compounds indicative for biomass burning (levoglucosan) and temperature (long-chain diols). This multiproxy approach combining several temperature sensitive proxies (alkenones, long-chain diols) and fire indicators aims to contribute to the ongoing discussion if socio-cultural behaviour on the NE-TP, specifically the settling of higher altitudes, was influenced by Holocene cold-events. (Part A). Further, I propose to conduct compound-specific-radiocarbon analysis (CSRA) of a minimum of 6 selected samples from central Asian Lake Karakul and its catchment to better understand the fate of terrestrial organic compounds and potential lag-times during their transport into the sediment in a hyperarid environment (Part B).