Seismic Pre-Site Survey for ICDP Drilling Locations at Lake Nam Co, Tibet

通过不莱梅大学和耶拿大学与中国科学院北京青藏高原研究所的合作，2016年的第二次地震声学调查扩展了2014年的数据集，现在已经覆盖了青藏高原上最大的湖泊之一。该提案的目标是完成数据处理和解释新获得的数据（2016年）以及支持预定的2018年北京ICDP研讨会和预期的ICDP钻探提案。该湖类似于一个超过500米的深沉积物填充物，这可能代表了百万年时间尺度的气候档案。由于处于压扭和扭张构造背景，伴随着复杂的时空演化，伴随着局部沉降，促进了重要的可容纳空间的发展，甚至确保了湖平面低位的沉积。构造格局本身是详细重建的目标，也是湖泊沉积体系的响应和演变的目标。第三年的一个重要课题是重建湖泊水位变化，特别是在湖泊水位大幅升高的时期（大湖假说）。一些文件与有些矛盾的证据表明，湖泊水位至少比今天高100米，在海洋同位素阶段5。地震数据应通过细粒度低反射单元的存在来揭示这种情况，这些单元应通过地层模型进行测绘和约束。

Through a cooperation between the Universities of Bremen and Jena and the Institute of Tibetan Plateau Research/Chinese Academy of Sciences, Beijing, a second seismoacoustic survey in 2016 extended the 2014 data set and is now well covering one of the largest lakes on the Tibetan Plateau.This proposal targets for the finalization of data processing and interpretation of the newly acquired data (2016) as well as to support the scheduled ICDP workshop in Beijing 2018 and the intended ICDP drilling proposal. The lake resembles a deep sediment fill of more than 500 meters, which may represent of climate archive for a million year timescale.Being in a transpressional and transtensional tectonic setting, the associated local subsidence, which follows a complex evolution in space and time, has promoted the development of significant accommodation space, which has even ensured deposition during lake level lowstands. The tectonics pattern itself is a target for a detailed reconstruction, as well as the response and evolution of the lake depositional system.An important topic for the third year is targeting the reconstruction of lake level changes, in particular for times of much elevated lake levels (mega lake hypothesis). Few documents with somewhat conflicting evidence indicate lake levels of at least 100 m higher than today, during marine isotope stage 5. Seismic data should reveal such situation by the presence of fine grained low reflective units, which shall be mapped and constrained by the stratigraphic models.