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Dirk Scherler from GFZ Visited China for Cooperative Research with Our Institute

2015/12/29 9:31:39

At the invitation of Researcher Liu Jing of Division of Neotectonics and Landform, Assistant Professor Dirk Scherler of Helmholtz-Centre Potsdam - German Research Centre for Geosciences (GFZ) visited our institute from May 29, 2015 to June 16, 2015. His activity included giving a lecture, and making discussion and field investigation and with researchers of our institute, which focused on active tectonics and tectonic landform of the Tibetan plateau and neighboring areas.

From May 29 to 30, 2015, Dirk Scherler and Wang Ping discussed the latest  observations and measurement data about sedimentation of Yarlung Zangbo Grand Canyon Valley. His discussion with Wang Wei was concerning with the concentration change of cosmogenic nuclides after the 2008 Wenchuan earthquake. He offered   suggestions on further field study, collection of cosmogenic nuclide samples, as well as drafting of scientific papers.

Figure 1 Upper: Group photo of field study in Yunnan. Lower: Collecting samples of cosmogenic nuclide exposure age on the terrace obviously modified by human activity in later time

From May 30, 2015 to June 14, 2015, Dirk Scherler, Liu Jing and Zhang Jinyu of our institute carried out joint field study on river landform and erosion rate in the Nujiang River, Lancang River and Jinsha River basins in Yunnan Province (Figure 1). To address the landform evolution rate of the 3-river region on the southeastern margin of the Tibetan plateau, this travel focused on two pieces of field work: (1) discuss in situ the field observations, sampling and OSL dating of river terraces in the section from Deqin of Lancang River basin southward to Yongping, supplementarily collect cosmogenic nuclide exposure age of geomorphic surfaces; stress the importance of obtaining regional aggradation event time limit and sediment cutting rates from the perspective of angle representing long-term average incision rates of the river, and guide on how to collect cosmogenic nuclide exposure age samples as effectively as possible to limit the discarding time in the terraces obviously modified by human activity in later stage (Figure 1). (2) Investigate the development condition of river terraces in the section of Nujiang River Valley from Liuku northward to Binzhongluo, and sample gravel and bed rock surfaces of cosmogenic nuclides exposure age in critical terraces; for the river sections where river terraces did not developed, tributary basins with appropriate basin area and lithology are selected to jointly sample river sand to determine the average erosion rates of the basins. The success of this field study laid a good foundation for the project team’s further research on geomorphic erosion rates in the 3-river region on the southeastern margin of the Tibetan plateau. The two sides reached cooperation intention on mutual visit and sample analysis.

Figure 2 Dirk Scherler was making an academic report in our institute

After the field study, Dirk Scherler made an academic report on invitation. The topic is: Tectonic control on erosion in the Himalaya (Figure 2). In respect to the main controlling factor of erosion of Himalaya, Dirk Scherler collected river sand samples from a river in the north of India, which flows through Garhwal Himalaya, obtained the average erosion rate of the basin based on cosmogenic nuclides at different locations, compared it with river steepness index and unit hydrodynamic force. He found that river steepness index plays a dominant role in controlling the distribution pattern of erosion rates and supports the geometric feature that the major fault of Himalaya is a gentle-dip fault flatting below Lesser Himalaya as well as a mid-crust fault ramp below High Himalaya. More than 20 scientific research personnel and postgraduates of our institute listened to this report and actively discussed a series of issues, including the comparability of average erosion rates of the basin derived from cosmogenic nuclides with river steepness coefficients, low-temperature thermo chronological speed and the geomorphic erosion rates on different time scales, represented structures and climatic factors, technical details for determining basin erosion rates based on cosmogenic nuclides, and development conditions of the major faults in the Himalaya.