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Zhang Jinyu and Wang Wei Paid an Exchange Visit to German Potsdam GFZ

2016/6/7 14:17:39

At the invitation of assistant professor Dirk Scherler from German Potsdam GFZ (German Research Centre for Geosciences), research assistant Zhang Jinyu and doctoral student Wang Wei from the Institute of Geology went to GFZ for more than 70 days’ exchange visit from September 7, 2015 to November 22.

Figure 1 Einstein Science Park where GFZ is located

During this exchange visit, by relying on Helmholtz Surface Geochemistry Laboratory of this center, research assistant Zhang Jinyu and doctoral student Wang Wei carried out quartz purification and chemical treatment of cosmogenic nuclides (10Be and/or 26Al) of the river sand samples collected in Longmen Mountain area in the eastern margin of Qinghai-Tibet Plateau and river terrace samples collected in three-river area in the southeastern margin, as well as the work for preparation of AMS test sample targets (Figure 2). Before start of experiment, research assistant Zhang Jinyu and doctoral student Wang Wei systematically learned an Internet course for experimental safety knowledge, safety operation and emergency handling plan of laboratory and a training course for background knowledge of cosmogenic nuclides and their application in earth surface process provided by Dr. Hella Wittmann-Oelze of the center. During experiment, assistant professor Dirk Scherler explained in details and personally operated and guided the whole experimental process of quartz purification and chemical treatment, and looked for solutions to quartz dissolution, abnormal ion separation among particular samples in time. This experimental experience made research assistant Zhang Jinyu and doctoral student Wang Wei deeply feel the precise and serious experiment attitude, scientific and rigorous experiment methods and a strong sense of safety and self-protection in a German laboratory. Besides, research assistant Zhang Jinyu and doctoral student Wang Wei also attended the group meeting held by the laboratory in the morning of every Tuesday on a regular basis, involving daily affairs of the laboratory, introduction of executed projects and research progress, invitation of academic reports relevant with earth surface process, and application for domestic scientific research funds in Germany and international exchange funds.  

Figure 2 Cosmogenic nuclide target fabrication laboratory of Helmholtz Surface Geochemistry Laboratory, GFZ

 

During treatment of cosmogenic nuclide samples, research assistant Zhang Jinyu and doctoral student Wang Wei learned Topo Tooblx tool for landform analysis based on Matlab software under the guidance of assistant professor Dirk Scherler. According to the need for analysis of river landform in three-river area in the southeastern margin of Qinghai-Tibet Plateau, research assistant Zhang Jinyu learned in a centralized way how to compile scripts based on a digital elevation model to extract longitudinal sections of rivers and water system watersheds, transverse sections of watercourses, as well as river terraces and their attributes and also reconstructed downstream river profiles based on the river profiles in the upstream of knick points. Based on river knick point development positions of Lantsang River Basin, space distribution of river terraces, and optically stimulated luminescence (OSL) age obtained from sediment in river terraces at different heights, research assistant Zhang Jinyu and assistant professor Dirk Scherler as well as Prof Edward R. Sobel and Dr Paolo Ballato from University of Potsdam made in-depth discussion on issues in the aspects of river undercut rate change form of Lantsang River Basin in Late Quaternary Period, effects of structural and climatic factors on instantaneous undercutting of the river, and their possible constraint on tectonic deformation mechanism of the southeastern margin of Qinghai-Tibet Plateau. Based on 10Be data of river sand obtained after Wenchuan Earthquake, doctoral student Wang Wei mainly learned script compilation and calculation, and used images to express the spatial distribution of cosmogenic nuclide generation rate, as well as the distribution of coseismic landslides of Wenchuan Earthquake in the researched river basin and landslide density along watercourse, providing new cognition to mass migration process of post-earthquake landslides based on cosmogenic nuclide concentration of river sand. Besides, in respect to the migration process of landslides after Wenchuan Earthquake, doctoral student Wang Wei exchanged views with Prof Taylor Schildgen and assistant professor Dirk Scherler from GFZ and Dr Florian Kober from NAGRA, and received good feedback and suggestions.