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Researcher Chen Jie of IGL Went to University of Cincinnati for Cooperative Exchange

2016/12/29 15:17:25

At the invitation of Professor Lewis Owen, the Director of the Department of Geology, University of Cincinnati, Researcher Chen Jie of Neotectonic Chronology Laboratory, IGL went to University of Cincinnati in April 2016 for 18-day academic exchange visit, and dropped in Purdue Rare Isotope Measurement Laboratory (PRIME Lab).

The purpose of this visit is to use American advanced experimental conditions and experience to complete 10Be dating analysis of geomorphic surface and bedrock fault surface samples in related NSFC-funded projects and key director fund projects, write papers in cooperation, carry out in-depth exchange with American cooperator on how to apply high-resolution 10Be, 14C and 26Al data to judge the slip rate of bedrock faults, active stages of paleo-earthquakes and other related issues. During the visit, work in the following few aspects was mainly done:

1、The latest-version CRONUS 10Be-26Al calculation software published by Marrero et al. (2016) was adopted to calculate 10Be exposure age of 36 boulders on the dislocated geomorphic surface of five locations of the 250km long Kongur Extensional System and 10Be exposure age of the deep sections of six terrace surfaces or proluvial fan surfaces. The latest output rate was adopted to re-calculate the published 10Be exposure age of 26 boulders at five locations. A preliminary chronological framework of moraine dykes, alluvial-proluvial fan platform surfaces and other dislocated landforms at 11 locations.

2、The spatial distribution, geographic characteristics and displacement distribution characteristics of the 250km long Kongur Extensional System were preliminarily determined. The outline and related diagrams and tables of paper “Late Quaternary arc-parallel extension of the Kongur Extensional System (KES),Chinese Pamir” were discussed, main maps and drawings were drawn and some content was drafted.

3、The collection and experimental treatment process of bedrock fault samples of the Kongur Extensional System, Chinese Pamir, and the field sampling strategy of bedrock fault surface of Ancient Langshan Fault, Inner Mongolia and experimental treatment process of the samples were discussed. The first batch of samples needing nuclide separation and target preparation was determined (the concrete experiments were completed by Associate Researcher Han Fei). The samples from Langshan Mountain has extremely high content of feldspar and extremely low content of quartz (<5%). Professor Owen suggested total rock analysis of this batch of samples. If the particle size of quartz particles in the samples is small, a regular experiment process will be adopted, i.e.: etch by HF at first and then separate quartz by heavy liquid. HF may dissolve the quartz in a small particle size. He suggested separating quartz by heavy liquid and then shortening etching time of HF. Professor Marc Caffee of Purdue University suggested researching this batch of samples by adopting feldspar 36Cl dating technology, which is on trial of PRIME Lab. Professor Owen and Professor Marc Caffe both showed great interest in our ongoing Langshan Fault bedrock fault surface dating project and expressed wishes for cooperation in field study and indoor testing and analysis. After deliberation, we intend to invite the two professors to Langshan Fault, Inner Mongolia for field scientific investigation and sampling this November.

4、Researcher Chen Jie visited Cosmogenic Nuclide Dating Pretreatment and Ultra-Clean Laboratory, Optically Stimulated Luminescence Dating Laboratory, and Fission Track Dating Laboratory, Department of Geology, University of Cincinnati, and Purdue Rare Isotope Measurement Laboratory (PRIMELab). PRIME Lab is impressive. Laboratory Director Professor MarcCaffee showed us around an accelerator mass spectrometer in the basement of the physics building. The accelerator mass spectrometer occupies 2900m2 of floor space. It is one of two American laboratories that can carry out measurement of 10Be. 26Al. 14C. 36Cl. 41Ca, 129I and other radionuclides. At present, it can measure at least 2000 10Be samples a year. After upgrading, it may measure about 5000 samples a year. The laboratory has only 10 fixed staffs, postgraduates, doctoral students and other members and owns very rich experience in maintenance of large laboratory equipment. It is a laboratory with very high operating efficiency and very high opening level.

Fig. 1 PRIME Lab Director Professor Marc Caffee introduced the composition and

new development of the accelerator mass spectrometer

Fig. 2 Discuss with Professor Lewis Owen and Professor Marc Caffee about cosmogenic

nuclide technology of bedrock fault exposure surfaces

Through this visit, Researcher Chen Jie fulfilled predetermined missions with satisfaction and knew the latest international trends of cosmogenic nuclide dating, bedrock fault surface dating in particular. Chinese and American sides discussed a plan for further cooperation in bedrock fault surface dating.