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The Electron Spin Resonance Laboratory 

Using electron spin resonance (ESR) to date the age of rocks is a new approach. The effective time span of this dating method is around thousands to a million years, which is good for identifying the last activation of the fault.
Through the decay of natural radioactive elements in rocks, free electrons and holes will be produced in crystals.  The amount of the electrons and holes to the volume of the crystal is referred to as "paramagnetic center concentration (density?)".  Samples are collected when the paramagnetic center concentration is not saturated. With laboratory simulation of field environment under different doses of neutron irradiation, the signal intensity of electron spin resonance (ESR) is measured in samples. With additional mathematical calculations, the age of the sample can be obtained.
To date the activation of the fault using ESR is based on the fact that the original ESR signal in the quartz will be erased due to the faulting induced heat and pressure. Under the bombardment of natural radioactive elements, the ESR clock will be reset.  Therefore, identifying the reset of ESR in quartz will give the timing of the last slip of the fault.
The main test objects the ERS include stalactite, stalagmite, shell, bone fossils, quartz and feldspar separated from the fault gouge, and vein minerals in fault zones such as gypsum, calcite, quartz and etc.
Projects undertaken by the Laboratory in recent years include "New tectonics and the impact on the environment differentiation along the eastern and western geomorphologic boundaries of China" as a key research project of the Ministry of Land and Resources, "Cenozoic basins and paleomagnetic study in northern Tibetian Plateau" as the National 973 Project, "New tectonics and the current activity in the major blocks in western China", "New tectonic investigation and research on the Tancheng-Lujiang fault zone" and " New tectonic activity investigation and geological disaster assessment in the upper Yellow River" as the Geological Survey Project, "Geological disaster assessment, active fault investigation, geostress measurement and engineering application along the Qinghai-Tibet Railway" as the national key project.

The Electron Spin Resonance Laboratory

y-axis: ESR signal intensity  x-axis: irradiation dose
The response curve of the signal intensity of gypsum vein to the dose from Tibetian area
This graph shows a positive relationship between the ESR signal and the the neutron irradiation dose.

y-axis: signal intensity  x-axis: time interval
ESR test pattern of gypsum vein samples in Tibet area






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