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| Geochemical characteristics of soil gas in the Yanhuai basin, northern China |
| Ying Li1, Jianguo Du1, Fukuan Wang2, Xiaocheng Zhou1, Xiaodong Pan3, Ruqing Wei4 |
1 Institute of Earthquake Science, China Earthquake Administration, Beijing 100036, China
2 Inner Mongolia Corporation Ltd. of Geologic Engineering, Hohhot 010051, China
3 Earthquake Administration of Jilin Province, Changchun 130022, China
4 Liaocheng Seismology Hydro-chemistry Test Station, Liaocheng 252000, China
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Abstract The geochemical backgrounds and origins of soil gases in the Yanhuai basin are discussed based on the regional seismogeological data and concentrations of Rn, Hg, CO2 , H2, He and CH4 in soil gas measured at 422 investigating sites in field during September to October 2007. The geochemical background values of Rn, Hg, CO2 , H2, He and CH4 are (8105.8±5937.4) Bq/m3, (9.7±5.8) ng/m3, (395.9±35.3)×10-6, (4.0±2.3)×10-6, (15.9±10.4)×10-6 and (12.7±8.1)×10-6, respectively. The geochemical backgrounds of the soil gases are higher in the eastern part of the Yanhuai basin. The main factors affecting the gasgeochemical backgrounds are gaseous origins, structure of the crust, faults, stratum and microbe activity. The higher values of gasgeochemical backgrounds in the eastern part are attributed to the existence of low-velocity zones in the upper crust, stronger tectonic activity and more contributions of Hg and He derived from the deep-earth and Rn originated from granite, corresponding to stronger seismic activity. The results can be applied to identifying seismic precursor from monitoring data of gases in the studied area.
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Received: 15 May 2008
Published: 10 February 2009
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| Fund:Science Fund of Institute of Earthquake Science, China Earthquake Administration (02076902-32); Joint Seismological Science Foundation of China (B07002); National Natural Science Foundation of China (40703013) |
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Corresponding Authors:
Jianguo Du
E-mail: jianguodu@hotmail.com
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