Japan Geoscience Union Meeting 2014

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International Session (Oral)

Symbol S (Solid Earth Sciences) » S-CG Complex & General

[S-CG09_28PM1] Deep Carbon Cycle

Mon. Apr 28, 2014 2:15 PM - 4:00 PM 315 (3F)

Convener:*Yuji Sano(Division of Ocean and Earth Systems, Atmosphere and Ocean Research Institute, University of Tokyo), Eiji Ohtani(Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University), Hiroyuki Kagi(Geochemical Laboratory, Graduate School of Science, University of Tokyo), Chair:Yuji Sano(Division of Ocean and Earth Systems, Atmosphere and Ocean Research Institute, University of Tokyo), Hiroyuki Kagi(Geochemical Laboratory, Graduate School of Science, University of Tokyo)

2:15 PM - 2:33 PM

★ [SCG09-04] 3He/4He distributions near the Tancheng-Lujiang faults zones, at Liaoning, NE China

*Guodong ZHENG1, Sheng XU1, Shun'ichi NAKAI2, Hiroshi WAKITA3, Xianbin WANG1 (1.Institute of Geology and Geophysics, Chinese Academy of Sciences, 2.Earthquake Research Institute, The University of Tokyo, 3.Faculty of Science, The University of Tokyo)

Keywords:helium, fault, china, isotopes

Chemical and isotopic compositions have been measured for natural gases near the NNE trending Tancheng-Lujiang Fault Zones (TLFZ) at Liaoning Province, NE China, including hydrocarbon-rich natural gases from Liaohe basin (121oE-124oE, 40.5oN-42oN) and nitrogen-rich geothermal gases from the eastern Liaoning Mountains. Observed 3He/4He ratios show two orders of magnitude variability from 0.04 RA to 3.5 RA where RA is atmospheric 3He/4He ratio 1.4x10-6. The following geochemical observations are noted: (1) at Liaohe basin and the adjacent geothermal fields, 3He/4He ratios show positive correlations with He contents; (2) in Liaohe basin, the 3He/4He ratios are largely variable (0.04-3.5 RA), generally high in the eastern depress and low in the western depress; (3) in the eastern Liaoning mountains, geothermal 3He/4He ratios are generally low (0.2-0.7 RA) but have closed relationship with distribution of seismic activity and heat flow; and (4) overall there is a spatial distribution pattern that 3He/4He ratios gradually decrease from the TLFZ eastwards and westwards. Such a 3He/4He distribution feature shows strong evidence that the TLFZ played an important role on mantle-derived helium transform from mantle upwards and groundwater circulation along the deep major faults.