Helium and carbon isotope variations in Liaodong Peninsula, NE China

Xu, S., Zheng, G., Wang, X., Wang, H., Nakai, S.’i. and Wakita, H. (2014) Helium and carbon isotope variations in Liaodong Peninsula, NE China. Journal of Asian Earth Sciences, 90, pp. 149-156. (doi: 10.1016/j.jseaes.2014.04.019)

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Abstract

Chemical and C–He isotopic compositions have been measured for N2-rich hydrothermal gases from the Liaodong (abbreviation of East Liaoning Province) Peninsula from which the oldest crustal rocks in China with ⩾3.8 Ga outcrop. With the exception of one sample containing tritogenic 3He and atmospheric 4He in Liaoyang, the observed 3He/4He ratios from 0.1 Ra to 0.7 Ra indicate 1–8% helium from mantle, 92–98% from crust and 0.1–0.8% from atmosphere. Despite the lack of Quaternary volcanism, such 3He/4He ratios suggest, together with geophysical evidences, the existence of intrusive magmas that contain mantle helium and heat within the Liaodong middle-lower crust. The 3He/4He ratios are high along the NE-trending Jinzhou faults and gradually decrease with the increase of distance from the faults. Such a spatial distribution suggests that the mantle helium exsolves from magmatic reservoir in the middle-lower crust, becomes focused into the root zones of Jinzhou faults, and subsequently traverses the crust via permeable fault zones. When transversely migrated by groundwater circulation in near surface, mantle helium with high 3He/4He ratio may have been further diluted to the observed values by addition of radiogenic helium produced in the crust. This pattern shows strong evidence that the major faults played an important role on mantle-derived components transport from mantle upwards.

Item Type:Articles
Additional Information:This study was partly supported by the Natural Science Foundation of China (Nos. 41273112 and 41020124002).
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Xu, Dr Sheng
Authors: Xu, S., Zheng, G., Wang, X., Wang, H., Nakai, S.’i., and Wakita, H.
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Journal of Asian Earth Sciences
Publisher:Elsevier
ISSN:1367-9120
Published Online:09 May 2014

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