He and Ar isotopes in mantle megacryst minerals from Nushan and Yingfengling in Southeast China
He and Ar isotopes in mantle megacryst minerals from Nushan and Yingfengling in Southeast China
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DOI：
10.1007/bf03183972
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发表时间：
2003-08
影响因子：
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通讯作者：
Shijin Xu;Z. Fang;T. Matsumoto;J. Matsuda;M. Yasuda;Jinhai Yu;Rucheng Wang;Wen-zhao Liu
中科院分区：
文献类型：
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作者：
Shijin Xu;Z. Fang;T. Matsumoto;J. Matsuda;M. Yasuda;Jinhai Yu;Rucheng Wang;Wen-zhao Liu
采用真空破碎萃取技术，测定了地幔包体中巨晶矿物的He、Ar同位素组成。所用样品分别为安徽女山和广东鹰峰岭新生代碱性玄武岩中的单斜辉石、石榴石和钛铁矿，代表了中国东南大陆边缘上地幔的物质。结果表明，3 He/4 He比值为7.99 ~ 8.58 Ra，符合MORB型地幔的特征比值，40 Ar/39 Ar比值为313 ~ 909，表明MORB型地幔与空气氩的二元混合。这可能反映了大洋沉积物中吸附的空气氩因大洋板块俯冲作用而进入大陆边缘地幔。首次报道了钛铁矿巨晶中含有丰富的流体包裹体和地幔捕虏体中的稀有气体。
He and Ar isotopic compositions of megacrystal minerals from mantle xenoliths were measured by the technique of vacuum crushing extraction. The used samples were clinopyroxene, garnet and ilmenite in Cenozoic alkaline basalts, which were from Nushan in Anhui Province and Yingfengling in Guangdong Province, respectively, and represented materials from the upper mantle in the continental margin of SE China. The results show3He/4He ratios of 7.99 Ra to 8.58 Ra, consistent with the characteristic ratios of the MORB-type mantle.40Ar/39Ar ratios vary from 313 to 909, suggesting a binary mixing between the MORB-type mantle and air argons. This may reflect the incorporation of the air argon absorbed in oceanic sediments into the mantle beneath the continental margin by subduction of oceanic plate. This study presents the first report that ilmenite megacrysts contain abundant fluid inclusions and noble gases in the mantle xenoliths.