摘要
Following the researches of helium isotopic compositions in mantle-derived xenoliths in eastern China, this study reported noble gas abundances and isotopic compositions of mantle-derived xenoliths from Kuandian of Liaoning Province, Huinan of Jilin Province and Hannuoba of Hebei Province. Compared with the middle ocean ridge basalt (MORB) and other continental areas, mantle-derived xenoliths in NE China are characterized by slightly low noble gas abundances, 3He/4He equivalent to or lower than that of MORB, 40Ar/36Ar lower than that of MORB, 38Ar/36Ar and Ne-Kr-Xe isotopic ratios equivalent to those of atmosphere. These results indicate the heterogeneity of subcontinental lithospheric mantle beneath northeastern China, that is, a MORB reservoir-like mantle beneath Kuandian and an enriched/metasomatized mantle beneath Huinan. Low 40Ar/ 36Ar ratios in the three studied areas may imply that a subducted atmospheric component has been preserved in the subcontinental lithospheric mantle.
Following the researches of helium isotopic compositions in mantle-derived xenoliths in eastern China, this study reported noble gas abundances and isotopic compositions of mantle-derived xenoliths from Kuandian of Liaoning Province, Huinan of Jilin Province and Hannuoba of Hebei Province. Compared with the middle ocean ridge basalt (MORB) and other continental areas, mantle-derived xenoliths in NE China are characterized by slightly low noble gas abundances, 3He/4He equivalent to or lower than that of MORB, 40Ar/36Ar lower than that of MORB, 38Ar/36Ar and Ne-Kr-Xe isotopic ratios equivalent to those of atmosphere. These results indicate the heterogeneity of subcontinental lithospheric mantle beneath northeastern China, that is, a MORB reservoir-like mantle beneath Kuandian and an enriched/metasomatized mantle beneath Huinan. Low 40Ar/ 36Ar ratios in the three studied areas may imply that a subducted atmospheric component has been preserved in the subcontinental lithospheric mantle.
基金
This work was supported by the National Climbing Program (Grant No. 95-P-39).
