Geological and Geochemical Characteristics of Early Cretaceous Mafic Dikes in Northern Jiangxi Province, SE China and Th

The development of Early Cretaceous mafic dikes in northern and southern Jiangxi allows an understanding of the geodynamic setting and characteristics of the mantle in southeast China in the Cretaceous. Geological and geochemical characteristics for the mafic dikes from the Wushan copper deposit and No. 640 uranium deposit are given in order to constrain the nature of source mantle, genesis and tectonic implications. According to the mineral composition,the mafic dikes in northern Jiangxi can be divided into spessartite and olive odinite types, which belong to slightly potassium-rich calc-alkaline lamprophyre characterized by enrichment in large ion lithophile elements (LILE) and light rare earth elements (LREE), large depletion in high strength field elements (HSFE) and with negative Nb, Ta and Ti anomalies, as well as 87Sr/86Sr ratios varying from 0.7055 to 0.7095 and 143Nd/144Nd ratios varying from 0.5119 to 0.5122.All features indicate that the magma responsible for the mafic dikes was derived mainly from metasomatic lithosphere mantle related to dehydration and/or upper crust melting during subduction. Differences in geochemical characteristics between the mafic dikes in northern Jiangxi and the Dajishan area, southern Jiangxi were also studied and they are attributed to differences in regional lithosphefic mantle components and/or magma emplacement depth. Combining geological and geochemical characteristics with regional geological history, we argue that southeast China was dominated by an extensional tectonic setting in the Early Cretaceous, and the nature of the mantle source area was related to enrichment induced by asthenosphere upwelling and infiltration of upper crust-derived fluids responding to Pacific Plate subduction.

作 者： Xie Guiqing HU Ruizhong MAO Jingwen LI Ruiling CAO Jinjian Jiang Guohao QI Liang   作者單位： Xie Guiqing(Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, Guizhou 550002;Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037;Faculty of Earth Sciences, China University of Geosciences, Beijing 100083)

HU Ruizhong,LI Ruiling,Jiang Guohao,QI Liang(Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, Guizhou 550002)

MAO Jingwen(Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037)

CAO Jinjian(Earth Science Department, Sun Yat-Sen University, Guangzhou, Guangdong 510275) 

刊 名： 地質(zhì)學(xué)報（英文版）  SCI 英文刊名： ACTA GEOLOGICA SINICA  年，卷(期)： 2005 79(2)  分類號：   關(guān)鍵詞：  

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