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《Acta Petrologica Sinica》 2008-02
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Geochemistry of the Cenozoic Kamafugites from west Qinling and its constraint for the nature of magma source region.

DONG Xin ZHAO ZhiDan MO XuanXue YU XueHui ZHANG HongFe Li Bing DEPAOLO DJ State Key Laboratory of Geological Processes and Mineral Resources,and School of Earth Science and Mineral Resources,China University of Geosciences,Beijing 100083,China State Key Laboratory of Geological Processes and Mineral Resources,and Faculty of Earth Sciences,China University of Geosciences,Wuhan 430074,China Institute of Geophysical and Geochemical Exploration,Chinese Academy of Geological sciences,Langfang,Hebei 065000,China University of California,Berkeley,CA 94720,USA  
The Cenozoic kamafugites in Lixian County of West Qinling have lower SiO_2 and Al_2O_3 contents and high CaO,MgO, TiO_2 and K_2O+Na_2O compositions.The modal mineral assemblage composed mainly of olivine,clinopyroxene,nepheline,melilite, leucite and magnetite.The total REE composition (∑REE) ranges from 97.82×10~(-6) to 639.1×10~(-6).The rocks are enriched in LILE (such as Rb,Ba,K,and Sr) and high field strench elements (HFSE,such as Nb,Th,Ta,P,Zr and Hf),with negative Pb and Ti anomalies.The rocks have high ~(143)Nd/~(144)Nd ratios (0.512007~0.512130,ε_(Nd)=+3.4~+ 5.8) and lower Sr isotopic ratios (~(87)Sr/~(86)Sr=0.703374~0.704726 ).The ~(206)Pb/~(204)Pb,~(207)Pb/~(204)Pb,and ~(208)Pb/~(204) Pb ratios are in the ranges of 18.088~19.112, 15.476~15.626,and 38.071~39.680,respectively.These trace elements,and Sr-Nd-Pb isotopic compositions of the kamafugitic rocks show distinct geochemical features similar to those of OIB and suggest an evolvement of three geochemical end-members ( DM, HIMU,and EMII) into the magma source region.
【Fund】: 国家重点基础研究发展规划项目(2002CB412603);; 国家自然科学基金(40473020,40234052);; 中国地调局综合研究项目;; 中国科学院广州地球化学研究所同位素开放实验室基金;; 高等学校学科创新引智计划(B07011)资助
【CateGory Index】: P584
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