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湘东南中生代花岗闪长质小岩体的岩石地球化学特征
引用本文:王岳军,范蔚茗,郭锋,李旭.湘东南中生代花岗闪长质小岩体的岩石地球化学特征[J].岩石学报,2001,17(1):169-176.
作者姓名:王岳军  范蔚茗  郭锋  李旭
作者单位:中国科学院长沙大地构造研究所,
基金项目:本项目得到G-1999-04-32-09、KZCX2-102和40002007的联合资助.
摘    要:湘东南花岗闪长质岩石以高K2O/Na2O,K2O+Na2O>6.0%为特征,属高钾钙碱性系列岩石,其形成主要受部分熔融作用制约;岩石稀土元素富集,铕负异常不明显,δEu=0.71~0.89;富集大离子亲石元素,Nb-Ta亏损,P、Ti或亏损或不亏损,具岛弧型岩浆作用微量元素分配模式,属板内钾质岩石,源区可能存在早期俯冲组分改造的岩石圈富集地幔组分,或是源于软流圈的岩浆与中下地壳混合作用的产物;其形成与该带中生代早期岩石圈的伸展-减薄作用有关。

关 键 词:花岗闪长质岩石  元素地球化学  岩石圈伸展-减薄作用  中生代  成因
修稿时间:2000年8月21日

Petrological and geochemical characteristics of Mesozoic granodioritic intrusions in Southeast Hunan Province, China
WANG YueJun,FAN WeiMing,GUO Feng and LI Xu.Changsha Institute of Geotectonics,Chinese Academy of Sciences,Changsh,China.Petrological and geochemical characteristics of Mesozoic granodioritic intrusions in Southeast Hunan Province, China[J].Acta Petrologica Sinica,2001,17(1):169-176.
Authors:WANG YueJun  FAN WeiMing  GUO Feng and LI XuChangsha Institute of Geotectonics  Chinese Academy of Sciences  Changsh  China
Abstract:Mesozoic granodioritic intrusions occurring in Southeast Hunan Province belong to high-K calc-alkaline series with high K2O/Na2O ratios and K2O+Na2O>6.0%. The chondrite-normalized REE patterns are characterized by LREE enrichment with weakly negative Eu anomalies (δEu=0.71~0.89), different from those of Mesozoic granitic plutons in which intensely negative Eu anomalies were observed. In the primitive mantle-normalized spidergrams, they are enriched in LILE and LREE with significant Nb-Ta depletion. Additionally, some of the rocks demonstrate a clear Ti and P depletion while it is inapparent for other samples. The geochemical characteristics of the Mesozoic granodioritic intrusions suggest the involvement of an enriched lithosphere mantle that had been modified by ancient recycling continental crust, or source mixing between asthenosphere-derived basalts and the lower/middle crust. Combining with the regional tectonic evolution, it is reasonable that the formation of Mesozoic granodioritic intrusions should be related to the early Mesozoic lithospheric extension and thinning.
Keywords:Granodioritic intrusions  Elemental geochemistry  Lithospheric extension or thinning  Mesozoic  Southeast Hunan province
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