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| 秦岭造山带早中生代花岗岩成因及其构造环境 | |
| 引用本文： | 张成立,王涛,王晓霞.秦岭造山带早中生代花岗岩成因及其构造环境[J].高校地质学报,2008,14(3). |
| 作者姓名： | 张成立 王涛 王晓霞 |
| 作者单位： | 1. 西北大学,大陆动力学国家重点实验室,西北大学,地质系,西安710069 2. 中国地质科学院,地质研究所,北京,100037 3. 中国地质科学院矿产资源研究所,北京,100037 |
| 基金项目： | 国家自然科学基金，中国石油化工集团公司资助项目 |
| 摘 要： | 秦岭早中生代花岗岩以准铝到过铝质中钾-高钾钙碱性岩石为主.它们具有相对富集LILE,LREE,贫化HFSE和Nb,Ta不同程度亏损的后碰撞花岗岩的地球化学特征,部分花岗岩显示了埃达克质(或高Sr、低Y)花岗岩和I-A型过渡的环斑结构花岗岩的特征.综合分析这些花岗岩体的构造和岩石地球化学特征,并结合与其同时代煌斑岩和基性岩脉构成的双峰式岩浆作用特点,认为秦岭早中生代花岗岩主要形成于后碰撞环境.其中,埃达克质花岗岩形成较早,与后碰撞早期环境的地壳增厚紧密相关,其后产出的大量正常块状花岗结构的花岗岩类主要形成于后碰撞阶段拆沉作用发生的伸展阶段,最终侵位的高分异富钾花岗岩和环斑花岗岩标志着秦岭已进入后碰撞晚期阶段. |
| 关 键 词： | 花岗岩 岩石地球化学 早中生代 后碰撞 秦岭造山带 |
Origin and Tectonic Setting of the Early Mesozoic Granitoids in Qinling Orogenic Belt |
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| ZHANG Cheng-li,WANG Tao,WANG Xiao-xia.Origin and Tectonic Setting of the Early Mesozoic Granitoids in Qinling Orogenic Belt[J].Geological Journal of China Universities,2008,14(3). | |
| Authors: | ZHANG Cheng-li WANG Tao WANG Xiao-xia |
| Abstract: | The Early Mesozoic granitoids in Qinling Mts are characterized by the metaluminous to peraluminous and moderate- to high-K calc-alkaline rocks with enrichment in LILE and LREE and poorness in HFSE, as well as relative depletion in Nb and Ta, showing the geochemical features similar to those of post-collisional granitoids. Some of them are adakite-like and rapakivi- textured granitoids. The adakite-like granitoids display high Sr and low Y contents, and rapakivi-textured granitoids show transitional geochemical characters from I- to A-type granites. The structure and geochemistry of these granitic intrusions, together with the bimodal features of the coeval lamprophyres and mafic dykes, suggest that the Early Mesozoic granitoids in Qinling Mts region were formed in a post-collisional setting. The early adakite-like granitoids were formed under the thickened crust during the early post-collision period. The large numbers of normal massive granitoids were produced under the crustal extension environment after delamination in Qinling Mts region, and the occurrence of rapakivi-textured and high differentiated granitoids indicates that Qinling region had evolved into the late stage of post-collisional environment. |
| Keywords: | granitoids petro-geochemistry Early Mesozoic post-collisional environment Qinling orogenic belt |
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