摘要
秦岭造山带中的新元古代岩浆岩带分为南、北两带,北带主要发育于秦岭岩群分布区,由新元古代早期花岗质岩石组成,由于受到强烈变质、变形,构成了NW向花岗片麻岩体群。岩石总体化学特征反映一种挤压性的动力学背景,其形成时代集中在95 5～84 4 Ma。南带分布于陡岭岩群分布区、南秦岭及“勉略构造带”以南的汉南一带,由双峰式火山岩、基性辉长岩侵入体及板内花岗质侵入岩组成。与北带花岗质岩石所受到的强烈变质、变形形成鲜明对比,除邻近构造带的岩体外,它们变质、变形程度较弱,以弱片麻状至块状构造为主,形成时代介于810～710 Ma之间,反映大陆地壳处于减薄的伸展机制。这条岩浆岩带的发育,显示秦岭造山带南部曾存在一条新元古代中期裂谷带,它是劳伦、澳大利亚和塔里木—扬子等大陆初始裂解的产物,也是古太平洋形成的前兆。
The magmatic belts of the Neoproterozoic in the Qinling Orogen can be divided into the North and South ones. The north belt is mainly developed within the distributed area occupied by the Qinling supracrusts. It is made up of the early Neoproterozoic granitoids, which are affected by strong metamorphism and deformation. The plutonic rocks demonstrate arc-related geochemical characteristics and formed between 950~840Ma. The south one is distributed in the south Qinling Range and around Hannan area with near EW direction. The magmatic belt is composed of bi–modal volcanics, gabbro bodies, basic dyke swarms, A–type granite and plutons within plates. In contrast to strong deformation of the plutons in the north belt, the rocks show weak deformation with dominant massive and weak gneiss structure, and formed between 810~710Ma. The belt took place a extension tectonic regime, which is response to initial rifting among Australia, Tarim–Yangzi and Laurentia continents in the western Rodinia.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2005年第2期165-173,共9页
Acta Geologica Sinica
基金
国家自然科学基金重点项目 (编号 40 0 3 2 0 10 -C)
中国地质调查综合研究项目 (编号 2 0 0 113 90 0 0 70 )资助的成果
