摘要
为了探讨桂东北中生代构造演化特征,文章对桂东北姑婆山复式花岗岩体及其闪长质暗色包体进行了详细的岩石学、年代学和地球化学研究。年代学测试结果表明,闪长质暗色包体的形成时代为142±1 Ma,为首次在本区识别出了早白垩世闪长质暗色包体。元素地球化学分析结果显示闪长质暗色包体的SiO_(2)含量为55.66%~56.72%,MgO为2.26%~2.30%,Fe_(2)O__(3) T为10.43%~10.77%;寄主花岗岩样品的SiO_(2)含量为68.33%~68.67%,Fe_(2)O__(3) T为3.73%~3.89%,MgO为0.60%~0.64%,具有较高的10000Ga/Al比值和Zr+Nb+Ce+Y含量,整体表现出A型花岗岩的地球化学特征。寄主岩石和暗色包体均富含大离子亲石元素和高场强元素。综合上述数据,表明闪长质暗色包体是岩浆混合作用的产物,其形成与华南晚中生代岩石圈的伸展减薄作用有关;结合相关区域地质资料,表明华南中生代时期的岩石圈伸展减薄呈幕式发生,从而导致华南发育多期次、多阶段的岩浆作用。
In order to figure out the Mesozoic tectonic evolution of the northeastern Guangxi,this paper presented detailed petrological,chronological and geochemical data on the Guposhan composite rock mass and its dioritic enclaves.The chronological results show that the formation age of the dioritic enclaves is 142±1 Ma,for the first time to identify Early Cretaceous dioritic enclaves in this area.Elemental geochemical analysis results show that the contents of SiO_(2),MgO and Fe_(2)O_(3) T of the dioritic enclaves are 55.66%-56.72%,2.26%-2.30%and 10.43%-10.77%,respectively;the contents of SiO_(2),MgO and Fe_(2)O_(3) T of the host granite sample are 68.33%-68.67%,0.60%-0.64%and 3.73%-3.89%,respectively.The granites are characterized by high 10000*Ga/Al ratios and Zr+Nb+Ce+Y contents,similar with those of A-type granite.Both the host rock and the dioritic enclave are enriched in large ion lithophile elements and high field strength elements.The above data indicate that the dioritic enclaves are produced by magmatic mixing,and their formation is related to extension and thinning of the lithosphere in the Late Mesozoic.Together with regional geological data,it is suggested that the Mesozoic extension of the lithosphere in South China was episodic,which led to the development of multi-stage magmatism in South China.
作者
刘风雷
周云
史水平
冯佐海
蔡永丰
付伟
赵锴
LIU Fenglei;ZHOU Yun;SHI Shuiping;FENG Zuohai;CAI Yongfeng;FU Wei;ZHAO Kai(Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration,Guilin University of Technology,Guilin 541004,China;Zhejiang Nonferrous Geological Exploration Group Co.,Ltd,Shaoxing 321000,China;Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resources in Guangxi,Guilin University of Technology,Guilin 541004,China;Earthquake Agency of Guangxi Zhuang Autonomous Region,Nanning 530022,China)
出处
《高校地质学报》
CAS
CSCD
北大核心
2023年第3期455-470,共16页
Geological Journal of China Universities
基金
广西重点研发计划项目(桂科AB22035045)
广西自然科学基金项目(2018GXNSFBA281069,2020GXNSFGA297003)
国家自然科学基金项目(42072259)联合资助。
