摘要
东秦岭商丹地区的武关岩群是从原刘岭群北部分解出来的新的构造岩石地层单位，已获得其中变质基性火山岩Ｓｍ－Ｎｄ同位素年龄为（１３８２±３０）Ｍａ，原岩建造主体为碎屑沉积岩－碳酸盐岩－基性火山岩组合。变质基性火山岩及碎屑沉积岩的岩石地球化学特征表明，他们分别属于大陆板内拉斑玄武岩和大陆岛弧－活动陆缘型杂砂岩，因而武关岩群主体形成于中元古代晚期秦岭造山带拉张裂谷体制构造环境，于晋宁期（１０００～８００Ｍａ）的俯冲碰撞造山过程中拼贴于商丹构造带南侧。
The Wuguan group in the Shangnan Denfeng area of the East Qinling is a new tectono lithostratigraphic unit disintegrated from the north part of the original Liuling group (D).The protolith formation of the Wuguan group is detrital sedimentary rock carbonatite-basic volcanic rock assemblage.The metamorphic basic volcanic rock has been determined to have a Sm Nd isotopic geochronological age of (1 382±30)Ma.The characteristics of the lithogeochemistry shows that the metamorphic basic volcanic rock belongs to continental or intraplate tholeiite and the metamorphic detrital sedimentary rock belongs to graywacke of the continental island arc active continental margin.Therefore,the Wuguan group was mainly formed in the tectonic environment of the extensional rift machanism in the Qinling orogenic belt during the late mesoproterozoic era and was amalgamated with the southern side of the Shangdan structrual zone in the subduction collision orogenic processes during the Jinning cycle (1 000￣800 Ma).
出处
《西安工程学院学报》
1998年第1期1-5,9,共6页
Journal of Xi'an Engineering University
基金
地质矿产部区域地质调查填图项目
关键词
东秦岭
武关岩群
中元古代
地球化学
构造环境
East Qinling,Wuguan group ,Mesoproterozic,geochemistry,tectonic environment
