辽宁后仙峪硼矿区古元古代电气石岩：锆石特征及SHRIMP定年  

The Hyalotourmalites of Houxianyu Borate Deposit in Eastern Liaoning:Zircon Features and SHRIMP Dating

作　　者：张艳飞[1,2] 刘敬党 肖荣阁[3] 王生志[2] 王瑾 包德军 

机构地区：[1]辽宁工程技术大学,辽宁阜新123000 [2]辽宁省化工地质勘查院,辽宁锦州121000 [3]中国地质大学地球科学与资源学院,北京100083

出　　处：《地球科学（中国地质大学学报）》2010年第6期985-999,共15页Earth Science-Journal of China University of Geosciences

基　　金：国家自然科学基金项目(No.40073013);辽宁省国土资源厅基金项目(No.20050142)

摘　　要：为了确定辽东硼矿含硼岩系中电气石岩的形成时代,对后仙峪硼矿区电气石岩首次进行了锆石SHRIMP U-Pb年龄测定.阴极发光图像显示,锆石具核-边结构,锆石核部多具振荡环带,为高Th/U值的岩浆碎屑锆石;锆石边部无明显结构变化,为变质成因.岩浆碎屑锆石和变质锆石的年龄分别为2171～2175Ma和1894～1906Ma.结合野外地质和岩相学研究,认为后仙峪硼矿区电气石岩原岩为古元古代克拉通裂谷环境中源于地壳再循环组分混染的亏损地幔的中酸性岩浆活动引发海底喷流作用的产物,其原岩形成时代为古元古代中期(2171～2175Ma),并在稍后(1894～1906Ma)遭受变质作用叠加改造.SHRIMP zircon U-Pb dating results are firstly reported for the hyalotourmalites in Houxianyu borate deposit in order to determine its formation time.The zircons commonly have core-rim structures.Most cores show oscillatory zoning in CL and plane polarized light images,suggesting a magmatic detrital origin.The zircon without distinct structural change may represent a metamorphic origin.Magmatic detrital zircons and metamorphic zircons from three samples yield ages of 2171-2175 Ma and 1894-1906 Ma,respectively.Combined with geology and lithology,the protolith of hyalotourmalite is concluded to be the product of exhalation of submarine hot water caused by the magmatic activity with the magma derived from the depleted mantle source with crustal contamination in the cratonic rift environment,which occurred in the middle Palaeoproterozoic（2171-2175 Ma） and underwent the late metamorphism during a period of 1894-1906 Ma.

关 键 词：电气石岩 SHRIMP 后仙峪硼矿区 古元古代 地质年代. 

分 类 号：P597[天文地球—地球化学]