摘要
采用LA—ICP-MS锆石U—Pb定年分析方法，对辽南海城斜长角闪岩进行了年代学测定。锆石的阴极发光图像显示其内部结构均匀，呈条纹状均匀吸收，具有典型的基性岩中锆石的特点，结合其高的Th／U比值（0．55～4．34），表明了岩浆成因的特点。16颗锆石的LA-ICP—MS U—Pb定年结果显示，^207Pb／，^206Pb年龄为2001～2159Ma，16个点的加权平均年龄为（2059±22）Ma。这一结果表明，辽南海城斜长角闪岩原岩的形成时代为古元古代。区域地质和同位素年代学新资料表明，海城地区斜长角闪岩与吉南和辽南、胶北地区的火山岩和花岗质岩石共同构成了古元古代双峰式的火成岩岩石组合，暗示古元古代辽南地区强烈伸展环境的存在。
By method of LA-ICP-MS zircon U-Pb dating, Haicheng amphibolite in southern Liaoning was determined in chronology. The zircon cathodoluminescence （CL） images displayed its homogeneous internal structure with a typical zoning absorption, similar to those from basic igneous rocks. Together with high Th/U ratios （0.55--4.34）, the results show the characters of magmatic origin. LA-ICP-MS zircon U-Pb dating indicates that ^207Pb/^206Pb ages forselected 16 grains ranging from 2 001 Ma to 2 159 Ma, and weighted mean age is （2 059 ± 22） Ma; Which indicates the protolith of Haicheng amphibolite was formed in the Paleoproterozoic. Based on regional geology and some new isotopic data, the Haicheng amphibolite, with volcanite and granitoids from southern Liaoning, southern Jilin andnorthern Shandong, constitutes a Paleoproterozoic bimodal igneous rock association, implying the existence of strongly extensional environment in southern Liaoning in the Paleoproterozoic.
出处
《世界地质》
CAS
CSCD
2007年第4期391-396,408,共7页
World Geology
基金
国家自然科学基金项目(40472033)
