秦岭佛坪变质结晶岩系年龄和物质组成特征——SHRIMP锆英石U-Pb年代学和全岩Sm-Nd年代学数据  

Age and material composition of the Foping metamorphic crystalline complex in the Qinling Mountains : SHRIMP zircon U-Pb and whole-rock Sm-Nd geochronology

作　　者：张宗清[1] 宋彪[1] 唐索寒[1] 张寿广[1] 杨永成 王进辉[1] 

机构地区：[1]中国地质科学院地质研究所,北京100037 [2]陕西省地勘局区调研究院,陕西咸阳712000

出　　处：《中国地质》2004年第2期161-168,共8页Geology in China

基　　金：国家自然科学基金项目(40072071);中国地质调查局地质大调查项目(200313000057)资助

摘　　要：秦岭是长期多阶段发展的复杂大陆碰撞造山带。本文报道了位于造山带中部佛坪变质结晶杂岩系的SHRIMP锆英石U-Pb年龄和全岩Sm-Nd年龄同位素分析结果。变质岩SHRIMP锆英石U-Pb年龄十分复杂,除有少量太古宇形成的锆英石外,还存在大量元古宇至显生宇的锆英石,并在2000Ma,1200Ma,800Ma,400Ma,200Ma左右形成峰期。片麻岩Nd模式年龄tDM1372～2081Ma。佛坪变质结晶岩系主体可能形成于古元古代,年龄2000Ma左右。在后期强烈地质作用中有少量地幔物质加入。岩系形成于新太古代的意见笔者没有得到证实。秦岭造山带中部可能存在或存在过太古宙结晶基底岩石。The Qinling is a complex continental collisional orogenic belt resulting from long-continued, multi-stage development. This paper reports the results of isotopic analyses of the SHRIMP zircon U-Pb ages and whole-rock Sm-Nd ages for the Foping metamorphic crystalline complex in the central part of the orogenic belt. The SHRIMP zircon U-Pb ages are very complex; except for small amount of Archean zircon, there are also significant amounts of Proterozoic to Phanerozoic zircon.The metamorphic peaks occurred at -1 200, 800, 400 and 200 Ma. Gneiss has a Nd model age tDM of 1 372-208 Ma. The main part of the Foping metamorphic crystalline rock series possibly formed in the Paleoproterozoic, with an age of -2 000 Ma. In the subsequent strong geological processes, a small amount of mantle material was introduced. The view of the formation of the rock series in the Neo-archean has not been verified by the authors. Archean crystalline basement rocks may occur or may have occurred in the central part of the Qinling orogenic belt.

关 键 词：秦岭 大陆碰撞造山带 变质结晶岩系 年龄 SHRIMP锆英石U-Pb年龄 全岩Sm-Nd年代学 同位素年代学 

分 类 号：P597[天文地球—地球化学]