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.
出处
《中国地质》
CAS
CSCD
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
