山东沂水太古宙蔡峪和大山岩体SHRIMP锆石年代学  

Emplacement and Metamorphism Ages of the Caiyu and Dashan Igneous Bodies, Yishui County, Shandong Province: Zircon SHRIMP Chronology

作　　者：沈其韩[1] 宋彪[1] 徐惠芬[1] 耿元生[1] 沈昆 

机构地区：[1]中国地质科学院地质研究所,北京100037 [2]山东省地质科学实验研究院,济南250013

出　　处：《地质论评》2004年第3期275-284,共10页Geological Review

基　　金：国家自然科学基金

摘　　要：本文首次报道了山东沂水蔡峪岩体和大山岩体锆石 SHRIMP 测年结果。结果显示,蔡峪岩体的侵位(或结晶)年龄为 2562±14 Ma(12个点的^(207)Pb/^(206)Pb 年龄平均值,95％置信度误差,下同),MSWD=4.5;大山岩体的侵位(或结晶)年龄为 2545±10 Ma(10个点),MSWD=6.1。两个岩体的岩相学、岩石化学和地球化学有所差别,但都属于该区同一岩体群,时代为新太古代。蔡峪岩体和大山岩体变质年龄分别为 2518±13 Ma和 2508±5Ma,它们曾分别遭受过麻粒岩相和角闪岩相变质作用,对应的是太古宙末期一次重要的变质构造事件。两个岩体中均含有数量不等、时代不同的古老残余锆石,其中在蔡峪岩体中获得 2.64～2.69 Ga、2.70 Ga、2.82 Ga、2.93 Ga和 3.07 Ga 5 组年龄,在大山岩体的残留锆石中获得 2.63～2.67 Ga和 2.82 Ga两组年龄。2.93 Ga和 3.07 Ga古老残余锆石的发现,进一步证明本区确有中太古亩地体的存在,这对探讨本区太古宙地壳演化具有重要意义。The Caiyu and Dashan igneous bodies are parts of the Neoarchaean granitoids, ie the Yishui complex, intruding in the Yishui Group complex abroad situated in the Yishui County, Shandong Province. The Caiyu and Dashan bodies are very important constitutes of the complex, and were suffered metamorphisms of granulite facies and amphibolite facies, respectively. The emplacement (or crystallization) ages of Caiyu and Dashan igneous bodies are 2562 ±14 Ma (95% confidence, MSWD = 4. 5) and 2545 ±10 Ma (95% confidence, MSWD =6. 1), the first reports of the zircon dating by SHRIMP technique. And the authors also yielded the metamorphism age of 2518±5 Ma in Caiyu body and 2508±5 Ma in Dashan body, similar to that obtained in other igneous in the complex, so the age may represent a very important metamorphic-tectonic event in the Late Archaean in this area. There are also residual zircons in the two igneous bodies, ie of 2. 64-2. 70 Ga, 2. 82 Ga, 2. 93 Ga and 3. 07 Ga in Caiyu body, and 2. 63 - 2. 67 Ga and 2. 82 Ga in Dashan body. The zircons of 2. 93 Ga and 3. 07 Ga is a new evidence that there is Mesoarchaean material in this region.

关 键 词：锆石 太古宙 SHRIMP 年代学 

分 类 号：P597[天文地球—地球化学]