华北克拉通鲁西地区早前寒武纪表壳岩系重新划分和BIF形成时代  

Redefinition of Early Precambrian supracrustal rocks and formation age of BIF in western Shandong,North China Craton

作　　者：万渝生[1] 刘敦一[1] 王世进[2] 焦秀美 王伟[4] 董春艳[1] 颉颃强[1] 马铭株[1] 

机构地区：[1]中国地质科学院地质研究所北京离子探针中心,北京100037 [2]山东省地质调查院,济南250013 [3]山东省地矿局,济南250013 [4]中国科学院地质与地球物理研究所,北京100029

出　　处：《岩石学报》2012年第11期3457-3475,共19页Acta Petrologica Sinica

基　　金：国家973项目(2012CB416601);国家自然科学基金项目(41172172);中国地质调查局重点项目(1212010811033;1212011120151)联合资助

摘　　要：鲁西花岗-绿岩带是华北克拉通早前寒武纪变质基底典型代表。表壳岩系包括泰山岩群、孟家屯岩组和济宁岩群。其中,泰山岩群是鲁西地区规模最大的表壳岩系,曾认为形成于新太古代早期,而济宁岩群曾认为形成于古元古代。根据野外地质和表壳岩系及相关岩石的锆石SHRIMP U-Pb定年,本文对表壳岩系形成时代进行了重新划分。1)新太古代早期(2.70～2.75Ga)表壳岩系,包括原泰山岩群的雁翎关岩组和柳行岩组下段的大部分及孟家屯岩组。2)新太古代晚期(2.525～2.56Ga)表壳岩系,包括原泰山岩群的山草峪岩组、柳行岩组上段和下段的一部分及济宁岩群。它们在岩石组合、变质变形等方面存在明显区别,BIF形成于新太古代晚期。这是华北克拉通迄今唯一分辨出新太古代早期和晚期表壳岩系的地区。Western Shandong is one of the typical areas in the North China Craton where granite-greenstone belts were well developed. Supracrustal rocks in western Shandong include the Taishan Group （including the Yanlingguan, Shancaoyu and Liuhang formations）, Jining Group and Mengjiatun Formation. The Taishan Group and Jining Group were once considered as being formed during the Early Neoarchean and Late Paleoproterozoic, respectively. Based on field observation and SHRIMP U-Pb zircon dating, we redefine the times of deposition of supracrustal rocks in western Shandong： 1） Supracrustal rocks deposited during the Early Neoarchean （2.75～2.70Ga）, including the Yanlingguan Formation and most of the lower part of the Liuhang Formation and the Mengjiatun Formation; 2） supracrustal rocks deposited during the Late Neoarchean （2.55～2.525Ga）, including the Shancaoyu Formation, the Jining Group, and the upper part and some of the lower part of the Liuhang Formation. They are different in rock association, metamorphism and deformation, with the banded iron formation belonging to the Late Neoarchean supracrustal rock. Western Shandong is the only terrane in the North China Craton where both early and late Neoarchean supracrustal rocks have been identified.

关 键 词：BIF SHRIMP定年 新太古代 鲁西 华北克拉通 

分 类 号：P597[天文地球—地球化学]