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鲁西新太古代济宁群含铁岩系形成时代——SHRIMP U-Pb锆石定年
引用本文:王伟,王世进,刘敦一,李培远,董春艳,颉颃强,马铭株,万渝生.鲁西新太古代济宁群含铁岩系形成时代——SHRIMP U-Pb锆石定年[J].岩石学报,2010,26(4):1175-1181.
作者姓名:王伟  王世进  刘敦一  李培远  董春艳  颉颃强  马铭株  万渝生
作者单位:1. 中国地质科学院地质研究所,北京 100037;北京离子探针中心,北京 100037
2. 山东省地质调查院,济南,250013
3. 山东省物化探勘查院,济南,250013
基金项目:国家自然科学基金项目(40672127)、山东省地质系列图件编制与综合研究项目(1212010811029)、国土资源部重点项目(1212010711815)和北京离子探针中心基础研究项目联合资助
摘    要:济宁群以隐伏的地质体分布于华北克拉通鲁西地区,以往被划归古元古代。近年来在济宁群的钻探和地球物理研究中,发现存在较大规模条带状硅铁建造,其形成时代引起地学界极大关注。本文对济宁群变质碎屑沉积岩和长英质火山岩进行了锆石SHRIMP年龄测定。含砾绿泥绢云千枚岩的碎屑锆石年龄主要集中在~2.7Ga,可靠的最年轻碎屑锆石年龄为2.61±0.01Ga。变质长英质火山岩岩浆锆石年龄为2.56±0.02Ga。研究表明,济宁群形成于新太古代晚期,而不是以往认为的古元古代。华北克拉通条带状铁建造主要形成于新太古代晚期。济宁群在岩石组合、变质作用方面与鞍山、冀东以及五台地区同时代含硅铁建造的表壳岩系有差别,但是与本溪南芬铁矿的岩石组合有相似之处。这些可能为我国的隐伏太古宙BIF铁矿的研究与勘探提供了重要依据。

关 键 词:济宁群    新太古代    变质长英质火山岩    BIF    SHRIMP定年    鲁西    华北克拉通
收稿时间:2009/11/26 0:00:00
修稿时间:2010/3/30 0:00:00

Formation age of the Neoarchaean Jining Group(banded iron formation) in the western Shandong Province: Constraints from SHRIMP zircon U-Pb dating
Wang W,Wang SJ,Liu DY,Li PY,Dong CY,Xie HQ,Ma MZ and Wan YS.Formation age of the Neoarchaean Jining Group(banded iron formation) in the western Shandong Province: Constraints from SHRIMP zircon U-Pb dating[J].Acta Petrologica Sinica,2010,26(4):1175-1181.
Authors:Wang W  Wang SJ  Liu DY  Li PY  Dong CY  Xie HQ  Ma MZ and Wan YS
Affiliation:Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;Shandong Geological Survey Institute, Jinan 250013, China;Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;Shandong Provincial Academy of Geophysical and Geochemical Prospecting, Jinan 250013, China;Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China
Abstract:The Jining Group, located in the Jining area, western Shandong Province, is covered by young sediments and was once considered to be formed during the Early Palaeoproterozoic. Much attention was paid on the supracrustal rocks because of the discovery of a huge banded iron formation (BIF) through drilling and geophysical study in recent years. There were arguments about the formation age and origin of the BIF. This paper reports SHRIMP U-Pb zircon ages for the metamorphic rocks of the Jining Group. A pebble-bearing chlorite sericite phyllite sample has detrital zircons mainly of ~2.7Ga, with a grain with a believable age of 2.61±0.01Ga. An upper intercept age of 2.56±0.02Ga was obtained for magmatic zircons from meta-felsic volcanic rock. These indicate that the Jining Group was formed at the end of Neoarchaean, not Palaeoproterozoic, as thought before. In the North China Craton, BIFs were mainly formed during the Late Neoarchaean. The Jining Group is different in rock association and metamorphism from the BIF-bearing supracrustal rcoks in the Anshan, eastern Hebei and Wutai areas, but similar to ones in the Nanfen-Benxi area. This is important for the research and exploration of Archaean BIF-type iron deposits in China.
Keywords:Jining Group  Neoarchaean  Felsic volcanic rock  BIF  SHRIMP dating  Western Shandong Province  North China Craton
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