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华北克拉通胶东地区粉子山群碎屑锆石SHRIMPU-Pb定年
引用本文:谢士稳,王世进,颉颃强,刘守偈,董春艳,马铭株,刘敦一,万渝生.华北克拉通胶东地区粉子山群碎屑锆石SHRIMPU-Pb定年[J].岩石学报,2014,30(10):2989-2998.
作者姓名:谢士稳  王世进  颉颃强  刘守偈  董春艳  马铭株  刘敦一  万渝生
作者单位:中国地质科学院地质研究所, 北京离子探针中心, 北京 100037;山东省地质调查院, 济南 250013;中国地质科学院地质研究所, 北京离子探针中心, 北京 100037;中国地质科学院地质研究所, 北京离子探针中心, 北京 100037;中国地质科学院地质研究所, 北京离子探针中心, 北京 100037;中国地质科学院地质研究所, 北京离子探针中心, 北京 100037;中国地质科学院地质研究所, 北京离子探针中心, 北京 100037;中国地质科学院地质研究所, 北京离子探针中心, 北京 100037
基金项目:本文受国家973项目(2012CB416600)、中国地质科学院地质研究所基本科研业务经费(J1330)和中国地质调查局重点项目(12120113013700、1212010811033)联合资助。
摘    要:胶东是华北克拉通重要的变质基底出露区之一。对该区古元古代粉子山群和荆山群中碎屑锆石的年龄分布特征的研究,可以为胶东地区早前寒武纪演化提供重要依据。由于Pb丢失作用,前人仅在粉子山群中获得少量锆石谐和年龄。本文对粉子山群长石石英片岩中碎屑锆石进行了SHRIMP定年。52颗锆石的61个数据点分析,获得36个谐和年龄(不谐和度10%)。所有具谐和年龄的锆石都具有高的Th/U比值,大多显示明显的岩浆环带,原为岩浆成因。谐和锆石年龄分布在2033~3429Ma之间,主要峰值分别为~2.19Ga和~2.48Ga。该样品中还含有2颗年龄大于3.3Ga的锆石,位于谐和线上的2颗最年轻碎屑锆石的年龄为~2.08Ga。结合前人研究,可得出如下结论:1)粉子山群和荆山群原岩沉积时代可进一步限制在1.9~2.1Ga之间;2)粉子山群与荆山群的碎屑锆石年龄分布形式存在明显区别,指示其源区可能不同;3)胶东地区可能存在古太古代地壳物质。

关 键 词:碎屑锆石  SHRIMP  古元古代  古太古代  粉子山群  胶东
收稿时间:2014/1/18 0:00:00
修稿时间:2014/3/15 0:00:00

SHRIMP U-Pb dating of detrital zircons from the Fenzishan Group in eastern Shandong, North China craton
XIE ShiWen,WANG ShiJin,XIE HangQiang,LIU ShouJie,DONG ChunYan,MA MingZhu,LIU DunYi and WAN YuSheng.SHRIMP U-Pb dating of detrital zircons from the Fenzishan Group in eastern Shandong, North China craton[J].Acta Petrologica Sinica,2014,30(10):2989-2998.
Authors:XIE ShiWen  WANG ShiJin  XIE HangQiang  LIU ShouJie  DONG ChunYan  MA MingZhu  LIU DunYi and WAN YuSheng
Institution:Beijing SHRIMP Center, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;Shandong Institute of Geological Survey, Ji'nan 250013, China;Beijing SHRIMP Center, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;Beijing SHRIMP Center, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;Beijing SHRIMP Center, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;Beijing SHRIMP Center, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;Beijing SHRIMP Center, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;Beijing SHRIMP Center, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China
Abstract:An important exposure of Early Precambrian basement rocks in the North China craton is eastern Shandong, where the Paleoproterozoic Fenzishan and Jingshan groups are well preserved. Age histograms of detrital zircons from the Fenzishan and Jingshan groups can provide clues to understand the geological evolution of eastern Shandong. We report SHRIMP U-Pb zircon dating of a feldspar quartz schist from the Fenzishan Group. A total of 61 analyses were taken on 52 zircon grains and 36 analyses gave concordant ages (Discordance<10%). All the concordant zircons have high Th/U ratios and most show oscillatory zoning, indicating that they were derived from a magmatic source. They show age peaks at ~2.19Ga and ~2.48Ga, with two grains having Paleoarchean ages (>3.3Ga). Two youngest, concordant detrital zircons have 207Pb/206Pb ages of ~2.08Ga. Combined with early studies, some conclusions can be drawn as follows. 1) The formation age of the Fenzishan and Jingshan groups can be further limited in between 1.9 and 2.1Ga; 2) the detrital zircon age histogram of the Fenzishan Group is distinct from that of the Jingshan Group, suggesting the differences of their source regions; 3) Paleoarchean crustal material may occur in eastern Shandong.
Keywords:Detrital zircon  SHRIMP dating  Paleoproterozoic  Paleoarchean  Fenzishan Group  Eastern Shandong
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