以地质事件性质讨论华北克拉通古元古界典型地层时代--以五台地区滹沱群为例  

Discussing the age of the typical Paleoproterozoic stratigraphy in the North China Craton based on geological events:A case study of the Hutuo Group in Wutai Mountains

作　　者：杜利林[1] 杨崇辉[1] 宋会侠[1] 刘平华[1] 任留东[1] 张文[1] DU Li-lin;YANG Chong-hui;SONG Hui-xia;LIU Ping-hua;REN Liu-dong;ZHANG Wen(Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China)

机构地区：[1]中国地质科学院地质研究所,北京100037

出　　处：《岩石矿物学杂志》2023年第6期767-787,共21页Acta Petrologica et Mineralogica

基　　金：中国地质调查局项目(DD20230209,DD20221649,DD20190003);国家自然科学基金(42372237,41772191,41572175,41972205,41172171)。

摘　　要：从滹沱群底部四集庄组不同的分布区选择了1件正长花岗斑岩、1件似斑状二长花岗岩砾石及1件侵入于蒋村四集庄组的正长花岗斑岩,进行了锆石U-Pb-Hf同位素分析。获得正长花岗斑岩和似斑状二长花岗岩砾石的锆石207Pb/206Pb加权平均年龄分别为2507±14 Ma和2519±35 Ma,推断花岗岩砾石的物源可能为五台新太古代晚期峨口花岗岩和兰芝山花岗岩;侵入于四集庄组的正长花岗斑岩锆石207Pb/206Pb年龄为2157±15 Ma。结合四集庄组、五台地区高凡群火山岩年龄结果和华北克拉通2.2~2.0 Ga地质事件的性质,认为滹沱群底界可能为2.2~2.18 Ga,顶界时代约为2.0 Ga,其沉积对应一期强烈的陆内裂谷伸展过程。新太古代花岗岩砾石和古元古代花岗岩锆石Hf同位素结果指示,五台地区新太古代早期出现明显的地壳生长,新太古代晚期也存在地壳增长。From the different distribution areas of the Sijizhuang Formation at the bottom of the Hutuo Group,one sample of orthoclase granite-porphyry and one sample of porphyritic monzogranite gravels were selected,along with one sample of orthoclase granite-porphyry intruded into the Sijizhuang Formation in Jiangcun area.Zircon U-Pb-Hf isotope analysis was conducted.The weighted average ages of the orthoclase granite-porphyry and the porphyritic monzogranite gravel were determined to be 2507±14 Ma and 2519±35 Ma,respectively,indicating that the sources of the granite gravels were likely the late Neoarchean Ekou granite and Lanzhishan granite.The zircon~(207)Pb/~(206)Pb age of the orthoclase granite-porphyry intruded into the Sijizhuang Formation was determined to be 2157±15 Ma.Combining the ages of the Sijizhuang Formation and the Gaofan Group volcanic rocks in the Wutai area,and the geological events in the North China Craton from 2.2 to 2.0 Ga,it is inferred that the lower boundary of the Hutuo Group is likely to be 2.2 to 2.18 Ga,and its upper boundary age is approximately 2.0 Ga.The deposition process represents a period of intense intracontinental rift setting.The Hf isotope results of the Neoarchean granite gravel and the Paleoproterozoic granite zircons indicate that there was strong crustal growth in the early Neoarchean and crustal growth also existed in the late Neoarchean in the Wutai area.

关 键 词：五台地区 滹沱群 四集庄组 锆石U-Pb-Hf同位素 沉积时限 

分 类 号：P588.121[天文地球—岩石学] P588.3[天文地球—地质学]