浙赣三山地区早-中奥陶世斑脱岩SHR IMP锆石U-Pb精确定年

目前浙赣三山地区“金钉子”尚无精确的同位素年龄数据.基于钾质斑脱岩SHRIMP锆石U-Pb测试，三山地区早-中奥陶世宁国组Azygograptus suecicus带中部、Exigraptus clavus带底部、Acrograptus ellesae带中部的同位素年龄分别为482.9±6.1 Ma、477.6±8.3 Ma和467.0±4.4 Ma，为华南地区中奥陶世大坪阶和达瑞威尔阶底界的全球界线层型（GSSP）开展地层对比提供了精确的同位素年代学依据.结合生物带对比，大致将浙西地区早-中奥陶世普遍存在的地层缺失事件的发生时限界定于482.9~477.6 Ma之间，即杭州-嘉兴台地缺失牙形刺Oepikodus evae带-Lenodus anticariabilis带（或笔石Azygograptus suecicus带-Acrograptus ellesae带）地层，其代表了郁南运动在浙西地区的具体表现，拉开了华南地区早古生代构造运动的序幕，也可能是欧洲加里东造山过程中亨伯运动和塔康运动的远程响应. 

SHRIMP U-Pb Zircon Dating for the Early-Middle Ordovician K-Bentonites in Jiangshan-Changshan-Yushan,Zhejiang-Jiangxi Border Area

There are no exact isotopic age data for "Golden Spike" in Jiangshan-Changshan-Yushan, Zhejiang-Jiangxi border area. The analysis of SHRIMP U-Pb zircons from the Ningkuo Formation K-bentonites in Jiangshan-Changshan-Yushan, yielded the age of middle Azygograptus suecicus Zone as 482.9±6.1 Ma, bottom Exigraptus clavus Zone as 477.6±8.3 Ma, and the middle Acrograptus ellesae Zone as 467.0±4.4 Ma, which provides the basis for exact correlation from the GSSP of Dapingian and Darriwilian strata in South China to other areas. Combined with contrast of biozones, the general strata-lost events occurred from 482.9 Ma to 477.6 Ma in West Zhejiang, which equated to the lacuna of the Oepikodus evae Zone to the Lenodus anticariabilis Zone, or Azygograptus suecicus Zone to Acrograptus ellesae Zone in Hangzhou-Jiaxing platform. We consider that it embodied the Yunan Movement in West Zhejiang, and heralded the start of the Early Paleozoic tectonic movement in South China, while responding to the Humberian Movement and Tactonic Movement in the European Caledonian Orogeny.