浙东象山石浦生物礁灰岩时代厘定及其层位归属  

Geochronological definition on Shipu biohermal limestone and its regional stratigraphic attribution in Xiangshan,eastern Zhejiang Province

作　　者：余明刚[1] 洪文涛[1] 钱迈平[1] 段政[1] 姜杨[1] 陈荣[1] YU Minggang;HONG Wentao;QIAN Maiping;DUAN Zheng;JIANG Yang;CHEN Rong(Nanjing Center,China Geological Survey,Nanjing 210016,Jiangsu,China)

机构地区：[1]中国地质调查局南京地质调查中心,江苏南京210016

出　　处：《华东地质》2021年第3期260-268,共9页East China Geology

基　　金：中国地质调查局“全国陆域及海区地质图件更新与共享(编号:DD20190373)”;“中国大地构造演化和国际亚洲大地构造图编制(编号:DD20190361)”项目联合资助。

摘　　要：浙东象山石浦附近出露1套火山沉积岩系,前人称为石浦组,分为上、下两段:下段为泥岩、砂岩与叠层石虫管生物礁灰岩互层;上段以双峰式火山岩组合为特征。长期以来,关于石浦组层位归属和生物礁石灰岩的时代存在争议。文章对在象山石浦组上段流纹岩和下段沉积岩中新发现的玄武岩夹层进行了LA-ICP-MS锆石U-Pb定年,测得它们的年龄分别为(117.8±2.2)Ma和(116.1±1.0)Ma,表明象山地区石浦组形成于早白垩世晚期,经区域地层对比研究,确定石浦组与馆头组层位相当,属于同期异相地层。There is a set of volcanic-sedimentary rock series in Shipu area,Xiangshan County,eastern Zhejiang Province,which was previously named as Shipu Formation,including upper and lower members.The lower member is interbedded with mudstone,sandstone and stromatolite-wormtube biohermal limestone,while the upper member is characterized by bimodal volcanic rock.For a long time,there have been disputes about the stratification attribution of Shipu Formation and the age of the bioreef limestone.LA-ICP-MS zircon U-Pb ages of the basaltic interlayers newly discovered in rhyolite and sedimentary rocks of the Shipu Formation are obtained,which are(117.8±2.2)Ma and(116.1±1.0)Ma respectively,showing that Shipu Formation formed in late early Cretaceous.According to the regional stratigraphic correlation study,the stratigraphy of Shipu Formation and Guantou Formation is similar,both belongs to the contemporaneous heterogeneous sequence strata.

关 键 词：LA-ICP-MS锆石U-PB定年 生物礁灰岩 象山石浦 浙东 

分 类 号：P588.1[天文地球—岩石学]