武当山腹地晚古生代沉积与火山物质的识别：微体化石和锆石年代学证据  

The Determination of Late Paleozoic Volcanic and Sedimentary Substances in the Hinterland of Wudang Mountain,South Qinling Orogeny: Evidence from Microfossil and Zircon Geochronology

作　　者：王刚[1] 王宗起[1] 武昱东[1] 王东升[1] 王涛[2] 王嘉玮 张航 WANG Gang;WANG Zongqi;WU Yudong;WANG Dongsheng;WANG Tao;WANG Jiawei;ZHANG Hang(MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources ,CAGS, Beijing, 100037;Institute of Geolgoy ,CAGS, Beijing , 100037)

机构地区：[1]中国地质科学院矿产资源研究所,国土资源部成矿作用与资源评价重点实验室,北京100037 [2]中国地质科学院地质研究所,北京100037

出　　处：《地质学报》2018年第6期1163-1175,共13页Acta Geologica Sinica

基　　金：中国地质科学院基本科研业务费(项目编号：YK1701、K1615); 国家青年自然基金项目(编号：41402180)联合资助

摘　　要：普遍认为武当山为南秦岭前寒武纪基底,主要由新元古代武当群和耀岭河群构成,局部发育陡山沱组。野外路线调查查明,武当山黄龙-方滩地区岩石单元与区域上广泛分布的前寒武纪有序地层不同,具有明显"block-in-matrix"特征。进一步详细的微体化石和锆石LA-ICP-MS同位素年代学工作表明:原划归陡山沱组的变石英砂质板岩呈岩片产出,分离和鉴别出15属30余种晚泥盆世孢子化石;原划归耀岭河群的凝灰质砂岩亦呈岩片产出,获得382Ma单一加权峰值年龄,且碎屑锆石综合分析显示物源以晚泥盆世岩浆岩为主,仅少量可能来源于区域发育的武当群和耀岭河群。黄龙-方滩地区原划定的前寒武纪岩石地层中发现晚古生代沉积组合与火山活动物质的存在,为重新认识武当地区物质组成与演化提供了基础资料。该成果结合作者野外剖面构造解析和室内获得的玄武岩、大理岩及辉绿岩块体和砂岩基质多组新元古代-中生代锆石年代学数据,共同指示十堰黄龙-方滩地区岩石单元并非前寒武纪或显生宙有序构造-沉积层,而是混杂岩带。It is traditionally regarded that the Wudang Mountain is the Precambrian basement of South Qinling Orogeny and mainly composed of Neoproterozoic Wudang Group,Yaolinghe Group,regionally developed Doushantuo Formation.Field investigation indicates that the rock unit of the Huanglong-Fangtan area,which is different from widely distributed Precambrian orderly sequence,has the typical feature of＂block in matrix＂structure.Further study of microfossil and zircon isotopic geochronology indicates that the meta-quartz sandstone of formerly determined Doushantuo Formation occurs as slate,from which 15 species and more than 30 kinds of late Devonian sporopollen fossils were separated and identified.Tuffaceous sandstone,which was formerly determined as the Yaolinghe Group and occurs as schist,yielded a single weighted peak age of 382 Ma.And detrital zircon analysis suggests that provenance is dominated by late Devonian magmatic rocks,with minor from the developed Wudang Group and Yaolinghe Group.The discovery of Late Paleozoic sediments assemblage and volcanic active materials in the formerly named Precambrian rock unit in the Huanglong-Fangtan area provides the basic information for reunderstanding the material composition of Wudang Mountain.Neoproterozoic-Mesozoic zircon dating data obtained for basalt,mable,diabase and sandstone matrix,along with field investigation for structural sections,suggest that lithological units in the Huanglong-Fangtan area in Shiyang are not Precambrian orderly structural-sedimentary layer but a mélange belt.

关 键 词：锆石测年 孢子化石 晚古生代 混杂岩带 武当山 

分 类 号：P534.4[天文地球—古生物学与地层学] P597.3[天文地球—地质学] Q911.2[生物学—古生物学]