西秦岭南缘白水江群晚古生代微体化石的发现及其地质意义  

Discovery of Late Paleozoic Microfossils and Significance of Baishuijiang Group in South Belt of West Qinling Mountain

作　　者：王涛[1] 王宗起[1] 闫臻[1] 闫全人[1] 李秋根[1] 

机构地区：[1]中国地质科学院地质研究所,北京100037

出　　处：《地球科学与环境学报》2007年第2期120-125,共6页Journal of Earth Sciences and Environment

基　　金：中国地质调查局地质调查项目(200313000057);国家自然科学基金项目(40602026)

摘　　要：西秦岭南秦岭白水江群不是单一的地层,而是由一套浅变质的碎屑岩、灰岩块体、基性和超基性岩块组成,由于缺乏古生物化石证据,多年来一直划分为早古生代志留系地层。因此,通过地层剖面的测制和微体化石采样和分析,在碎屑岩所夹的砂屑灰岩、硅质岩中,获得晚二叠纪放射虫化石和遗迹化石。结合在白水江群所夹的灰岩块体中发现的奥陶纪和泥盆纪化石,以及在火山岩块体中获得元古代的锆石U-Pb年龄,进而推断出白水江群为晚古生代最终形成的混杂岩。The Baishuijiang Group is composed of low-grade metamorphic elastic rocks, limestone blocks and mafic-ultramafic rock blocks in the south belt of western Qinling. Because it is lack of fossils evidence, the Baishuijiang Group was regarded as Silurian stratum. According to the measuring crossing section and sampling in fieldwork, and ofter analyzing the samples, the fossils including later Permian radiolarians and trace fossils were discovered in intercalary arenaceous limestones and silica. With the discovered Ordovician and Devonian fossils in limestome blocks, and with the acquired Proterozoic U-Pb date in the volcanic rock pieces, the Baishuijiang Group is considered to be the late paleozoic mélange.

关 键 词：南秦岭 白水江群 放射虫 微体化石 混杂岩 

分 类 号：P548[天文地球—构造地质学]