滇西西部中奥陶统施甸组的腕足类  

MIDDLE ORDOVICIAN BRACHIOPODS FROM THE SHIHTIEN FORMATION OF WESTERN WEST YUNNAN,CHINA

作　　者：许汉奎[1] 

机构地区：[1]中国科学院南京地质古生物研究所,南京210008

出　　处：《古生物学报》2016年第3期291-313,共23页Acta Palaeontologica Sinica

摘　　要：滇西西部中奥陶统施甸组虽创名很早,但其时代一直有争论,尽管大都是依据其地层中的笔石来确定,但有的学者把它归于早奥陶世Floian期至中奥陶世Darriwilian期,而有的却认为只应属于Floian期至Dapingian期,或是Darriwilian期,甚至是Darriwilian期延至晚奥陶世Sandbian期。施甸组产有许多腕足类,但未经详细研究,其它化石相对较少,笔石详细研究也很晚,三叶虫、棘皮动物、头足类等研究也很少。本文报道了张远志新厘定的施甸组下部的腕足类,共有27属29种,它们可分为Leptellina(Leptellina)和Saucrorthis两个腕足类群落,时代属Darriwilian期中、晚期。另据施甸组下部腕足类与邻区的对比表明,滇西应分为东西两部分,东部属印支地体,西部归滇缅马地体。Ordovician strata are exposed intermittently in Shidian （Shihtien）, Baoshan Luxi and Cangyuan counties of western West Yunnan, where they were divided into, in ascending order, the Yanqing, Mantang, Laojianshan, Shihtien （Shidian） and Pupiao formations. The lower part of the Shihtien Formation is 400 m thick and consists of thick-bedded to thin-bedded grayish yellow mudstone intercalated with fine sandstone and sandy shales, yielding abundant brachiopods and rare graptolites, trilobites, cephalopod and crinoids. Brachiopods from the lower part of the Shihtien Formation, including 29 species referred to 27 genera, are studied. 9 species are described as new and 13 species are remained as indeterminate. By analyzing the range of studied brachiopods it is noticed that Nothorthis Ulrich and Cooper is a worldwide form that appeared in the Tremadocian to Darriwilian; Sulcatorthis Zhen, Lepidorthis Wang, Protoskenidioides Neuman, Eodiothelasma Xu and Liu and Martellia Wang were from the Floian to Dapingian Syndielasma Cooper and Calyptolepta Neuman were only found in the Darriwilian; Glyptorthis Foerste ranges from the Darriwilian to middle Silurian. In addition, there are seven genera （Bimuria Ulrich and Cooper, Kajinaria Nikitin and Popor, Shlyginia Nikitin and Popov, Palaeostrophomena Holtedahl, Plectodonta Kozlowski, Phragrnorthis Cooper and Protozyga Hall and Clarke） that are younger than the Darriwilian. Saucrorthis was first found in the Shihtzupu Formation in Guizhou Province with the age of middle and late Darriwilian （Xu et al., 1974; Zhan and Jin, 2005b） and then in the Dashaba Formation in Sichuan Province regarded as the late Dapingian to Darriwilian （Zhan and Rong, 2003; Zhan and Jin, 2005a）; Leptellina （Leptellina） is almost a worldwide subgenus with the range of Darriwilian to Upper Ordovician （Cocks and Rong, 2000）. The age of the Shihtien Formation has long been debated. However, viewed from the range of brachiopods as a whole it is inclined to believe that the age of the l

关 键 词：腕足动物群 滇缅马地体 施甸组 中奥陶统 滇西西部 

分 类 号：Q915[天文地球—古生物学与地层学]