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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。
Although the Middle Ordovician Shidian Formation in western western Yunnan Province was very early in name, its age has been controversial. Although mostly based on the petrulites in its strata, some scholars refer it to the period from the Floian Period of Early Ordovician to The Middle Ordovician Darriwilian period while others believe that it should belong only to the Floian to Dapingian or Darriwilian or even Darfurian to the late Ordovician Sandbian. There are many kinds of brachiopods in Shidian group, but there are few other fossils without detailed study. So far, the study on penoliths is very late. There are few studies on trilobites, echinoderms and cephalopods. This paper reports the newly discovered Brachiopods of the Shidian group, a total of 27 genera and 29 species, which can be divided into two families, Leptellina (Leptellina) and Saucrorthis. The era belongs to Darriwilian period. According to the Shidian lower brachiopods and adjacent areas comparison shows that the western Yunnan should be divided into two parts, the eastern part of Indo-China and western Yunnan Burma.