上扬子区西北缘米仓山地区卡拉道克中期的三叶虫相  

Middle Caradoc Trilobite Biofacies of the Micangshan Area, Northwestern Margin of the Yangtze Block

作　　者：周志强[1] 周志毅[2] 袁文伟[2] 

机构地区：[1]西安地质矿产研究所,陕西西安710054 [2]中国科学院南京地质古生物研究所,江苏南京210008

出　　处：《地层学杂志》2000年第4期264-274,共11页Journal of Stratigraphy

基　　金：中国科学院南京地质古生物研究所现代古生物学与地层学开放研究实验室项目 !(No. 913 113 );国家自然科学基金项目 !(No.49772 0 87)成

摘　　要：通过对上扬子区西北缘米仓山地区 9个剖面的详细采集 ,在宝塔灰岩 (组 )的 Xenocyclopyge jaskovitchi- Sagavia chuanxiensis三叶虫间隔带 (Caradoc中期 )获得了十分丰富的三叶虫。依据动物群的组成、属的分异度和各个属的相对丰度 ,识别出 4个与深度相关的三叶虫相 :Ovalocephalus- Dislobosaspis相和 Panderia相 ,仅含少量的cyclopygid较浅层浮游的 Microparia(Microparia) cf.speciosa,代表了浅外陆棚的环境 ;Amphytrion- Ovalocephalus相和 Cyclopyge- Cyamella相则出现了较多的在较深水域浮游的 cyclopygid分子 ,属的分异度大大增高 。On the basis of abundant trilobites collected from nine measured sections at the interval of the trilobite Xenocyclopyge jaskovitchi Sagavia chuanxiensis Zone (middle Caradoc) of the Pagoda Formation in the Micangshan area, northwestern margin of the Yangtze Block, four trilobite biofacies related to a water depth gradient are distinguished according to the faunal composition, diversity and relative abundance of trilobite genera. The Ovalocephalus Dislobosaspis and Panderia Biofacies represent a shallow outer shelf envirnoment; benthic forms are only associated with a few specimens of mesopelagic cyclopygid Microparia (Microparia) cf. speciosa (Hawle and Corda). The Amphytrion Ovalocephalus and Cyclopyge Cyamella Biofacies contain much more diversified cyclopygids, such as Cyclopyge, Xenocyclopyge, Sagavia, Psilacella, Gastropolus, Ellipsotaphrus, indicating deeper outer shelf conditions.

关 键 词：米仓山 陕西 奥陶纪 卡拉道克期 三叶虫相 

分 类 号：Q915.642[天文地球—古生物学与地层学]