甘肃平凉上奥陶统牙形石和笔石生物地层
作者:
作者单位:

作者简介:

通讯作者:

中图分类号:

基金项目:

本文为国家自然科学基金项目(编号41702031)和国家十三五油气重大专项(编号2017ZX05001001- 003)资助的成果。


Upper Ordovician conodont and graptolite biostratigraphy of Pingliang,Gansu Province, China
Author:
Affiliation:

Fund Project:

  • 摘要
  • |
  • 图/表
  • |
  • 访问统计
  • |
  • 参考文献
  • |
  • 相似文献
  • |
  • 引证文献
  • |
  • 资源附件
  • |
  • 文章评论
    摘要:

    在经典的平凉官庄剖面附近的一个采石场内,出露一套新鲜的奥陶纪地层。为了确定其精确层位,在灰岩和页岩层段分别密集地采集了牙形石和笔石样品并获得丰富的化石标本。鉴定结果显示,牙形石动物群存在不同生物地理区化石属种混生的现象,其中北美中大陆型的以Belodina compressa(Branson et Mehl,1933)、Erismodus typus Branson et Mehl,1933和Plectodina aculeatus(Stauffer,1930)等属种为代表,北大西洋型的以Pygodus anserinus Lamont et Lindstrm,1957、Periodon aculeatus Hadding,1913和Protopanderodus varicostatus(Sweet et Bergstrom,1962)等属种为代表。Belodina compressa系北美中大陆生物地理区重要的且常见的带化石,在本次获得的所有牙形石属种中其指示的层位最高。据此,判定研究剖面的牙形石动物群属于Belodina compressa牙形石带。本次研究的笔石动物群以带化石Climacograptus bicornis(Hall,1847)的出现为主要特征,与之伴生的其它重要的属种包括Nemagraptus gracilis(Hall,1847)、Normalograptus brevis(Elles et Wood,1906)、Dicranograptus brevicaulis Elles et Wood,1904以及Archiclimacograptus meridionalis(Ruedemann,1947)等,共计14属20种。显然,该动物群对应Climacograptus bicornis笔石带。Belodina compressa牙形石带和Climacograptus bicornis笔石带同为晚奥陶世桑比期全球广布性的重要的化石带。这表明两类生物地层研究结果高度吻合、统一,研究剖面的地层时代为晚奥陶世桑比期晚期,对比官庄剖面(标准剖面)平凉组的顶段。不同生物地理区牙形石属种混生的现象,反映了研究区在这一地质历史时期发生过令水体加深、水温下降的古构造活动事件。

    Abstract:

    The Ordovician sequence outcrops in a quarry, not far from the wellknown Guanzhuang section in Pingliang, Gansu Province. A large number of specimens of conodont and graptolite are recovered from the sequence. The conodont fauna is characterized by a particular taxa mixture. The North American Midcontinent fauna including Belodina compressa (Branson et Mehl, 1933), Erismodus typus Branson et Mehl, 1933, Plectodina aculeatus (Stauffer, 1930) et al., cooccurs with the North Atlantic fauna such as Pygodus anserinus Lamont et Lindstrm, 1957, Periodon aculeatus Hadding, 1913, Protopanderodus varicostatus (Sweet et Bergstrom, 1962). The presence of the late Sandbian index fossil, Belodina compressa indicates the sequence corresponds to the eponymous conodont biozone. The graptolite fauna recovering 20 species of 14 genera, is represented by Climacograptus bicornis (Hall, 1847), Nemagraptus gracilis (Hall, 1847), Normalograptus brevis (Elles et Wood, 1906), Dicranograptus brevicaulis Elles and Wood, 1904 and Archiclimacograptus meridionalis (Ruedemann, 1947). It shows the feature of the Climacograptus bicornis biozone, which is consistent with the biostratigraphic result of the conodont. It suggests that the sequence is of the late Sandbian and correlates well with the uppermost part of the Pingliang Formation in the Guanzhuang section. The particular conodont taxamixture phenomenon reveals that tectonic events during this period deepen the water and make it much cooler in the study area.

    参考文献
    相似文献
    引证文献
引用本文

樊茹,马雪莹,吕丹,卢远征,张学磊,张元动,邓胜徽,谭聪,宋昊南,张凤廉,李鑫,张师本,段文哲.2020.甘肃平凉上奥陶统牙形石和笔石生物地层[J].地质学报,94(11):3213-3227.
FAN Ru, MA Xueying, Lü Dan, LU Yuanzheng, ZHANG Xuelei, ZHANG Yuandong, DENG Shenghui, TAN Cong, SONG Haonan, ZHANG Fenglian, LI Xin, ZHANG Shiben, DUAN Wenzhe.2020. Upper Ordovician conodont and graptolite biostratigraphy of Pingliang,Gansu Province, China[J]. Acta Geologica Sinica,94(11):3213-3227.

复制
分享
文章指标
  • 点击次数:
  • 下载次数:
  • HTML阅读次数:
  • 引用次数:
历史
  • 收稿日期:2020-03-27
  • 最后修改日期:2020-07-25
  • 录用日期:2020-08-19
  • 在线发布日期: 2020-09-17
  • 出版日期: