Middle Viséan (Mississippian) coral biostrome in central Guizhou, southwestern China and its palaeoclimatological implications
Middle Viséan (Mississippian) coral biostrome in central Guizhou, southwestern China and its palaeoclimatological implications
复制标题
DOI：
10.1016/j.palaeo.2015.08.031
复制
发表时间：
2016-04
期刊：
影响因子：
--
通讯作者：
L. Yao;Xiangdong Wang;Wei Lin;Yue Li;S. Kershaw;Wenkun Qie
中科院分区：
文献类型：
--
作者：
L. Yao;Xiangdong Wang;Wei Lin;Yue Li;S. Kershaw;Wenkun Qie
本文首次报道了黔中鸭水地区上寺组中Viséan（密西西比期）珊瑚生物层（古地理位于古特提斯东部）。该生物层宽约500米，厚2.5-3.9米，横向可变，由5属4种皱纹珊瑚和1种平板珊瑚组成，分类多样性低。根据珊瑚分类群的不同组成，区分了生物层的三个生长阶段。生物层的平均珊瑚含量从38.7%增加到72.0%，主要建造者是Siphonodendron pentalaxoidea，Syringopora sp.和Kueichouphyllumsinense。伴生化石包括丰富的腕足类、海百合类和常见有孔虫，以及罕见的钙质藻类、苔藓虫、腹足类和介形类。相对海平面的变化被解释为有控制的生长和消亡的生物层，不断增长的海平面上升和减少水的能量，从泥晶含量和原位珊瑚群落的逐渐增加明显。然而，随着海平面的下降和水动力能量的加强，生物层下降并死亡，这表明生物碎屑和亮晶方解石水泥（表明由于能量较高而缺乏微晶基质）覆盖生物层。这种珊瑚生物层的生物组成与欧洲和北非（古特提斯西部）的维森期中晚期珊瑚生物层相似。在古特提斯岛东部和西部的珊瑚生物层的近似同时代的发生表明，一个相对全球性的温暖事件存在于维森阶段。
A middle Viséan (Mississippian) coral biostrome is reported for the first time from the Shangsi Formation in Yashui area, central Guizhou Province, southwestern China (palaeogeographically located in eastern Palaeotethys). The biostrome, which is about 500 m across and 2.5–3.9 m thick, is laterally variable and composed of rugose and tabulate corals with low taxonomic diversity comprising 4 rugose and 1 tabulate coral species belonging to 5 genera. Three growth stages of the biostrome are distinguished, based on different compositions of coral taxa. Average coral contents of the biostrome increase from 38.7% to 72.0% upward and themain builders are Siphonodendron pentalaxoidea, Syringopora sp. and Kueichouphyllumsinense. Associated fossils include abundant brachiopods, crinoids and common foraminifers togetherwith rare calcareous algae, bryozoans, gastropods and ostracods. Relative sea-level changes are interpreted to have controlled growth and demise of the biostrome, which grew continuously during sea-level rise and decreasing water energy, as evident from the gradually increasing of micrite content and in situ coral colonies. However, the biostrome declined and died as the sea level fell and hydrodynamic energy strengthened, indicated by an increase of bioclasts and sparry calcite cement (indicating lack of micritic matrix due to higher energy) overlying the biostrome. This coral biostrome has similar biotic composition to middle to late Viséan coral biostromes in Europe and North Africa (western Palaeotethys). The approximately coeval occurrence of coral biostromes in both eastern and western Palaeotethys suggests that a relatively global warm episode existed during the Viséan Stage.