New data on Hirnantian (latest Ordovician) postglacial carbonate rocks and fossils in northern Guizhou, Southwest China
New data on Hirnantian (latest Ordovician) postglacial carbonate rocks and fossils in northern Guizhou, Southwest China
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DOI：
10.1139/cjes-2015-0197
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发表时间：
2016-07
影响因子：
1.4
通讯作者：
Guangxu Wang;Renbin Zhan;I. Percival
中科院分区：
文献类型：
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作者：
Guangxu Wang;Renbin Zhan;I. Percival
观音桥组（Hirnantian，上奥陶统）是中国南方Hirnantian全球界线层型剖面和点（GSSP）地区冰川期冷水沉积的代表，是Hirnantia动物群的典型代表。最近的研究表明，该组的最上部碳酸盐岩为主的部分产生了一个温暖的水皱纹珊瑚动物群与志留纪的亲缘关系在北方贵州省的许多地方，这与下面的冷水动物群有很大的不同。这表明，这些碳酸盐可能是冰后期的温水沉积物，而不是像以前认为的那样形成于赫南期冰期。这一结论与相关腕足动物群的证据一致，即，Dalmanella testudinaria - Dorytreta longicrura群落，这与下面的典型Hirnantia动物群类似不同。沉积学资料显示，该海域具有暖水特征。
The Kuanyinchiao Formation (Hirnantian, Upper Ordovician), yielding the typical Hirnantia fauna, has commonly been accepted as representing cool-water sediments deposited during the glacial interval in the Hirnantian Global Boundary Stratotype Section and Point (GSSP) region of South China. Recent investigation reveals that the uppermost carbonate-dominated part of this formation yields a warm-water rugose coral fauna with Silurian affinities at many localities of northern Guizhou Province, which substantially differs from the underlying cool-water fauna. This suggests that these carbonates were probably postglacial warm-water sediments, rather than having formed during the Hirnantian glacial interval as previously thought. Such a conclusion is consistent with the evidence from the associated brachiopod fauna, i.e., the Dalmanella testudinaria – Dorytreta longicrura community, which is similarly distinct from the underlying typical Hirnantia fauna. The sedimentological data show warm-water features at the...