| 论石炭系与二叠系的分界 |
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| 摘 要： | <正> 石炭系与二叠系的分界问题是国际上长期争论至今尚未解决的系间地层界线问题之一。多年来,各国学者虽致力于这条界线的研究,积累了丰富的资料,但由于下列几个原因,使各家对石炭系与二叠系界线的位置始终未能取得一致的认识。(1)石炭系源出于英国,二叠系则创名于苏联乌拉尔西坡,两地的石炭-二叠系界线地层属于不同相区,难以确切对比;(2)到目前为止,石炭-二叠系界线在理论上还没有一个确切的定义,以致各家都以自己的界线定义来确定界线的位置;(3)有些学者对一些关键性的阶如Asselian和Wolfcampian的化石带的分布情况及其对比有所误解;(4)界线地层中各门类化石的
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On the Carboniferous-Permian boundary |
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| Abstract: | Definition of the Carboniferous-Permian boundary is one of unsolved problems in the world. Up to date, about thirty opinions about the Carboniferous-Permian boundary have been proposed. However, most of them are very similar in substance, and may be grouped into the following eight proposals: 1) The boundary is placed between the top of the Sphaeroschtvagerina sphaerica zone and the base of the Schwagerina tschernyschewi zone, the Darvasites ordinaius zone, the Schivagerina cushmani zone, the Pamirina zone, the Robustoschwagcrina schellwioni zone, or the Neostreptognathodus pequopensis-Swc-etoganthus whitei-Lonchodina festiva assemblage. This boundary is known as the revised traditional boundary in China and can be corresponded to the boundary between the Asselian and Sakmarian stages in USSR; 2) The boundary is drawn at the base of the Wolfcampian stage, i.e. Triticites-Schwagerina zone; 3) The boundary is defined at the base of the Asselian stage; i.e. Schwagerina vulgaris-S. fusi-formis zone or the zone of Daixina bosbytauensis-D. robusta (Leven, 1986); 4) The boundary is drawn at the base of the Daixina sokensis zone; 5) The boundary is placed between the Schwagerina moel-leri-Pseudofusulina fecvnda zone and the Schwagerina sphaerica-Pseudofusulina firma zone; 6) The boundary is defined at the base of the Montiparus zone; 7) The boundary is placed at the base of the Artinskian stage; 8) The boundary in terrestrial and non-marine sequences is drawn at the base of the Autunian stage or its equivalent Emplectopteris iriangularis-Emplectoptcridium alatum assemblage. To sum up, it is clear that the confusion still exists in recognizing the Carboniferous-Permian boundary and the stratigraphers are of so different opinions about the definition of the Carboniferous-Permian boundary that the boundaries quite differ from each other even in the same section. Hence, in order to define a theoretical Carboniferous and Permian boundary, the writers propose three possible horizons for defining boundary between the Carboniferous and Permian boundary. They are 1), 5) and 8) mentioned above. In the bordering regions of Guizhou, Guangxi and Yunnan of southwestern China, such as Na-shui of Luodian county and Yangchang of Wangmo county, Guizhou province, the continuous and fos-siliferous sections straddling the Carboniferous-Permian boundary have been known to exist, and moreover, there can be found both benthic and planktonic fossils such as fusulinids, conodonts, radiolarians, etc., associated with each other. The sections are undoubtedly useful for definition and choice of GSSP of the Carboniferous-Permian boundary. |
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