| 陕南志留系五峡河组地层的沉积环境与笔石生活和保存的关系 |
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| 引用本文： | 雒昆利,邓宝.陕南志留系五峡河组地层的沉积环境与笔石生活和保存的关系[J].沉积学报,1992,10(2):79-87. |
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| 作者姓名： | 雒昆利 邓宝 |
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| 作者单位： | 西安矿业学院, |
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| 摘 要： | 笔者测制五峡河组剖面时,在约1m2的面积内,逐层系统地采集笔石和岩性标本;统计了典型层层面上笔石的丰度,绘制了一些属种的死亡曲线;系统鉴定了围岩岩石的矿物成分,分析了岩石中的二价铁(Fe++),三价铁(Fe+++),硫(S),碳(C)的含量和pH值.在此基础上,本文讨论了五峡河组的沉积环境、笔石的生存及保存状态以及它们之间的关系.
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| 关 键 词： | 五峡河组 沉积环境 笔石生存 保存 |
| 收稿时间： | 1990-06-23 |
Depositional Environment and Its Relationship with the Life and Preservation of Graptolites of the Silurian Wuxiahe Formation,Southern Shaanxi |
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| Institution: | Xi'an Mining Institute |
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| Abstract: | The present paper focus on the depositional enviroment and its relationship with the life and the preservation of graptolites in the Silurian Wuxihe Formation, southern Shaanxi. First, The authors collected the fossils layer by layer in about one square metre and got the statistics of the fossils on the surface of each layer Then drawn the dead curves of some spcial species and analysed the characteristics and the content of some elements in country rocks, such as Fe++. Fe+++, S, C and pH, and so on, main conclusions obtained as follows: 1 .The depositional enviroment was a cutoff basin, the bottom water current was confined and the condition was reducing, so there no benthonic arganism could survive. 2.The rock types of Wuxiahe Formation is turbite, consisting of siltstone, silty shale, shale and black mudstone, correspond to the B、 C、 D and E divisions of the Bouma sequence, respectively, while A-divi sion(some time B-division) is lacuna, 3.The graptolites is richest in the siltyshale and shale, less in the mudstone and none in the siltstone. 4.The change of the graptolites abundance is mainly resulted from its sedimentary environment and the invasion of the turbidity current. When the current reached to the basin from the Yangtze Platform, croase sediments (sands) will deposite first, the dropping graptolites carcasses might be tear to shreds by the current so, none fossils was found in sandstone.while with the diffusion of the fine-grained particles to the upper water body, associate H2S which agitated up by turbidity current form the bottom of basin, with most of the graptolites would be killed and their carcasses can be preserved at the bottom, of basinso a great deal of graptotite fossiles can be found in silty shale and shale(corespond to D1 and D2 division of Bouma sequenco). |
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