| 滇黔桂盆地早二叠世亚丁斯克期的沉积环境分异与?有孔虫响应 |
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| 引用本文： | 黄明立,田坤烜,史宇坤.滇黔桂盆地早二叠世亚丁斯克期的沉积环境分异与?有孔虫响应[J].地学前缘,2020,27(6):313-328. |
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| 作者姓名： | 黄明立 田坤烜 史宇坤 |
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| 作者单位： | 南京大学 生物演化与环境科教融合中心, 江苏 南京 210023 |
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| 基金项目： | 国家自然科学基金项目(41772017) |
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| 摘 要： | 亚丁斯克期华南滇黔桂地区沉积环境分异明显,主要发育局限或半局限海台地沉积区、开阔海台地沉积区和台地边缘沉积区,不同沉积区?有孔虫动物群面貌也有所区别。本文详细研究了黔南地区的猴场打望剖面和惠水竹子冲剖面阿瑟尔期—亚丁斯克期的地层,在打望剖面识别出4个?类化石带,由老至新为Pseudoschwagerina beedei-Sphaeroschwagerina constans共存延限带、Staffella xiushuiensis-Eoparafusulina contracta富集带、Pseudofusulina ellipsoidalis富集带和Misellina subcycloidea间隔带。竹子冲剖面识别出3个化石带,由老至新为Pseudoschwagerina uddeni-Sphaeroschwagerina sphaerica组合带、Eoparafusulina certa富集带和Staffella discoides延限带。对滇黔桂地区不同沉积相区剖面?类动物群以及沉积相特征的综合研究显示:开阔台地或台地边缘环境的?动物群以Pamirina为特征分子,同时还产出丰富的希瓦格?亚科(Schwagerininae)分子;局限或半局限台地环境的?类以史塔夫?亚科分子(Staffellininae)为主。沉积环境对?有孔虫的影响可能主要来自水动力、光照和氧气含量。个体较大、隔壁褶皱强烈的纺锤形希瓦格?亚科分子更适应水动力强、透光性好、氧气充足的水体;小个体、结构简单的史塔夫?亚科分子可在透光性差、含氧量较低的水体中生存。
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| 关 键 词： | 亚丁斯克期 滇黔桂盆地 ?有孔虫 生物地层 古生态 |
| 收稿时间： | 2020-03-17 |
Artinskian (Early Permian) marine environmental disparity and evolved fusulinid foranminifa in the Dianqiangui Basin,South China |
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| HUANG Mingli,TIAN Kunxuan,SHI Yukun.Artinskian (Early Permian) marine environmental disparity and evolved fusulinid foranminifa in the Dianqiangui Basin,South China[J].Earth Science Frontiers,2020,27(6):313-328. |
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| Authors: | HUANG Mingli TIAN Kunxuan SHI Yukun |
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| Institution: | Centre for Research Education on Biological Evolution and Environment, Nanjing University, Nanjing 210023, China |
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| Abstract: | During the Artinskian age of the Early Permian, the marine environment was diverse in the Yunnan-Guizhou-Guangxi junction area, namely the Dianqiangui Basin, in South China, where restricted or semi-restricted marine lagoon and open and marginal marine platforms have been recognized and distinct fusulinid fauna evolved. The current study is designed to pursue the relationships among different marine environments and fusulinids. Two carbonate sections, the Dawang and Zhuzichong Sections in southern Guizhou, were studied in detail and described here for their Asselian to Artinskian strata. The Artinskian strata of the Dawang Section are mainly composed of sparite bioclastic and microcrystalline bioclastic limestones, indicating an open or marginal marine platform environment. Eighty-two fusulinid species belonging to 19 genera are recovered there, and four fusulinid biostratigraphic zones are recognized, including, in ascending order, the Pseudoschwagerina beedei-Sphaeroschwagerina constans concurrent range zone, the Staffella xiushuiensis-Eoparafusulina contracta abundance zone, the Pseudofusulina ellipsoidalis abundance zone, and the Misellina subcycloidea interval zone. In the Zhuzichong Section, calcareous mudstones were deposited during the Artinskian, suggesting a restricted or semi-restricted marine lagoon environment. Sixty-two fusulinid species belonging to 14 genera are found there and three fusulinid zones have been defined, ascendingly: the Pseudoschwagerina uddeni-Sphaeroschwagerina sphaerica assemblage zone, the Eoparafusulina certa abundance zone, and the Staffella discoides range zone. Moreover, another section of this area, the Zongdi Section, was introduced for its Artinskian strata, as well as the Staffella-Pseudoendothyra assemblage zone recognized there. An extended cross-sectional study, covering sections featuring different types of marine environments in the Dianqiangui Basin, revealed the characteristics of fusulinid fauna that evolved there. During the Artinskian, Pamirina was the typical genus in the open or marginal marine platform along with thriving schwagerines, while staffellines developed abundantly in the restricted or semi-restricted environment. The main marine environmental factors affecting the fusulinid foraminifera included hydrodynamics and sunlight and oxygen, which could explain the fusulinid distributions in different marine environments. Fusulinids developed large fusiform tests and strong septa flutes, such as schwagerines, with small test surface-to-volume ratios, therefore are more suited for the open and marginal platform environments with strong waves, good sunlight, and sufficient oxygen. However, staffellines have small lenticular tests and simple inner structures with large test surface-to-volume ratios, which enabled their survival in restricted environments with less sunlight and low oxygen. |
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| Keywords: | Artinskian Dianqiangui Basin fusulinid foraminifera biostratigraphy paleoecology |
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