| 川南先锋地区二叠系-三叠系界线附近碳酸盐微相及沉积演化 |
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| 引用本文： | 焦学文,巩磊,王超勇,孙旭,亓乐.川南先锋地区二叠系-三叠系界线附近碳酸盐微相及沉积演化[J].沉积学报,2015,33(5):865-877. |
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| 作者姓名： | 焦学文 巩磊 王超勇 孙旭 亓乐 |
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| 作者单位： | 1.山东电力工程咨询院有限公司 济南 250100; |
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| 基金项目： | 江苏高校优势学科建设工程项目 |
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| 摘 要： | 根据川南先锋地区二叠系-三叠系界线地层的沉积特征,结合钻孔岩相及其组合特征,识别出等斜碳酸盐缓坡和局限台地2种沉积相,包括高能生屑浅滩、内缓坡、潮间带等7种亚相。同时采用微相分析的方法,对碳酸盐岩的生物组合、颗粒成分以及支撑类型等微相特征进行了研究,将界线地层沉积归纳为14种微相类型,并由此建立了该时期的沉积相序及其演化。研究区产出一层微生物岩,显微镜观察显示:微生物岩主要是叠层石;在它们内部发现了大量的蓝藻球粒、钙化鞘和微亮晶包覆层等微生物成因的显微组构。对ZK1501孔所采集的0.58 m K9灰岩岩芯连续磨片后进行生物组合分析,在距底6 cm地层中发现了丰富的三叶虫、腹足类和叶枝藻化石,其上出现小型化的介形虫(小于200 μm),表明二叠纪末期生物主灭绝界线应位于飞仙关组底面之上6 cm处,而二叠系-三叠系界线应位于小型化介形虫层的中下部。
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| 关 键 词： | 微生物岩 沉积微相 二叠系-三叠系界线 沉积序列 四川南部 |
| 收稿时间： | 2014-06-12 |
Microfacies and Evolution of Sedimentary on Carbonate Rocks around the Permian-Triassic Boundary in Xianfeng,South Sichuan |
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| Institution: | 1.Electric Power Engineering Consulting Institute Co. LTD of Shandong, Jinan 250100;2.School of Resources and Earth Science, China University of Mining and Technology, Key Laboratory of Coalbed Methane Resource & Reservoir Formation History, Ministry of Education, Xuzhou, Jiangsu 221116 |
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| Abstract: | Based on the sedimentary characteristics of the Permian-Triassic boundary (PTB) strata in Xianfeng, combined with analysis from boreholes lithofacies, the stratum was divided into two kinds of sedimentary facies, including homoclinal carbonate ramp and rimmed carbonate platform, and seven kinds of subfacies, such as high-energy bioclastic shoal, inner ramp and intertidal flat and so on. Then analyzing microfacies characters of the carbonate rocks, such as biotic assemblage, grain composition and supported type. Boundary strata of the studied section can be mainly divided into fourteen microfacies types. From this, the sedimentary facies sequences and evolution of this period were established. The studied section outputs one layer of microbialites. From observations of plain microscope, the following results were obtained: microbialites consist of stromatolites; in most of these microbialites, coccoid cyanobacterias, calcified sheaths and microsparry cladding layer were found largely. Characteristics of the biotic assemblage were be analyzed after grinding the thin sections continuously for rock core of K9 limestone which is 0.58 m long and comes from borehole ZK1501. There are abundant fossils in this place where 6 cm away from the bottom of the admitted major extinction horizon, such as Trilobites, Gastropods and Phylloid Algae. Above the stratum, miniaturized Ostracods(<200 μm) were found. We concluded obviously that the major extinction horizon of Permian should be located at the place, while PTB is at the middle and lower segments of the miniaturized Ostracods layer. |
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| Keywords: | microbialites microfacies the Permian-Triassic boundary sedimentary sequences south of Sichuan province |
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