| 鄂尔多斯盆地上三叠统延长组长7段富有机质页岩中藻类化石的发现及地质意义 |
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| 引用本文： | 袁伟,柳广弟,袁红旗.鄂尔多斯盆地上三叠统延长组长7段富有机质页岩中藻类化石的发现及地质意义[J].地质论评,2023,69(1):365-374. |
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| 作者姓名： | 袁伟 柳广弟 袁红旗 |
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| 作者单位： | 东北石油大学地球科学学院，黑龙江大庆，163318;中国石油大学（北京）地球科学学院，北京，102249 |
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| 基金项目： | 本文为国家自然科学基金资助项目（编号：41772127）和东北石油大学人才引进科研启动项目（编号：1305021845）的成果 |
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| 摘 要： | 鄂尔多斯盆地上三叠统延长组长7段富有机质页岩是该盆地中生界含油系统的主力烃源岩，其有机质丰度高，类型好，具有巨大的生烃潜力。该套烃源岩中有机质的富集很大程度上取决于长7期的高古生产力及其提供的充足的有机质。长7期藻类勃发的存在已被多数学者所接受，但是目前还缺乏直观、有力的证据。笔者等通过薄片和扫描电镜观察、能谱分析，在长7段的脉状黄铁矿附近和碳酸盐结核中发现了属种单一、分布丰度高的藻类化石，它们呈现出近似球状的轮廓，在中部分布着一条裂缝。这些藻类化石的发现具有重要的地质意义，它为长7期的藻类勃发提供了很好的证据，也为该时期热液活动的重要作用提供了有力的支撑。
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| 关 键 词： | 黄铁矿 碳酸盐结核 营养元素 藻类勃发 热液活动 上三叠统延长组长7段 鄂尔多斯盆地 |
| 收稿时间： | 2022/3/8 0:00:00 |
| 修稿时间： | 2022/5/22 0:00:00 |
Discovery of algal fossils in the Chang- 7 organic- rich shale of Upper Triassic Yanchang Formation in Ordos Basin and its geological significance |
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| YUAN Wei,LIU Guangdi,YUAN Hongqi.Discovery of algal fossils in the Chang- 7 organic- rich shale of Upper Triassic Yanchang Formation in Ordos Basin and its geological significance[J].Geological Review,2023,69(1):365-374. |
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| Authors: | YUAN Wei LIU Guangdi YUAN Hongqi |
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| Institution: | College of Geoscience, Northeast Petroleum University, Daqing, Heilongjiang, 163318;College of Geoscience, China University of Petroleum, Beijing, 102249 |
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| Abstract: | The Chang- 7 organic- rich shale in the Upper Triassic Yanchang Formation of Ordos Basin, with high abundance of organic matter and good type, is the main source rock of Mesozoic oil system, which has great hydrocarbon generation potential. The enrichment of organic matter in this unit mainly depends on the high paleoproductivity and the sufficient supply of organic matter during the Chang- 7 sedimentary period. Many researchers have accepted the occurrence of algal bloom in the Chang- 7 period, but there are still no direct and powerful evidences to prove it. In this study, algal fossils characterized by single species and high abundance are found in carbonate nodules and the vicinity of vein pyrite, which provides a good evidence for the algal bloom and strong support for the nutrition of hydrothermal activities during the Chang- 7 period. Methods: Microscope and scanning electron microscopy (SEM) are used to observed algae fossils. Energy spectrum analyzer is used to analyze the element composition of algae fossils. Thin section observation is carried out at the State Key Laboratory of Petroleum Resource and Prospecting, China University of Petroleum (Beijing). SEM observation and energy spectrum analysis are carried out the Microstructure Laboratory for Energy Materials, China University of Petroleum (Beijing).Results:Many algal fossils have been found on the edge of vein pyrite. They are single species, densely distributed and rich in organic matter.Conclusion: In the vicinity of vein pyrite and carbonate nodules in Chang- 7 organic- rich shale, algal fossils have been well preserved due to pyritization, calcitization and dolomitization. These algal fossils are characterized by single genus and species, and high distribution abundance. The discovery of algae fossils has important geological significance. It can not only provide direct and powerful evidence for algae bloom during the Chang- 7 sedimentary period, but also provide support for the nutritional role of hydrothermal activities in the same period. |
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| Keywords: | pyrite carbonate nodules nutrient element algae bloom hydrothermal activity Chang- 7 Member Yanchang Formation Upper Triassic Ordos Basin |
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