| 福建白垩系沙县组地层磁学特征及其环境意义 |
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| 引用本文： | 吕镔,刘秀铭,郭晖,郑兴芬,陈梓炫,何梅菊,赵国永.福建白垩系沙县组地层磁学特征及其环境意义[J].沉积学报,2019,37(3):519-531. |
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| 作者姓名： | 吕镔 刘秀铭 郭晖 郑兴芬 陈梓炫 何梅菊 赵国永 |
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| 作者单位： | 福建师范大学湿润亚热带山地生态国家重点实验室培育基地,福州 350007;福建师范大学地理研究所,福州 350007;福建师范大学湿润亚热带山地生态国家重点实验室培育基地,福州 350007;福建师范大学地理研究所,福州 350007;Department of Environment and Geography,Macquarie University,Sydney NSW 2109,Australia;甘肃省油气资源研究重点实验室/中国科学院油气资源研究重点实验室,兰州,730000;信阳师范学院地理科学学院,河南信阳,464000 |
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| 基金项目： | 国家自然科学基金项目（U1405231,41602187）;福建省自然科学基金（2015J05079）;福建省大学生创新创业训练计划（201810394069）;福建师范大学创新团队项目（IRTL1705） |
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| 摘 要： | 广泛分布于中国南方的白垩系巨厚地层被认为是河湖相沉积,蕴含着丰富的古气候古环境变化的信息。白垩纪是典型的温室时期,其气候特征可以为当代和未来温室气候研究提供重要借鉴。对位于中国东南的福建省三明市沙县和永安地区的白垩系沙县组典型地层进行了系统的环境磁学参数测量,结合漫反射光谱(DRS)和色度指标,探讨了该地层磁学特征及其环境指示意义和红色的成因。结果表明:1)红色调和黄色调地层的主要磁性矿物分别为赤铁矿和针铁矿,均含有顺磁性矿物和极少量的亚铁磁性矿物;2)相对于粗粒的砂岩,细粒的粉砂岩赤铁矿含量较高;3)红色赤铁矿与黄色针铁矿均形成于成岩阶段之前,具体形成阶段与形成原因需要具体分析;4)红色调地层的赤铁矿指示高温的气候环境;黄色调地层的针铁矿指示局部的湿润环境。磁学参数变化的具体环境指示意义需要进一步研究。
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| 关 键 词： | 环境磁学 磁性矿物 白垩系 红层 沙县组 |
| 收稿时间： | 2018-05-28 |
Magnetic Properties of the Cretaceous Shaxian Formation Stratum in Fujian Province and Their Environmental Significance |
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| Lü Bin,LIU XiuMing,GUO Hui,ZHENG XingFen,CHEN ZiXuan,HE MeiJu,ZHAO GuoYong.Magnetic Properties of the Cretaceous Shaxian Formation Stratum in Fujian Province and Their Environmental Significance[J].Acta Sedimentologica Sinica,2019,37(3):519-531. |
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| Authors: | Lü Bin LIU XiuMing GUO Hui ZHENG XingFen CHEN ZiXuan HE MeiJu ZHAO GuoYong |
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| Institution: | (State Key Laboratory for Subtropical Mountain Ecology (Funded by Ministry of Science and Technology and Fujian Province),Fujian Normal University,Fuzhou 350007,China;Institute of Geography,Fujian Normal University,Fuzhou 350007,China;Department of Environment and Geography,Macquarie University,Sydney NSW 2109,Australia;Key Laboratory of Petroleum Resources,Gansu Province/ Key Laboratory of Petroleum Resources Research,Chinese Academy of Sciences,Lanzhou 730000,China;School of Geographic Sciences,Xinyang Normal University,Xinyang,Henan 464000,China) |
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| Abstract: | The giant thick Cretaceous stratum that is widely distributed in Southern China is regarded as fluvio-lacustrine sediment and contains a wealth of information about paleoclimate and paleoenvironmental change. The climate during the Cretaceous period represents one of the "greenhouse states" of Earth's history. Study of Cretaceous climate change can inform current and further greenhouse climate research. This paper reports a preliminary study on the magnetic properties of three Cretaceous Shaxian Formation sections located in Shaxian and Yong'an, Sanming city, Fujian Province. Rock magnetic parameters (including magnetic susceptibility, frequency-dependent magnetic susceptibility, remnant magnetization, hystersis loop, and temperature-dependent magnetization), the diffuse reflectance spectrum (DRS), and chroma parameters (lightness L*, redness a*, yellowness b*) were measured and analyzed to discuss the variations in magnetic properties, their environmental significance, and the origin of red pigments. The results show that:1) The main magnetic minerals of the red and yellow beds are hematite and goethite, respectively. Both contain paramagnetic minerals and a few ferromagnetic minerals. The content of these weakly magnetic minerals is low, so the numerical value of the magnetic susceptibility is low. 2) The hematite content in the siltstone is higher than in the sandstone. 3) The redness and yellowness are controlled by the hematite and goethite content, respectively. Hematite and goethite were formed before the diagenetic stage. The details about the formation stage need further study. Hematite was mainly formed in the provenance area and can carry the detrital remnant magnetization, which is important to the magnetostratigraphy. 4) Red bed hematite suggests hot weather, and yellow bed goethite suggests local wet conditions. Because the magnetic properties were controlled by many factors, further research is needed to determine the environmental significance of the magnetic parameters. |
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| Keywords: | environmental magnetism magnetic minerals Cretaceous Red beds Shaxian Formation |
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