| 台湾国姓地区中新世海相菱铁矿的成因 |
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| 引用本文： | 陈成业,王钦贤,陈多福.台湾国姓地区中新世海相菱铁矿的成因[J].沉积学报,2022,40(6):1691-1701. |
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| 作者姓名： | 陈成业 王钦贤 陈多福 |
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| 作者单位： | 1.上海海洋大学海洋科学学院, 上海深渊科学工程技术研究中心, 上海 201306 |
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| 基金项目： | 国家重点研发计划2018YFC0310003国家自然科学基金41673029国家自然科学基金41730528 |
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| 摘 要： | 菱铁矿很好地记录了过去地质流体的信息,能够用于示踪生物地球化学反应相关的成岩作用带。台湾国姓地区中新世海相泥页岩中发育自生的菱铁矿结核,其成因尚未厘清。野外观察发现菱铁矿以不连续透镜体平行散布于泥页岩中,主要由自生碳酸盐菱铁矿（78.63%）等矿物组成。菱铁矿的稀土元素配分模式为轻稀土亏损、中稀土富集,无Ce异常,指示菱铁矿形成于弱氧化的沉积环境,弱氧化的环境促进了菱铁矿在次氧化带的沉淀。菱铁矿的δ13CVPDB和δ18OVPDB值分别为-3.69‰~+0.08‰和-1.09‰~+0.25‰,指示菱铁矿形成于次氧化带,碳源很可能是海水和有机质降解混合产生。研究表明自生菱铁矿能够被用于识别沉积物中的生物地球化学过程和指示成岩作用带。
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| 关 键 词： | 菱铁矿 碳、氧同位素 次氧化带 稀土元素 |
| 收稿时间： | 2021-01-06 |
Genesis of Siderite in Miocene Marine Shale in Kuohsing Area,Taiwan |
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| Affiliation: | 1.Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai 201306, China2.CAS Key Laboratory of Ocean and Marginal Sea Geology, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China |
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| Abstract: | Siderite records historical geological information about fluids, and thus can be used to trace diagenetic zones related to biogeochemical reactions. Siderite nodules have been found in Miocene marine shale in the Kuohsing area of Taiwan, but their genesis is not clear. Field observations show that the siderite is scattered in parallel discontinuous lenses in the shale, which consists mainly of authigenic siderite （78.63%） and other minerals. The REE distributions of the siderite are characterized by MREE enrichment with no Ce anomaly. This indicates that the siderite was formed in weakly oxidizing conditions, facilitating the precipitation of siderite in a suboxic zone. The δ13C and δ18O values of this siderite are from -3.69‰ to +0.08‰ and from -1.09‰ to +0.25‰, respectively, suggesting that it was precipitated in the suboxic zone with an admixture of seawater and organic matter. Studies show that authigenic siderite can be used to identify biogeochemical processes in sediments and indicate diagenetic zones. |
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