| 摘要: |
| 样品为1989年来自南黄海，利用显微镜、电子显微镜、电子探针和化学分析方法，对生黄铁矿的形态、成份和同位素特征进行研究，在此基础上就其成因与形成环境的关系进行初步探讨。研究结果表明，自生黄铁矿集合体形态可以分为聚莓、单莓和细粒3种，莓体特征的形态是早期成岩作用阶段沉积物随机堆积的结果，可以作为沉积成因黄铁矿的形态标型；黄铁矿微量成份特征显示其沉积成因，同时亦表现出对泥质沉积物地球化学背景值的继承性，黄铁矿晶体与胶状黄铁矿在形态及化学成份上的差异说明了自生黄铁矿在形成过程中经历过FeS-胶黄铁矿-黄铁矿的成份演化和胶体-胶状-晶体的结构演化；黄铁矿形成的层段为表层或次表层，Ⅰ型为弱碱-碱性条件下形成，Ⅱ型为弱酸-弱碱性条件下形成；莓伏黄铁矿的大量出现代表一种富氧水体和局部还原微环境的存在，指示有较强的上升流活动和不同水体的混合作用；黄铁矿与泥质沉积物在空间上共存，二者在成因上互相依存，黄铁矿的最终形成决定于局部微环境，而其富集条件则为总体地质背景。 |
| 关键词: 自生黄铁矿 标型 成因 环境 |
| DOI： |
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| 基金项目:自然科学基金(49376263)和中国科学院院长基金资助 |
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| ORIGIN AND ENVIRONMENTAL SIGNIFICANCE OF AUTHIGENIC PYRITE FROM THE SOUTH YELLOW t (HUANGHAI) SEA SEDIMENTS |
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Chu Fengyou, Chen Lirong, Shen Shunxi, Li Anchun, Shi Xuefa
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Institute of Oceanology Academia Sinica. Qingdao 266071
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| Abstract: |
| Preliminary results of optical microscope, electron microscope and electron probe study of the morphology, composition and isotopes of authigenic pyrite sampled from the South Yellow (Huanghai) Sea in 1989 and the relationship between the origin and formation environment suggest that the aggregate morphology of the authigenic pyrite can be classified as framboids, single framboid and fine grain. The morphology characteristic of framboids was the result of sediment random accumulation in the early diagenetic period, and can serve as morphological feature of sedimentary pyrite. The rare composition charocteristic of pyrite shows its sedimentary origin, as inferred from the geochemical background value of muddy sediment. The difference between pyrite crystals and colloid pyrite in morphology and chemical composition suggested that in the forming processes, authigenic pyrite charged in composition from FeS to colloid pyrite and then to pyrite, and charged in structure from colloid to colloid state and then to crystal. The segment pyrite formed in surface or subsurface sediment. The first type of pyrite was formed at wick alkaline or alkaline condition. The second type of pyrite was formed at wick acid or wick alkaline condition. The abundance of pyrite reflects rich oxygen and locally reducing microenvironment, with strong upwelling activity and mixing of different water masses. Pyrite and mud sediments spatially coexisted and were interdependent in origin. Final formation of pyrite depended on the local environment, while its abundance reflected the general geological background. |
| Key words: Authigenic pyrite, Morphological features, Origin, Environment |
