印度洋卡尔斯伯格脊卧蚕1号和卧蚕2号热液区含金属沉积物的矿物学和地球化学对比研究

发布时间：2024-03-27 19:34

　　含金属沉积物是海底热液活动的产物之一,由热液成因的含金属矿物与远洋沉积物混合沉积而成。由于含金属沉积物携带了热液的源区和热液循环的动力学信息,对其矿物学和地球化学研究对于重建热液活动的历史、位置、强度和演化至关重要。对远轴深海沉积物中热液成因矿物的识别能为隐伏热液矿床的勘探提供有效手段。卡尔斯伯格脊(简称卡脊)位于西北印度洋,是印度洋板块与索马里板块的构造边界。卡脊的扩张速率为22～32 mm/yr,属于慢速扩张洋脊。与同为慢速扩张洋脊的大西洋中脊相比,卡脊的研究程度非常有限,一直以来都没有发现热液活动和多金属硫化物。2013年,中国在卡脊中段一处新火山脊的西北坡发现了以玄武岩为围岩的卧蚕热液区。初步的调查显示,该热液区包含两处热液点,卧蚕-1#和卧蚕-2#,其中,卧蚕-1#水深2970～2990m,目前仍存在高温热液活动,而非活动的卧蚕-2#位于卧蚕-1#西北方向～2.7km处,水深3100m,主要产出坍塌的硫化物烟囱。一般来讲,在海底热液循环中,热液上升系统的动态活动能够直接观察得到,热液补给系统却不可见。由于针对卧蚕热液区获取的信息还十分有限,对含金属沉积物的地球化学研究不仅能够...

【文章页数】：123 页

【学位级别】：博士

【文章目录】：
Acknowledgement
中文摘要
ABSTRACT
1 Introduction
    1.1 Seafloor hydrothermal systems
        1.1.1 Active hydrothermal vent systems
        1.1.2 Inactive hydrothermal vent systems
    1.2 Products of seafloor hydrothermal circulations
        1.2.1 Massive sulfides
        1.2.2 Hydrothermal mounds
        1.2.3 Chimneys
        1.2.4 Hydrothermal breccia
        1.2.5 Ochreous and Gossan deposits
        1.2.6 Fe-oxyhydroxides and silica deposits
        1.2.7 Metalliferous sediments
    1.3 Geological settings of Carlsberg Ridge
    1.4 Geological characteristics of Wocan hydrothermal field
    1.5 Research objectives and Thesis content
2 Materials and methods
    2.1 Wet-sieve analysis
    2.2 Mineral abundance and chemistry
    2.3 Bulk sediment geochemistry and mineralogy
    2.4 Sulfur isotope analysis
    2.5 XRF Core Scanning and AMS ¹⁴C dating on sediment core
3 Mineralogical and geochemical signatures of metalliferous sediments in Wocan-1 andWocan-2 hydrothermal sites:Implication for the dynamics of hydrothermal circulationand post-depositional process
    3.1 Mineralogy, morphology, and abundance of sulfide and non-sulfide grains
    3.2 Bulk sediment geochemistry
    3.3 Mineral chemistry of sulfide separates
    3.4 Sulfur isotopes
    3.5 The effect of primary and post-depositional changes, evidence from grain texture,bulk chemical compositions and mineral chemistry
    3.6 The contributions of hydrothermal fluid, evidence from S isotope values
    3.7 Summary
4 Geochemical investigations of Fe-Si-Mn oxyhydroxides deposits in Wocan-1 andWocan-2 hydrothermal sites: Constraints on their origin in relation to the hydrothermalprocess
    4.1 Bulk sediment mineralogy
    4.2 Morphology and relative abundance of Fe-oxyhydroxide separates
    4.3 Origin and formation process of Wocan-1 Fe-oxyhydroxides and their associationwith the hydrothermal process
    4.4 Origin and formation process of Wocan-2 Fe-oxyhydroxides and their associationwith the hydrothermal process
    4.5 Origin and formation process of oxyhydroxide separates from the Ridge flanksediment
    4.6 Summary
5 A mineralogical and geochemical study of bulk sediments core from 4°07'N/69°20'E,Indian Ocean:Implication for the transportation of hydrothermal particles from theCarlsberg Ridge
    5.1 Mineralogical and chemical investigations
    5.2 Age model and sedimentation rate
    5.3 Vertical and temporal changes in mineralogical variations
    5.4 Implications on the vertical and temporal changes in the mineralogical variations
    5.5 Summary
6 Conclusions and Future work
    6.1 Conclusions
    6.2 Future Research
References
Appendices
    Appendix 1: Bulk chemical composition (ICPMS data) of metalliferous sedimentsfrom WHF and Ridge flanks
    Appendix 2. EPMA data on chalcopyrite grain separate from Wocan-1 and Wocan-2hydrothermal site
    Appendix 3. EPMA data on pyrite grain separate from Wocan-1 and Wocan-2hydrothermal site
    Appendix 4. EPMA data on sphalerite grain separate from Wocan-1 and Wocan-2hydrothermal site
    Appendix 5. Analytical equipment and approach methodology
    Appendix 6. Authored works 1
    Appendix 7. Authored works 2
Biography



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