红土型镍矿床成因的多样性:基于全球尺度的对比研究
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国家自然科学青年基金(编号41102051)、广西自然科学基金(编号 2012GXNSFAA053187)、广西自然科学青年基金(编号 桂科青0991083)和广西重点实验室建设项目(编号 11-031-20;12-071-20)


Diversified Genesis of the Laterite Nickel Deposits: A Comparative Study Based on the Global Scale
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    摘要:

    红土型镍矿床是全球镍矿成因体系中资源储量最大的一类。为探讨红土型镍矿床成因机制的多样性,基于全球广域尺度,选择以载镍矿物为分类视角,开展铁氧化物型、水镁硅酸盐型和粘土型等3类矿床的对比研究。铁氧化物型矿床在矿化剖面上以铁质红土层为优势岩(土)相层,以针铁矿为主要载镍矿物,矿石中镍品位偏低但伴生钴矿化。矿床的成矿条件依赖于热带气候环境、稳定大地构造背景、纯橄榄岩母岩和剪切构造带等多种因素的集成耦合。强氧化和水解作用是载镍铁氧化物和氢氧化物发育的主要机制,镍在红土化过程中主要以类质同象进入低结晶度针铁矿晶格或被吸附的方式富集成矿;水镁硅酸盐型矿床以风化壳中出现厚大腐岩层为标志,以镍蛇纹石、镍滑石等水镁硅酸盐矿物为主要载镍矿物相,矿石多为高品位硅镁镍矿。矿床的发育严格受控于热带雨林或热带草原气候环境,与活跃大地构造背景及富镁橄榄岩母岩条件密切相关,属强淋滤表生作用的产物。离子交换作用和次生沉淀作用共同构成了水镁硅酸盐矿床发育的成矿机制;粘土型矿床以红土剖面中出现稳定的粘土矿物层为标志,局限于偏干旱的热带气候背景,与低缓的地形地貌、排水受阻的水文环境及蛇纹岩母岩条件等具有专属性联系,属未遭受充分表生淋滤作用的产物。镍与次生蒙脱石类矿物发生离子交换作用是粘土型矿床发育的主要机制。

    Abstract:

    The laterite has the biggest reserves among the global nickel deposits. Comparative study reveals that laterite nickel deposits are characterized by diversity and oriented occurrence in the mineralization and metalogenic mechanism. The Fe oxide type is characteristics of the deep laterite layer as the main petrographic face in the ore bearing weathering crust, the abundant goethite as the main nickel bearing mineral and lower Ni ore grade but higher Co accompanied. The Fe oxide type is better developed under tropical climate, stable tectonic background, dunite as the parent rock and locally shear belt occurred. The intense oxidation is the key process determinate the deposit formation. The Ni is adopted by ferrous minerals, or enters the lattice of low crystalline goethite, which makes the supergene nickel enrichment. The hydrated Mg silicate type is characteristics of the deep saprolite layer as the dominant petrographic face, the serpentine and talc as the main nickel bearing minerals, and the occurrence of high grade garnierite ore. This type is limited under the combined conditions of tropical rainforest or monsoon climate, active tectonic background and olive rich parent rock. The intense leaching, the Ni ion exchange reaction between the residue serpentine and leached fluids and the secondary precipitation of garnierite are essential for nickel mineralization. The clay type is characteristics of the special nontronite layer as the intermediate section between the laterite and saprolite layer, and the nontronite as the main nickel bearing minerals. This type is restricted under coupling conditions of relative dry tropical climate, stable tectonic background, low terrain, impeded drainage, and serpentine as parent rock. The inadequate leaching leads to nontronite mineral formation and becomes excellent carrier by the Ni ion exchange reaction.

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付伟,牛虎杰,黄小荣,杨梦力,陈远荣.2013.红土型镍矿床成因的多样性:基于全球尺度的对比研究[J].地质学报,87(6):832-849.
fuwei.2013. Diversified Genesis of the Laterite Nickel Deposits: A Comparative Study Based on the Global Scale[J]. Acta Geologica Sinica,87(6):832-849.

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  • 收稿日期:2012-08-24
  • 最后修改日期:2013-02-28
  • 录用日期:2013-06-27
  • 在线发布日期: 2013-07-02
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