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首页> 外文期刊>Geochemistry, geophysics, geosystems >Phosphorites, Co-rich Mn nodules, and Fe-Mn crusts from Galicia Bank, NE Atlantic: Reflections of Cenozoic tectonics and paleoceanography
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Phosphorites, Co-rich Mn nodules, and Fe-Mn crusts from Galicia Bank, NE Atlantic: Reflections of Cenozoic tectonics and paleoceanography

机译：大西洋东北加利西亚银行的磷矿，富钴锰结核和铁锰外壳：新生代构造和古海洋学的反映

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摘要

A wide variety of marine mineral deposits were recovered from 750 to 1400 m water depths on Galicia Bank, Iberian margin. Mineral deposits include: (1) carbonate fluorapatite phosphorite slabs and nodules that replaced limestone and preserved original protolith fabric. (2) Ferromanganese vernadite crusts with high Mn and Fe (Mn/Fe=1) contents, and thick stratabound layers consisting mainly of Mn (up to 27% MnO) and Fe (15% Fe2O3), which impregnated and replaced the phosphorite. (3) Co-rich Mn nodules are composed of romanechite and todorokite laminae. Mn-rich layers (up to 58% MnO) contain up to 1.8% Co. (4) Goethite nodules with Fe up to 67% Fe2O3 have low Mn and trace metals. We interpret this mineralization paragenesis to be related to major changes in oceanographic and tectonic regimes. Three phosphatization generations formed hardgrounds dated by Sr-87/Sr-86 isotopes as late Oligocene, early Miocene, and latest early Miocene. During the latest early Miocene, the hardground was fractured and breached due to regional intraplate tectonism, which was coeval with a widespread regional erosional unconformity. The stratabound layers and Co-rich manganese nodules were derived from low-temperature geothermally driven hydrothermal fluids, with fluid conduits along reactivated faults. During middle and late Miocene, the introduction of vigorous deep water flow from the Arctic generated growth of hydrogenetic ferromanganese crusts. Finally, growth of diagenetic Fe-rich nodules (late Pliocene) was promoted by the introduction of hypersaline Mediterranean Outflow Water into the Atlantic Ocean.
机译：在伊比利亚边缘的加利西亚河岸，从750至1400 m的水深中发现了各种各样的海洋矿物沉积物。矿藏包括：（1）碳酸盐氟磷灰石亚磷酸盐板和结核，代替了石灰石并保留了原始的原生石织物。 （2）锰铁白云母皮具有高的锰和铁含量（Mn / Fe = 1），以及主要由锰（高达27％MnO）和铁（15％Fe2O3）组成的厚层结合层，其浸渗并替代了磷矿。 （3）富钴锰结核是由锰铁矿和钙锰矿的薄片组成。富锰层（高达58％的MnO）包含高达1.8％的Co。（4）含Fe高达67％的Fe2O3的针铁矿结核具有低Mn和痕量金属。我们认为这种成矿共生作用与海洋和构造机制的重大变化有关。 Sr-87 / Sr-86同位素的三个磷化世代形成了硬地带，分别是渐新世晚期，中新世早期和最新中新世。在最近的中新世早期，由于区域性板内构造作用，硬地层破裂并破裂，这与广泛的区域侵蚀不整合面同时出现。地层结合层和富钴锰结核源于低温地热驱动的热液流体，流体管道沿重新活化的断层延伸。在中新世中期和后期，北极强​​烈的深层水流导致了氢铁锰结壳的生长。最后，通过向大西洋引入高盐度的地中海流出水，促进了成岩性富铁结核（上新世晚期）的生长。

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