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在南海台西南区GC10岩芯中发现了大量自生管状黄铁矿,它是海洋沉积物缺氧硫酸盐还原过程的主要产物。扫描电镜和高分辨率透射电镜测试结果显示,这些管状黄铁矿主要由草莓状黄铁矿组成,且在管内各圈层分布不均:内层主要是单个的大颗粒草莓状黄铁矿,直径为40μm左右;中间致密层为具外壳结构的草莓状黄铁矿,经后期压实作用后呈五角十二面体紧密堆积;外层是疏松的混有部分杂质的黄铁矿。高分辨率透射电镜观测显示,草莓状黄铁矿中存在面缺陷,在平行于黄铁矿的(001)面存在白铁矿层。草莓状黄铁矿中的黄铁矿与白铁矿是同质异构体,而且,白铁矿的(101)平行于黄铁矿的(001),白铁矿的[010]方向平行于黄铁矿的[100],这是黄铁矿与白铁矿之间最易相互生长的面。草莓状黄铁矿微晶的形态各异,包括有序规则排列的球粒、部分有序排列的五角十二面体、无序排列的球粒、截角立方体、不规则体及亚微晶颗粒等,说明草莓状黄铁矿是在微生物参与下,在由强还原到局部弱氧化的环境中形成的。这种微环境的变化正好是下部上溢的甲烷在管状通道内与硫酸盐发生反应的结果。
A large amount of authigenic tubular pyrite was found in the core of GC10 in the Southwest Taiwan area, which is the main product of the anoxic sulfate reduction process in marine sediments. Scanning electron microscopy and high-resolution transmission electron microscopy results showed that these tubular pyrite mainly composed of strawberry-like pyrite, and the distribution of the various layers of the ring uneven: the inner layer is mainly a single large-particle strawberry-like pyrite, The diameter of about 40μm; the middle of the compact layer is a shell-like strawberry-like pyrite, post-compaction pentagonal dodecahedron closely packed; the outer layer is mixed with some impurities pyrite. High-resolution transmission electron microscopy showed that there were surface defects in the strawberry-like pyrite, with the presence of a layer of white iron on the (001) plane parallel to the pyrite. The pyrite in the strawberry-like pyrite is isomorphic with the white iron ore, and the (101) of the white iron is parallel to the [001] direction of the pyrite (001) and the pyrite Pyrite [100], which is the most interplanetary surface between pyrite and white iron ore. Morphology of strawberry-like pyrite crystallites are different, including ordered regularly arranged spherulites, partially ordered pentagonal dodecahedron, disordered spherulites, truncated cubes, irregularities and submicron grains Etc., indicating that strawberry-like pyrite is formed by the strong reduction to the local weak oxidation environment with the participation of microorganisms. This microenvironment changes exactly as a result of the reaction of underflowed methane with sulphate in the tubular channel.