Abstract Polymetallic nodules from the Clarion and Clipperton Zone of the equatorial Pacific Ocean were studied using X-ray diffraction, X-ray absorption, Fourier-transformed infrared spectroscopy and transmission electron microscopy. This study includes nodules found at the sediment surface as well as subsurface (14–16 cm sediment depth) and deeply buried (530–985 cm sediment depth) nodules. The surface and subsurface nodules are currently under oxic conditions whereas the deeply buried nodules are under suboxic conditions. Surface nodules consist mainly of turbostratic phyllomanganates (7 A and 10 A vernadite and Fe-vernadite); todorokite is a minor phase, if present at all. In contrast, subsurface and especially deeply buried nodules predominantly consist of todorokite, which increases in abundance with depth in the sediment. Thus, upon burial of nodules within the shallow sediment, phyllomanganates transform to todorokite, probably through the combined action of time and change in the ambient chemical conditions. Nodules from deeper sediment depth (>500 cm) consist primarily of todorokite and additionally show signs of dissolution. The transformation of phyllomanganates to todorokite and their further dissolution upon nodule burial under suboxic conditions induces modifications in the crystal-chemistry of Ni, Co, and Cu. In surface nodules, Ni and Co are incorporated in the octahedral sheets of phyllomanganates, whereas Cu mainly is located at the edges of those phyllomanganate sheets. In buried nodules Cu and to a lesser extent Ni are incorporated in todorokite by forming outer-sphere complexes within the tunnels. However, Ni is predominantly incorporated within the octahedra of the newly formed todorokite structure. Co is also enriched in the octahedra of todorokite as a result of dissolution of hydrogenetic vernadite and re-incorporation in the more stable Mn-phase formed during the diagenetic transformation. Co enrichment under suboxic conditions after burial within the sediments is noteworthy since Co in surface nodules is characteristic for oxic conditions.

中文翻译：

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多金属结核矿物学转变及沉积物埋藏后镍、铜、钴晶体化学变化

摘要 利用X射线衍射、X射线吸收、傅里叶变换红外光谱和透射电子显微镜研究了赤道​​太平洋克拉里昂和克利珀顿带的多金属结核。这项研究包括在沉积物表面发现的结核以及地下（14-16 厘米沉积深度）和深埋（530-985 厘米沉积深度）结核。地表和地下结核目前处于好氧条件下，而深埋结核处于低氧条件下。表面结核主要由涡层叶锰酸盐组成（7 A 和 10 A vernadite 和 Fe-vernadite）；todorokite 是次要阶段，如果存在的话。相比之下，地下和特别是深埋结核主要由 todorokite 组成，随着沉积物深度的增加，其含量增加。因此，在浅层沉积物中埋藏结核后，可能通过时间和环境化学条件变化的共同作用，叶锰酸盐转变为 todorokite。来自更深沉积深度 (>500 cm) 的结核主要由 todorokite 组成，另外还显示出溶解迹象。在低氧条件下结核掩埋后，叶锰酸盐转化为 todorokite 以及它们的进一步溶解导致 Ni、Co 和 Cu 的晶体化学发生变化。在表面结核中，Ni 和 Co 结合在叶锰酸盐的八面体片中，而 Cu 主要位于这些叶锰酸盐片的边缘。在埋藏的结核中，铜和少量的镍通过在隧道内形成外球复合体而被结合到 todorokite 中。然而，Ni 主要结合在新形成的 todorokite 结构的八面体中。Co 也富集在 todorokite 的八面体中，这是由于氢化绿绿岩的溶解和在成岩转变过程中形成的更稳定的 Mn 相中的重新结合。沉积物中埋藏后在缺氧条件下的 Co 富集值得注意，因为表面结核中的 Co 是有氧条件的特征。