The chrome spinel (chromite) in mantle peridotites from ophiolites can shed light on the formation and evolution process of ophiolites. Podiform chromites were found in the Late Proterozoic Miaowan ophiolitic complex (MOC), Yangtze Craton. Due to the metamorphism and intense deformation, most chromite grains in the MOC peridotites show typical chemical zoning (core-rim texture). The values of major and trace elements largely vary from core to rim within chromite grains, indicating that the chromites have undergone strong alteration and element mobility. Major and trace elements in the core parts of chromites are used to infer the tectonic origins and evolution of mantle peridotites in the MOC. The chromites from the MOC peridotites have higher Cr# values and lower Ni and Ga contents with respect to those from Phanero-zoic mantle peridotites, indicating a higher degree of depletion. In-situ major and trace elements (e.g., Ga) characteristics of podiform chromites in the MOC show that chromites from both harzburgites and dunites have strong subduction-related signatures, indicating that the MOC has formed in a supra-subduction setting which is consistent with the geological and geochemical data presented in previous studies.

中文翻译：

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长江克拉通元古代苗湾蛇绿岩复合体橄榄岩中带状铬铁矿的地球化学特征：对元素移动性和构造环境的影响

蛇绿岩中地幔橄榄岩中的铬尖晶石（铬铁矿）可以揭示蛇绿岩的形成和演化过程。在元古代晚期的湾湾蛇绿岩复合体（MOC）扬子克拉通中发现了亚铬铁矿。由于变质作用和强烈变形，MOC橄榄岩中的大多数铬铁矿晶粒都表现出典型的化学分区（核-边缘纹理）。在铬铁矿晶粒内，主要元素和痕量元素的值在核心与边缘之间变化很大，这表明铬铁矿经历了强烈的变化和元素迁移。在铬铁矿核心部分的主要和微量元素被用来推断MOC中地幔橄榄岩的构造起源和演化。与Phanero-新生代地幔橄榄岩相比，MOC橄榄岩中的铬铁矿具有较高的Cr＃值和较低的Ni和Ga含量，MOC中豆状铬铁​​矿的原位主要和微量元素（例如Ga）特征表明，来自哈茨堡岩和盾构岩的铬铁矿具有强烈的俯冲相关特征，表明MOC在超俯冲环境中形成，与先前研究中提供的地质和地球化学数据。