Abstract The understanding of ophiolites as hosts to economic–scale chromitite ore deposits requires the integration of research relating their geochemical metallogenesis with studies of the mode and nature of their lithospheric-scale deformation. The Neotethyan Vourinos ophiolite in Northern Greece represents a well-preserved ophiolite complete with sheeted dikes, an in-situ Moho transition zone, and a nearly 8-km-thick upper mantle sequence. Chromitite bodies and sub-economic chrome ores occur throughout its ultramafic section, and above and below the petrological Moho; but, economic concentrations of chromitite are restricted to a region referred to as the “metalliferous zone” within the upper mantle domain. Ductile deformation, which developed synchronously with mineral re-equilibration and late magmatic activity, re-concentrated chromite grains in mesoscopic fold noses and created massive-textured ore bodies. Re-equilibration of chromite and chromite–olivine grains on microscopic–scale during this ductile deformation produced geochemical patterns that are compatible with strain distribution. Whether re-equilibration varied with strain rate in the mantle lithosphere due to regional heterogeneous conditions, or whether the change in deformation–induced modal distribution of the mineral aggregate more strongly affected the process of re-equilibration is yet to be determined. The richest ore bodies in Vourinos are represented by the schlieren ores of the Xerolivado Mine, and occur as extensive lenses of mylonitic chromitite, marking the highest degree of deformation within the complex. These textures display patterns of re-equilibration geochemical halos and transition from ductile into brittle deformation conditions.

中文翻译：

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Vourinos蛇绿岩（希腊）中铬矿成因的结构方法：韧性和脆性变形过程在大洋上地幔橄榄岩经济矿体形成中的意义

摘要 将蛇绿岩理解为经济规模铬铁矿矿床的主体，需要将其地球化学成矿作用的研究与其岩石圈规模变形的模式和性质的研究相结合。希腊北部的 Neotethyan Vourinos 蛇绿岩代表了一种保存完好的蛇绿岩，具有片状岩脉、原位莫霍面过渡带和近 8 公里厚的上地幔层序。铬铁矿体和亚经济铬矿遍布其超基性岩段，以及岩石莫霍面之上和之下；但是，铬铁矿的经济集中地仅限于上地幔域内被称为“含金属带”的区域。韧性变形，与矿物再平衡和晚期岩浆活动同步发展，在细观褶皱鼻中重新浓缩铬铁矿颗粒并产生块状纹理矿体。在这种韧性变形过程中，铬铁矿和铬铁矿-橄榄石晶粒在微观尺度上的重新平衡产生了与应变分布相适应的地球化学模式。重新平衡是否因区域非均质条件而随着地幔岩石圈应变率的变化而变化，或者矿物聚集体的变形诱导模态分布的变化是否更强烈地影响了重新平衡的过程，尚待确定。Vourinos 中最丰富的矿体以 Xerolivado 矿的纹状体矿石为代表，并以糜棱铬铁矿的广泛透镜形式出现，标志着复合体中变形程度最高。