中文摘要：

蛇绿岩地幔橄榄岩中产出的豆荚状铬铁矿是铬的主要来源,是中国极缺的重要战略资源。开展豆荚状铬铁矿成矿作用及围岩地幔橄榄岩的研究,是进一步寻找铬铁矿床和缓解中国铬铁矿资源的瓶颈状态的必要手段。本文以西藏雅鲁藏布江蛇绿岩带内几个主要的地幔橄榄岩体及其中的铬铁矿体为研究主体。在野外地质调查的基础上,系统总结了蛇绿岩的组成、矿物成分、岩石地球化学成分和Re-Os同位素等特征,探讨铬铁矿和地幔橄榄岩的形成过程,取得以下进展和认识：（1）雅鲁藏布江缝合带各段的岩石组合存在较大差异,构造背景的演化过程也不同,佐证了特提斯洋演化过程的不均一性;（2）在雅江西段存在高铝型和高铬型两类铬铁矿矿体,其余都为高铬型铬铁矿,铬尖晶石的矿物化学特征记录了不同构造背景的痕迹;（3）地幔橄榄岩的矿物学和地球化学表明地幔橄榄岩及铬铁矿具有深海地幔橄榄岩和岛弧地幔橄榄岩两者的特点,是岩石/熔体反应和部分熔融作用叠加的结果;（4）提出豆荚状铬铁矿为多阶段形成的认识,经历了早期俯冲到地幔过渡带,在地幔柱/地幔对流驱动下,运移到过渡带顶部冷凝固结,在侵位过程和俯冲带环境,含水熔体与方辉橄榄岩反应的过程;（5）在雅鲁藏布江缝合带中金刚石等超高压矿物的普遍存在,西段的几个大型岩体与罗布莎存在较多相似之处,均经历了相同的构造背景和豆荚状铬铁矿的成矿作用,存在较大的找矿空间。

英文摘要：

Podiform chromitite is the main source of chromium, and is a kind of important strategic material of extreme shortage in China; therefore, the study of chromitite and peridotite has become the first way to solve the long-term dependence on imports. In this study, the authors focused on the main ultramafic body and chromitite from Yarlung Zangbo ophiolite belt. On the basis of field geological work, the authors summarized the sequence of ophiolite, mineral composition, geochemistry, Re- Os isotopic composition and other characteristics, so as to discuss the formation of chromite and mantle peridotite. Some conclusions have been reached：（1） The ophiolite in different segments of Yarlung Zangbo suture zone exhibits quite different rock assemblages, with different tectonic evolution backgrounds, which proves the heterogeneity of Tethys evolution;（2） There are two types of high aluminum and high chrome chromitie found in western YZSZ, and the mineral chemical characteristics of chrome spinel have recorded traces of different tectonic settings, mineralogy and geochemistry;（3） The mineralogy and geochemistry of mantle peridotites peridotite and chromite have both the features of deep mantle peridotite and the island arc mantle peridotite, suggesting multi-processes of rock/melt reaction and partial melting;（4） The podiform chromite formation experienced multiple stages, from the early subduction to the mantle transition zone; driven by plume / mantle convection, the materials migrated onto the top of the transition zone, where they condensed and consolidated, and reacted with harzburgite in the emplacement process under a subduction zone environment;（5） The diamond and other UHP minerals extensively exist in all of the Yarlung Zangbo suture zone,with the western part bearing similarity to Luobusha in that they both experienced the same tectonic setting and ore mineralization,thus having potential for further prospecting.