中国地质Issue(2)：525-546,22.
雅鲁藏布江缝合带西段达机翁地幔橄榄岩及铬铁矿的铂族元素特征
Platinum-group element characteristics of the peridotite and podiform chromitite from Dajiweng ophiolite of the western segment of Yarlung-Zangbo suture zone, Tibet
摘要
Abstract
Located in the northern subbelt of the western Yarlung Zangbo ophiolite zone, Dajiweng ophiolite is mainly composed of peridotite, basalt and silicious rocks. The peridotite is dominated by harzburgite with minor dunite. Dunite occurs as patches in the peridotites. Podiform chromitite can be found in the harzburgite with dunitic envelope. According to the texture and mineralogy of the chromitite, Dajiweng podiform chromitite can be divided into three types, namely massive chromitite, disseminated chromitite and nodular chromitite. This paper mainly reports the research on the harzburgite and podiform chromitite and makes a discussion on the petrogenesis of the peridotite, the origin of the chromitite and chromitite prospect in the Yarlung Zangbo suture zone combined with the major and platinum group elements. Dajiweng harzburgite has a depleted whole rock composition with higher MgO content and lower Al2O3, CaO content than the primitive mantle, indicating that Dajiweng peridotite has experienced a high degree of partial melting. Dajiweng harzburgite has higher PGEs content (23.68 × 10−9-31.02 × 10−9) than primitive mantle. The Cu and Pd content of Dajiweng harzburgite strongly deviates from the modeled partial melting curves, which is a symbol of melt-rock reaction. During the process of melt-rock reaction, sulfides were enriched with PPGEs and these materials were added to the Dajiweng harzburgite. In the primitive mantle-normalized PGE patterns of podiform chromitite, Dajiweng chromitite shows obvious enrichment of IPGE and Rh, and depletion of Pt and Pd. Podiform chromitites of different types have consistent primitive mantle-normalized PGE patterns. Ultramafic rock in the Yarlung Zangbo ophiolite belt shows remarkable similarities in such aspects as rock assemblage, rock geochemistry, formation age and petrogenesis, suggesting that the Yarlung-Zangbo ophiolite is a promising prospecting area for chromitite.关键词
雅鲁藏布江缝合带/达机翁/地幔橄榄岩/豆荚状铬铁矿/铂族元素Key words
Yarlung-Zangbo suture zone/Dajiweng/peridotite/podiform chromitite/PGEs分类
天文与地球科学引用本文复制引用
连东洋,杨经绥,熊发挥,刘飞,王云鹏..雅鲁藏布江缝合带西段达机翁地幔橄榄岩及铬铁矿的铂族元素特征[J].中国地质,2015,(2):525-546,22.基金项目
国家行业专项（SinoProbe-05-02）、国家自然科学基金重点项目（40930313）、国家自然科学基金创新群体项目（41221061）、国家自然科学基金项目（41202036、40921001）和中国地质调查局工作项目（1212011121263、12120114061801）联合资助。 （）
