摘要
近十余年来的研究,在西藏雅鲁藏布江缝合带中的罗布莎蛇绿岩型铬铁矿中,发现可能来自深部(>300km深度)异常地幔矿物群。该矿物群中具有深部成因指示意义的矿物有:①呈斯石英假象的柯石英;②微粒金刚石和产在锇铱矿中的原位金刚石;③铬铁矿和锇铱矿中发现硅尖晶石;④铬铁矿中发现硅金红石;⑤呈八面体假象的蛇纹石和绿泥石,并具有清晰的爆炸结构;⑥方铁矿和自然铁矿物组合。此外,罗布莎铬铁矿中有4个新矿物获批准,并在极地乌拉尔蛇绿岩铬铁矿中也发现了大量微粒金刚石和碳硅石等地幔超高压矿物。蛇绿岩铬铁矿中发现来自地幔深部的超高压矿物,提供了铬铁矿可能深部成因的重要信息,该发现有可能改变传统的蛇绿岩铬铁矿的形成于俯冲带上的浅部环境(<50 km深度)的认识以及蛇绿岩成因的概念。
An unusual mineral group was discovered in the Luobusa ophiolitic chromitite on the Yarlung Zangbu suture of Tibet, which probably originated from the depth of over 300 km in the mantle. Minerals with indication significance of deep origin include：①coesite with pseudomorphs of stishovite;②tiamond as individual grains or inclusions in Oslr alloy; ③Si-spi-nel within OsIr alloy or arsenite;④Si-rutile in chromite; ⑤psuedomorphs of octahedral silicate minerals;⑥mineral assem- blage of wustite and native iron. In addition, four new minerals have been approved by ICMS. Similar to things of the Luobusa chrornitite, ultrahigh minerals such as diamond and moissanite were also recently discovered from the ophiolitic chromitites in Polar Ural, Russia. The ultrahigh pressure minerals provide an important perspective for deep genesis of the ophiolitic chromitites, and upgrade the traditional knowledge of the shallow-depth genesis of ophiolitic mantle and podiform chromitite.
出处
《地球学报》
EI
CAS
CSCD
北大核心
2008年第3期263-274,共12页
Acta Geoscientica Sinica
基金
中国地质调查项目(编号:1212010610107
1212010610105)
国家自然科学基金重大国际合作项目(编号:40610098)联合资助
