The discovery of Early Ordovician ophiolite melange in Taerbahatai Mts., Xinjiang, NW China.

在我国境内塔尔巴哈台山下石炭统黑山头组泥岩、粉砂岩、凝灰岩和火山熔结角砾岩夹基性熔岩的底部识别出一套蛇绿混杂岩。火山角砾岩的角砾由蛇纹石化橄榄岩(蛇纹岩)、辉长岩、玄武质粗面安山岩、粗面岩和硅质岩组成。蛇绿混杂岩由蚀变辉长岩、蛇纹岩和硅质岩组成。橄榄岩虽然发生了强烈蛇纹岩化(现在为蛇纹岩),但蛇纹岩中保留了斜方辉石和橄榄石的假象。覆盖在该蛇绿岩套之上的火山角砾岩属于爆发性很强的火山喷发产物。巨大的粗粒辉长岩、玄武质粗面岩、粗面岩、硅质岩和蛇纹石化橄榄岩角砾被熔岩胶结,说明火山通道穿切了蛇绿岩套。蚀变辉长岩中的斜方辉石已经完全蛇纹石化(保留了斜方辉石假象),斜长石完全被水钙铝榴石交代(保留斜长石...We report a discovery of an ophiolite melange in Taerbahatai Mts. ( Xinjiang, NW China), which underlies the Early Carboniferous Heishantou Group consisting mainly of mudstone, siltstone, tuff, alloclastic rocks, volcanic breccia and lava. The breccia includes serpentite, gabbro, basaltic trachyandesite, trachyte, and silicalite. The Ophiolite melange consisting of altered gabbro, serpentine peridotite, and silicalite occurs on the bottom of this volcanic stratum. Peridotite has undergone strong serpentinization and was completely replaced by serpentinite, but the pseudomorph of olivine and orthopyroxene still are preserved. Volcanism obviously postdated the emplacements of the Ophiolite melange, and the eruption was strong as large gabbro and other breccia are frequently observed. Clinopyroxene grains in the altered gabbro from the bottom of the Ophiolite melange are relatively fresh and show a kind of exsolution texture ( whilst all plagioclase grains were replaced by hydrogrossular showing pseudomorph of plagioclase). All the exsolution lamellae are brown spinel. The spinel lamellae (or leafs) are parallel to each other. Zircon separated from this altered gabbro is dated to be 478.3 +/- 3.3 Ma ( MSWD = 1.09, n = 14) by SHRIMP method. This age represents the emplacement time of the Taerbahatai Ophiolite melange during the Early Ordovician epoch.SCI(E)中文核心期刊要目总览(PKU)中国科技核心期刊(ISTIC)中国科学引文数据库(CSCD)82122833-28422