甘孜—理塘蛇绿混杂岩带存在N型洋脊玄武岩

N-TYPE OCEANIC RIDGE BASALT IN THE GARGE -LITANG OPHIOLITE MELANGE ZONE

甘孜—理塘蛇绿混杂岩带历经 3 0余年的研究与争论 ,无论持何种观点者 ,均未能在带中找到N型洋脊玄武岩。近年我队在该带内的研究中已发现三处。最具典型意义的是产于甘孜电站的笨得古蛇绿混杂岩中的玄武岩 ,不仅具有“N”型洋脊玄武岩特有的亏损型稀土模式 ,同时具有蛇绿岩的典型层序 ,为该带古洋壳的存在增添新证据。

N-type Oceanic Ridge Basalt had been not found in the Gargê-Litang Ophiolite Mélange Zone in the past 30 years. Recently, it has been discovered by Regional Geological Surveying Team, BGEEMRSP in 3 places. Typical N-type Oceanic Ridge Basalt with depletion-type REE distribution patterns and typical ophiolitic sequence is encountered in Ophiolite Mélange in Bende, near the Gargê Hydroelectric Station which support existence of an old oceanic crust.