新疆北山地区罗东镁铁质-超镁铁质层状岩体岩石成因

罗东镁铁质-超镁铁质岩体位于塔里木板块东北部的新疆北山地区,岩体平面形态为眼球状,出露面积约2.1 km2.由纯橄岩、单辉橄榄岩、斜长二辉橄榄岩、橄榄二辉岩、方辉辉石岩、橄长岩、橄榄辉长岩、辉长岩、苏长辉长岩和淡色辉长岩组成,堆晶结构和堆晶韵律发育,属于层状岩体.岩浆演化过程中主要分离结晶/堆晶相是橄榄石和单斜辉石,此...

Petrogenesis of Luodong mafic-ultramafic layered intrusion,Beishan region,Xinjiang

Lens shaped Luodong mafic-ultramafic intrusion lies in Beishan region of Xinjiang in Northeastern Tarim Plate and covers an area of 2.1 km2.It consists of dunite,wehrlite,plagio-lherzolite,olivine websterite,peridotite pyroxenite,troctolite,olivine gabbro,gabbro,noritegabbro and leucogabbro.The Luodong intrusion is a layered intrusion with obvious cumulus textures and rhythmics.The mainly fractional crystallized or cumulated phases are olivine and clinopyroxene,together with minor plagioclase,orthopyroxene and Cr-spinel during magma evolution.The geochemical feature indicates weak crustal contamination.The primary magma is picritic with MgO contents up to 14.7% and high crystallization temperature of 1412 ℃.OIB-like Nd,Sr isotopic compositions and high temperature picritic primary magma indicate that Luodong intrusion may have an affinity with mantle plume and be formed by partial melting of axis plume.The Early Permain mantle-derived magmatic rocks in Northeastern Tarim Plate are thus a part of Tarim Large Igneous Province.