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对西昆仑普鲁新生代火山岩的矿物学进行了系统的研究。结果表明:该地区火山岩主要由橄榄石、单斜辉石和斜长石组成,并有少量的斜方辉石、黑云母、角闪石、碱性长石和铁钛氧化物。其矿物学特征指示了岩浆的性质有点类似于碱性岩浆,但与典型的碱性玄武岩又有明显的区别,属于橄榄安粗岩系列。利用橄榄石-熔体平衡原理估算了进入高位岩浆房中的熔体的MgO含量约为6.2%,Mg#为0.57,说明其不是地幔熔融形成的原始岩浆,而是经历了深部岩浆房的分离结晶过程。由单斜辉石估算的高位岩浆房的深度约7~9 km。岩浆在高位岩浆房中发生了较长时间的强烈分离结晶作用,分离结晶相主要为橄榄石、单斜辉石和斜长石以及少量的斜方辉石、黑云母、角闪石、碱性长石和铁钛氧化物。不同时期形成的铁钛氧化物指示了分离结晶过程由相对高温高氧逸度向相对低温低氧逸度演化。与此相对照的是岩浆在深部岩浆房中可能只发生了橄榄石和辉石等铁镁矿物的分离结晶作用,且分异作用时间较短。深部岩浆房可能存在于岩石圈地幔或壳幔过渡带中,岩浆由深部岩浆房上升到高位岩浆房中的过程是近绝热的,从浅部岩浆房到地表是快速上升的过程。
The mineralogy of the Pulau Cenozoic volcanic rocks in western Kunlun was systematically studied. The results show that the volcanic rocks in this area are mainly composed of olivine, clinopyroxene and plagioclase, and a small amount of orthopyroxene, biotite, amphibole, alkaline feldspar and iron titanium oxide. Its mineralogical characteristics indicate that the magma is somewhat similar to alkaline magma, but distinguishes it from the typical alkaline basalts and belongs to the Olig’angan series. Based on the olivine-melt equilibrium principle, it is estimated that the MgO content in the melt entering the upper magma chamber is about 6.2% and the Mg # is 0.57, indicating that it is not the original magma formed by the mantle melting but undergoes the separation of the deep magma chamber Crystallization process. The estimated height of the magma chamber from the clinopyroxenes is about 7 to 9 km. The strong separation and crystallization occurred in the magmatic chamber for a long time in the magma chamber. The main crystalline phases were olivine, clinopyroxene and plagioclase, a small amount of orthopyroxene, biotite, amphibole, alkaline long Stone and iron titanium oxide. Iron-titanium oxides formed at different stages indicate that the separation and crystallization progress from relatively high temperature and high oxygen fugacity to relatively low temperature and low oxygen fugacity. In contrast, magma may only separate and crystallize iron-magnesium minerals such as olivine and pyroxene in the deep magma chamber, and the differentiation time is short. The deep magma chamber may exist in the lithospheric mantle or crust-mantle transitional zone. The process of the magma rising from the deep magma chamber into the upper magma chamber is near adiabatic, and the process from the shallow magma chamber to the surface is rapidly rising.