【作者】 李永生；

【导师】 张招崇；

【作者基本信息】 中国地质大学(北京) ， 矿物学、岩石学、矿床学， 2012， 博士

【摘要】 位于我国西南云贵川三省的二叠纪的峨眉山大火成岩省是我国唯一被国际承认的大火成岩省，一般被认为是地幔柱作用的产物，其主要证据是存在高温苦橄岩和喷发前存在公里级的地壳隆升。公里级隆升是大火成岩省火山作用前深部地幔柱上涌碰撞岩石圈底部并且造成地壳大规模隆升的最好的一个例子。然而，这一结论受到了挑战，因为在峨眉山大火成岩省隆升幅度最大的地区发现了一些代表海底喷发环境的玄武岩。所以，峨眉山大火成岩省是否是地幔柱活动的产物以及地幔柱的模型需要更多的检验。玄武岩成分可以反映地幔熔融温度和熔融压力，因为其成分随着地幔潜温（Tp）、初始熔融压力（P0）和终止熔融压力（Pf）的变化而变化。因此，本文利用峨眉山大火成岩省已发表的玄武岩数据，筛选掉明显遭受同化混染的样品。并且通过Klein and Langmuir的方法校正玄武岩成分至MgO为8%，再利用PRIMELT2软件计算原始岩浆成分。通过计算的温度和压力约束大火成岩省形成时地幔的热状态和它的地球化学、物理结构、岩石学特征。计算结果显示峨眉山大火成岩省原始岩浆形成压力在0.4~4.0GPa之间，接近15~130 km深部的地幔源区。地幔潜温在1 420~1 637℃之间，高出正常地幔温度100~300℃，从而为峨眉山地幔柱提供了进一步的证据。此外，地幔熔融的P-T分布关系也为峨眉山地幔柱提供了新证据，中心在丽江地区。另外，伴随着大火成岩省玄武岩巨量喷发，携带的大量的能量和物质与周围地壳相互作用，在一些构造活跃部位，由于岩浆的侵入还会形成各种类型的与岩浆成因相关的矿床。峨眉山大火成岩省是全球矿产资源最为丰富的大火成岩省之一。镁铁‐超镁铁岩侵入体是重要的矿产赋矿岩体，主要以岩浆铜镍硫化物‐铂族元素矿床和钒钛磁铁矿矿床为主。本文通过最新的能量控制下的同化混染分离结晶（EC-AFC）模型模拟了峨眉山大火成岩省岩浆与地壳相互作用，结果表明力马河铜镍硫化物矿床的形成是镁铁‐超镁铁质岩浆与围岩相互作用的结果，EC-AFC过程是矿床形成的重要约束。更多还原

【Abstract】 The Permian Emeishan large igneous province(LIP) in Sichuan, Yunnanand Guizhou Provinces is only internationally admitted large igneous provincein China, generally considered to be a product of mantle plume, the mainevidences are the existence of high-temperature picrites and kilometers crustaluplift prior to the eruption. Kilometers uplift is a commonly cited example ofa LIP that formed as a result of a deep-mantle plume impinging on the base ofthe lithosphere and generating large regional-scale up-doming prior tovolcanism. However, this conclusions were challenged for reporting the lavashad been emplaced in submarine where is the most uplift in the Emeishanlarge igneous province. Thus, it is needs more tests weather Emeishan largeigneous province is the result of mantle plume and mantle plume simulations.Basalts can be used as melting temperature and pressure probes of themantle because their compositions change with variations in mantle potentialtemperature(Tp), initial melting pressure(P0) and final melting pressure(Pf).Thus, we collect more than 600 published basaltic samples of Emeishan largeigneous province, and exclude samples which significantly contaminated.Then the remaining samples were corrected to MgO=8% using the Fe8.0 andSi8.0 expressions from Klein and Langmuir, and calculated primary magmasusing PRIMELT2 software. The calculated temperatures and pressures areused to define the thermal state, geochemistry, lithology and physicalstructure of the melting region in the underlying mantle when large igneousprovince forming. The results show that the primary magmas of EmeishanLarge igneous could be generated in the pressure range 0.4~4.0 GPa at anapproximate depth of 15~130 km from mantle sources. And the generated temperatures in range 1 420~1 637℃, which excess normal mantletemperature 100~300℃, provide further evidence of Emeishan mantle plume.Furthermore, the distributions of P-T also strengthen the existence ofEmeishan mantle plume, and Lijiang most probably is the mantle plume axis.Additionally, large igneous province erupted with huge amounts ofbasaltic melt, heat and materials, and interacted with the surrounding crust. Ina number of tectonic active sites, there are various types of deposits due tomagma intrusion. Emeishan large igneous province is one of the world’s mostabundant mineral resources of the large igneous provinces. Mafic-ultramaficintrusions are major mineral ore-bearing terranes, mainly magmaticcopper-nickel sulphide - PGE deposits and vanadium-titanium magnetitedeposits. We modeling Emeishan large igneous province magmatism andcrustal interaction using the latest energy-constrained assimilation-fractionalcrystallization (EC-AFC) model. The results show that the Limahecopper-nickel sulfide deposit is the result of the interaction of mafic-ultramafic magma and wall rock. EC-AFC process is an important constraintto deposit formation.更多还原