Quantitative Modeling Of The Emeishan Large Igneous Province Magmatism Processes

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.