On Magma -Genetic Characteristics of Skarn and Its Formation Mechanism

(整期优先)网络出版时间:1993-01-11
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Forskarntypedeposits,therearetwokindsofskarns,skarnformedbyfiltrating-diffusingmetasomatismandveinskarnformedbyfilling.Theveinskarn,discussedthispaperandconsideredtobemagmaticgenesis,ischaracterizedby:(1)occurringasveinwithdistinctboundarieswithcountryrocks,yetjustthesameeveninmarbleeasytobereplaced;(2)composedofamineralassemblagesimi-lartothatofgranite,containingpegmatiteaswellascoarseskarnmineralpockets,andsometimestran-sitedwithdikerocks;(3)clearcrystallinefeatureofdeposition;(4)sideronintietexture;(5)showingvesicular,bean-likeandflowstructures;(6)verycommonliquidimmiscibility;(7)verticalzoningofgravitationaldifferentiationcausedbyvolatileconcentrationupwards;(8)associatedandtransitedwithiron-copperorebodiesofmagmaticgenesisandtungsten-bearingquartzveinsofsilicatemagmaticgene-sisrichinvolatile;(9)meltinclusions.Twooriginsofskammagma,originatedbyassimilationofsilicatemagmaatitsemplacem