简介：Phlogopite-amphibole-pyroxenitexenolithscontainedinthealkalibasic-ultrabasicsubvolcaniccomplexinLangao,shaanxiProvinece,arecomposedofdiopside,Ti-richpargasite,phlogopiteapatite,spheneandilmenite,whichhavesubsolidusmetamorphism-deformationtexturessuchastriple-points,cataclasticboundariesandkink-bands,MineralChemicalcharacteristicsshowthatthediopside,Ti-richPargasiteandphlogopitearederivedfromthemantleandaretheprioductsofmantlemetasomatism,Comparedwithnormalmantle-derivedspinel-lherzolites,thexenolithsareenrichedinTiO2,Fe2O3,CaO,Na2OandK2O,withapparentdepletioninMgO,Chondrite-normalizedREEpatternsandprimordial-mantlenormalizedtraceelementsdatashowthattheyareenrichedinREE(EspeciallyLREE)andincompatibletraceelements,Thepetropraphic,mineralogicalandpetrochemicalcharacteristicsindicatethatthexenolithsaremetasomatizedmantlexenoliths,whichofferstheevidenceformantlemetasomatismandrepresentstheanomalousmantlebeneaththeEarlyPaleozoicriftinnorthernDabaMountains,Theagentsofmantlemetasomatismareprobablyderivedfromtherisingofmantlehotplumes,Thepriocessesofmetasomatismvariedfromlimited-rangefluidmetasomatismindeepmantle(>90km)topervasivemetasomatismofsilicatemelt.