变质泥质岩总结课件.ppt

变质泥质岩Metapelites变质泥质岩:板岩、千枚岩、片岩、片麻岩主要变质矿物:白云母、黑云母、钾长石绿泥石、硬绿泥石、十字石、堇青石、石榴石、紫苏辉石、假蓝宝石(sapphirine-(Al,Mg)8(Al,Si)6O20)、铁尖晶石红柱石、蓝晶石、矽线石、刚玉斜长石,石英Distinguishingchemicalcharacteristics:highAl2O3andK2O,mondevelopmentoffoliatedrocks,suchasslates,phyllites,andmicaschists高级变质(高角闪岩相-麻粒岩相)形成钾长石片麻岩,并伴随有深熔作用(anatexis)和混合岩化UHTmetamorphism(T>900oC)变质泥质岩的特征MetamorphicZonesBarrovianmetamorphiczonesaredefinedbyreactionsthatresultintheappearanceordisappearanceofmineralsandcanbemappedasisograds:chl—>bi—>gt—>st—>ky—>sill—>sill+orBarrovianzonemineralassemblagechloritezonechlorite+ms+qtz+H2O+relictmineralsbiotitezonechlorite+biotite+ms+qtz+zonechlorite+biotite++ms+qtz+H2Ostaurolitezonestaurolite+gt+bi+ms+qtz+H2Okyanitezonekyanite+gt+bi+ms+qtz+H2OsillimanitezoneSillimanite+gt+bi+ms+qtz+H2Osillimanite+orthoclasezonesill+or+qtz+H2O+meltandnomuscovite低级变质:绿片岩相,特征矿物有绿泥石,白云母,硬绿泥石,叶蜡石,钠长石中级变质:低角闪岩相,特征矿物有石榴石,十字石,Al2SiO5,黑云母,白云母稳定存在高级变质:高角闪岩相-麻粒岩相,特征矿物有钾长石(条纹长石),Al2SiO5超高温(UHT)变质:Spr+Q,Spl+Q,Opx+Sill+Q,OsmGraphiticslate(Upper)Veryfine-grainedChl+illite成岩作用的高级阶段和变质作用的初级阶段低绿片岩相Sideritephyllite(Lower)Ms+ChlChloritezone绿泥石带G+ms+bi+q(+pl+H2O+ilm)高绿片岩相(绿帘角闪岩相)zone硬绿泥石+绿泥石+石英=铁铝石榴石+H2O白云母+绿泥石+石英=铁铝石榴石+黑云母+H2O十字石铁铝石榴石二云母片岩Chlorite+Muscovite=staurolite+biotite+Quartz+H2OChlorite+muscovite+quartz=cordierite+biotite+Al2SiO5+H2O泥质岩石中以出现十字石(中压)和堇青石(低压)和在白云母存在时富铁绿泥石及硬绿泥石的消失为标志,低角闪岩相??