实习五 岩浆岩

实习五岩浆岩（一）中酸性岩目的：1、学会岩石的鉴定和描述方法

2、掌握岩浆岩的结构、构造类型

3、认识几种主要的岩浆岩类岩石内容：1、观察并描述：花岗岩、似斑状花岗岩、花岗斑岩、流纹岩、伟晶岩、浮岩等

2、观察：细晶岩、黑曜岩、珍珠岩、花岗闪长岩等岩石Rocks岩石：矿物的天然混合物或集合体。RocksarenaturalmixturesoraggregatesofmineralsHowtoIdentifyRocksRockscanbeclassifiedasigneous,metamorphic,orsedimentaryaccordingtothemannerinwhichtheywereformed.Theirspecificcharacteristicsdependonthemineralsthatconstitutethem.Basedonthisinformation,itispossibletoknowhowrocksgainedtheircolor,texture,andcrystallinestructure.Withalittleexperienceandknowledge,peoplecanlearntorecognizeandidentifysomeoftherocksthattheyoftensee.ColorThecolorofarockisdeterminedbythecolorofthemineralsthatcomposeit.Somecolorsaregeneratedbythepurityoftherock,whereasothersareproducedbytheimpuritiespresentinit.Marble,forinstance,canhavedifferentshadesifitcontainsimpurities.TextureTexturereferstothesizeandarrangementofgrainsthatformarock.Thegrainscanbethick,fine,orevenimperceptible.Therearealsorocks,suchasconglomerates,whosegrainsareformedbythefragmentsofotherrocks.Thetextureisasmall-scalepropertyofarock,butdeterminedmanyofitslarge-scaleproperties.MineralCompositionRocksarenaturalcombinationsoftwoormoreminerals.Thepropertiesofrockswillchangeinaccordancewiththeirmineralogicalcomposition.Forinstance,granitecontainsquartz,feldspar,andmica;theabsenceofanyoftheseelementswouldresultinadifferentrock.TheThreeGreatRockFamilies三大岩类：Sedimentary：沉积岩

Hasobviousstratification层理

Verysoft(easilyscratchedbyaknife)软

Obviouslymadeofparticlescementedtogether碎屑被胶结在一起

Containsfossils化石Igneous-Volcanic火山岩Containsnumerousbubble-likecavitiesthatmayormaynotbelinedwithminerals气孔Hasobviousbubblyorfrothytexture气孔Isfine-grained,uniformintexture,andhard

细粒、均匀、坚硬GlassyorhighlyvesicularrocksarealmostalwaysigneousIgneous-Plutonic侵入岩Madeofdiscretemineralgrainslockedtogether(maybeloosenedbyweathering)Containslargecrystalsinafiner-grainedmassRockmassobviouslycutsacrossotherrockstructures.Metamorphic变质岩Hasafinetexturewithanobviousdirectionalgrain(foliation)定向Hasobviousbands,streaksorclumpsofdifferentminerals不同矿物的条带Ismademostlyofquartzorcalcitebutiscoarse-grainedandlackssedimentaryfeatures石英方解石Containsdistinctivemetamorphicmineralslikegarnetorkyanite特殊的变质矿物Mayoftenhavefeaturesoforiginalrockbutisrecrystallizedorchemicallychanged.IgneousRocksandMagma火成岩和岩浆火成岩的产状分类喷出岩－火山岩侵入岩－深成岩侵入岩－浅成岩5kmIgneousRocksare

formedbycrystallizationfromaliquid,ormagma.

Theyincludetwotypes：

Volcanicorextrusive

igneousrocksformwhenthemagmacoolsandcrystallizesonthesurfaceoftheEarth

Intrusiveorplutonic

igneousrockswhereinthemagmacrystallizesatdepthintheEarth.岩浆岩的结构岩浆岩的结构按照结晶程度划分显晶质结构隐晶质结构流纹岩玻璃质结构黑曜岩斑状结构斑状和似斑状结构：区别主要在基质的粒度斑状结构斑晶基质斑晶似斑状结构斑晶基质文象结构(GraphicTexture)石英呈一定的外形(如象形文字）有规律地镶嵌在钾长石中。SomeIgneousRocksAreNamedonTexturalCriteria结构构造的命名Scoria:Porous火山渣Pumice浮岩Obsidian-Glass黑曜岩Tuff-CementedAsh火山灰Breccia-CementedFragments角砾岩Pegmatite-ExtremelyLargeCrystals伟晶岩Aplite-SugaryTexture,Quartz&Feldspar细晶岩Porphyry-FineMatrix,LargeCrystals斑岩岩石的构造均一块状构造斑杂构造条带状构造流动构造气孔构造杏仁构造枕状构造块状构造条带状构造流纹构造气孔状构造杏仁构造化学组成及分类以氧化物形式表示：如SiO2、Al2O3、CaO、Na2O、K2O等等SiO2是最重要的组分，是岩石分类的最主要指标，可以划分为：酸性岩，SiO2>65％中性岩，65%>SiO2>52％基性岩，52%>SiO2>45％超基性岩，SiO2<45％岩石中的矿物组成主要为硅酸盐矿物，分为浅色和暗色两类：浅色矿物：斜长石、正长石、石英暗色矿物：橄榄石、辉石、角闪石、黑云母不同酸性程度的岩石具有特征的矿物组成ThegeologistN.L.Bowenfoundthatmineralstendtoforminspecificsequencesinigneousrocks,橄榄石辉石角闪石黑云母石英白云母钾长石钠长石中长石钙长石岩石的观察描述细粒颜色玻璃质或隐晶质结构构造粗粒：颜色结构、构造主要矿物成分及其鉴定特征和含量其它斑状结构颜色斑状或似斑状结构斑晶：成分及其鉴定特征、大小、含量基质：特征及含量构造其它实习五岩浆岩（一）中酸性岩目的：1、学