篇沉積巖第二章沉積巖各論沉積巖分類(lèi)

第二章沉積巖各論邵龍義講授（1.中國(guó)礦業(yè)大學(xué)（北京）地球科學(xué)與測(cè)繪工程學(xué)院，

北京

100083）ShaoL@Petrography?Classification?Majorsub-classes?2.1.1目前流行的分類(lèi)2.1Classificationofsedimentaryrocks以沉積作用方式和巖石成分把沉積巖分為三大類(lèi)：碎屑巖類(lèi)（Clasticrocktypes）粘土巖類(lèi)（Clayrocktypes）

化學(xué)巖和生物化學(xué)巖（Chemicalandbiochemicalrocktypes）F.J.裴蒂莊（1975），塞利（1976）等，對(duì)沉積巖的分類(lèi)多強(qiáng)調(diào)其物質(zhì)來(lái)源，他們把沉積巖物質(zhì)來(lái)源的差別作為沉積巖分類(lèi)的基礎(chǔ)。F.J.裴蒂莊（1975）分為：外生沉積物和內(nèi)生沉積物；塞利（1976）分為：自生沉積和他生沉積；劉寶珺1980分為：陸源沉積巖、火山沉積巖和內(nèi)源沉積巖。

大類(lèi)

類(lèi)1、自生沉積1）化學(xué)沉積：蒸發(fā)巖2）有機(jī)沉積：煤、石灰?guī)r3）殘余沉積：紅土、鋁土巖2、他生沉積4）陸源沉積：粘土、碎屑巖5）火山碎屑沉積：集塊巖、火山角礫巖、凝灰?guī)r塞利的沉積巖分類(lèi)Classificationofsedimentaryrocks/barnes/geos435/3a_G435.ppsGrain-SizeClassificationforClasticSedimentsNameMillimetersMicrometersBoulderCobblePebbleGranuleVeryCoarseSandCoarseSandMediumSandFineSandVeryFineSandCoarseSiltMediumSiltFineSiltVeryFineSiltClay4,096256644250.0630.0310.0160.0080.00450025012562311684(modifiedfromBlatt,1982)Commonly,phi-sizesareusedforsedimentanalysisRelativeAbundancesSiltstoneandshale(clastic)~75%Sandstoneandconglomerate(clastic)~11%Limestoneanddolomite

~14%SEDIMENTARYROCKTYPES,2.1.2、Terrigenousclastics

“FromtheEarth”Terrigenousclasticsedimentaryrocksarecomposedofclastsofpre-existingrocksandminerals.Alsoreferredas:

Detrital(detachedfrompre-existingrocksbyerosionorweathering),or;

Epiclastic(derivedfromthesurface).

（外源）陸源碎屑巖沉積物（碎屑）剝蝕-搬運(yùn)-沉積剝蝕區(qū)搬運(yùn)區(qū)沉積區(qū)GrainSize1(mm)SedimentnameRockNameAdjectives>2GravelRuditeCobble,pebble,wellsorted,etc.0.063-2SandAreniteCoarse,medium,wellsorted,etc.<0.063MudMudstoneorLutiteSiltorclay1Forthepurposesofthisgeneralclassificationwewillassigntherockorsedimentnameshownifmorethan50%oftheparticlesareintherangeshown.Moredetailedclassificationschemeswilllimittermsonthebasisofdifferentproportionsofsedimentwithinagivengrainsize.Asimpleclassificationofterrigenousclasticrocksandsedimentisbasedonthepredominantgrainsizeofthematerial:Classificationbasedongrainsize2PyroclasticRocksBasicclassificationotbo

(onthebasisof)particlesizeBlocks(solid)andbombs(molten)(>64mm)VolcanicbrecciadepositsLapilli(2-64mm)LapillistoneAsh(<2mm)TuffAdditionalClassificationotbocompositionCrystalsLithicVitricfragments/barnes/geos435/3a_G435.pps3、內(nèi)源沉積巖類(lèi)

亦稱(chēng)內(nèi)生沉積巖，組成巖石的主要物質(zhì)直接來(lái)自沉積盆地的溶液或沉積場(chǎng)所的溶液內(nèi)，是溶液中的溶解物質(zhì)通過(guò)化學(xué)或生物化學(xué)作用沉淀的。內(nèi)源沉積巖按其成分不同分為：

鋁質(zhì)巖鐵質(zhì)巖錳質(zhì)巖磷質(zhì)巖硅質(zhì)巖碳酸鹽巖蒸發(fā)巖可燃性有機(jī)巖等八類(lèi)。2.2Terrigenousclasticrocks

2.21GeneralcharacteristicofTerrigenousclasticrocks

1、CompositionalMaturityACompositionalMaturityreflectstheweatheringprocessesinthesourceareaandthedegreeandextentofreworkingandtransportation.CompositionalMaturitycanbeexpressedbytheratioofquartz+chertgrainstofeldspars+rockfragments,thisCompositionalMaturityindexisusefulifcomparisonsbetweendifferentsandstonesarerequired.2.MaterialcompositionofTerrigenousclasticrocks

MaterialcompositionofTerrigenousclasticrocksaremainlyclasticmaterial,chemicalmaterialandmatrix.1）clasticmaterial（1)DetritalMineralGrains

Averylargenumberofdifferentmineralsmayoccurinsandsandinsandstone.themostcommondetritalmineralGrainsarequartz,feldspar,mica,heavymineralandmiscellaneousmineral.（2)LithicFragments

Thebreakdownofpre-existing,fine-tomediumigneous,metamorphicandsedimentaryrocksresultsinsand-sizedfragments.LithicFragmentaregeneratedwhenpre-existingstrataareuplifted,weatheredanderoded.2）ChemicalcementandAuthigenicMineral

Themostcommoncementaresilicaandcalcitecementation.Mineralswhichgrowcrystalsinadepositinalenvironmentarecalledauthigenicminerals.Cementation:CementingmaterialisusuallysecondarySilica(Siliceouscement),Calciumcarbonate(Carbonatecement),Ironrich(ferruginouscement)CementitselftosomeextentisthesourceofweaknessinthesedimentaryrocksBecausecementingmaterialandtheclasticsedimentsareusuallyofdifferentcomposition,leadingtoheterogeneityintheirphysicalcharacteristics.

Hencesuchrockwillnotbehavehomogeneouslyunderstress,resultingintodevelopmentofcracksorfissureswhichdevelopsincementingmaterial.IfthecementisCalciumCarbonateitisundesirable,becauseitissusceptibletodissolveinCarbondioxideinwater.However,ifcementationprocesscontinuousforlongerspanoftime.cementationwillbecomemorecomplete,whichreducetheporosityandpermeabilityintherockmassandincreasecompetence.Shapeofgrains:i.e.ifcoarsergrainsareroundedorsubroundedcementmaterialwillnothavefirmgripsuchrocksbehaveasincompetentrocks.3）Matrix

Matrix:fineinterstitialparticles.

matrixcompositiondependsupon:Sourcematerialwhattypeofrockisbeingweatheredanderoded?ThechemicalandphysicalpropertiesofthemineralsstrongeronesareatthebottomofBowensReactionSeries(e.g,Quartz).Degreeofweatheringanderosionprocessestotransportsecondarydependenceuponclimate.3.TexturesofTerrigenousclasticrocks

(1)Textures

Maturity:Chemicalandphysicalweatheringgraduallybreaksdownrocktoquartzandclayminerals.Maturityisameasureofthisprocess.Dependson:Time,Climate,TransportHistory,DepositionalEnvironment.Immature:poorlysorted,clays+mineralfragments(olivine,pyroxene,amphibole,etc.),rockfragments.Grainsareangularandvaryinsize.Mature:wellsorted,noclays,mostlymadeupofroundedquartzgrains.(2)陸源碎屑巖的結(jié)構(gòu)

陸源碎屑巖的結(jié)構(gòu)主要有陸源碎屑結(jié)構(gòu)和泥狀結(jié)構(gòu)兩種類(lèi)型。1)陸源碎屑結(jié)構(gòu)這是陸源沉積巖最主要的結(jié)構(gòu)，它由碎屑顆粒和膠結(jié)物（或基質(zhì)）兩部分組成。巖石結(jié)構(gòu)的特征取決于顆粒的結(jié)構(gòu)、膠結(jié)物（或基質(zhì)）的結(jié)構(gòu)以及二者之間的量比和相互關(guān)系。（1)Structurecharacteristicsofclasticgrain

Structurecharacteristicsofclasticgrainincludesizeofgrain,sorting,morphology,surfacecharacteristicsandsoon.

A、SizeofgrainWealwaysusediametertomeasurethesizeofclasticgrain.Wecandividesizeofgrainasfollows：＞2mmConglomerate2—0.05mmSandstone0.05--0.005mmSiltstone＜0.005mmMudstone

Grain-SizeSortinginSandstoneVeryWellSortedWellSortedModeratelySortedPoorlySortedVeryPoorlySortedSORTINGB.sortingnormalSortingA-positive/negativeskew(正偏/負(fù)偏)%coarsefinenegativeskewpositiveskewnormalB-kurtosis（峰態(tài)）%coarsefineleptokurticplatykurticSortingC-bimodaldistributions%coarsefineROUNDNESSANDSPHERICITYOFCLASTICGRAINSHighSPHERICITYLowVeryAngularAngularSub-AngularSub-RoundedRoundedWell-RoundedROUNDNESSGrainMorphologyC-sphericityhigh medium low4)GrainFabricA-orientation-causedbywaterflowOrientation,packingandnatureofcontactsbetweengrainsHowever-thisisalsostableNote:viewfromabove4)GrainFabricB-imbrication-causedbywaterflowormassmovementOrientation,packingandnatureofcontactsbetweengrainsNote:viewfromside4)GrainFabricC-packingofgrainsOrientation,packingandnatureofcontactsbetweengrainscubicpackingrhombohedralpackingQ.Whichismoreporous?4)GrainFabricD-pointcontactsOrientation,packingandnatureofcontactsbetweengrainsImportant:trytoimaginethisin3-D4)GrainFabricE-concavo-convexcontactsOrientation,packingandnatureofcontactsbetweengrainsBut-wherehasthesilicagone???4)GrainFabricF-suturedcontactsOrientation,packingandnatureofcontactsbetweengrainsGrainMineralogyQuartzFeldsparRockFragmentsMicasClaymineralsHeavymineralsPPL-plane-polarizedlightXPL-crossedpolarsGrainMineralogy

1-QuartzRoundedquartzgrains(originalshapemoreangular)PA9-PPLGrainMineralogy

1-QuartzRoundedquartzgrainsPA9-XPLGrainMineralogy

1-QuartzSeeminglynormalroundedQuartzgrains...PA9-PPLGrainMineralogy

1-QuartzSeeminglynormalroundedQuartzgrains…areactuallypolycrystallinemanysmallersuturedgrainsPA9-XPLGrainMineralogy

1-QuartzThisquartzgraingoesintoextinctioninpoorlydefinedbandsIthasbeenstrainedunduloseextinctionPA27-XPLGrainMineralogy

2-FeldsparFeldspar-islessstablethanquartzchemicallyweatherstomicasandclaymineralsisbestpreservedinmechanically-weatheredrocksGrainMineralogy

2-FeldsparTwoorthreetypes!Potassium(K-,oralkaline)feldsparsorthoclasemicroclineCalcicfeldsparplagioclaseGrainMineralogy

2-K-FeldsparSmokey……..OrthoclaseFeldsparGrainMineralogy

2-K-FeldsparSmokey……..OrthoclaseFeldsparGrainMineralogy

2-FeldsparAK-feldsparPA27-PPLmicroclinefeldsparGrainMineralogy

2-FeldsparAK-feldsparCross-hatchtwinningPA27-XPLmicroclinefeldsparGrainMineralogy

2-FeldsparAcalcicfeldspar

BG2-PPLplagioclasefeldsparGrainMineralogy

2-FeldsparAcalcicfeldsparmultipletwinning(albite)

BG2-XPLplagioclasefeldsparBG2-XPLGrainMineralogy

2-FeldsparAK-feldsparwithmanyblebsorlamellaeofsodium-richfeldspar

perthiteBG2-XPLGrainMineralogy

2-FeldsparAcalcicfeldsparsimpletwinning(Carlsbad)

plagioclasefeldsparEXP1-PPLGrainMineralogy

3-MicaPlatysheetsilicatemineralbrown/greenpleochroisminPPLbiotitemicaEXP1-PPLGrainMineralogy

3-MicaPlatysheetsilicatemineralbrown/greenpleochroisminPPL

biotitemicaLowerpolarizerrotated90°EXP1-XPLGrainMineralogy

3-MicaPlatysheetsilicatemineralbrown/greenpleochroisminPPL

brightinterferencecoloursmuscovitemorecommonbiotitemicaR62-XPLGrainMineralogy

5-LithicFragmentsAnyreworkedfragmentsofrocke.g.cherts,mudstones,volcanics,limestones,polycrystalinequartzR62-XPLGrainMineralogy

6-MatrixGrainslessthat30μmSedimentMaturityTheconceptofmaturityrelatestotheaccumulatedprocessesofmechanicalandchemicaldegradationthathaveoccurredtoasedimentbeforedepositioni.eamaturesedimenthasbeenworkedmorethananimmaturesedimentMaturityisconsideredintermsofTEXTUREandCOMPOSITIONTexturalMaturityAtexturallymaturesedimenthasbeenrounded,sortedandhaslittlematrixTexturalMaturitySedimenttexturereflectthematurityofasediment.Mostchangesarerelatedtotransportdistance,natureofweatheringatthesiteofsedimentformationandnumberofpassesthroughtherockcycle.Changesingrainsizeandshape.IncreasingtexturalmaturityIncreasedsortingIncreasedsphericityIncreasedroundingCompositionalMaturityAsasedimentisworkedthemicaandotherweakergrainsaredestroyedMostlyquartzandalittlefeldsparisleftThemostmaturesedimentsare100%quartzMatureor?????AngulargrainsPoorlysortedLotsofmatrixTexturallyimmatureLithoclastsandothergrainsCompositionallyimmatureMatureor?????WellroundedgrainsVerywellsortedNomatrixTexturallysupermatureMainlyQzCompositionallymatureGRAINSIZEConglomerate>256-2mmSand2-0.063mmClay<0.004mmSilt0.063-0.004mmBoulder:>256mmCobble:64-256mmPebble:4-64mmGranule:2-4mmFinegravel（三）Conglomerates

Conglomeratesislithifiedgravelmadeupofroundedtosubroundedclastswhosediametersexceed2mm.Conglomeraterocksaresedimentaryrocks.Theyaremadeupoflargesedimentslikesandandpebbles.Thesedimentissolargethatpressurealonecannotholdtherocktogether;itisalsocementedtogetherwithdissolvedminerals.

京西妙峰山礫巖和角礫巖的分類(lèi)

通常依礫石的圓度可把巖石分為：

礫巖（主要由次圓至圓狀的礫石組成）

角礫巖（主要由棱角狀礫石組成）。

按粒度可分為：

巨礫巖＞256mm；

卵石礫巖256-64mm；

粗礫巖64-16mm；

中礫巖16-4mm；

細(xì)礫巖4-2mm.

Twodistinctivevarietiesofconglomerates(andbreccias)aredefinedonthebasisoftexture:Orthoconglomerates(literally,“true”conglomerates)consistmainlyofgravel-sizedframeworkgrains.Matrix(sandorfiner)islessthan15%.So,grain-supportedframework.Paraconglomeratehaveamatrixofsandandfinerclasts.Matrixisatleast15%;mosthave50%matrixandareactuallysandstoneandmudrocksinwhichpebbles,cobblesandbouldersarescattered.粗碎屑巖類(lèi)巖石的命名a)粗碎屑巖類(lèi)巖石的命名按:膠結(jié)物+礫石成分+結(jié)構(gòu)+基本名稱(chēng)。如:鈣質(zhì)膠結(jié)石灰?guī)r質(zhì)粗礫b)膠結(jié)物占巖石總量的10%以上，以XX質(zhì)膠結(jié)作為附加修飾詞。c)混入其他粒級(jí)陸源碎屑的命名，按5.3條規(guī)定的量限，以含X質(zhì)、X質(zhì)作為附加修飾詞。d)粗碎屑巖性單一，直接參加命名;粗碎屑巖性較復(fù)雜，以其占粗碎屑總量50%以上的粗碎屑巖性作為附加修飾詞;無(wú)任何一種粗碎屑巖性超過(guò)粗碎屑總量的5000，則以其量相對(duì)為主的兩種粗碎屑巖性，用“一”號(hào)連接作為附加修飾詞;具三種或三種以上粗碎屑巖性，其量相近并均不超過(guò)粗碎屑總量的50，則以復(fù)成分作為附加修飾詞。e)命名時(shí)應(yīng)予反映成因。（四）砂巖類(lèi)(Sandstones)1．一般特征

粒度為2一0．063毫米的陸源碎屑含量在50％以上的沉積巖稱(chēng)為砂巖。砂巖的碎屑成分主要是石英、長(zhǎng)石和巖屑三種.砂巖中的膠結(jié)物常見(jiàn)的有鈣質(zhì)、硅質(zhì)、鐵質(zhì)等，有時(shí)還有海綠石、石膏等和泥質(zhì)基質(zhì)所膠結(jié)。砂巖中常見(jiàn)各種類(lèi)型的斜層理、交錯(cuò)層理以及平行層理、粒序?qū)永?，波痕、沖刷痕跡、槽模、溝模和生物擾動(dòng)構(gòu)造等沉積構(gòu)造。2．砂巖的分類(lèi)(Classificationofsandstone)（1）砂巖按其顆粒大小可分為：

巨粒砂巖2～1mm粗粒砂巖1～0.5mm中粒砂巖0.5～0.25mm細(xì)粒砂巖0.25～0.05mm

砂巖成分分類(lèi)的方案很多，這里采用四端元分類(lèi)法。四端元分類(lèi)法是以砂巖中的主要碎屑成分石英、長(zhǎng)石、巖屑作為三端元組分劃分巖石類(lèi)型，再把基質(zhì)也作為一個(gè)端元組分參加巖石的分類(lèi)命名。首先根據(jù)基質(zhì)含量將砂巖分為兩類(lèi)：一類(lèi)稱(chēng)為凈砂巖類(lèi)；另一類(lèi)稱(chēng)為雜砂巖類(lèi)。（2）成分分類(lèi)ClassificationofSandstonesMostsandstoneclassificationsarebasedonthecompositionoftherock.Dott’sclassificatonschemeisusedinmostcoursesatBrock.Itisbasedontherelativeproportionsof:Martrix

(fine-grained-<0.03mm-materialthatisassociatedwiththesandgrains).QuartzFeldsparRockfragments(sandgrainsthataremadeupcrystalsoftwoormoredifferentminerals).Pettijohn(1975沉積巖)的砂巖分類(lèi)Wackes-15-75%matrix07515increasingpercentagematrixareniteswackesmudrockslithicgreywackefeldspathicgreywackeSANDSTONECLASSIFICATIONQuartz+ChertFeldsparUnstableRockFragments552525252525255050501010QuartzareniteSubarkoseSublithareniteLithicSubarkoseArkoseLithicArkoseFelspathicLithareniteLitharenite(modifiedfromMcBride,1963)Thisclassificationisbasedonthemajorcomponentofmostsandstonesandprovidesabasisforaconsistentnomenclatureforsandstones.Specifictypesofrockfragmentsmayalsobeimportantindeterminingthehistoryofthesediment.Fragmentsoflimestoneordolomitearesimplyclassedas“rockfragments”usingDott’sscheme.Suchgrainsbreakdownrapidlywithtransportsothattheirpresencesuggeststhatthesedimentwasdepositedveryclosetotheareathatitwasproduced.Thenamescanbemodifiedtoreflectothercomponentsoftherock:e.g.,Calcareousquartzarenite:aquartzarenitewithacalcitecement.1、石英(雜)砂巖；2、長(zhǎng)石(雜)砂巖；3、巖屑(雜)砂巖；4、長(zhǎng)石石英(雜)砂巖；5、巖屑石英(雜)砂巖；6、巖屑長(zhǎng)石(雜)砂巖；7、長(zhǎng)石巖屑(雜)砂巖QFR123456790753/11/11/3755025F/RF雜基>15%雜砂巖雜基<15%凈砂巖FrameworkMatrixCementPoresSand(andSilt)SizeDetritalGrainsSiltandClaySizeDetritalMaterialMaterialPrecipitatedPost-Depositionally,DuringBurial.CementsFillPoresandReplaceFrameworkGrainsVoidsAmongtheAboveComponentsFOURMAJORCOMPONENTSOFSANDSTONEFOURCOMPONENTSOFSANDSTONEMATRIXFRAMEWORK(QUARTZ)FRAMEWORK(FELDSPAR)CEMENTPORENotedifferentuseof“matrix”bygeologistsandengineers0.25mmFrameworkMatrixCementPoresEngineering“matrix”Geologist’sClassification中碎屑巖（砂巖）類(lèi)命名原則a)中碎屑巖類(lèi)巖石的命名按:膠結(jié)物+結(jié)構(gòu)+碎屑成分十基本名稱(chēng)。如:中粒長(zhǎng)石石英砂巖。b)膠結(jié)物占巖石總量的10%以上，以XX質(zhì)膠結(jié)作為附加修飾詞。c)混入其他粒級(jí)陸源碎屑的命名，按5.3條規(guī)定的量限，以含X質(zhì)、X質(zhì)作為附加修飾詞。d)巖屑砂巖和巖屑雜砂巖中的巖屑成分單一，直接參加命名;巖屑成分較復(fù)雜，以其占巖屑總量50%以上的巖屑成分參加命名;無(wú)任何一種巖屑成分超過(guò)巖屑總量的50%，則以其量相對(duì)為主的兩種巖屑成分，用“一”號(hào)連接參加命名;具三種或三種以上巖屑成分，其量相近并均不超過(guò)巖屑總量的一半，則總稱(chēng)巖屑作為附加修飾詞。e)石英砂巖中部分硅質(zhì)膠結(jié)物，發(fā)生次生加大成為再生石英，具砂狀結(jié)構(gòu)，再生長(zhǎng)式膠結(jié)，稱(chēng)石英巖狀砂巖;膠結(jié)物已全部重結(jié)晶圍繞石英顆粒呈次生加大邊，稱(chēng)沉積石英巖。f)砂巖中若出現(xiàn)特殊礦物，其含量小于5%也應(yīng)參加命名。如:海綠石細(xì)粒石英砂巖。

Quartzsandstone

;Arkose

;Lithicsandstone

;Greywacke;Commontypesofsandstone（五）粉砂巖Siltstones(d=0.063-0.004)Themineralogyandtexturalparametersofsiltaremoredifficulttodeterminethanforsandstonebecauseofthesmallparticlesize.Quartzi