《主量元素地球化学》PPT课件.ppt

MajorElements Wet chems gravimetric volumetric MajorElements ModernSpectroscopicTechniques Figure8 1 Thegeometryoftypicalspectroscopicinstruments FromWinter 2001 AnIntroductiontoIgneousandMetamorphicPetrology PrenticeHall Majorelements usuallygreaterthan1 SiO2Al2O3FeO MgOCaONa2OK2OH2OMinorelements usually0 1 1 TiO2MnOP2O5CO2Traceelements usually 0 1 everythingelse AbundanceoftheelementsintheEarth scrust Atypicalrockanalysis Mustmultiplyby ofcationsinoxide TableChemicalanalysesofsomerepresentativeigneousrocks Peridotite Basalt Andesite Rhyolite Phonolite SiO2 42 26 49 20 57 94 72 82 56 19 TiO2 0 63 1 84 0 87 0 28 0 62 Al2O3 4 23 15 74 17 02 13 27 19 04 Fe2O3 3 61 3 79 3 27 1 48 2 79 FeO 6 58 7 13 4 04 1 11 2 03 MnO 0 41 0 20 0 14 0 06 0 17 MgO 31 24 6 73 3 33 0 39 1 07 CaO 5 05 9 47 6 79 1 14 2 72 Na2O 0 49 2 91 3 48 3 55 7 79 K2O 0 34 1 10 1 62 4 30 5 24 H2O 3 91 0 95 0 83 1 10 1 57 Total 98 75 99 06 99 3 99 50 99 23 CIPWNorm Modeisthevolume ofmineralsseenNormisacalculated idealized mineralogy VariationDiagrams Howdowedisplaychemicaldatainameaningfulway Bivariate x y diagrams HarkerdiagramforCraterLake Figure8 2 Harkervariationdiagramfor310analyzedvolcanicrocksfromCraterLake Mt Mazama OregonCascades DatacompiledbyRickConrey personalcommunication Bivariate x y diagrams HarkerdiagramforCraterLake Figure8 2 Harkervariationdiagramfor310analyzedvolcanicrocksfromCraterLake Mt Mazama OregonCascades DatacompiledbyRickConrey personalcommunication 橄榄石 Fe Mg 2SiO4SiO239 MgO40 斜方辉石 Fe Mg 2Si2O6SiO254 普通辉石 CaNaK Al AlSi 2O6SiO248 角闪石CaNaK Al4O11 2 OH SiO239 黑云母KAl AlSiO3O10 OH SiO239 K2O10 石英SiO2SiO2100 钾长石KAlSi3O8SiO271 K2O8 斜长石NaAlSi3 CaAl2Si2O8SiO268 50 霞石NaAlSiO4SiO240 Na2O16 例钾长石SiO2 的计算K2O Al2O3 6SiO2SiO2 60 1 6 44 2 102 4 60 1 6 71 实用矿物化学 TernaryVariationDiagrams Example AFMdiagram alkalis FeO MgO Figure8 2 AFMdiagramforCraterLakevolcanics OregonCascades DatacompiledbyRickConrey personalcommunication ModelsofMagmaticEvolution HarkerdiagramSmoothtrendsModelwith3assumptions 1RocksarerelatedbyFX2Trends liquidlineofdescent3Thebasaltistheparentmagmafromwhichtheothersarederived Figure8 6 StackedvariationdiagramsofhypotheticalcomponentsXandY eitherweightormol P parent D daughter S solidextract A B C possibleextractedsolidphases Forexplanation seetext FromRagland 1989 BasicAnalyticalPetrology OxfordUniv Press Figure8 7 StackedHarkerdiagramsforthecalc alkalinevolcanicseriesofTable8 5 darkcircles FromRagland 1989 BasicAnalyticalPetrology OxfordUniv Press ExtrapolateBA BandfurthertolowSiO2K2Oisfirstelementto 0 atSiO2 46 5redline Thustheblueline theconcentrationofallotheroxides Figure8 7 StackedHarkerdiagramsforthecalc alkalinevolcanicseriesofTable8 5 darkcircles FromRagland 1989 BasicAnalyticalPetrology OxfordUniv Press ExtrapolatetheothercurvesbackBA B bluelineandreadoffXofmineralextract OxideWt CationNormSiO246 5ab18 3TiO21 4an30 1Al2O314 2di23 2Fe2O3 11 5hy4 7MgO10 8ol19 3CaO11 5mt1 7Na2O2 1il2 7K2O0Total98 1100 Results Removeplagioclase olivine pyroxeneandFe Tioxide ThenrepeatforeachincrementBA Aetc Figure8 8 Variationdiagramonacationbasisforthefractionalcrystallizationofolivine augite andplagioclasetoformBAfromB Table8 6 FromRagland 1989 BasicAnalyticalPetrology OxfordUniv Press Figure8 9 Equilateraltriangleshowingthesolutiontothebulkmineralextract shadedarea bestfittingthecriteriaforthevariationdiagramsinFigure8 8 FromRagland 1989 BasicAnalyticalPetrology OxfordUniv Press MagmaSeries Canchemistrybeusedtodistinguishfamiliesofmagmatypes EarlyonitwasrecognizedthatsomechemicalparameterswereveryusefulinregardtodistinguishingmagmaticgroupsTotalAlkalis Na2O K2O Silica SiO2 andsilicasaturationAlumina Al2O3 Alkalivs SilicadiagramforHawaiianvolcanics Seemstobetwodistinctgroupings alkalineandsubalkaline Figure8 11 Totalalkalisvs silicadiagramforthealkalineandsub alkalinerocksofHawaii AfterMacDonald 1968 GSAMemoir116 TheBasaltTetrahedronandtheNe Ol QbaseAlkalineandsubalkalinefieldsareagaindistinct Figure8 12 Left thebasalttetrahedron afterYoderandTilley 1962 J Pet 3 342 532 Right thebaseofthebasalttetrahedronusingcationnormativeminerals withthecompositionsofsubalkalinerocks black andalkalinerocks gray fromFigure8 11 projectedfromCpx AfterIrvineandBaragar 1971 Can J EarthSci 8 523 548 Thermaldivideseparatesthesilica saturated subalkaline fromthesilica undersaturated alkaline fieldsatlowpressureCannotcrossthisdividebyFX socan tderiveoneseriesfromtheother atleastvialow PFX AFMdiagram canfurthersubdividethesubalkalinemagmaseriesintoatholeiiticandacalc alkalineseries Figure8 14 AFMdiagramshowingthedistinctionbetweenselectedtholeiiticrocksfromIceland theMid AtlanticRidge theColumbiaRiverBasalts andHawaii solidcircles plusthecalc alkalinerocksoftheCascadevolcanics opencircles FromIrvingandBaragar 1971 AfterIrvineandBaragar 1971 Can J EarthSci 8 523 548 Figure18 2 AluminasaturationclassesbasedonthemolarproportionsofAl2O3 CaO Na2O K2O A CNK afterShand 1927 Commonnon quartzo feldspathicmineralsforeachtypeareincluded AfterClarke 1992 GranitoidRocks ChapmanHall Figure8 10a PlotofCaO green and Na2O K2O red vs SiO2fortheCraterLakedata Peacock 1931 usedthevalueofSiO2atwhichthetwocurvescrossedashis alkali limeindex dashedline b Aluminasaturationindices Shand 1927 withanalysesoftheperaluminousgraniticrocksfromtheAchalaBatholith Argentina LiraandKirschbaum 1990 InS M