微量元素地球化學(xué)課件（中國(guó)地質(zhì)大學(xué)）5微量元素?cái)?shù)據(jù)的利用和地球化學(xué)解釋

微量地球化學(xué)

TraceElementGeochemistry

“Geochemistryreallyisforeveryone!〞

ByFersman(1958)5.微量元素?cái)?shù)據(jù)的利用和地球化學(xué)解釋有用的參考書H.Rollinson–“Usinggeochemicaldata〞(Longman,London,1993)F.Albarède–“Introductiontogeochemicalmodelling〞&“Geochemistry〞M.Wilson–“Igneouspetrology,aglobaltectonicapproach〞5.2.微量元素?cái)?shù)據(jù)分析??????5.2.微量元素?cái)?shù)據(jù)分析數(shù)據(jù)質(zhì)量評(píng)價(jià)數(shù)據(jù)分析原理數(shù)據(jù)分析的常規(guī)方法數(shù)據(jù)分析實(shí)例有用的軟件數(shù)據(jù)的獲得與樣品進(jìn)行比照y=0.8627x+0.3289R2=0.99980102030405060020406080元素i測(cè)定值)元素i理論值標(biāo)準(zhǔn)樣品未知樣品數(shù)據(jù)質(zhì)量評(píng)價(jià)？？？？實(shí)際樣品監(jiān)控國(guó)際標(biāo)準(zhǔn)物質(zhì)，如BHVO-2、BCR-2、G-2、GSR-1、GSR-3、AGV-1、1640等等。實(shí)驗(yàn)室內(nèi)部標(biāo)準(zhǔn)重復(fù)樣品空白樣品對(duì)實(shí)際數(shù)據(jù)的了解〔如REE〕數(shù)據(jù)質(zhì)量評(píng)價(jià)指標(biāo)相對(duì)誤差〔RE〕標(biāo)準(zhǔn)偏差〔SD〕相對(duì)標(biāo)準(zhǔn)偏差〔RSD〕內(nèi)部精度外部精度檢出限〔方法檢出限和儀器檢出限〕國(guó)際標(biāo)準(zhǔn)物質(zhì)實(shí)驗(yàn)室內(nèi)部標(biāo)準(zhǔn)重復(fù)樣品〔分析樣品或標(biāo)準(zhǔn)物質(zhì)〕空白樣品(全流程空白和儀器噪音)中國(guó)地質(zhì)大學(xué)(武漢)地質(zhì)過(guò)程與礦產(chǎn)資源國(guó)家重點(diǎn)實(shí)驗(yàn)室LA-ICP-MS室Agilent7500aGeoLas2005-10-50510RE(%)BeScVCrCoNiCuZnGaRbSrYZrNbCsBaLaCePrNdSmEuGdTbDyHoErTmYbLuHfTaTlThUAGV-2BCR-2BHVO-2GSR-3問(wèn)題某廠家給定其產(chǎn)品玻璃棒中Cu含量為5ppm，Pb含量為5ppm，他們所用的儀器為ICP-AES。請(qǐng)問(wèn)該數(shù)據(jù)是否可靠？某廠家給定產(chǎn)品玻璃光纖中Cu含量為0.5ppm，Pb含量0.1ppm，他們所用的儀器為ICP-MS。請(qǐng)問(wèn)該數(shù)據(jù)是否可靠？REE配分曲線對(duì)數(shù)據(jù)可靠性的評(píng)價(jià)數(shù)據(jù)分析原理局部元素具有相同或相似的地球化學(xué)行為〔如REE〕;不同元素在不同地質(zhì)作用過(guò)程的地球化學(xué)行為存在差異〔相容性/活動(dòng)性變化〕；地質(zhì)作用過(guò)程中的物理、化學(xué)條件對(duì)元素的地球化學(xué)行為具有影響〔如P-T-X-fO2等〕.局部元素具有相同或相似的地球化學(xué)行為〔如REE〕以下圖所示趨勢(shì)的原因是什么？平衡部分熔融作用LaL/LaO

=1/(DLa(1-F)+F)SmL/SmO

=1/(DSm(1-F)+F)LaL=LaO/[DLa+F(1-DLa)]F=(LaO-LaLD)/LaL(1-D)SmL=SmO/[DSm+F(1-DSm)]F=(SmO-SmLD)/SmL(1-D)LaL/SmL=LaL[(DSmb-DLa)/bSmO]+LaO/bSmOb=(1-DLa)/(1-DSm)DSm>DLab

>1DSmb-DLa>0K>0DLa

–DSm~0應(yīng)用實(shí)例漢諾壩玄武巖中的麻粒巖包體漢諾壩玄武巖中的麻粒巖包體漢諾壩玄武巖中的麻粒巖包體石榴石邊部明顯富集MREESD014SD0060.01高Rb,Sr,Cs,Ba,U,PbCCSD榴輝巖綠輝石邊部明顯富集所有REE角閃巖相退變質(zhì)作用與Rb,Sr,Cs,Ba,U,Pb密切相關(guān)磷灰石的成分分帶10000QQ磷灰石綠輝石石榴石利用石榴石、單斜輝石、磷灰石中REE的分配系數(shù)隨溫度變化的實(shí)驗(yàn)資料對(duì)該過(guò)程進(jìn)行了模型計(jì)算模型計(jì)算假設(shè)溫度從800℃升溫到830℃,磷灰石,綠輝石和石榴石分別占全巖1.5%,48.5%和50%溫度升高磷灰石釋放LREE-MREE、石榴石釋放HREEREE在榴輝巖各礦物相間重新分配石榴石、綠輝石、磷灰石的REE成分環(huán)帶受增溫作用影響,直徑(d)為0.4mm和1mm的石榴石和磷灰石晶體核部REE組成發(fā)生變化所需要的時(shí)間與溫度之間的關(guān)系.計(jì)算方法為Dt/r2=0.03(Crank，1965),

其中t是半徑為r的礦物(設(shè)為球體)核部REE組成發(fā)生變化所需要的最小時(shí)間,D為REE在礦物中的擴(kuò)散系數(shù).因?yàn)槭袷蠸m和磷灰石中Yb的環(huán)帶特征明顯,并且具有相應(yīng)的實(shí)驗(yàn)擴(kuò)散系數(shù)資料,所以選擇石榴石中Sm和磷灰石中Yb進(jìn)行計(jì)算.石榴石Sm的擴(kuò)散系數(shù)取自Tironeetal.(2005)磷灰石Yb的擴(kuò)散系數(shù)取自Cherniak(2000).模型計(jì)算

金紅石Zr溫度計(jì)存在巨大應(yīng)用潛力100um榴輝巖中金紅石包裹體金紅石：處于石榴石中，大小50~150μm粒間金紅石：處于石榴石和綠輝石之間，大小80~250μmCCSD榴輝巖包裹體金紅石溫度(平均614℃)低于粒間金紅石溫度(平均660℃)

ZMK粒間金紅石溫度是否代表超高壓峰期變質(zhì)溫度？該溫度計(jì)的結(jié)果是否有地質(zhì)意義？粒間金紅石核部溫度較邊部高，且核部溫度隨粒徑增加而升高。在660℃條件下金紅石中Zr擴(kuò)散1μm需要12萬(wàn)年，因此粒間金紅石邊部Zr含量的降低不太可能由正常擴(kuò)散作用引起。粒間金紅石Zr含量受到了后期流體活動(dòng)的改造？！金紅石中Zr擴(kuò)散速率方程（據(jù)Watson）

粒間金紅石邊部明顯富集Pb、Sr，但Zr逐漸降低。低溫的機(jī)理是什么？Fig.2PetrologicandgeochemicalprofileoftheCCSD-MH(followingZhangetal.(2004)).Circlesonthepetrologicprofilemarkthesamplingdepths.Layer*=layersclassifiedbyZhangetal.(2004)basedonpetrology.Fig.3PlotsofTiO2

vs.NbandZrforeclogitesfromCCSD-MHandultramaficrocksfromZK703(a,b)andoceanicgabbrosfromtheIndianRidge(c,d).Eclogites(literatures)from(Zhangetal.,2004;Zhangetal.,2000b).Moderncontinentalfloodbasalts()areshownforcomparison.Oceanicgabbrosfrom(Cooganetal.,2001;Hartetal.,1999).Fig.7Fig.7PlotsofEuanomaliesvs.Fe2O3totalandTiO2foreclogitesandultramaficrocks.Darkpentacleistheaverageofmoderncontinentalfloodbasalts(CFB)withMgO>8wt%(n=562,://georoc.mpch-mainz.gwdg.de/georoc/).GraylineshowsFe2O3totalrangeofcumulatesofolivine+pyroxene,whichiscalculatedassumingDFeol=0.51-1.55(Beattie,1994),DFecpx=0.57-1.04(DaleandHenderson,1972).Fig.8Fig.8PlotsofMgO-TiO2and-VandFe2O3total-MgOand-V.Solidcyclesaredataofthiswork,rectanglesaredatafromZhangetal.(2004;2000b).1=trendofpyroxene±olivinecrystallization,2=trendofmagnetitecrystallization,3=trendofmeltevolution.PentacleistheaverageofcontinentalfloodbasaltswithMgO>8wt%().Fig.9Fig.9PlotofNivs.MgO.Graydiamondrepresentsmantlecompositexenolithsformedbymelt-peridotiteinteraction(Liuetal.,2005).DM:depletedmantle(SaltersandStracke,2004).Solidlineshowsfractionalcrystallization(F=4%)of0~80%ol+80~10%cpx+10~20%opxwith2%trappedmeltfrombasalticmagma(Table6).Crossesonthelineindicatevariationsofolivineproportions(0-80%).KD(Fe/Mg)(=(Fe/Mg)crystal/(Fe/Mg)melt)wereassumedtobe0.29,0.26and0.25forol,cpxandopx,respectively(BakerandEggler,1987).PartitioncoefficientsofNibetweenbasalticmeltandol,cpxandopxarelistedinTable6.Fig.10Fig.10TiO2-Nb,-Zrvariationsduringfractionalcrystallizationofcpx+pl+opx+mtwith15%trappedmeltfollowing5%fractionalcrystallizationofultramaficrocks(70%ol+20%cpx+10%opx)fromabasalticmagma.mt10andmt20arecumulatesof40%cpx+35%pl+15%opx+10%mtand30%cpx+35%pl+15%opx+20%mt,respectively.pl80andpl30aremagnetite-freecumulatesof80%pl+15%opx+5%cpxand55%cpx+30%pl+15%opx,respectively.CompositionsofbasalticmagmaandpartitioncoefficientsusedinmodelingarelistedinTable6.研究方法REE配分曲線/REEpattern蛛網(wǎng)圖/SpiderDiagrams元素比值和含量變化圖相關(guān)分析模型計(jì)算REE配分曲線/REEpattern

選擇歸一化值球粒隕石〔CI〕北美頁(yè)巖〔NASC〕后太古代澳大利亞頁(yè)巖〔PAAS〕某特殊樣品ChondritevaluesusedinnormalizingREE(ppm)

ReferenceNotesLaCePrNdSmEuGdTbDyHoErTmYbLuTaylorandMcLennan(1985)Avg.CI0.3670.9570.1370.7110.2310.0870.3060.0580.3810.0850.2490.0360.2480.038McDonoughetal.(1991)Primitivemantle0.7081.8330.2781.3660.4440.1680.5950.1080.7370.1630.4790.0740.4800.074Wakitaetal.(1971)Composite(12)0.3400.9100.1210.6400.1950.0730.2600.0470.3000.0780.2000.0320.2200.034Haskinetal.,(1968)Composite(9)0.3300.8800.1120.6000.1810.0690.2490.047

0.0700.2000.0300.2000.034Masuda(1973)Leedey0.3780.976

0.7160.2300.0870.311

0.390

0.255

0.2490.039Nakamura(1974)Composite0.3290.865

0.6300.2030.0770.276

0.343

0.225

0.2200.034Evensenetal.(1978)Avg.CI0.2450.6380.0960.4740.1540.0580.2040.0370.2540.0570.1660.0260.1650.025Boynton(1984)Avg.CI0.3100.8080.1220.6000.1950.0740.2590.0470.3220.0720.2100.0320.2090.032StandardsedimentraycompositionsusedinnormalizingREE(ppm)insedimentaryrocks

Grometetal.,1984NASC31.167.0

30.4005.981.255.500.855.54

3.28

3.110.46HaskinandFrey,1966NASC39.076.010.3037.0007.002.006.101.30

1.404.000.583.400.60HaskinandHaskin,1966NASC32.070.07.9031.0005.701.245.210.85

1.043.400.503.100.48Haskinetal.,1968NASC32.073.07.9033.0005.701.245.200.85

1.043.400.503.100.48Grometetal.,1984NASC31.166.7

27.4005.591.18

0.85

3.060.46HaskinandHaskin,1966ES41.181.310.4040.1007.301.526.031.05

1.203.550.563.290.58McLennan,1989PAAS38.279.68.8333.9005.551.084.660.774.680.992.850.412.820.43TaylorandMcLennan,1981Uppercrust30.064.07.1026.0004.500.883.800.643.500.802.300.332.200.32ElderfieldandGreaves,1982Typicalseawater20.89.64

21.1004.320.825.20

5.61

4.94

4.66

Hoyleetal.,1984Riverwater425601

36580.420.783.5

97.9

64.6

51.7

SampleLaCePrNdSmEuGdTbDyHoErTmYbLuCI0.3670.9570.1370.7110.2310.0870.3060.0580.3810.0850.2490.0360.2480.038SFX0293.018125.293.815.14.1111.71.225.230.842.140.281.570.23SFX1386.917123.688.814.33.9811.21.134.990.802.040.261.540.23SFX1986.716823.688.514.33.8911.11.154.960.822.040.281.500.24SFX2787.317023.788.714.13.9111.01.165.050.842.070.271.560.23CI-normalizedSFX02253.3189.5183.6132.065.547.238.321.013.79.98.67.76.36.1SFX13236.8179.1172.3124.961.945.736.519.513.19.48.27.46.25.9SFX19236.2175.5172.1124.561.844.736.219.813.09.68.27.86.06.2SFX27237.9177.8173.1124.761.144.936.020.013.39.88.37.76.36.0不同礦物的影響Ce和Eu異常；中稀土元素相對(duì)于輕、重稀土元素的富集可能反映角閃石的控制作用；輕、重稀土元素的分異那么可能反映橄欖石、輝石的作用等；極端的重稀土元素虧損那么可能反映了石榴石的作用。河水和海水的REE配分曲線不同礦物的影響2.蛛網(wǎng)圖/SpiderDiagrams按照元素相容性順序，利用球粒隕石、原始地幔等進(jìn)行標(biāo)準(zhǔn)化后所作的一種線條圖。Differentestimatesdifferentordering(poorstandardization)選擇歸一化值火成巖PrimitiveMantleChondriteMORB沉積巖NASC平均大陸上地殼平均顯生宙灰?guī)r平均顯生宙石英砂巖蛛網(wǎng)圖/SpiderDiagramsMORB-normalizedSpiderOceanislandbasaltplottedonamid-oceanridgebasalt(MORB)normalizedspiderdiagramofthetypeusedbyPearce(1983).DatafromSunandMcDonough(1989).FromWinter(2001)AnIntroductiontoIgneousandMetamorphicPetrology.PrenticeHall.TraceelementsinCPX火成巖蛛網(wǎng)圖解釋兩大類元素活動(dòng)性強(qiáng)的大離子親石元素活動(dòng)性較弱的高場(chǎng)強(qiáng)元素特定礦物對(duì)局部元素的控制作用如Zr、P、Sr、Ti、Nb、Ta等個(gè)別元素的特殊指示意義如Nb、Ta〔地殼混染〕強(qiáng)活動(dòng)元素〔流體活動(dòng)或地殼混染〕沉積巖蛛網(wǎng)圖解釋沉積物源區(qū)組成某些特殊礦物風(fēng)化程度局部熔融過(guò)程中的相容性流體作用中的活動(dòng)性用某一特殊樣品歸一化相對(duì)于新鮮局部微量元素呈現(xiàn)出互補(bǔ)的關(guān)系3.元素比值元素比值通常比元素含量在識(shí)別某礦物或地質(zhì)作用上更有效。指示分異程度：(La/Yb)N、(La/Sm)N指示沉積物源區(qū)：La/Sc、Th/Sc、La/Co、Th/Co、Eu/Sm、La、LuNi/CrorNi/Sc可以區(qū)別由局部熔融或分餾結(jié)晶作用形成的巖石中橄欖石和輝石的作用Nb/TaNb/LaZr/Hf4.雙變量圖不相容元素對(duì)局部熔融作用敏感識(shí)辨源區(qū)特征相容元素對(duì)別離結(jié)晶作用敏感01020304050010203040506070ArcheanTTG&Slabmelts(La/Yb)NPost-Archeangranites&modernarcsHigh(La/Yb)N=garnetinsource:lowercrustoruppermantle?Y(ppm)XinglonggouhiMglavasFig.3PlotsofTiO2

vs.NbandZrforeclogitesfromCCSD-MHandultramaficrocksfromZK703(a,b)andoceanicgabbrosfromtheIndianRidge(c,d).Eclogites(literatures)from(Zhangetal.,2004;Zhangetal.,2000b).Moderncontinentalfloodbasalts()areshownforcomparison.Oceanicgabbrosfrom(Cooganetal.,2001;Hartetal.,1999).Fig.8Fig.8PlotsofMgO-TiO2and-VandFe2O3total-MgOand-V.Solidcyclesaredataofthiswork,rectanglesaredatafromZhangetal.(2004;2000b).1=trendofpyroxene±olivinecrystallization,2=trendofmagnetitecrystallization,3=trendofmeltevolution.PentacleistheaverageofcontinentalfloodbasaltswithMgO>8wt%().50607080101520253035Y(ppm)Fe/MnHawaiiOIBMORBCFB5060708011.522.5Yb(ppm)Fe/MnHawaiiOIB石榴石的作用石榴石/單斜輝石富集地幔D(Y,Yb)cpx/basalt<1DFe/DMncpx/basalt<1D(Y,Yb)grt/basalt>1DFe/DMngrt/basalt<1119-136Ma玄武巖:

斜方輝石富集的地幔0.0100.0200.0300.0400.0500.0600.05060708090Fe/MnNi(ppm)<110Ma玄武巖119-136Ma玄武巖Hawaii玄武巖平均值5.模型計(jì)算TiO2-Nb,-Zrvariationsduringfractionalcrystallizationofcpx+pl+opx+mtwith15%trappedmeltfollowing5%fractionalcrystallizationofultramaficrocks(70%ol+20%cpx+10%opx)fromabasalticmagma.mt10andmt20arecumulatesof40%cpx+35%pl+15%opx+10%mtand30%cpx+35%pl+15%opx+20%mt,respectively.pl80andpl30aremagnetite-freecumulatesof80%pl+15%opx+5%cpxand55%cpx+3