微量元素地球化学（中国地质大学）5微量元素数据的利用和地球化学解释课件

1、微量地球化学Trace Element Geochemistry“Geochemistry really is for everyone!”By Fersman (1958)5. 微量元素数据的利用和地球化学解释 有用的参考书H. Rollinson “Using geochemical data” (Longman, London, 1993)F. Albarde “Introduction to geochemical modelling” & “Geochemistry”M. Wilson “Igneous petrology, a global tectonic approach”5.

2、2. 微量元素数据分析?数据的获得与已知样品进行对比y = 0.8627x + 0.3289R2 = 0.99980102030405060020406080元素i 测定值)元素i理论值标准样品未知样品数据质量评价？数据质量评价指标相对误差（RE）标准偏差（SD）相对标准偏差（RSD）内部精度外部精度检出限（方法检出限和仪器检出限）国际标准物质实验室内部标准重复样品（分析样品或标准物质）空白样品(全流程空白和仪器噪音)中国地质大学(武汉)地质过程与矿产资源国家重点实验室LA-ICP-MS室Agilent7500aGeoLas 2005-10-50510RE(%)BeScVCrCoNiCuZnG

3、aRbSrYZrNbCsBaLaCePrNdSmEuGdTbDyHoErTmYbLuHfTaTlThUAGV-2BCR-2BHVO-2GSR-3问题某厂家给定其产品玻璃棒中Cu含量为5ppm，Pb含量为5ppm，他们所用的仪器为ICP-AES。请问该数据是否可靠？某厂家给定产品玻璃光纤中Cu含量为0.5ppm，Pb含量0.1ppm，他们所用的仪器为ICP-MS。请问该数据是否可靠？数据分析原理部分元素具有相同或相似的地球化学行为（如REE）;不同元素在不同地质作用过程的地球化学行为存在差别（相容性/活动性变化）；地质作用过程中的物理、化学条件对元素的地球化学行为具有影响（如P-T-X-fO2等

4、）.部分元素具有相同或相似的地球化学行为（如REE）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 DLa b 1DSmb -DLa0K0DLa DSm 0应用实例汉诺坝玄武岩中的麻粒岩包体汉诺坝玄武岩 中的麻粒岩包体石榴石边部明显富集MREESD014SD006

5、0.01高Rb,Sr,Cs,Ba,U,PbCCSD榴辉岩磷灰石的成分分带10000QQ磷灰石绿辉石石榴石利用石榴石、单斜辉石、磷灰石中REE的分配系数随温度变化的实验资料对该过程进行了模型计算模型计算假设温度从800升温到830, 磷灰石, 绿辉石和石榴石分别占全岩1.5%, 48.5%和50%温度升高磷灰石释放LREE-MREE、石榴石释放HREEREE在榴辉岩各矿物相间重新分配石榴石、绿辉石、磷灰石的REE成分环带受增温作用影响, 直径(d)为0.4mm和1mm的石榴石和磷灰石晶体核部REE组成发生变化所需要的时间与温度之间的关系. 计算方法为Dt/r2=0.03 (Crank，1965)

6、, 其中t是半径为r的矿物(设为球体)核部REE组成发生变化所需要的最小时间, D为REE在矿物中的扩散系数. 因为石榴石中Sm和磷灰石中Yb的环带特征明显, 并且具有相应的实验扩散系数资料, 所以选择石榴石中Sm和磷灰石中Yb进行计算. 石榴石Sm的扩散系数取自Tirone et al.(2005)磷灰石Yb的扩散系数取自Cherniak(2000).模型计算 金红石Zr温度计 存在巨大应用潜力100um榴辉岩中金红石包裹体金红石：处于石榴石中，大小50150m粒间金红石：处于石榴石和绿辉石之间，大小80250mCCSD榴辉岩包裹体金红石温度(平均614)低于粒间金红石温度(平均660) Z

7、MK粒间金红石温度是否代表超高压峰期变质温度？该温度计的结果是否有地质意义？粒间金红石核部温度较边部高，且核部温度随粒径增加而升高。在660条件下金红石中Zr扩散1m需要12万年，因此粒间金红石边部Zr含量的降低不太可能由正常扩散作用引起。粒间金红石Zr含量受到了后期流体活动的改造？！金红石中Zr扩散速率方程（据Watson） 粒间金红石边部明显富集Pb、Sr，但Zr逐渐降低。低温的机理是什么？Fig. 2Petrologic and geochemical profile of the CCSD-MH (following Zhang et al. (2004). Circles on th

8、e petrologic profile mark the sampling depths. Layer* = layers classified by Zhang et al. (2004) based on petrology.Fig. 3Plots of TiO2 vs. Nb and Zr for eclogites from CCSD-MH and ultramafic rocks from ZK703 (a, b) and oceanic gabbros from the Indian Ridge (c, d). Eclogites (literatures) from (Zhan

9、g et al., 2004; Zhang et al., 2000b). Modern continental flood basalts (http:/georoc.mpch-mainz.gwdg.de/georoc/) are shown for comparison. Oceanic gabbros from (Coogan et al., 2001; Hart et al., 1999).Fig. 7Fig. 7 Plots of Eu anomalies vs. Fe2O3total and TiO2 for eclogites and ultramafic rocks. Dark

10、 pentacle is the average of modern continental flood basalts (CFB) with MgO 8 wt% (n = 562, http:/georoc.mpch-mainz.gwdg.de/georoc/). Gray line shows Fe2O3total range of cumulates of olivine + pyroxene, which is calculated assuming DFeol = 0.51 - 1.55 (Beattie, 1994), DFecpx = 0.57 - 1.04 (Dale and

11、Henderson, 1972). Fig. 8Fig. 8 Plots of MgO-TiO2 and -V and Fe2O3total -MgO and -V. Solid cycles are data of this work, rectangles are data from Zhang et al. (2004; 2000b). 1 = trend of pyroxene olivine crystallization, 2 = trend of magnetite crystallization, 3 = trend of melt evolution. Pentacle is

12、 the average of continental flood basalts with MgO8 wt% (http:/georoc.mpch-mainz.gwdg.de/georoc/).Fig. 9Fig. 9 Plot of Ni vs. MgO. Gray diamond represents mantle composite xenoliths formed by melt-peridotite interaction (Liu et al., 2005). DM: depleted mantle (Salters and Stracke, 2004). Solid line

13、shows fractional crystallization (F=4%) of 080%ol + 8010%cpx + 1020%opx with 2% trapped melt from basaltic magma (Table 6). Crosses on the line indicate variations of olivine proportions (0-80%). KD(Fe/Mg) (=(Fe/Mg)crystal/(Fe/Mg)melt) were assumed to be 0.29, 0.26 and 0.25 for ol, cpx and opx, resp

14、ectively (Baker and Eggler, 1987). Partition coefficients of Ni between basaltic melt and ol, cpx and opx are listed in Table 6. Fig. 10Fig. 10 TiO2-Nb, -Zr variations during fractional crystallization of cpx + pl + opx + mt with 15% trapped melt following 5% fractional crystallization of ultramafic

15、 rocks (70%ol + 20%cpx + 10%opx) from a basaltic magma. mt10 and mt20 are cumulates of 40%cpx + 35%pl + 15%opx + 10%mt and 30%cpx + 35%pl + 15%opx + 20%mt, respectively. pl80 and pl30 are magnetite-free cumulates of 80%pl + 15%opx + 5%cpx and 55%cpx + 30%pl + 15%opx, respectively. Compositions of ba

16、saltic magma and partition coefficients used in modeling are listed in Table 6.研究方法REE配分曲线/REE pattern蛛网图/Spider Diagrams元素比值和含量变化图相关分析模型计算REE配分曲线/REE pattern选择归一化值球粒陨石（CI）北美页岩（NASC）后太古代澳大利亚页岩（PAAS）某特殊样品Chondrite values used in normalizing REE (ppm)ReferenceNotesLaCePrNdSmEuGdTbDyHoErTmYbLuTaylor an

17、d McLennan (1985)Avg.CI 0.367 0.957 0.137 0.711 0.231 0.087 0.306 0.058 0.381 0.085 0.249 0.036 0.248 0.038 McDonough et al. (1991)Primitive mantle0.708 1.833 0.278 1.366 0.444 0.168 0.595 0.108 0.737 0.163 0.479 0.074 0.480 0.074 Wakita et al. (1971)Composite (12)0.340 0.910 0.121 0.640 0.195 0.073

18、 0.260 0.047 0.300 0.078 0.200 0.032 0.220 0.034 Haskin et al., (1968)Composite (9)0.330 0.880 0.112 0.600 0.181 0.069 0.249 0.047 0.070 0.200 0.030 0.200 0.034 Masuda (1973)Leedey0.378 0.976 0.716 0.230 0.087 0.311 0.390 0.255 0.249 0.039 Nakamura (1974)Composite0.329 0.865 0.630 0.203 0.077 0.276

19、0.343 0.225 0.220 0.034 Evensen et al. (1978)Avg.CI0.245 0.638 0.096 0.474 0.154 0.058 0.204 0.037 0.254 0.057 0.166 0.026 0.165 0.025 Boynton (1984)Avg.CI0.310 0.808 0.122 0.600 0.195 0.074 0.259 0.047 0.322 0.072 0.210 0.032 0.209 0.032 Standard sedimentray compositions used in normalizing REE (pp

20、m) in sedimentary rocksGromet et al., 1984NASC31.167.030.4005.981.255.500.855.543.283.110.46Haskin and Frey, 1966NASC39.076.010.3037.0007.002.006.101.301.404.000.583.400.60Haskin and Haskin, 1966NASC32.070.07.9031.0005.7051.043.400.503.100.48Haskin et al., 1968NASC32.073.07.9033.0005.701.

21、245.200.851.043.400.503.100.48Gromet et al., 1984NASC31.166.727.4005.591.180.853.060.46Haskin and Haskin, 1966ES41.181.310.4040.1007.301.526.031.051.203.550.563.290.58McLennan, 1989PAAS38.279.68.8333.9005.551.084.660.774.680.992.850.412.820.43Taylor and McLennan, 1981Upper crust30.064.07.1026.0004.5

22、00.883.800.643.500.802.300.332.200.32Elderfield and Greaves, 1982Typical seawater20.89.6421.1004.320.825.205.614.944.66Hoyle et al., 1984River water42560136580.420.783.597.964.651.7SampleLaCePrNdSmEuGdTbDyHoErTmYbLuCI0.367 0.957 0.137 0.711 0.231 0.087 0.306 0.058 0.381 0.085 0.249 0.036 0.248 0.038

23、 SFX0293.0 181 25.2 93.8 15.1 4.11 11.7 1.22 5.23 0.84 2.14 0.28 1.57 0.23 SFX1386.9 171 23.6 88.8 14.3 3.98 11.2 1.13 4.99 0.80 2.04 0.26 1.54 0.23 SFX1986.7 168 23.6 88.5 14.3 3.89 11.1 1.15 4.96 0.82 2.04 0.28 1.50 0.24 SFX2787.3 170 23.7 88.7 14.1 3.91 11.0 1.16 5.05 0.84 2.07 0.27 1.56 0.23 CI-

24、normalizedSFX02253.3 189.5 183.6 132.0 65.5 47.2 38.3 21.0 13.7 9.9 8.6 7.7 6.3 6.1 SFX13236.8 179.1 172.3 124.9 61.9 45.7 36.5 19.5 13.1 9.4 8.2 7.4 6.2 5.9 SFX19236.2 175.5 172.1 124.5 61.8 44.7 36.2 19.8 13.0 9.6 8.2 7.8 6.0 6.2 SFX27237.9 177.8 173.1 124.7 61.1 44.9 36.0 20.0 13.3 9.8 8.3 7.7 6.

25、3 6.0 不同矿物的影响Ce和Eu异常；中稀土元素相对于轻、重稀土元素的富集可能反映角闪石的控制作用；轻、重稀土元素的分异则可能反映橄榄石、辉石的作用等；极端的重稀土元素亏损则可能反映了石榴石的作用。河水和海水的REE配分曲线不同矿物的影响2. 蛛网图/Spider Diagrams按照元素相容性顺序，利用球粒陨石、原始地幔等进行标准化后所作的一种线条图。Different estimates different ordering (poor standardization)选择归一化值火成岩Primitive MantleChondriteMORB沉积岩NASC平均大陆上地壳平均显生宙灰岩

26、平均显生宙石英砂岩蛛网图/Spider DiagramsMORB-normalized Spider Ocean island basalt plotted on a mid-ocean ridge basalt (MORB) normalized spider diagram of the type used by Pearce (1983). Data from Sun and McDonough (1989). From Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall.Tr

27、ace elements in CPX火成岩蛛网图解释两大类元素活动性强的大离子亲石元素活动性较弱的高场强元素特定矿物对部分元素的控制作用如Zr、P、Sr、Ti、Nb、Ta等个别元素的特殊指示意义如Nb、Ta（地壳混染）强活动元素（流体活动或地壳混染）沉积岩蛛网图解释沉积物源区组成某些特殊矿物风化程度部分熔融过程中的相容性流体作用中的活动性用某一特殊样品归一化相对于新鲜部分微量元素呈现出互补的关系3. 元素比值元素比值通常比元素含量在识别某矿物或地质作用上更有效。指示分异程度：(La/Yb)N、(La/Sm)N指示沉积物源区：La/Sc、Th/Sc、La/Co、Th/Co、Eu/Sm、La、L

28、uNi/Cr or Ni/Sc 可以区别由部分熔融或分馏结晶作用形成的岩石中橄榄石和辉石的作用Nb/TaNb/LaZr/Hf4. 双变量图不相容元素对部分熔融作用敏感识辨源区特征相容元素 对分离结晶作用敏感01020304050010203040506070Archean TTG & Slab melts(La/Yb)NPost-Archean granites & modern arcsHigh (La/Yb)N = garnet in source: lower crust or upper mantle? Y (ppm)Xinglonggou hi Mg lavasFig. 3Plots

29、 of TiO2 vs. Nb and Zr for eclogites from CCSD-MH and ultramafic rocks from ZK703 (a, b) and oceanic gabbros from the Indian Ridge (c, d). Eclogites (literatures) from (Zhang et al., 2004; Zhang et al., 2000b). Modern continental flood basalts (http:/georoc.mpch-mainz.gwdg.de/georoc/) are shown for

30、comparison. Oceanic gabbros from (Coogan et al., 2001; Hart et al., 1999).Fig. 8Fig. 8 Plots of MgO-TiO2 and -V and Fe2O3total -MgO and -V. Solid cycles are data of this work, rectangles are data from Zhang et al. (2004; 2000b). 1 = trend of pyroxene olivine crystallization, 2 = trend of magnetite c

31、rystallization, 3 = trend of melt evolution. Pentacle is the average of continental flood basalts with MgO8 wt% (http:/georoc.mpch-mainz.gwdg.de/georoc/).50607080101520253035Y (ppm)Fe/MnHawaii OIBMORBCFB5060708011.522.5Yb (ppm)Fe/MnHawaii OIB石榴石的作用石榴石/单斜辉石富集地幔D(Y, Yb)cpx/basalt 1 DFe/DMncpx/basalt 1 DFe/DMngrt/basalt 1119-136 Ma 玄武岩: 斜方辉石富集的地幔0.0100.0200.0300.0400.0500.0600.05060708090Fe/MnNi (ppm)110 Ma 玄武岩119-136 Ma 玄武岩Hawaii玄武岩平均值5. 模型计算TiO2-Nb, -Zr variations during fractional crystallization of cpx + pl + opx + mt with 15% trapped melt following 5% fractional crystalli