| Professional Committee of Rock and Mineral Testing Technology of the Geological Society of China, National Geological Experiment and Testing Center | Host |
| Citation: |
Shuang-shuang WANG, Yan-bing HAN, Yan-guang LI, Xiao-yan WEI, Meng-qi JIN, Xiu-hua CHENG. U-Th-Pb Dating of Monazite by LA-ICP-MS Using Ablation Spot Sizes of 16 μm and 10 μm[J]. Rock and Mineral Analysis, 2016, 35(4): 349-357. doi: 10.15898/j.cnki.11-2131/td.2016.04.003
|
U-Th-Pb Dating of Monazite by LA-ICP-MS Using Ablation Spot Sizes of 16 μm and 10 μm
-
Abstract
Monazite is a common geological chronometer and has complex textures and different chemical domains. Meaningful U-Th-Pb ages for different domains can be obtained only using a suitably small laser beam spot. Based on optimizing the parameters of Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and matching two channels of carrier gas flows (Ar and He), two groups of laser ablation parameters, 16 μm-3 J/cm2-5 Hz and 10 μm-3 J/cm2-4 Hz, can be obtained for dating monazite using small ablation spot sizes. A standard sample (44069) and an unknown sample (15SLS-01) were dated using the above laser ablation parameters. For 44069, the single-point precision of 208Pb/232Th and 206Pb/238U ratios were less than 3%, and U-Th-Pb age was found to be consistent with the previous SHRIMP and TIMS U-Pb ages. For 15SLS-01, the single-point precision of 208Pb/232Th is less than 3%, whereas that of 206Pb/238U ratios is 3%-8%. However, the weighted average ages of 208Pb-232Th and 206Pb-238U are consistent within the uncertainties, and the 208Pb-232Th age is more representative. The study demonstrated that monazite U-Th-Pb age can be successfully measured by LA-ICP-MS using laser beam spot sizes of 16 μm and 10 μm, which greatly improve the spatial resolution of this micro-dating method.-
Keywords:
- monazite /
- geological chronometer /
- element fractionation /
- LA-ICP-MS /
- weighted average age
-
-
References
[1] Smith H A,Giletti B J.Lead Diffusion in Monazite[J].Geochimica et Cosmochimica Acta,1997,51(5):1047-1055. [2] Kelly N M,Harley S L,Müller A.Complexity in the Behavior and Recrystallization of Monazite during High-T Metamorphism and Fluid Infiltration[J].Chemical Geology,2012,322-323:192-208. doi: 10.1016/j.chemgeo.2012.07.001 [3] Seydoux-Guillaume A M,Montel J M,Bingen B, et al.Low-temperature Alteration of Monazite:Fluid Mediated Coupled Dissolution-Precipitation, Irradiation Damage, and Disturbance of the U-Pb and Th-Pb Chronometers[J].Chemical Geology,2012,330-331:140-158. doi: 10.1016/j.chemgeo.2012.07.031 [4] Wawrzenitz N,Krohe A,Rhede D.Dating Rock Deforma-tion with Monazite:The Impact of Dissolution Precipitation Creep[J].Lithos,2012,134-135:52-74. doi: 10.1016/j.lithos.2011.11.025 [5] Mahan K H,Wernicke B P,Jercinovic M J.Th-U-Total Pb Geochronology of Authigenic Monazite in the Adelaide Rift Complex,South Australia,and Implications for the Age of the Type Sturtian and Marinoan Glacial Deposits[J]. Earth and Planetary Science Letters,2010,289:76-86. doi: 10.1016/j.epsl.2009.10.031 [6] 杨荣生,陈衍景,张复新,等.甘肃阳山金矿独居石Th-U-Pb化学年龄及其地质和成矿意义[J].岩石学报,2006,22:2603-2610. Yang R S,Chen Y J,Zhang F X,et al.Chemical Th-U-Pb Ages of Monazite from the Yangshan Gold Deposit, Gansu Province and Their Geologic and Metallogenic Implications[J]. Acta Petralogica Sinica,2006,22:2603-2610. [7] Aleinikoff J N,Schenck W S,Plank M O,et al.Deci-phering Igneous and Metamorphic Events in High-grade Rocks of the Wilmington Complex,Delaware:Morphology,Cathodoluminescence and Backscattered Electron Zoning,and SHRIMP U-Pb Geochronology of Zircon and Monazite[J].Geological Society of America Bulletin,2006,118(1/2):39-64. [8] Kempe U,Seltmann R,Graupner T,et al.Concordant U-Pb SHRIMP Ages of U-rich Zircon in Granitoids from the Muruntau Gold District (Uzbekistan):Timing of Intrusion, Alteration Ages, or Meaningless Numbers[J].Ore Geology Reviews,2015,65:308-326. doi: 10.1016/j.oregeorev.2014.10.007 [9] Wang Y H,Xue C J,Zhang F F,et al.SHRIMP Zircon U-Pb Geochronology,Geochemistry and H-O-Si-S-Pb Isotope Systematics of the Kanggur Gold Deposit in Eastern Tianshan,NW China:Implication for Ore Genesis[J].Ore Geology Reviews,2015,68:1-3. doi: 10.1016/j.oregeorev.2015.01.009 [10] Fletcher I R,McNaughton N J,Davis W J,et al.Matrix Effects and Calibration Limitations in Ion Probe U-Pb and Th-Pb Dating of Monazite[J].Chemical Geology,2010,270(1-4):31-44. doi: 10.1016/j.chemgeo.2009.11.003 [11] Xu W G,Fan H R,Hu F F, et al.Geochronology of the Guilaizhuang Gold Deposit,Luxi Block,Eastern North China Craton:Constraints from Zircon U-Pb and Fluorite-Calcite Sm-Nd Dating[J].Ore Geology Reviews,2015,65:390-399. doi: 10.1016/j.oregeorev.2014.10.010 [12] Xu X S,Zhang M,Zhu K Y,et al.Reverse Age Zonation of Zircon Formed by Metamictisation and Hydrothermal Fluid Leaching[J].Lithos,2012,150:256-267. doi: 10.1016/j.lithos.2011.12.014 [13] 崔玉荣,周红英,耿建珍,等.LA-MC-ICP-MS独居石微区原位U-Pb同位素年龄测定[J].地球学报,2012,33(6):865-876. Cui Y R,Zhou H Y,Geng J Z,et al.In Situ LA-MC-ICP-MS U-Pb Isotopic Dating of Monazite[J].Acta Geoscientica Sinica,2012,33(6):865-876. [14] 强山峰,毕诗健,邓晓东,等.豫西小秦岭地区秦南金矿床热液独居石U-Th-Pb定年及其地质意义[J].地球科学,2013,38(1):43-56. Qiang S F,Bi S J,Deng X D,et al.Monazite U-Th-Pb Ages of the Qinnan Gold Deposit,Xiaoqinling District: Implications for Regional Metallogenesis and Tectonic Setting[J].Earth Science,2013,38(1):43-56. [15] Alexandre R C,Armin Z.Detrital Zircon without Detri-tus:A Result of 496-Ma-old Fluid-Rock Interaction during the Gold-lode Formation of Passagem,Minas Gerais,Brazil[J].Lithos,2015,212-215:415-427. doi: 10.1016/j.lithos.2014.10.011 [16] 李艳广,汪双双,刘民武,等.斜锆石LA-ICP-MS U-Pb定年方法及应用[J].地质学报,2015,89(12):2400-2418. Li Y G,Wang S S,Liu M W,et al.U-Pb Dating Study of Baddeleyite by LA-ICP-MS:Technique and Application[J]. Acta Geologica Sinica,2015,89(12):2400-2418. [17] 万渝生,刘敦一,简平.独居石和锆石 SHRIMP U-Pb定年对比[J].科学通报,2004,49(12):1185-1190. Wan Y S,Liu D Y,Jian P.SHRIMP U-Pb Dating of Monazite and Zircon[J].Chinese Science Bulletin,2004,49(12):1185-1190. [18] Catlos E J,Gilley L D,Harrison T M.Interpretation of Monazite Ages Obtained via in Situ Analysis[J].Chemical Geology,2002,188:193-215. doi: 10.1016/S0009-2541(02)00099-2 [19] Williams M L,Jercinovic M J,Harlov D E,et al.Resetting Monazite Ages during Fluid-related Alteration[J].Chemical Geology,2011,283:218-225. doi: 10.1016/j.chemgeo.2011.01.019 [20] Janots E,Berger A,Gnos E,et al.Constraints on Fluid Evolution during Metamorphism from U-Th-Pb Systematics in Alpine Hydrothermal Monazite[J].Chemical Geology,2012,326-327:61-70. doi: 10.1016/j.chemgeo.2012.07.014 [21] Bosse V,Boulvais P,Gautier P,et al.Fluid-induced Disturbance of the Monazite Th-Pb Chronometer:In Situ Dating and Element Mapping in Pegmatites from the Rhodope (Greece,Bulgaria)[J].Chemical Geology,2009,261:286-302. doi: 10.1016/j.chemgeo.2008.10.025 [22] Stepanov A S,Hermann J,Rubatto D,et al.Experimental Study of Monazite/Melt Partitioning with Implications for the REE,Th and U Geochemistry of Crustal Rocks[J].Chemical Geology,2012,300-301:200-220. doi: 10.1016/j.chemgeo.2012.01.007 -
Access History
Figures(4)
Tables(2)
Export File
Citation
Shuang-shuang WANG, Yan-bing HAN, Yan-guang LI, Xiao-yan WEI, Meng-qi JIN, Xiu-hua CHENG. U-Th-Pb Dating of Monazite by LA-ICP-MS Using Ablation Spot Sizes of 16 μm and 10 μm[J]. Rock and Mineral Analysis, 2016, 35(4): 349-357. doi: 10.15898/j.cnki.11-2131/td.2016.04.003
Format
Content
DownLoad:
- Figure 1. Back scattering images of monazite sample called 15SLS-01 (The circles represent laser ablation spot, whose diameter is 16 μm and 10 μm, respectively)
- Figure 2. Result comparison of laser condition experiment under laser beam of different diameters (a: 16 μm；b: 10 μm)
- Figure 3. Analytical results of U-Th-Pb age for monazite standard called 44069 by LA-ICP-MS. And, a is concordia plot of U-Pb isotopic data under laser beam of 16 μm; b is distribution map of 208Pb-232Th weighted age under laser beam of 16 μm; c is concordia plot of U-Pb isotopic data under laser beam of 10 μm; d is distribution map of 208Pb-232Th weighted age under laser beam of 10 μm
- Figure 4. Analytical results of U-Th-Pb age for monazite standard called 15SLS-01 by LA-ICP-MS. And, a is concordia plot of U-Pb isotopic data under laser beam of 16 μm; b is distribution map of 208Pb-232Th weighted age under laser beam of 16 μm; c is concordia plot of U-Pb isotopic data under laser beam of 10 μm; d is distribution map of 208Pb-232Th weighted age under laser beam of 10 μm