Laser Raman Spectroscopic Study and LA-ICP-MS U-Pb Dating of Zircons from the Badaling Granitic Complex
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摘要: α通量基体效应是由标准锆石与样品锆石之间的晶体损伤（以α通量表示）不同引起的激光剥蚀速率和坑下分馏行为的差异，已被证实是导致锆石LA-ICP-MS U-Pb定年结果存在系统偏倚的重要原因。α通量越高，剥蚀速率越快，坑下分馏越明显，然而α通量基体效应的校正尚未引起足够的重视。本文采用激光拉曼光谱和LA-ICP-MS对八达岭花岗杂岩样品进行研究，结果表明：实际α通量（DαP）≤0.75×1018 g-1的锆石样品，蜕晶化程度较弱，其定年结果存在的α通量基体效应可以忽略；DαP>0.75×1018 g-1的锆石样品，蜕晶化程度较高，其定年结果受α通量基体效应的影响明显，依据年龄差-DαP经验方程如y=347.8×exp（0.260×10-15x）进行校正可获得准确的年龄结果。本研究认为：采用激光拉曼光谱和半高宽（FWHM）-DαP校准曲线获得目标锆石DαP，利用年龄差-DαP经验方程估计LA-ICP-MS系统偏倚，是校正α通量基体效应的可行途径。
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关键词:
- 锆石 /
- 激光拉曼光谱 /
- LA-ICP-MS U-Pb定年 /
- α通量基体效应 /
- 八达岭花岗杂岩
Abstract: Alpha dose matrix effect is the discrepancy of ablation rate and down-hole fractionation induced by the difference of crystal damage degree (alpha dose) between standard zircons and sample zircons. It has been proved to be the cause of systematic bias of zircon U-Pb dating by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS). Alpha dose is closely related to ablation rate and down-hole fractionation behaviour of zircon. The higher the alpha dose, the faster the ablation rate and more obvious is the down-hole fractionation. However, the correction of alpha dose matrix effect has received little attention thus far. In this study, Laser Raman Spectroscopy and LA-ICP-MS were used to analyze zircons from the Badaling Granitic Complex rocks. Results show that the metamictization degree is low when the actual retained alpha dose (DαP) is no more than 0.75×1018 g-1 and the matrix effect is negligible. However, when the actual retained alpha dose (DαP) is larger than 0.75×1018 g-1, metamictization degree is high and the dating results are obviously affected byalpha dose matrix effect. For this reason, U-Pb data of zircons need to be corrected using the'Age offset-DαP'empirical equation such as y=347.8×exp(0.260×10-15x). In conclusion, it was found that this is a feasible method to correct alpha dose matrix effect by using Laser Raman Spectroscopy and a full width at half maximum (FWHM)-DαP correction curve to obtain DαP values of analyzed zircons by using age deviations-DαP empiric formula to determine the systematic deviations of LA-ICP-MS. -
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表 1 4件样品锆石的U、Th含量
Table 1. U and Th contents of zircons from four rock samples
样品锆石 U含量(μg/g) Th含量(μg/g) BTS1 45~158 57~518 BTS3 2212~3846 897~2650 BTS9 56~487 43~471 BTS10 17~150 13~168 
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表 2 22个测点的ν(SiO4)拉曼特征峰参数及DαP数据
Table 2. DαP and the Raman band of ν(SiO4) of 22 points
测点编号 测点
位置峰位
(cm-1)半高宽
(cm-1)(DαP)a
(1018 g-1)(DαP)b
(1018 g-1)Δ(DαP)
(%)BTS1-5-1.1 核部 1007 4.8±0.3 0.26 0.28±0.02 7.69 BTS1-5-1.2 边部 1007 6.2±0.3 0.36 0.37±0.02 2.78 BTS1-5-10.1 核部 1007 6.2±0.3 0.36 0.37±0.02 2.78 BTS1-5-10.2 边部 1007 6.2±0.3 0.36 0.37±0.02 2.78 BTS3-6-1.1 中心 1000 12.7±0.3 0.82 0.86±0.03 4.88 BTS3-6-1.2 边缘 1000 (44.8)c / # # BTS3-6-2.1 边缘 999 28.9±0.3 / 3.87±0.15 / BTS3-6-2.2 中心 1004 12.7±0.3 0.82 0.86±0.03 4.88 BTS3-1-1.1 边缘 999 25.6±0.3 / 2.71±0.08 / BTS3-1-1.2 次边缘 997 19.2±0.3 1.29 1.55±0.04 20.16 BTS3-1-1.3 次中心 996 22.4±0.3 / 2.04±0.05 / BTS3-1-1.4 中心 999 19.2±0.3 1.29 1.55±0.04 20.16 BTS9-8-3.1 幔部 1005 6.2±0.3 0.36 0.37±0.02 2.78 BTS9-8-3.2 边部 1005 6.2±0.3 0.36 0.37±0.02 2.78 BTS9-8-3.3 核部 1004 12.7±0.3 0.82 0.87±0.03 6.10 BTS9-7-1.1 核部 1005 9.5±0.3 0.59 0.60±0.02 1.69 BTS9-7-1.2 边部 1005 6.7±0.3 0.39 0.40±0.02 2.56 BTS10-3-4.1 中心 1007 6.3±0.3 0.36 0.37±0.02 2.78 BTS10-3-4.2 边缘 1007 6.2±0.3 0.36 0.37±0.02 2.78 BTS10-3-1.1 中心 1007 6.2±0.3 0.36 0.37±0.02 2.78 BTS10-3-1.2 边缘 1005 9.5±0.3 0.59 0.60±0.02 1.69 BTS10-3-1.3 边缘 1005 9.5±0.3 0.59 0.60±0.02 1.69 Plešoviced — — 10~30 0.63~/ 0.64~4.62 / 91500e — — 2~8 0.06~0.49 0.11~0.49 / 注：(DαP)a代表采用Nasdala等[12](2001)的经验方程计算的DαP；(DαP)b代表采用Palenik等[13](2003)的经验方程计算的DαP；Δ(DαP)=[(DαP)b-(DαP)a]/(DαP)a×100；c表示BTS3-6-1.2测点的半高宽由于峰强过低，受背景干扰影响大而未能准确计算；d：Plešovice的1008 cm-1半高宽引自Sláma等[15](2008)；e：91500的1008 cm-1半高宽引自Wiedenbeck等[16](2004)。“/”表示不适用，“#”表示无法进行计算，“—”表示不涉及。
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[1] Schaltegger U, Schmitt A K, Horstwood M S A.U-Th-Pb Zircon Geochronology by ID-TIMS, SIMS, and Laser Ablation ICP-MS:Recipes, Interpretations, and Opportunities[J].Chemical Geology, 2015, 402:89-110. doi: 10.1016/j.chemgeo.2015.02.028
[2] Li X H, Liu X M, Liu Y S, et al.Accuracy of LA-ICPMS Zircon U-Pb Age Determination:An Inter-laboratory Comparison[J].Science China:Earth Sciences, 2015, 58(10):1722-1730. doi: 10.1007/s11430-015-5110-x
[3] 李凤春, 侯明兰, 栾日坚, 等.电感耦合等离子体质谱仪与激光器联用测量条件优化及其在锆石U-Pb定年中的应用[J].岩矿测试, 2016, 35(1):17-23. http://www.ykcs.ac.cn/ykcs/ch/reader/view_abstract.aspx?file_no=20160104&flag=1
Li F C, Hou M L, Luan R J, et al.Optimization of Analytical Conditions for LA-ICP-MS and Its Application to Zircon U-Pb Dating[J].Rock and Mineral Analysis, 2016, 35(1):17-23. http://www.ykcs.ac.cn/ykcs/ch/reader/view_abstract.aspx?file_no=20160104&flag=1
[4] Wang J S, Peng L N, Xu Y W, et al.Types and Correction Methods of Matrix Effect during Zircon LA-ICP-MS U-Pb Dating[J].Acta Geologica Sinica (English Edition), 2015, 89(6):2099-2100. doi: 10.1111/acgs.2015.89.issue-6
[5] Allen C M, Campbell I H.Identification and Elimination of a Matrix-induced Systematic Error in LA-ICP-MS 206Pb/238U Dating of Zircon[J].Chemical Geology, 2012, 332-333:157-165. doi: 10.1016/j.chemgeo.2012.09.038
[6] Marillo-Sialer E, Woodhead J, Hergt J, et al.The Zircon Matrix Effect:Evidence for an Ablation Rate Control on the Accuracy of U-Pb Age Determinations by LA-ICP-MS[J].Journal of Analytical Atomic Spectrometry, 2014, 29:981-989. doi: 10.1039/c4ja00008k
[7] Mattews W A, Angelo T V, Guest B.Developing a Correction to Remove Systematic Bias in U-Pb LA-ICP-MS Zircon Ages Related to Zircon Matrix Effects[C]//Abstract V41A-4788 Presented at 2014 Fall Meeting.San Francisco, 2014.
[8] von Quadt A, Gallhofer D, Guillong M, et al.U-Pb Dating of CA/Non-CA Treated Zircons Obtained by LA-ICP-MS and CA-TIMS Techniques:Impact for Their Geological Interpretation[J].Journal of Analytical Atomic Spectrometry, 2014, 29:1618-1629. doi: 10.1039/C4JA00102H
[9] Solari L A, Ortega-Obregón C, Bernal J P.U-Pb Zircon Geochronology by LAICPMS Combined with Thermal Annealing:Achievements in Precision and Accuracy on Dating Standard and Unknown Samples[J].Chemical Geology, 2015, 414:109-123. doi: 10.1016/j.chemgeo.2015.09.008
[10] Gao Y Y, Li X H, Griffin W L, et al.Screening Criteria for Reliable U-Pb Geochronology and Oxygen Isotope Snalysis in Uranium-rich Zircons:A Case Study from the Suzhou A-type Granites, SE China[J].Lithos, 2014, 192-195:180-191. doi: 10.1016/j.lithos.2014.02.002
[11] Nasdala L, Reiners P W, Garver J I, et al.Incomplete Retention of Radiation Damage in Zircon from Sri Lanka[J].American Mineralogist, 2004, 89:219-231. doi: 10.2138/am-2004-0126
[12] Nasdala L, Wenzel M, Vavra G, et al.Metamictisation of Natural Zircon:Accumulation Versus Thermal Annealing of Radioactivity-induced Damage[J].Contributions to Mineralogy and Petrology, 2001, 141:125-144. doi: 10.1007/s004100000235
[13] Palenik C S, Nasdala L, Ewing R C.Radiation Damage in Zircon[J].American Mineralogist, 2003, 88:770-781. doi: 10.2138/am-2003-5-606
[14] 焦守涛, 颜丹平, 张旗, 等.八达岭花岗岩的年龄、地球化学特征及其地质意义[J].岩石学报, 2013, 29(3):769-780. http://www.cnki.com.cn/Article/CJFDTOTAL-YSXB201303004.htm
Jiao S T, Yan D P, Zhang Q, et al.Zircon U-Pb Age, Geochemistry Characteristics of Badaling Granitoid Complex and Their Geological Significance[J].Acta Petrologica Sinica, 2013, 29(3):769-780. http://www.cnki.com.cn/Article/CJFDTOTAL-YSXB201303004.htm
[15] Sláma J, Košler J, Condon D J, et al.Plešovice Zircon:A New Natural Reference Material for U-Pb and Hf Isotopic Microanalysis[J].Chemical Geology, 2008, 249:1-35. doi: 10.1016/j.chemgeo.2007.11.005
[16] Wiedenbeck M, Hanchar J M, Peck W H, et al.Further Characterisation of the 91500 Zircon Crystal[J].Geostandards and Geoanalytical Research, 2004, 28:9-39. doi: 10.1111/ggr.2004.28.issue-1
[17] Deng J F, Su S G, Mo X X, et al.The Sequence of Magmatic-Tectonic Events and Orogenic Processes of the Yanshan Belt, North China[J].Acta Geologica Sinica, 2004, 78(1):260-266. http://mall.cnki.net/magazine/Article/DZXW200401032.htm
[18] Su S G, Niu Y L, Deng J F, et al.Petrology and Geochronology of Xuejiashiliang Igneous Complex and Their Genetic Link to the Lithospheric Thinning during the Yanshanian Orogenesis in Eastern China[J].Lithos, 2007, 96(1-2):90-107. doi: 10.1016/j.lithos.2006.09.020
[19] Wang X L, Coble M A, Valley J W, et al.Influence of Radiation Damage on Late Jurassic Zircon from Southern China:Evidence from in-situ Measurements of Oxygen Isotopes, Laser Raman, U-Pb Ages, and Trace Elments[J].Chemical Geology, 2014, 389:122-136. doi: 10.1016/j.chemgeo.2014.09.013
[20] Liu Y S, Gao S, Hu Z C, et al.Continental and Oceanic Crust Recycling-induced Melt-Peridotite Interactions in the Trans-North China Orogen:U-Pb Dating, Hf Isotopes and Trace Elements in Zircons from Mantle Xenoliths[J].Journal of Petrology, 2010, 51(1-2):537-571. doi: 10.1093/petrology/egp082
[21] Ludwig K R.User's Manual for Isoplot 3.75:A Geolo-gical Toolkit for Microsoft Excel[M].Berkeley:Berkeley Geochronology Centre.
[22] Nasdala L, Pidgeon R T, Wolf D, et al.Metamictization and U-Pb Isotopic Discordance in Single Zircons:A Combined Raman Microprobe and SHRIMP Ion Probe Study[J].Mineralogy and Petrology, 1998, 62:1-27. doi: 10.1007/BF01173760
[23] Nasdala L, Kostrovitsky S, Kennedy A K, et al.Retention of Radiation Damage in Zircon Xenocrysts from Kimberlites, Northern Yakutia[J].Lithos, 2014, 206-207:252-261. doi: 10.1016/j.lithos.2014.08.005
[24] Kl tzli U, Kl tzli E, Günes Z, et al.Accuracy of Laser Ablation U-Pb Zircon Dating:Results from a Test Using Five Different Reference Zircons[J].Geostandards and Geoanalytical Research, 2009, 33(3):5-15. http://lithosphere.univie.ac.at/fileadmin/user_upload/dep_lithosphaere/Kloetzli_et_al_2009.pdf
[25] Davis G S, Zhang Y D, Wang C, et al.Mesozoic Tectonic Evolution of the Yanshan Fold and Thrust Belt, with Emphasis on Hebei and Liaoning Provinces, Northern China[J].Geological Society of America Memoir, 2001, 194:171-197. https://www.researchgate.net/profile/Gregory_Davis4/publication/283364958_Mesozoic_tectonic_evolution_of_the_Yanshan_fold_and_thrust_belt_With_emphasis_on_Hebei_and_Liaoning_provinces_northern_ChinaHendrix_Davis_Paleozoic_and_Mesozoic_Tectonic_evolution_of_central_Asia_From/links/577d227908aeaa6988aba3d9.pdf?origin=publication_detail
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