摘要
目前常规的激光剥蚀器样品室与等离子体质谱连接的方法是通过一根直径约为3mm的塑料管将激光剥蚀样品与载气混合形成的气溶胶直接送至ICP-MS的炬管,经等离子体质谱仪检测确定样品中各种元素(同位素)的准确含量。由于目前使用的193um激光器剥蚀脉冲频率通常为10Hz,而ICP-MS的信号采集速率快,因此样品分析标准偏差RSD(相对标准偏差)较大,通常接近10%。考虑样品是否能够均匀地由激光样品室运送到等离子体质谱仪炬管是影响样品分析数据精度的关键,本次研究在LA和ICP-MS之间设计添加了一个外置器皿使得LA剥蚀气溶胶可进行适宜体积的积累后再送入ICP-MS,即将LA剥蚀样品向ICP-MS的输送转化为近似连续送样模式。
本次研究将不同体积的圆球形和圆柱形玻璃混样器皿在中国地质大学(北京)激光等离子体质谱实验室进行了系统的联机实验,并对不添加混样器皿和将混样器皿加载于New Wave 193um激光器与Agilent 7500a型四级杆等离子体质谱仪之间后的标准样品(NIST 610)测试结果,如轻、中、重质量代表性元素的RSD、CPS值(信号强度计数值),以及等离子体质谱图形态等进行系统分析,综合评价了不同形态和体积混样器皿的优劣。本次研究确定直径30mm、高40mm的圆柱体混样器皿具有较好性能,可使人工合成国际标样NIST610的样品分析标准偏差RSD稳定至5%左右,且样品分析过程中ICP-MS接受信号速度较快,检测灵敏度较高。
利用通过加载混样器皿进行仪器性能优化后的中国地质大学(北京)激光等离子体质谱实验室的LA-ICP-MS,对新疆巴楚麻扎塔格碱性基性杂岩体辉长闪长岩中岩浆锆石和新疆榆树沟麻粒岩相变质蛇绿岩地体中石榴二辉麻粒岩中典型变质锆石进行了点状和线状剥蚀取样两组U-Pb年龄测试结果的对比,显示加载30mm、高40mm的圆柱状混样器皿后,点状和线状剥蚀取样的测试结果在误差范围内一致,且榆树沟变质锆石的测试结果与前人进行的该样品中变质锆石SHRIMP U-Pb年龄测定结果也在误差范围内一致。初步研究表明利用加载混样器皿进行优化的LA-ICP-MS,可进行线状浅剥蚀取样方式的锆石U-Pb年龄和微量元素丰度测定,这一测试方法将有效拓展LA-ICP-MS在地学精细研究中的应用,特别是对变质锆石U-Pb年龄和微量元素丰度测定等有重要意义。
At present, the conventional device used to link sample chamber of laser ablation and ICP-MS is through a plastic tube whose diameter is about 3mm. The device is used to directly send the aerosol mixed by the laser ablation sample and carrier gas to the torch of ICP-MS. Then ICP-MS detects the exact content of various elements (isotopes) in the sample. Pulse frequency of currently used 193 um laser ablation is usually 10Hz and the ICP-MS signal acquisition rate is fast, so the RSD (relative standard deviation) of the sample analysis is large, usually close to 10%.
The key of influencing data accuracy of sample analysis is whether the sample can be uniformly delivered from the laser sample chamber to the torch of ICP-MS. In view of this, I designed to add an external container between LA and ICP-MS in this study. By doing so, the accumulation of appropriate volume of aerosol ablated by LA can be sent to ICP-MS. In this way, the pattern of aerosol delivered to ICP-MS is approximately continuous.
The study made spherical and cylindrical glass mixed sample containers of different volume for systematic on-line experiment at the laser plasma mass spectrometer laboratory of China University of Geosciences (Beijing). According to the testing results of standard samples (NIST 610) which were getting from loading non-mixed sample containers and will-mixed sample containers in New Mave193 um laser and Agilent 7500a quadrupole plasma mass spectrometer, such as RSD and cps (signal intensity count) values of light, medium and heavy representative elements and the morphology of plasma mass spectrum, I made a system analysis and evaluated advantages and disadvantages of mixed sample containers of different shape and size. Through making the experiments, I thought the cylinder mixed sample containers with the diameter of 30mm and height of 40mm had good functions which could make RSD of artificial synthesis international standard sample-NIST 610 stably up to 5%. And in the process of sample analysis, ICP-MS had the fast rate of receiving signal and high sensitivity.
Using LA-ICP-MS at the laser plasma mass spectrometer laboratory of China University of Geosciences (Beijing) which was optimized by loading mixed sample containers, I did a testing between the Xinjiang Bachumazatage alkaline basic complex body gabbro-diorite igneous zircon and Xinjiang Yushugou granulite facies metamorphism granulite garnet second level typical metamorphism zircon in the ophiolite terrene, and then made a comparison of testing results about punctuate and linear ablation U-Pb age of two samples. It was showed that after loading the cylinder mixed sample containers with the diameter of 30mm and height of 40mm, the testing results of the punctuate and linear ablation sampling were consistent within the error and the testing results of Yushugou metamorphic zircon were consistent with the previous metamorphic zircon SHRIMP U-Pb age testing results carried out in the same samples within the error. Preliminary studies showed that the use of LA-ICP-MS optimized by loading containers, could detect simple linear ablation sampling of zircon U-Pb age and the abundance of trace elements. This kind of testing method will effectively expand the applications of LA-ICP-MS in earth science fine research, especially having significance in detecting metamorphic zircon U-Pb age and the abundance of trace elements.
引文
[1] Krogh T E. Improved Accuracy of U-Pb Zircon Ages by the Creation of More Concordant Systems Using an Air Abrasion Technique [J] . Geochim Cosmochim Acta. 1982 , 46 (4) : 637.
[2] Kober B. Single2zircon Evaporation Combined with Pb Emmitter Bedding for 207Pb/206 Pb - age Investigation Using Thermal Ion Mass Spectrometry and Implications to Zirconology [J] . Cont rib Mineral Pet rol . 1987 , 96(1) : 63.
[3] Compston W, Willians I S, Meyer C.U-Pb Geochronology of Zircons from Lunar Braccia 73217 Using Sensitive High-resolution Ion Microprobe[J]. J Geophys Res S up. pl .1984 (89) : B525.
[4] Blake L P, Willians I S , Compston W. Foure Zircon Ages from One Rock: The History of a 3930 Ma old Granulite from Mount Sones, Enderby Land, Antarctica [J]. Contrib Mineral Petrol. 1986, 94 (4):427.
[5] Fryer B J, Jackson S E, Longerich H P. The Application of Laser Ablation Microprobe Inductively Coupled Plasma-Mass Spectrometry (LAM-ICP-MS) to in situ (U)-Pb Geochronology [J]. Chemical Geology. 1993, 109(1/4):1-8.
[6] Hirata T, Nesbitt R W. U-Pb Isotope Geochronology of Zircon:Evaluation of the Laser Probe Inductively Coupled Plasma Mass Spectrometry Technique[J]. Geochim Cos mochim Acta. 1995, 59 (12):24-91.
[7] Wilde S A, Valley J W, Peck W H, et al. Evidence from detrital zircon for the existence of continental crust and oceans on the Earth 4.4 Gyr ago. Nathre. 2001, 409:170-178.
[8] Mojzsis S J. Harrison T M. Pidgeon R T.Oxygen-isotope evidence from ancient zircons for liquid water at the Earth’s surface 4300 Myr ago. Nathre. 2001, 409:176-183.
[9]李冰,尹明.感耦祸等离子体质谱法进展[J] ,岩矿测试. 1995, 14:254-273.
[10]胡圣虹,罗彦,马艳芳,等.近年来等离子体质谱分析技术进展[J].国外分析仪器. 2000,127:l-18.
[11] Jeffries T E, Jackson S E, Longerich H P. J.Anal.At.Spectrom,1998,13 (9) :935-940.
[12] Chu Zhuyin(储著银), Sun Min(孙敏) , Zhou Xinhua (周新华). Rock and Mineral Analysis (岩矿测试), 1998, 17 (2) :152-158.
[13] Chen Zhongxing, Doherty W, Gregoire D C. J . Anal. At.Spectrom,1997, 12:653-667.
[14] Norman M D, Griffin WL, Pearson N J, Garcia M O, O′Reilly S. J. Anal. At. Spectrom, 1998, Vol. 13:477-488.
[15] Ludden JN, Feng R,Gauthier G, Stix J, Shi J, France D, Machado N, Wu G P. Canadian Mineralogist, 1995, 33:410-435.
[16] Feng R, Machado N, Ludden J. Geochimica Cosochiica Acta, 1993, 57:3478-3487.
[17] Fryer B J, Jackson S E, Longerich H P. Chemical Geology, 1993, 109:1-8.
[18] Hirata T, Nesbitt R W. Geochimica Cosochiica Acta, 1995, 59:2491-2510.
[19] Feng R ,Machado N , Ludden J . Lead geochronology of zircon by laser-inductively coupled plasma mass spectrometry ( LP-ICP-MS) [ J ]. Geochim. Cosmochim. Acta,1993 , 57 (14) :3 479 - 3 486.
[20] Poit rasson F , Hanchar J M ,Schaltegger U. The Current State of Accessory Mineral Research [J] . Chemical Geology , 2002 ,191:3-24.
[21]刘海臣,朱炳泉,张展霞. LAM-ICPMS法用于单颗粒锆石定年研究[J],科学通报, 1998, 43(10):103-106.
[22]阎欣,储著银,孙敏,等.激光探针等离子质谱法锆石微区207Pb/206Pb测试尝试[J].科学通报,1998, 43(19):2001-2109.
[23]徐平,关鸿,孙敏等.激光探针等离子体质谱用于锆石Pb-Pb定年的分析和校正方法的进一步探讨[J] .地球化学,1999, 28(2):130-145.
[24] Hirata T.Soft ablation technique for laser ablation-inductively coupled plasma mass spectrometry [J]. Anal At Spectrom, 1997. 12:1336-1345.
[25]靳兰兰,张宏飞,胡圣虹,等.双气流路-激光剥蚀电感耦合等离子体质谱测定铅同位素比值[J] .分析化学, 2007, 35(2):191-195.
[26]王小如.电感耦合等离子体质谱应用实例[M] .北京:化学工业出版社,2005 :113-120.
[27] Gunther,C A Heinrich.Enhanced sensitivity in laser-ablation-ICP mass Spectrometry rusing helium-argon mixtures as aerosol carrier.J Anal.At.Spectrom.1999,14:1363-1368.
[28]K E Javris,A L Gray,R S Houk et al.;尹明,李冰.电感祸合等离子体质谱手册.见:Handbook of Inductively Coupled plasma Mass Speetrometry.北京:原子能出版社,1997.7.
[29]韩占忠,王敬,兰小平,等. Fluent流体工程仿真计算实例与应用[M].北京:北京理工大学出版社, 2008.
[30]金之钧,朱东亚,胡文瑄,等.塔里木盆地热液活动地质地球化学特征及其对储层影响[J] .地质学报,2006, 80 (2) :246-253.
[31]金之钧,张刘平,杨雷,等.沉积盆地深部流体的地球化学特征及油气成藏效应初探[J].中国地质大学学报, 2002, 27 (6): 659-665.
[32]聂保锋,于炳松,朱金富.巴楚地区碳酸盐岩中深成侵入岩特征及其对储层发育的影响[J] .地学前缘,2008,15 (2) :90-99.
[33]周清杰,郑建京.塔里木构造分析.北京:科学出版社.1990.12.
[34]夏林圻.夏祖春,徐学义,等.天山石炭纪大火成岩省与地幔柱.地质通报[J],2004.23 (9-10):903-910.
[35]夏林圻,李向民,夏祖春,等.天山石炭—二叠纪大火成岩省裂谷火山作用与地幔柱.西北地质.2006, 39 (1) :1-49.
[36]姜常义,贾承造,李良辰,等,新疆麻扎尔塔格地区铁富集型高镁岩浆的源区[J].地质学报,2004a,78 (6) : 770-780.
[37]姜常义,张篷勃,卢登蓉,等.柯坪玄武岩的岩石学、地球化学、Nd、Sr、Pb同位素组成与岩石成因[J].地质论评. 2004b, 50 (5) :492-500.
[38]杨树锋,历子龙,陈汉林,等.塔里木盆地二叠纪石英正长斑岩岩墙的发现及其构造意义[J] .岩石学报,2006,22 (5):1405-1412.
[39]李勇,苏文,孔屏,等.塔里木盆地塔中—巴楚地区早二叠世岩浆岩的LA-ICP-MS锆石U-Pb年龄.岩石学报[J] ,2007,23 (5) :1097-1107.
[40]贾承造,魏国齐,王良书,等.中国塔里木盆地构造特征与油气[M].北京:石油工业出版社, 1997.
[41]孙龙德,周新源,王国林.塔里木盆地石油地质研究新进展和油气勘探主攻方向[J].地质科学,2005,40 (2) :167-178.
[42]肖安成,杨树锋,李曰俊,等.塔里木盆地巴楚隆起断裂系统主要形成时代的新认识[J].地质科学,2005.40 (2) :291-302.
[43]杨树锋,陈汉林,董传万,等.塔里木盆地二叠纪正长岩的发现及其地球动力学意义[J] .地球化学,1996,25(2):121-128.
[44]孙林华,王岳军,范蔚茗,等.再论巴楚麻扎山正长岩体岩石成因和构造意义[J] .吉林大学学报(地球科学版),2008.38 (1):8-20.
[45]孙燕,肖渊甫,赵锡奎,等.塔里木盆地麻扎尔塔格碱性杂岩体LA-ICP-MS锆石U-Pb年龄及地质意义[J].地质学报,2009, 83(6):775-781.
[46]李曰俊.塔中-巴楚地区断裂系统、火成岩及其对油气的控制作用[A] .李曰俊等.中国石化西部新区勘探指挥部科技成果报告[C] .2005.
[47]陈莉,徐军,苏犁.场发射环境扫描电子显微镜上阴极荧光谱仪特点及其在锆石研究中的应用[J] .自然科学进展,2005,15 (11) :1403-1408.
[48] Michael Wiedenbeck, John M Hanchard ,William H Peck, et al . Furt her characterisation of the 91500 zircon crystal. Geostandards and Geoananalytical Research,2006, 28 (1):9-39.
[49]杨树锋,历子龙,陈汉林,等.塔里木盆地二叠纪石英正长斑岩岩墙的发现及其构造意义[J] .岩石学报, 2006, 22 (5):1405-1412.
[50]李勇,苏文,孔屏,等.塔里木盆地塔中—巴楚地区早二叠世岩浆岩的LA-ICP-MS锆石U-Pb年龄[J] .岩石学报, 2007, 23 (5) :1097-1107.
[51]肖序常,汤耀庆,冯益民,等.新疆北部及其邻区大地构造[M].北京:地质出版社, 1992. 1-171.
[52]张驰.新级蛇绿岩某些地质特征[J].地质论评,1981. 27:307-314.
[53]李春显等.亚洲大地构造图说明书[M] . 1982.北京:地质出版社.
[54]李茂松,何国琦,高峻,等.中国西南天山的蛇绿岩带[A],张旗.蛇绿岩与地球动力学研讨会论文集[C].北京:地质出版社.1996.112-116.
[55]张旗,周国庆.中国蛇绿岩[M].北京:科学出版社. 2001, 16-22.
[56]马瑞士,王赐银,叶尚夫,等.东天山构造格架及地壳演化[M].南京:南京大学出版社. 2003,9-22.
[57]周鼎武,张成立,刘良.大陆造山带古洋盆恢复的有关问题讨论[J].西北大学学报(自然科学版) ,1997,27(5):427-430.
[58]吴文奎,姜长义,杨复,等.榆树沟—铜花山地区蛇绿构造混杂体特征[J].西安地质学院学报,1992,14 (1) :8-13 .
[59]王润三,王居里,周鼎武,等.南天山榆树沟遭受麻粒岩相变质改造的蛇绿岩套研究[J].地质科学, 1999a, 34(2):166-176.
[60]王润三,周鼎武,王居里,等.南天山榆树沟华力西期深地壳麻粒岩地体研究[J].中国科学(D辑) ,1999b,29(4):306-313.
[61]王焰,王润三,周鼎武,等.南天山榆树沟麻粒岩地体的尖晶石研究.岩石矿物学杂志[J],1999,18(3):247-253.
[62]董云鹏,王润三,周鼎武.南天山北缘榆树沟变质基性一超基性岩的地球化学及其成因机制[J].地球化学, 2001, 30(6):559-568.
[63]王居里,王润三,周鼎武,等.南天山榆树沟麻粒岩相构造岩研究[J].岩石学报,1999,15(4):500-574.
[64]周鼎武,苏犁,王居里,等.南天山榆树沟蛇绿岩地体中高压麻粒岩SHRIMP锆石U-Pb年龄及构造意义[J].科学通报, 2004,49(14):1411-1415.
[65] Ringwood A E.地幔的成分与岩石学(杨美娥,何永平,胥怀济,等译) .北京:地震出版社, 1981. 1-181.
[66]王润三,王焰,刘养杰,等.新疆南天山榆树沟层状杂岩体中的副麻粒岩-岩石学特征及其地球动力学意义[J] .西北大学学报,1997,27 (5): 411-416 .
[67]王润山,周鼎武,王焰,等.南天山榆树沟高压麻粒岩地体多期变质定年研究[J].岩石学报, 2003,19:452-460.
[68]刘敦一,简平.大别山双河硬玉石英岩的超高压变质和退变质年龄SHRIMP测年的证据[J].地质学报, 2004, 78: 211~217.
[69]简平,刘敦一,孙晓猛.滇西北白马雪山和鲁甸花岗岩基SHRIMP U-Pb年龄及其地质意义[J].地球学报, 2003,24: 337~ 342.
[70] Composton W,Williams I S, Kirschvink J L, et al. Zircon U-Pb ages of early Cambrian time-scale. Journal of Geological Socciety.1992, 149:150-193.
[71] Williams I S,Claesson S. Isotope evidence for the Precambrian province and Caledonian metamorphism of high grade paragneiss from the Seve Nappes, Scandinavian Caledonides,Ⅱ. Ion micro-probe Zircon U-Th-Pb. Contributions to Mineralogy Petrology, , 1987,97: 205-217.
[72] Tom Andersen, Correction of common lead in U-Pb analysesthat do not report 204Pb. Chemical Geology. 2001,192 (2002) 59– 79.
[73] Black L P, Kamo S L, Allen C M, et al. TEMORA 1: A new zircon standard for Phanerozoic U-Pb geochronology. Chem Geol, 2003, 200: 155-170.
[74] Black L P, Kamo S L, Williams I S, et al. The application of SHRIMP to Phanerozoic geochronology:A critical appraisal of four zircon standards. Chem Geol, 2003, 200: 171-188.
[75] Wiedenbeck M, Alle P, Corfu F, et al. Three natural zircon standards for U-Th-Pb, Lu-Hf, trace element, and REE analyses. Geostand Newsl, 1995, 19: 1-23.
[76] Lopez R, Cameron K L, Jones N W. Evidence for Paleoproterozoic, Grenvillian and Pan-African age Gondwana crust beneath northeastern Mexico. Precambrian Res, 2001, 107: 195-214.
[77]Paquette J L, Pin C. A new minimaturized extraction chromatography method for precise U-Pb zircon geochronology. Chem Geol,2001, 176: 311-319.
[78]Amelin Y V, Zaitsev A N. Precise geochronology of phoscorites and carbonatites: The critical role of U-series disequilibrium in age interpretations. Geochim Cosmochim Acta, 2002, 66: 2399-2419.
[79]Chen F, Siebel W, Satir M. Zircon U-Pb and Pb-isotope fractionation during stepwise HF acid leaching and geochronological implications. Chem Geol, 2002, 191: 155-164.
[80]Nebel-Jacobsen Y, Scherer E E, Munker K, et al. Separation of U, Pb, Lu, and Hf from single zircons for combined U-Pb dating and Hf isotope measurements by TIMS and MC-ICPMS. Chem Geol, 2005, 220: 105-120.
[81] Li, X. H, X. Liang, M. Sun, H. Guan, and J. G. Malpas(2001), Precise206Pb/238U age determination on zircons by laser ablation microprobe-inductively coupled plasma-mass spectrometry using continuous linear ablation, Chen, Geol,175, 209-219. doi:10.1016/S0009-2541(00)00394-6.
[82] Xian-Hua Li, Yu Liu, Qiu-Li and Chun-Hua Guo, Precise determination of Phanerozoic zircon Pb/Pb age bymulticollector SIMS without external standardization. Chem. Geol, 10,1-21 doi:10.1029/2009GC002400.
[83]王润三,王焰,李惠民,等.南天山榆树沟高压麻粒岩地体锆石U-Pb定年及其地质意义[J].地球化学.1998.27(6):517-522.
[84]刘斌,钱一雄.东天山三条高压变质带地质特征和流体作用[J].岩石学报, 2003, 19: 283-296.