測(cè)試項(xiàng)目：Hf同位素
測(cè)試對(duì)象：鋯石、斜鋯石
測(cè)試周期：來(lái)電詳詢
送樣要求：鋯石靶，鋯石樣品176Yb/177Hf信號(hào)比值低于0.15，大于此范圍的樣品請(qǐng)?zhí)崆案嬷?/span>
完成標(biāo)準(zhǔn)：提供鋯石標(biāo)樣作為外標(biāo)及數(shù)據(jù)質(zhì)量監(jiān)控樣。測(cè)試內(nèi)精度及標(biāo)樣外精度和準(zhǔn)確度確保達(dá)到國(guó)際水平。
方法描述：
采用LA-MC-ICP-MS準(zhǔn)確測(cè)試鋯石Hf同位素的難點(diǎn)在于176Yb和176Lu對(duì)176Hf的同量異位素的干擾扣除。研究表明，Yb的質(zhì)量分餾系數(shù)(βYb)在長(zhǎng)期測(cè)試過(guò)程中并不是一個(gè)固定值，而且通過(guò)溶液進(jìn)樣方式測(cè)試得到的βYb 并不適用于激光進(jìn)樣模式中的鋯石Hf同位素干擾校正（Woodhead et al. 2004）。βYb 的錯(cuò)誤估算會(huì)明顯地影響176Yb對(duì)176Hf的干擾校正，進(jìn)而影響176Hf/177Hf比值的準(zhǔn)確測(cè)定。在實(shí)際中，我們實(shí)時(shí)獲取了鋯石樣品自身的βYb用于干擾校正。179Hf/177Hf =0.7325和 173Yb/171Yb=1.132685（Fisher et al. 2014）被用于計(jì)算Hf和Yb的質(zhì)量分餾系數(shù)βHf 和βYb 。使用176Yb/173Yb =0.79639（Fisher et al. 2014）來(lái)扣除176Yb 對(duì) 176Hf的同量異位干擾。使用176Lu/175Lu =0.02656（Blichert-Toft et al. 1997）來(lái)扣除干擾程度相對(duì)較小的176Lu對(duì) 176Hf的同量異位干擾。由于Yb和Lu具有相似的物理化學(xué)屬性，因此在本實(shí)驗(yàn)中采用Yb的質(zhì)量分餾系數(shù)βYb來(lái)校正Lu的質(zhì)量分餾行為。分析數(shù)據(jù)的離線處理（包括對(duì)樣品和空白信號(hào)的選擇、同位素質(zhì)量分餾校正）采用軟件ICPMSDataCal（Liu et al. 2010）完成。
為確保分析數(shù)據(jù)的可靠性，Plešovice、91500和GJ-1三個(gè)國(guó)際鋯石標(biāo)準(zhǔn)與實(shí)際樣品同時(shí)分析，Plešovice用于進(jìn)行外標(biāo)校正以進(jìn)一步優(yōu)化分析測(cè)試結(jié)果。91500和GJ-1作為第二標(biāo)樣監(jiān)控?cái)?shù)據(jù)校正質(zhì)量。Plešovice、91500和GJ-1的外部精密度（2SD）優(yōu)于0.000020。測(cè)試值與推薦值確保在誤差范圍內(nèi)一致。同時(shí)為了監(jiān)控高Yb/Hf比值鋯石的測(cè)試數(shù)據(jù)，采用國(guó)際常用的高Yb/Hf比值標(biāo)樣Temora 2監(jiān)控高Yb/Hf比值鋯石的測(cè)試數(shù)據(jù),。以上標(biāo)樣推薦值請(qǐng)參考Zhang et al. (2020）。
The major limitation to accurate in situ zircon Hf isotope determination by LA-MC-ICP-MS is the very large isobaric interference from 176Yb and, to a much lesser extent 176Lu on 176Hf. It has been shown that the mass fractionation of Yb (βYb) is not constant over time and that the βYb that is obtained from the introduction of solutions is unsuitable for in situ zircon measurements (Woodhead et al. 2004). The under- or over-estimation of the βYb value would undoubtedly affect the accurate correction of 176Yb and thus the determined 176Hf/177Hf ratio. We applied the directly obtained βYb value from the zircon sample itself in real-time in this study. The 179Hf/177Hf and 173Yb/171Yb ratios were used to calculate the mass bias of Hf (βHf) and Yb (βYb), which were normalized to 179Hf/177Hf =0.7325 and 173Yb/171Yb=1.132685 (Fisher et al. 2014) using an exponential correction for mass bias. Interference of 176Yb on 176Hf was corrected by measuring the interference-free 173Yb isotope and using 176Yb/173Yb =0.79639 (Fisher et al. 2014) to calculate 176Yb/177Hf. Similarly, the relatively minor interference of 176Lu on 176Hf was corrected by measuring the intensity of the interference-free 175Lu isotope and using the recommended 176Lu/175Lu =0.02656 (Blichert-Toft et al. 1997) to calculate 176Lu/177Hf. We used the mass bias of Yb (βYb) to calculate the mass fractionation of Lu because of their similar physicochemical properties. Off-line selection and integration of analyte signals, and mass bias calibrations were performed using ICPMSDataCal (Liu et al. 2010).
In order to ensure the reliability of the analysis data, three international zircon standards of Plešovice, 91500 and GJ-1 are analyzed simultaneously with the actual samples. Plešovice is used for external standard calibration to further optimize the analysis and test results. 91500 and GJ-1 are used as the second standard to monitor the quality of data correction. The external precision (2SD) of Plešovice, 91500 and GJ-1 is better than 0.000020. The test value is consistent with the recommended value within the error range. At the same time, in order to monitor the test data of the high Yb/Hf ratio zircon, the internationally used high Yb/Hf ratio standard sample Temora 2 is used to monitor the test data of the high Yb/Hf ratio zircon. The Hf isotopic compositions of Plešovice,91500 and GJ-1 have been reported by Zhang et al. (2020）.
References
Hu, Z.C., Zhang, W., Liu, Y.S., Gao, S., Li, M., Zong, K.Q., Chen, H.H. and Hu, S.H., 2015. “Wave” Signal-Smoothing and Mercury-Removing Device for Laser Ablation Quadrupole and Multiple Collector ICPMS Analysis: Application to Lead Isotope Analysis. Analytical Chemistry, 87(2), 1152–1157.
Hu, Z.C., Liu, Y.S., Gao, S., Liu, W., Yang, L., Zhang, W., Tong, X., Lin, L., Zong, K.Q., Li, M., Chen, H. and Zhou, L.,, Improved in situ Hf isotope ratio analysis of zircon using newly designed X skimmer cone and Jet sample cone in combination with the addition of nitrogen by laser ablation multiple collector ICP-MS, Journal of Analytical Atomic Spectrometry, 2012, 27, 1391–1399.
Woodhead, J., Hergt, J., Shelley, M., Eggins, S. and Kemp, R., 2004. Zircon Hf-isotope analysis with an excimer laser, depth profiling, ablation of complex geometries, and concomitant age estimation. Chemical Geology, 209(1-2): 121-135.
Fisher, C.M., et al., 2014, Guidelines for reporting zircon Hf isotopic data by LA-MC-ICPMS and potential pitfalls in the interpretation of these data, Chemical Geology, 363, 125-133.
Blichert-Toft, J., Chauvel, C. and Albarède, F., Separation of Hf and Lu for high-precision isotope analysis of rock samples by magnetic sector-multiple collector ICP-MS, Contributions to Mineralogy and Petrology, 1997, 127, 248–260.
Liu, Y.S., Gao, S., Hu, Z.C., Gao, C.G., Zong, K.Q. and Wang, D.B., 2010. 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 of mantle xenoliths. Journal of Petrology, 51(1–2): 537–571.
Zhang W , Hu Z , Spectroscopy A . Estimation of Isotopic Reference Values for Pure Materials and Geological Reference Materials[J]. Atomic Spectroscopy, 2020, 41(3):93-102.
測(cè)試對(duì)象：鋯石、斜鋯石
測(cè)試周期：來(lái)電詳詢
送樣要求：鋯石靶，鋯石樣品176Yb/177Hf信號(hào)比值低于0.15，大于此范圍的樣品請(qǐng)?zhí)崆案嬷?/span>
完成標(biāo)準(zhǔn)：提供鋯石標(biāo)樣作為外標(biāo)及數(shù)據(jù)質(zhì)量監(jiān)控樣。測(cè)試內(nèi)精度及標(biāo)樣外精度和準(zhǔn)確度確保達(dá)到國(guó)際水平。
方法描述：
21.1鋯石LA-MC-ICP-MS微區(qū)原位Hf同位素比值分析
微區(qū)原位鋯石Hf同位素比值測(cè)試在武漢上譜分析科技有限責(zé)任公司利用激光剝蝕多接收杯等離子體質(zhì)譜（LA-MC-ICP-MS）完成。激光剝蝕系統(tǒng)為Geolas HD （Coherent，德國(guó)）, MC-ICP-MS為Neptune Plus（Thermo Fisher Scientific，德國(guó)）。分析過(guò)程同時(shí)配備了信號(hào)平滑裝置以提高信號(hào)穩(wěn)定性和同位素比值測(cè)試精密度（Hu et al. 2015）。載氣使用氦氣，并在剝蝕池之后引入少量氮?dú)庖蕴岣逪f元素靈敏度（Hu et al. 2012）。分析采用Neptune Plus新設(shè)計(jì)高性能錐組合。前人研究表明，對(duì)于Neptune Plus的標(biāo)準(zhǔn)錐組合，新設(shè)計(jì)的X截取錐和Jet采樣錐組合在少量氮?dú)饧尤氲臈l件下能分別提高Hf、Yb和Lu的靈敏度5.3倍、4.0倍和2.4倍。激光輸出能量可以調(diào)節(jié)，實(shí)際輸出能量密度為~7.0 J/cm2。采用單點(diǎn)剝蝕模式，斑束固定為44 μm。詳細(xì)儀器操作條件和分析方法可參照(Hu et al. 2012)。采用LA-MC-ICP-MS準(zhǔn)確測(cè)試鋯石Hf同位素的難點(diǎn)在于176Yb和176Lu對(duì)176Hf的同量異位素的干擾扣除。研究表明，Yb的質(zhì)量分餾系數(shù)(βYb)在長(zhǎng)期測(cè)試過(guò)程中并不是一個(gè)固定值，而且通過(guò)溶液進(jìn)樣方式測(cè)試得到的βYb 并不適用于激光進(jìn)樣模式中的鋯石Hf同位素干擾校正（Woodhead et al. 2004）。βYb 的錯(cuò)誤估算會(huì)明顯地影響176Yb對(duì)176Hf的干擾校正，進(jìn)而影響176Hf/177Hf比值的準(zhǔn)確測(cè)定。在實(shí)際中，我們實(shí)時(shí)獲取了鋯石樣品自身的βYb用于干擾校正。179Hf/177Hf =0.7325和 173Yb/171Yb=1.132685（Fisher et al. 2014）被用于計(jì)算Hf和Yb的質(zhì)量分餾系數(shù)βHf 和βYb 。使用176Yb/173Yb =0.79639（Fisher et al. 2014）來(lái)扣除176Yb 對(duì) 176Hf的同量異位干擾。使用176Lu/175Lu =0.02656（Blichert-Toft et al. 1997）來(lái)扣除干擾程度相對(duì)較小的176Lu對(duì) 176Hf的同量異位干擾。由于Yb和Lu具有相似的物理化學(xué)屬性，因此在本實(shí)驗(yàn)中采用Yb的質(zhì)量分餾系數(shù)βYb來(lái)校正Lu的質(zhì)量分餾行為。分析數(shù)據(jù)的離線處理（包括對(duì)樣品和空白信號(hào)的選擇、同位素質(zhì)量分餾校正）采用軟件ICPMSDataCal（Liu et al. 2010）完成。
為確保分析數(shù)據(jù)的可靠性，Plešovice、91500和GJ-1三個(gè)國(guó)際鋯石標(biāo)準(zhǔn)與實(shí)際樣品同時(shí)分析，Plešovice用于進(jìn)行外標(biāo)校正以進(jìn)一步優(yōu)化分析測(cè)試結(jié)果。91500和GJ-1作為第二標(biāo)樣監(jiān)控?cái)?shù)據(jù)校正質(zhì)量。Plešovice、91500和GJ-1的外部精密度（2SD）優(yōu)于0.000020。測(cè)試值與推薦值確保在誤差范圍內(nèi)一致。同時(shí)為了監(jiān)控高Yb/Hf比值鋯石的測(cè)試數(shù)據(jù)，采用國(guó)際常用的高Yb/Hf比值標(biāo)樣Temora 2監(jiān)控高Yb/Hf比值鋯石的測(cè)試數(shù)據(jù),。以上標(biāo)樣推薦值請(qǐng)參考Zhang et al. (2020）。
21.2 In situ Hf isotope ratio analysis of zircon by LA-MC-ICP-MS
Experiments of in situ Hf isotope ratio analysis were conducted using a Neptune Plus MC-ICP-MS (Thermo Fisher Scientific, Germany) in combination with a Geolas HD excimer ArF laser ablation system (Coherent, Göttingen, Germany) that was hosted at the Wuhan Sample Solution Analytical Technology Co., Ltd, Hubei, China. A “wire” signal smoothing device is included in this laser ablation system, by which smooth signals are produced even at very low laser repetition rates down to 1 Hz (Hu et al. 2015). Helium was used as the carrier gas within the ablation cell and was merged with argon (makeup gas) after the ablation cell. Small amounts of nitrogen were added to the argon makeup gas flow for the improvement of sensitivity of Hf isotopes (Hu et al. 2012). Compared to the standard arrangement, the addition of nitrogen in combination with the use of the newly designed X skimmer cone and Jet sample cone in Neptune Plus improved the signal intensity of Hf, Yb and Lu by a factor of 5.3, 4.0 and 2.4, respectively. All data were acquired on zircon in single spot ablation mode at a spot size of 44 μm. The energy density of laser ablation that was used in this study was ~7.0 J cm-2. Each measurement consisted of 20 s of acquisition of the background signal followed by 50 s of ablation signal acquisition. Detailed operating conditions for the laser ablation system and the MC-ICP-MS instrument and analytical method are the same as description by Hu et al. (2012).The major limitation to accurate in situ zircon Hf isotope determination by LA-MC-ICP-MS is the very large isobaric interference from 176Yb and, to a much lesser extent 176Lu on 176Hf. It has been shown that the mass fractionation of Yb (βYb) is not constant over time and that the βYb that is obtained from the introduction of solutions is unsuitable for in situ zircon measurements (Woodhead et al. 2004). The under- or over-estimation of the βYb value would undoubtedly affect the accurate correction of 176Yb and thus the determined 176Hf/177Hf ratio. We applied the directly obtained βYb value from the zircon sample itself in real-time in this study. The 179Hf/177Hf and 173Yb/171Yb ratios were used to calculate the mass bias of Hf (βHf) and Yb (βYb), which were normalized to 179Hf/177Hf =0.7325 and 173Yb/171Yb=1.132685 (Fisher et al. 2014) using an exponential correction for mass bias. Interference of 176Yb on 176Hf was corrected by measuring the interference-free 173Yb isotope and using 176Yb/173Yb =0.79639 (Fisher et al. 2014) to calculate 176Yb/177Hf. Similarly, the relatively minor interference of 176Lu on 176Hf was corrected by measuring the intensity of the interference-free 175Lu isotope and using the recommended 176Lu/175Lu =0.02656 (Blichert-Toft et al. 1997) to calculate 176Lu/177Hf. We used the mass bias of Yb (βYb) to calculate the mass fractionation of Lu because of their similar physicochemical properties. Off-line selection and integration of analyte signals, and mass bias calibrations were performed using ICPMSDataCal (Liu et al. 2010).
In order to ensure the reliability of the analysis data, three international zircon standards of Plešovice, 91500 and GJ-1 are analyzed simultaneously with the actual samples. Plešovice is used for external standard calibration to further optimize the analysis and test results. 91500 and GJ-1 are used as the second standard to monitor the quality of data correction. The external precision (2SD) of Plešovice, 91500 and GJ-1 is better than 0.000020. The test value is consistent with the recommended value within the error range. At the same time, in order to monitor the test data of the high Yb/Hf ratio zircon, the internationally used high Yb/Hf ratio standard sample Temora 2 is used to monitor the test data of the high Yb/Hf ratio zircon. The Hf isotopic compositions of Plešovice,91500 and GJ-1 have been reported by Zhang et al. (2020）.
References
Hu, Z.C., Zhang, W., Liu, Y.S., Gao, S., Li, M., Zong, K.Q., Chen, H.H. and Hu, S.H., 2015. “Wave” Signal-Smoothing and Mercury-Removing Device for Laser Ablation Quadrupole and Multiple Collector ICPMS Analysis: Application to Lead Isotope Analysis. Analytical Chemistry, 87(2), 1152–1157.
Hu, Z.C., Liu, Y.S., Gao, S., Liu, W., Yang, L., Zhang, W., Tong, X., Lin, L., Zong, K.Q., Li, M., Chen, H. and Zhou, L.,, Improved in situ Hf isotope ratio analysis of zircon using newly designed X skimmer cone and Jet sample cone in combination with the addition of nitrogen by laser ablation multiple collector ICP-MS, Journal of Analytical Atomic Spectrometry, 2012, 27, 1391–1399.
Woodhead, J., Hergt, J., Shelley, M., Eggins, S. and Kemp, R., 2004. Zircon Hf-isotope analysis with an excimer laser, depth profiling, ablation of complex geometries, and concomitant age estimation. Chemical Geology, 209(1-2): 121-135.
Fisher, C.M., et al., 2014, Guidelines for reporting zircon Hf isotopic data by LA-MC-ICPMS and potential pitfalls in the interpretation of these data, Chemical Geology, 363, 125-133.
Blichert-Toft, J., Chauvel, C. and Albarède, F., Separation of Hf and Lu for high-precision isotope analysis of rock samples by magnetic sector-multiple collector ICP-MS, Contributions to Mineralogy and Petrology, 1997, 127, 248–260.
Liu, Y.S., Gao, S., Hu, Z.C., Gao, C.G., Zong, K.Q. and Wang, D.B., 2010. 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 of mantle xenoliths. Journal of Petrology, 51(1–2): 537–571.
Zhang W , Hu Z , Spectroscopy A . Estimation of Isotopic Reference Values for Pure Materials and Geological Reference Materials[J]. Atomic Spectroscopy, 2020, 41(3):93-102.
