ジルコンin situ分析によるLu-Hf同位体比
Thirlwall, M. F., & Walder, A. J. (1995). In situ hafnium isotope ratio analysis of zircon by inductively coupled plasma multiple collector mass spectrometry. Chemical Geology, 122(1-4), 241-247. https://doi.org/10.1016/0009-2541(95)00003-5
最初にLA-MC-ICPMSで分析した人たち。
これ以前にはSHRIMPでトライした Kinny et al. (1991) などがあるが、レアアース酸化物の干渉によりうまく行かなかった模様。溶液でWalder et al. (1993)がHf同位体比を測っており、さらにBlichert-Toft and Albarède (1997)、 Blichert-Toft et al.(1997)がコンドライトなどの分析に貢献。
イントロ部分で注意書きとしてPbロスについて触れている。 "Patchett (1983) has noted ".upwardly-biased" 176Hf/t77Hf ratios in zircons with very discordant U-Pb systemat- ics, while Patterson et al. (1992) have demonstrated that granite zircons with inherited Pb isotope signatures have substantially lower ~Nd at the time of emplacement than their granite hosts. Spatially resolved Hf isotope analysis of zircon would allow determination of the origin of the different growth stages of a complex zir- con, by characterizing the time-integrated Lu/Hf ratio of the magma from which a particular section of zircon grew. This would be of particular interest in studies of ancient crustal lithologies, to investigate whether old zircons ( > 3.7 Ga) preserve a record of >4-Ga Earth differentiation in non-zero initial eHf."
最初にLA-MC-ICPMSで分析した人たち。
これ以前にはSHRIMPでトライした Kinny et al. (1991) などがあるが、レアアース酸化物の干渉によりうまく行かなかった模様。溶液でWalder et al. (1993)がHf同位体比を測っており、さらにBlichert-Toft and Albarède (1997)、 Blichert-Toft et al.(1997)がコンドライトなどの分析に貢献。
イントロ部分で注意書きとしてPbロスについて触れている。 "Patchett (1983) has noted ".upwardly-biased" 176Hf/t77Hf ratios in zircons with very discordant U-Pb systemat- ics, while Patterson et al. (1992) have demonstrated that granite zircons with inherited Pb isotope signatures have substantially lower ~Nd at the time of emplacement than their granite hosts. Spatially resolved Hf isotope analysis of zircon would allow determination of the origin of the different growth stages of a complex zir- con, by characterizing the time-integrated Lu/Hf ratio of the magma from which a particular section of zircon grew. This would be of particular interest in studies of ancient crustal lithologies, to investigate whether old zircons ( > 3.7 Ga) preserve a record of >4-Ga Earth differentiation in non-zero initial eHf."
Vervoort, J. D., & Blichert-Toft, J. (1999). Evolution of the depleted mantle: Hf isotope evidence from juvenile rocks through time. Geochimica et cosmochimica acta, 63(3-4), 533-556.https://doi.org/10.1016/S0016-7037(98)00274-9
顕生代から中期太古代までの"juvenile rock"の全岩のSm-NdとLu-Hfに加えて、初期太古代の片麻岩中ジルコンのHf同位体比を報告。
"In this paper we present new Lu-Hf isotopic data (andSm-Nd data where needed) for 39 juvenile (mantle-derived)samples, middle Archean to Mesozoic in age, as well as newwhole-rock and zircon Hf isotope data for 13 early Archeangneisses from West Greenland..."
太古代初期の超枯渇した岩石を発見していて議論してる。
"In this paper we present new Lu-Hf isotopic data (andSm-Nd data where needed) for 39 juvenile (mantle-derived)samples, middle Archean to Mesozoic in age, as well as newwhole-rock and zircon Hf isotope data for 13 early Archeangneisses from West Greenland..."
太古代初期の超枯渇した岩石を発見していて議論してる。
Griffin, W. L., Pearson, N. J., Belousova, E., Jackson, S. V., Van Achterbergh, E., O’Reilly, S. Y., & Shee, S. R. (2000). The Hf isotope composition of cratonic mantle: LAM-MC-ICPMS analysis of zircon megacrysts in kimberlites. Geochimica et cosmochimica acta, 64(1), 133-147. https://doi.org/10.1016/S0016-7037(99)00343-9
キンバーライト中のジルコンでSCLMのおはなしなど。"The depleted and metasomatised lherzolites and harzburgites that make up much of the Archean lithospheric mantle have Lu/Hf ratios (#0.15) low enough to account for the lowest «Hf observed in the zircons, over time spans of 1–3.5 Ga. We therefore suggest that the magmas from which the kimberlitic zircons crystallised were derived from Depleted Mantle or OIB-type sources, and developed negative «Hf through reaction with the subcontinental lithospheric mantle."
キンバーライト中のジルコンでSCLMのおはなしなど。"The depleted and metasomatised lherzolites and harzburgites that make up much of the Archean lithospheric mantle have Lu/Hf ratios (#0.15) low enough to account for the lowest «Hf observed in the zircons, over time spans of 1–3.5 Ga. We therefore suggest that the magmas from which the kimberlitic zircons crystallised were derived from Depleted Mantle or OIB-type sources, and developed negative «Hf through reaction with the subcontinental lithospheric mantle."
その後のLA-MC-ICPMSの技術的な改良の数々=>
Woodhead et al., 2004;Iizuka and Hirata, 2005; Wu et al., 2006; Fisher et al., 2011; Kimura et al.,2012など。
Woodhead et al., 2004;Iizuka and Hirata, 2005; Wu et al., 2006; Fisher et al., 2011; Kimura et al.,2012など。
酸素同位体比との組み合わせで大陸成長議論や花崗岩体の起源の議論など。
Hawkesworth, C. J., & Kemp, A. I. S. (2006). Using hafnium and oxygen isotopes in zircons to unravel the record of crustal evolution. Chemical Geology, 226(3-4), 144-162. https://doi.org/10.1016/j.chemgeo.2005.09.018
Kemp, A. I. S., Hawkesworth, C. J., Foster, G. L., Paterson, B. A., Woodhead, J. D., Hergt, J. M., ... & Whitehouse, M. J. (2007). Magmatic and crustal differentiation history of granitic rocks from Hf-O isotopes in zircon. Science, 315(5814), 980-983. https://doi.org/10.1126/science.1136154
Hawkesworth, C. J., & Kemp, A. I. S. (2006). Using hafnium and oxygen isotopes in zircons to unravel the record of crustal evolution. Chemical Geology, 226(3-4), 144-162. https://doi.org/10.1016/j.chemgeo.2005.09.018
Kemp, A. I. S., Hawkesworth, C. J., Foster, G. L., Paterson, B. A., Woodhead, J. D., Hergt, J. M., ... & Whitehouse, M. J. (2007). Magmatic and crustal differentiation history of granitic rocks from Hf-O isotopes in zircon. Science, 315(5814), 980-983. https://doi.org/10.1126/science.1136154
↑アルバータ大学のレーザーアブレーションスプリッドストリームシステムに繋がれたThermoFisher Neptune MC-ICPMS
コメント
コメントを投稿