Concurrent Pb-Hf isotope analysis of zircon by laser ablation multi-collector ICP-MS, with implications for the crustal evolution of Greenland and the Himalayas

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Concurrent Pb-Hf isotope analysis of zircon by laser ablation multi-collector ICP-MS, with implications for the crustal evolution of Greenland and the Himalayas. / Kemp, Tony; Foster, Gavin; Scherstén, Anders; Whitehouse, Martin; Darling, Mike; Storey, Craig.

I: Chemical Geology, Vol. 261, Nr. 3-4, 2009, s. 244-260.

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskrift

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T1 - Concurrent Pb-Hf isotope analysis of zircon by laser ablation multi-collector ICP-MS, with implications for the crustal evolution of Greenland and the Himalayas

AU - Kemp, Tony

AU - Foster, Gavin

AU - Scherstén, Anders

AU - Whitehouse, Martin

AU - Darling, Mike

AU - Storey, Craig

PY - 2009

Y1 - 2009

N2 - Abstract in Undetermined The in situ Lu-Hf isotope analysis of zircon by laser ablation has emerged as a high-calibre tool for tackling magmatic and crustal evolution. The strength of the approach lies with the ability to target specific zircon growth domains identified by imaging, and thus to unravel polyphase crystallisation histories. However, due to the volume of material being sampled during analysis there remains the possibility of ablation-induced mixing between Hf from domains of different age. Inaccurate Hf isotope ratios and spurious geological interpretations could result. One approach to this problem involves dating the same volume of material analysed for Hf isotopes by concurrently measuring (207)Pb/(206)Pb ratios during ablation [Woodhead,J.D., Hergt,J.M.. Shelley, M., Eggins, S., Kemp, R. 2004. Zircon Hf-isotope analysis with an excimer laser, depth profiling, ablation of complex geometries, and concomitant age estimation. Chemical Geology 209,121-135.]. This paper explores the viability of this dual analysis by investigating complex zircons from three different geological contexts, detrital zircons in sedimentary rocks, inherited zircons in granites, and zircons in metamorphosed Eo-Archaean TTG gneisses from Greenland. The implications of the Greenland data for Archaean crustal evolution are discussed in the light of published solution zircon Hf isotope datasets from these gneisses. A case study of detrital zircons from modern river sands in the Himalayas highlights the potential of the technique for providing a rapid, cost-effective picture of crustal evolution that should complement regional bulk rock studies.

AB - Abstract in Undetermined The in situ Lu-Hf isotope analysis of zircon by laser ablation has emerged as a high-calibre tool for tackling magmatic and crustal evolution. The strength of the approach lies with the ability to target specific zircon growth domains identified by imaging, and thus to unravel polyphase crystallisation histories. However, due to the volume of material being sampled during analysis there remains the possibility of ablation-induced mixing between Hf from domains of different age. Inaccurate Hf isotope ratios and spurious geological interpretations could result. One approach to this problem involves dating the same volume of material analysed for Hf isotopes by concurrently measuring (207)Pb/(206)Pb ratios during ablation [Woodhead,J.D., Hergt,J.M.. Shelley, M., Eggins, S., Kemp, R. 2004. Zircon Hf-isotope analysis with an excimer laser, depth profiling, ablation of complex geometries, and concomitant age estimation. Chemical Geology 209,121-135.]. This paper explores the viability of this dual analysis by investigating complex zircons from three different geological contexts, detrital zircons in sedimentary rocks, inherited zircons in granites, and zircons in metamorphosed Eo-Archaean TTG gneisses from Greenland. The implications of the Greenland data for Archaean crustal evolution are discussed in the light of published solution zircon Hf isotope datasets from these gneisses. A case study of detrital zircons from modern river sands in the Himalayas highlights the potential of the technique for providing a rapid, cost-effective picture of crustal evolution that should complement regional bulk rock studies.

U2 - 10.1016/j.chemgeo.2008.06.019

DO - 10.1016/j.chemgeo.2008.06.019

M3 - Article

VL - 261

SP - 244

EP - 260

JO - Chemical Geology (Isotopic Geoscience) Section

JF - Chemical Geology (Isotopic Geoscience) Section

SN - 0009-2541

IS - 3-4

ER -