Recycled ancient ghost carbonate in the Pitcairn mantle plume

Xiao Jun Wang, Li Hui Chen, Albrecht W. Hofmann, Takeshi Hanyu, Hiroshi Kawabata, Yuan Zhong, Lie Wen Xie, Jin Hua Shi, Takashi Miyazaki, Yuka Hirahara, Toshiro Takahashi, Ryoko Senda, Qing Chang, Bogdan S. Vaglarov, Jun Ichi Kimura

研究成果: ジャーナルへの寄稿記事

7 引用 (Scopus)

抄録

The extreme Sr, Nd, Hf, and Pb isotopic compositions found in Pitcairn Island basalts have been labeled enriched mantle 1 (EM1), characterizing them as one of the isotopic mantle end members. The EM1 origin has been vigorously debated for over 25 years, with interpretations ranging from delaminated subcontinental lithosphere, to recycled lower continental crust, to recycled oceanic crust carrying ancient pelagic sediments, all of which may potentially generate the requisite radiogenic isotopic composition. Here we find that δ 26 Mg ratios in Pitcairn EM1 basalts are significantly lower than in normal mantle and are the lowest values so far recorded in oceanic basalts. A global survey of Mg isotopic compositions of potentially recycled components shows that marine carbonates constitute the most common and typical reservoir invariably characterized by extremely low δ 26 Mg values. We therefore infer that the subnormal δ 26 Mg of the Pitcairn EM1 component originates from subducted marine carbonates. This, combined with previously published evidence showing exceptionally unradiogenic Pb as well as sulfur isotopes affected by mass-independent fractionation, suggests that the Pitcairn EM1 component is most likely derived from late Archean subducted carbonate-bearing sediments. However, the low Ca/Al ratios of Pitcairn lavas are inconsistent with experimental evidence showing high Ca/Al ratios in melts derived from carbonate-bearing mantle sources. We suggest that carbonate-silicate reactions in the late Archean subducted sediments exhausted the carbonates, but the isotopically light magnesium of the carbonate was incorporated in the silicates, which then entered the lower mantle and ultimately became the Pitcairn plume source.

元の言語英語
ページ(範囲)8682-8687
ページ数6
ジャーナルProceedings of the National Academy of Sciences of the United States of America
115
発行部数35
DOI
出版物ステータス出版済み - 1 1 2018

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mantle plume
mantle
carbonate
isotopic composition
basalt
Archean
silicate
sediment
sulfur isotope
lower mantle
mantle source
oceanic crust
lower crust
continental crust
magnesium
lithosphere
fractionation
plume
melt

All Science Journal Classification (ASJC) codes

  • General

これを引用

Wang, X. J., Chen, L. H., Hofmann, A. W., Hanyu, T., Kawabata, H., Zhong, Y., ... Kimura, J. I. (2018). Recycled ancient ghost carbonate in the Pitcairn mantle plume. Proceedings of the National Academy of Sciences of the United States of America, 115(35), 8682-8687. https://doi.org/10.1073/pnas.1719570115

Recycled ancient ghost carbonate in the Pitcairn mantle plume. / Wang, Xiao Jun; Chen, Li Hui; Hofmann, Albrecht W.; Hanyu, Takeshi; Kawabata, Hiroshi; Zhong, Yuan; Xie, Lie Wen; Shi, Jin Hua; Miyazaki, Takashi; Hirahara, Yuka; Takahashi, Toshiro; Senda, Ryoko; Chang, Qing; Vaglarov, Bogdan S.; Kimura, Jun Ichi.

:: Proceedings of the National Academy of Sciences of the United States of America, 巻 115, 番号 35, 01.01.2018, p. 8682-8687.

研究成果: ジャーナルへの寄稿記事

Wang, XJ, Chen, LH, Hofmann, AW, Hanyu, T, Kawabata, H, Zhong, Y, Xie, LW, Shi, JH, Miyazaki, T, Hirahara, Y, Takahashi, T, Senda, R, Chang, Q, Vaglarov, BS & Kimura, JI 2018, 'Recycled ancient ghost carbonate in the Pitcairn mantle plume', Proceedings of the National Academy of Sciences of the United States of America, 巻. 115, 番号 35, pp. 8682-8687. https://doi.org/10.1073/pnas.1719570115
Wang, Xiao Jun ; Chen, Li Hui ; Hofmann, Albrecht W. ; Hanyu, Takeshi ; Kawabata, Hiroshi ; Zhong, Yuan ; Xie, Lie Wen ; Shi, Jin Hua ; Miyazaki, Takashi ; Hirahara, Yuka ; Takahashi, Toshiro ; Senda, Ryoko ; Chang, Qing ; Vaglarov, Bogdan S. ; Kimura, Jun Ichi. / Recycled ancient ghost carbonate in the Pitcairn mantle plume. :: Proceedings of the National Academy of Sciences of the United States of America. 2018 ; 巻 115, 番号 35. pp. 8682-8687.
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abstract = "The extreme Sr, Nd, Hf, and Pb isotopic compositions found in Pitcairn Island basalts have been labeled enriched mantle 1 (EM1), characterizing them as one of the isotopic mantle end members. The EM1 origin has been vigorously debated for over 25 years, with interpretations ranging from delaminated subcontinental lithosphere, to recycled lower continental crust, to recycled oceanic crust carrying ancient pelagic sediments, all of which may potentially generate the requisite radiogenic isotopic composition. Here we find that δ 26 Mg ratios in Pitcairn EM1 basalts are significantly lower than in normal mantle and are the lowest values so far recorded in oceanic basalts. A global survey of Mg isotopic compositions of potentially recycled components shows that marine carbonates constitute the most common and typical reservoir invariably characterized by extremely low δ 26 Mg values. We therefore infer that the subnormal δ 26 Mg of the Pitcairn EM1 component originates from subducted marine carbonates. This, combined with previously published evidence showing exceptionally unradiogenic Pb as well as sulfur isotopes affected by mass-independent fractionation, suggests that the Pitcairn EM1 component is most likely derived from late Archean subducted carbonate-bearing sediments. However, the low Ca/Al ratios of Pitcairn lavas are inconsistent with experimental evidence showing high Ca/Al ratios in melts derived from carbonate-bearing mantle sources. We suggest that carbonate-silicate reactions in the late Archean subducted sediments exhausted the carbonates, but the isotopically light magnesium of the carbonate was incorporated in the silicates, which then entered the lower mantle and ultimately became the Pitcairn plume source.",
author = "Wang, {Xiao Jun} and Chen, {Li Hui} and Hofmann, {Albrecht W.} and Takeshi Hanyu and Hiroshi Kawabata and Yuan Zhong and Xie, {Lie Wen} and Shi, {Jin Hua} and Takashi Miyazaki and Yuka Hirahara and Toshiro Takahashi and Ryoko Senda and Qing Chang and Vaglarov, {Bogdan S.} and Kimura, {Jun Ichi}",
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AU - Chen, Li Hui

AU - Hofmann, Albrecht W.

AU - Hanyu, Takeshi

AU - Kawabata, Hiroshi

AU - Zhong, Yuan

AU - Xie, Lie Wen

AU - Shi, Jin Hua

AU - Miyazaki, Takashi

AU - Hirahara, Yuka

AU - Takahashi, Toshiro

AU - Senda, Ryoko

AU - Chang, Qing

AU - Vaglarov, Bogdan S.

AU - Kimura, Jun Ichi

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