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Mantle dunites archive multistage melt metasomatism under a fossil slow-ultraslow spreading center: an example from the Tibetan Xigaze ophiolite.

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Title: Mantle dunites archive multistage melt metasomatism under a fossil slow-ultraslow spreading center: an example from the Tibetan Xigaze ophiolite.
Authors: Wang, Li1,2,3 (AUTHOR), Xiong, Qing1 (AUTHOR) xiongqing@cug.edu.cn, Dai, Hong-Kun1 (AUTHOR), Zhou, Xiang1 (AUTHOR), Zheng, Hong-Da1 (AUTHOR), Sun, Hao-Qin1 (AUTHOR), Li, Yi-Cong1 (AUTHOR), Xue, Long-Fei1 (AUTHOR), Sanfilippo, Alessio2,3 (AUTHOR), Basch, Valentin2,3 (AUTHOR), Zheng, Jian-Ping1 (AUTHOR)
Source: Contributions to Mineralogy & Petrology. Apr2026, Vol. 181 Issue 4, p1-21. 21p.
Subject Terms: *Dunite, *Metasomatism, *Petrology, *Lithosphere, *Geochemistry
Geographic Terms: Tibet (China)
Abstract: Previous studies on oceanic crust have revealed the diversity of mantle melts in oceanic lithosphere, but their origin within oceanic mantle and initial composition remain unclear. The Dazhuka dunitic channels within the deep mantle section of the Xigaze ophiolite (South Tibet), which has been interpreted to have formed in a Neo-Tethyan slow-ultraslow spreading center, present ideal targets to explore the origin of oceanic mantle melts and the relevant processes. Petrographic characteristics and geochemical data identify three distinct types of dunites, recording complex melt types and two-stage evolution processes. In stage 1, a melt/rock interaction likely occurring at the top of the asthenosphere between silica-undersaturated melts and wall-rock harzburgites caused a rapid decrease in orthopyroxene contents, an increase in olivine grain size, as well as elevated whole-rock MgO contents (47.9–50.8 wt.%) and spinel Cr# (0.46–0.83). In addition, the elevation of clinopyroxene Ca/Al ratios (6.74–54.8) and Mg# (0.93–0.96) within type 2 dunites suggests that small amounts of carbonatitic components (~ 0.4 wt.%) possibly coexisted with the silica-undersaturated melts, causing gradual dunitization of wall-rock harzburgites. In stage 2, the occurrence of disseminated pyroxenes and spinels crosscutting the dunites, along with the increased olivine Ca contents (492–1745 ppm) and spinel TiO2 contents (0.20–0.35), indicates that MORB-like melts reused the dunitic channels and resulted in the refertilization of the channel system. Our study highlights that, under oceanic slow-ultraslow spreading centers, the dunitic channels can act as critical archives of mantle melt evolution and thus a valid alternative for constraining the heterogeneity of the asthenosphere. [ABSTRACT FROM AUTHOR]
Database: Energy & Power Source
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DbLabel: Energy & Power Source
An: 193392360
AccessLevel: 6
PubType: Academic Journal
PubTypeId: academicJournal
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  Data: Mantle dunites archive multistage melt metasomatism under a fossil slow-ultraslow spreading center: an example from the Tibetan Xigaze ophiolite.
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  Data: <searchLink fieldCode="AR" term="%22Wang%2C+Li%22">Wang, Li</searchLink><relatesTo>1,2,3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Xiong%2C+Qing%22">Xiong, Qing</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> xiongqing@cug.edu.cn</i><br /><searchLink fieldCode="AR" term="%22Dai%2C+Hong-Kun%22">Dai, Hong-Kun</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Zhou%2C+Xiang%22">Zhou, Xiang</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Zheng%2C+Hong-Da%22">Zheng, Hong-Da</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Sun%2C+Hao-Qin%22">Sun, Hao-Qin</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Li%2C+Yi-Cong%22">Li, Yi-Cong</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Xue%2C+Long-Fei%22">Xue, Long-Fei</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Sanfilippo%2C+Alessio%22">Sanfilippo, Alessio</searchLink><relatesTo>2,3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Basch%2C+Valentin%22">Basch, Valentin</searchLink><relatesTo>2,3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Zheng%2C+Jian-Ping%22">Zheng, Jian-Ping</searchLink><relatesTo>1</relatesTo> (AUTHOR)
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  Data: <searchLink fieldCode="JN" term="%22Contributions+to+Mineralogy+%26+Petrology%22">Contributions to Mineralogy & Petrology</searchLink>. Apr2026, Vol. 181 Issue 4, p1-21. 21p.
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  Data: *<searchLink fieldCode="DE" term="%22Dunite%22">Dunite</searchLink><br />*<searchLink fieldCode="DE" term="%22Metasomatism%22">Metasomatism</searchLink><br />*<searchLink fieldCode="DE" term="%22Petrology%22">Petrology</searchLink><br />*<searchLink fieldCode="DE" term="%22Lithosphere%22">Lithosphere</searchLink><br />*<searchLink fieldCode="DE" term="%22Geochemistry%22">Geochemistry</searchLink>
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– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: Previous studies on oceanic crust have revealed the diversity of mantle melts in oceanic lithosphere, but their origin within oceanic mantle and initial composition remain unclear. The Dazhuka dunitic channels within the deep mantle section of the Xigaze ophiolite (South Tibet), which has been interpreted to have formed in a Neo-Tethyan slow-ultraslow spreading center, present ideal targets to explore the origin of oceanic mantle melts and the relevant processes. Petrographic characteristics and geochemical data identify three distinct types of dunites, recording complex melt types and two-stage evolution processes. In stage 1, a melt/rock interaction likely occurring at the top of the asthenosphere between silica-undersaturated melts and wall-rock harzburgites caused a rapid decrease in orthopyroxene contents, an increase in olivine grain size, as well as elevated whole-rock MgO contents (47.9–50.8 wt.%) and spinel Cr# (0.46–0.83). In addition, the elevation of clinopyroxene Ca/Al ratios (6.74–54.8) and Mg# (0.93–0.96) within type 2 dunites suggests that small amounts of carbonatitic components (~ 0.4 wt.%) possibly coexisted with the silica-undersaturated melts, causing gradual dunitization of wall-rock harzburgites. In stage 2, the occurrence of disseminated pyroxenes and spinels crosscutting the dunites, along with the increased olivine Ca contents (492–1745 ppm) and spinel TiO2 contents (0.20–0.35), indicates that MORB-like melts reused the dunitic channels and resulted in the refertilization of the channel system. Our study highlights that, under oceanic slow-ultraslow spreading centers, the dunitic channels can act as critical archives of mantle melt evolution and thus a valid alternative for constraining the heterogeneity of the asthenosphere. [ABSTRACT FROM AUTHOR]
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      – Type: doi
        Value: 10.1007/s00410-026-02308-x
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      – Code: eng
        Text: English
    PhysicalDescription:
      Pagination:
        PageCount: 21
        StartPage: 1
    Subjects:
      – SubjectFull: Dunite
        Type: general
      – SubjectFull: Metasomatism
        Type: general
      – SubjectFull: Petrology
        Type: general
      – SubjectFull: Lithosphere
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      – SubjectFull: Geochemistry
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      – SubjectFull: Tibet (China)
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      – TitleFull: Mantle dunites archive multistage melt metasomatism under a fossil slow-ultraslow spreading center: an example from the Tibetan Xigaze ophiolite.
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              Text: Apr2026
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              Y: 2026
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