Seismic reflection and magnetotelluric profiles across the Luobusa ophiolite: Evidence for the deep structure of the Yarlung Zangbo suture zone, southern Tibet

Jiang, Mei; Peng, Miao; Yang, J.; Tan, Handong; Qian, Rongyi; Zhang, Yuwen; Xu, Lina; Zhang, Li-Shu; Qing-qing, LI

doi:10.1016/j.jseaes.2015.03.019

Cited by 9 publications

(3 citation statements)

References 22 publications

(29 reference statements)

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“…From north to south (top to bottom of the reconstructed stratigraphy), they are the northern dunite zone (NDZ), northern harzburgite zone (NHZ), central harzburgite zone (CHZ) and southern lherzolite zone (SLZ). They form a continuous mantle section ~2 km wide in the N-S direction on the outcrop, reflecting an estimated maximum thickness for the Kangjinla ophiolitic mantle of ~2 km according to field and geophysical observations 20,37 . At the contact between the CHZ and the overlying Triassic black slates, the peridotites are strongly carbonated and were not sampled in this study (Fig.…”

Section: Resultsmentioning

confidence: 92%

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Vertical depletion of ophiolitic mantle reflects melt focusing and interaction in sub-spreading-center asthenosphere

et al. 2022

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Decompressional melting of asthenosphere under spreading centers has been accepted to produce oceanic lithospheric mantle with vertical compositional variations, but these gradients are much smaller than those observed from ophiolites, which clearly require additional causes. Here we conduct high-density sampling and whole-rock and mineral analyses of peridotites across a Tibetan ophiolitic mantle section (~2 km thick), which shows a primary upward depletion (~12% difference) and local more-depleted anomalies. Thermodynamic modeling demonstrates that these features cannot be produced by decompressional melting or proportional compression of residual mantle, but can be explained by melt-peridotite reaction with lateral melt/rock ratio variations in an upwelling asthenospheric column, producing stronger depletion in the melt-focusing center and local zones. This column splits symmetrically and flows to become the horizontal uppermost lithospheric mantle, characterized by upward depletion and local anomalies. This model provides insights into melt extraction and uppermost-mantle origin beneath spreading centers with high melt fluxes.

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Section: Resultsmentioning

confidence: 92%

“…The Luobusa ophiolite is a south-dipping tectonic slice (Fig. 1c ) with an exposed length of ~42 km and width of ~1–3 km as well as a geophysically constrained thickness of ~2–3 km 37 . It is sandwiched between northern Eocene molasse (Luobusa Formation) at the base and the southern Triassic flysch (Langjiexue Group) on top 20 .…”

Section: Resultsmentioning

confidence: 99%

Vertical depletion of ophiolitic mantle reflects melt focusing and interaction in sub-spreading-center asthenosphere

et al. 2022

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“…The Luobusa ophiolite is a south-dipping tectonic slice (Fig. 1c) with an exposed length of ~42 km and width of ~1-3 km as well as a geophysically constrained thickness of ~2-3 km 35 . It is sandwiched between northern Eocene molasse at the base and the southern Triassic flysch on top 19 .…”

Section: Resultsmentioning

confidence: 99%

Vertical depletion of ophiolitic mantle decodes melt focusing and interaction in the asthenospheric column under oceanic spreading centers

Xiong

Dai

Zheng

et al. 2022

Preprint

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Adiabatic decompressional melting of asthenosphere under spreading centers has been accepted to produce vertical compositional variations of oceanic lithospheric mantle. However, theoretical estimates of the compositional gradients are much smaller than those observed from ophiolites, clearly requiring additional processes. Here we conduct systematic high-density sampling and whole-rock and mineral compositional analyses of harzburgites in a Tibetan ophiolitic mantle section (~2 km thick), which shows a primary upward depletion (~12% difference over ~2 km) and local depleted anomalies. Thermodynamic modeling demonstrates that these features cannot be produced by decompressional melting or proportional compression of residual mantle. Instead, they can be explained by reaction between silica-undersaturated melts and peridotite with lateral melt/rock variations in the topmost asthenospheric upwelling column, showing stronger depletion in its melt-focusing center and local zones. This column will split from the center into two parts, which rotate in the mantle flow to become horizontal, thus forming the oceanic uppermost lithospheric mantle characterized by vertical depletion and local anomalies within a sub-spreading-center regime.

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Pyroxenite–harzburgite sequences in the Dazhuqu ophiolite (Southern Tibet) formed through hydrous melt infiltration and melt–peridotite reaction

Zhang,

Liu,

Liang

et al. 2023

Contrib Mineral Petrol

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Seismic reflection and magnetotelluric profiles across the Luobusa ophiolite: Evidence for the deep structure of the Yarlung Zangbo suture zone, southern Tibet

Cited by 9 publications

References 22 publications

Vertical depletion of ophiolitic mantle reflects melt focusing and interaction in sub-spreading-center asthenosphere

Vertical depletion of ophiolitic mantle reflects melt focusing and interaction in sub-spreading-center asthenosphere

Vertical depletion of ophiolitic mantle decodes melt focusing and interaction in the asthenospheric column under oceanic spreading centers

Pyroxenite–harzburgite sequences in the Dazhuqu ophiolite (Southern Tibet) formed through hydrous melt infiltration and melt–peridotite reaction

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