Interaction of upwelling asthenosphere with oceanic lithospheric mantle in Bangong-Nujiang subduction zone: A new mechanism for the petrogenesis of Nb-enriched basalts

When impinging on the lithosphere in spreading ridges or intra-plate settings, the asthenospheric mantle can significantly influence plate tectonics. However, the active role of the asthenospheric mantle on subducting slabs remains poorly understood. The main reason for this dispute is the lack of t...

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Bibliographic Details
Published in:Lithos 2023-07, Vol.448-449, p.107172, Article 107172
Main Authors: Huang, Qiang-Tai, Zhang, Cheng-Lei, Zhang, Kai-Jun, Hua, Yuan-Jun, Chen, Wen-Chao, Cao, Yu-Dong, Cheng, Peng
Format: Article
Language:English
Subjects:
Bangong-Nujiang Meso-Tethys
Geochemistry
Geochronology
Nb-enriched basalts
Sr-Nd isotopes
Tibet
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Summary:When impinging on the lithosphere in spreading ridges or intra-plate settings, the asthenospheric mantle can significantly influence plate tectonics. However, the active role of the asthenospheric mantle on subducting slabs remains poorly understood. The main reason for this dispute is the lack of typical geochemical mafic rocks in the subduction zone. In this paper, we first report the Early Jurassic (187 Ma) Yurongguo Nb-enriched basalts in the western segment of the Bangong-Nujiang suture zone. These samples show typical Nb-enriched basaltic features with high Na2O, TiO2, Nb (>7 ppm), high Nb/Th (average = 11.05), Nb/La (average = 1.37) and Nb/U (average = 72.98) ratios. Unlike the adakite-related Nb-enriched basalts, the Yurongguo Nb-enriched basalts formed from the mixture of magmas derived from upwelling asthenosphere (20–30%) and depleted mantle (70–80%) in the spinel lherzolite region (
ISSN:0024-4937
1872-6143
DOI:10.1016/j.lithos.2023.107172