Light Mo isotopes of post‐collisional ultrapotassic rocks in southern Tibet derived from subducted Indian continental crust

Zhang, Miao‐Yan, Huang, Cheng‐Cheng, Hao, Lu‐Lu, Qi, Yue, Wang, Qiang, Kerr, Andrew C. ORCID: https://orcid.org/0000-0001-5569-4730, Wei, Gang‐Jian, Li, Jie, Ma, Jin‐Long, Ma, Lin and Fan, Jing‐Jing 2023. Light Mo isotopes of post‐collisional ultrapotassic rocks in southern Tibet derived from subducted Indian continental crust. Geochemistry, Geophysics, Geosystems 24 (10) , e2023GC011053. 10.1029/2023gc011053

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Abstract

Recycling of molybdenum isotopes in continental subduction zones remains debated. In this contribution, we re‐visit the Mo isotope compositions of the Sailipu post‐collisional ultrapotassic rocks in the Himalaya‐southern Tibet orogen. These ultrapotassic rocks have very varying δ98/95Mo values of −0.66 to −0.07‰ and Mo/Ce ratios of 0.0008–0.005, which are lower than those of mid‐ocean ridge basalts (MORB; δ98/95Mo = −0.20 ± 0.06‰, and Mo/Ce = 0.03) and oceanic subduction‐related (i.e., mantle source involving fluids, residual slab, or oceanic sediments) magmatic rocks (e.g., modern arc lavas, Cenozoic OIB‐type basalts in eastern China and the central Mariana Trough basalts in the back‐arc basin, syn‐collisional andesitic rocks in southern Tibet). Combined with the light Mo isotopes of the Himalayan schists and gneisses, we suggest that the light Mo isotopic signature of the Sailipu ultrapotassic rocks is derived from subducted Indian continental crust. This is consistent with the extremely low δ11B (−17.4 to −9.7‰) and B/Nb (0.16–1) values and enriched Sr‐Nd‐Pb isotopes of the Sailipu ultrapotassic rocks. Thus, this study reveals the recycling of light Mo‐B isotopes during continental subduction and demonstrates that Mo‐B isotopes can effectively distinguish between continental and oceanic subduction.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Earth and Environmental Sciences
Additional Information:	License information from Publisher: LICENSE 1: URL: http://creativecommons.org/licenses/by-nc/4.0/
Publisher:	Wiley Open Access
ISSN:	1525-2027
Date of First Compliant Deposit:	3 October 2023
Date of Acceptance:	10 September 2023
Last Modified:	04 Oct 2023 19:31
URI:	https://orca.cardiff.ac.uk/id/eprint/162902

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