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Regional mantle heterogeneity regulates melt production along the Réunion hotspot-influenced Central Indian Ridge

Regional mantle heterogeneity regulates melt production along the Réunion hotspot-influenced Central Indian Ridge
Regional mantle heterogeneity regulates melt production along the Réunion hotspot-influenced Central Indian Ridge
To ascertain factors controlling melt production along a typical distal, 'hotspot-interacting' mid-ocean ridge, we investigated the extent and distribution of both plume-related and plume-unrelated basalt from the central Indian ridge (CIR) between 15°S and 20°S. Comprehensive geochemical data of fresh-quenched volcanic glasses and basalts were used. Variation of Sr, Nd, and Pb isotopic compositions and Nb/Zr, Ba/Nb, and Ba/La content were interpreted by mixing of three melt end members: the Indian depleted MORB mantle derived melt; radiogenic and enriched melt derived from source mantle for Rodrigues Ridge and the intermediate series of Mauritius Island (RE2, radiogenic enriched component 2); and radiogenic but depleted melt derived from source mantle for Gasitao Ridge (RD, radiogenic depleted component). On the basis of quantitative mantle melting and melt mixing model, results show that sources for RE2 and RD are geochemically distinct from those of the Réunion plume (RE1, radiogenic enriched melt component 1). Moreover, the geochemical variation of MORB of 15°S to 20°S is unrelated to contamination of the upper mantle by the Réunion plume. These results suggest strongly that plume-unrelated heterogeneity is widespread throughout the upper mantle. The chemical characteristics of RE2 are remarkably pronounced in basalt from the central portion of ridge segment 16 around 18°S, suggesting substantial magma production. The influence of RE2 decreases along with decreasing magma production to the north, and is only slightly identifiable in basalt from the northern part of segment 18. Although the influence of RE2 decreases somewhat to the south, basalts with extreme RE2 signature were produced in the center of segment 15 around 19°S, where magma production is high. In contrast to RE2, the geochemical signature of RD in basalt is geographically limited to two localities: the south end of segment 18 and the center of segment 15. However, these observations reveal that both RE2 and RD contribute strongly to magma production on segment 15. Results show that melting of ancient recycled plate materials with a low melting point regulates voluminous magma production along the CIR.
ridge-hotspot interaction, MORB geochemistry, crustal production, upper mantle, heterogeneity
0016-7002
433-449
Machida, Shiki
b40c53e8-35b4-46fa-9f41-16f21f7c5ec8
Orihashi, Yuji
27c160ca-1c82-4d37-ac58-57d54ce06ab4
Magnani, Marco
7344a94a-3807-4dff-8a5d-ce7c688a4d7f
Neo, Natsuki
e2309b9e-989b-4c4a-8c1a-6c651dc94b3b
Wilson, Samantha
ff2ac593-0195-4cf1-9d98-e239a796e365
Tanimizu, Masaharu
22125d7e-2d72-4c82-9077-74298d5670e3
Yoneda, Shigekazu
1b1b275b-074b-4be5-864c-3c7b22af17f2
Yasuda, Atsush
913b5552-cd8f-4d52-b6ec-8032915f1f9d
Tamaki, Kensaku
0052c7ce-e290-4c3f-96b2-91bf0b4e97b6
Machida, Shiki
b40c53e8-35b4-46fa-9f41-16f21f7c5ec8
Orihashi, Yuji
27c160ca-1c82-4d37-ac58-57d54ce06ab4
Magnani, Marco
7344a94a-3807-4dff-8a5d-ce7c688a4d7f
Neo, Natsuki
e2309b9e-989b-4c4a-8c1a-6c651dc94b3b
Wilson, Samantha
ff2ac593-0195-4cf1-9d98-e239a796e365
Tanimizu, Masaharu
22125d7e-2d72-4c82-9077-74298d5670e3
Yoneda, Shigekazu
1b1b275b-074b-4be5-864c-3c7b22af17f2
Yasuda, Atsush
913b5552-cd8f-4d52-b6ec-8032915f1f9d
Tamaki, Kensaku
0052c7ce-e290-4c3f-96b2-91bf0b4e97b6

Machida, Shiki, Orihashi, Yuji, Magnani, Marco, Neo, Natsuki, Wilson, Samantha, Tanimizu, Masaharu, Yoneda, Shigekazu, Yasuda, Atsush and Tamaki, Kensaku (2014) Regional mantle heterogeneity regulates melt production along the Réunion hotspot-influenced Central Indian Ridge. Geochemical Journal, 48 (5), 433-449. (doi:10.2343/geochemj.2.0320).

Record type: Article

Abstract

To ascertain factors controlling melt production along a typical distal, 'hotspot-interacting' mid-ocean ridge, we investigated the extent and distribution of both plume-related and plume-unrelated basalt from the central Indian ridge (CIR) between 15°S and 20°S. Comprehensive geochemical data of fresh-quenched volcanic glasses and basalts were used. Variation of Sr, Nd, and Pb isotopic compositions and Nb/Zr, Ba/Nb, and Ba/La content were interpreted by mixing of three melt end members: the Indian depleted MORB mantle derived melt; radiogenic and enriched melt derived from source mantle for Rodrigues Ridge and the intermediate series of Mauritius Island (RE2, radiogenic enriched component 2); and radiogenic but depleted melt derived from source mantle for Gasitao Ridge (RD, radiogenic depleted component). On the basis of quantitative mantle melting and melt mixing model, results show that sources for RE2 and RD are geochemically distinct from those of the Réunion plume (RE1, radiogenic enriched melt component 1). Moreover, the geochemical variation of MORB of 15°S to 20°S is unrelated to contamination of the upper mantle by the Réunion plume. These results suggest strongly that plume-unrelated heterogeneity is widespread throughout the upper mantle. The chemical characteristics of RE2 are remarkably pronounced in basalt from the central portion of ridge segment 16 around 18°S, suggesting substantial magma production. The influence of RE2 decreases along with decreasing magma production to the north, and is only slightly identifiable in basalt from the northern part of segment 18. Although the influence of RE2 decreases somewhat to the south, basalts with extreme RE2 signature were produced in the center of segment 15 around 19°S, where magma production is high. In contrast to RE2, the geochemical signature of RD in basalt is geographically limited to two localities: the south end of segment 18 and the center of segment 15. However, these observations reveal that both RE2 and RD contribute strongly to magma production on segment 15. Results show that melting of ancient recycled plate materials with a low melting point regulates voluminous magma production along the CIR.

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Published date: 2014
Keywords: ridge-hotspot interaction, MORB geochemistry, crustal production, upper mantle, heterogeneity
Organisations: Ocean and Earth Science

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Local EPrints ID: 372428
URI: http://eprints.soton.ac.uk/id/eprint/372428
ISSN: 0016-7002
PURE UUID: 8693f29e-aca0-4983-855e-7b671180521f

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Date deposited: 03 Dec 2014 13:41
Last modified: 15 Jul 2019 21:36

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Contributors

Author: Shiki Machida
Author: Yuji Orihashi
Author: Marco Magnani
Author: Natsuki Neo
Author: Samantha Wilson
Author: Masaharu Tanimizu
Author: Shigekazu Yoneda
Author: Atsush Yasuda
Author: Kensaku Tamaki

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