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Variations in Melt Productivity and Melting Conditions along SWIR (70°E–49°E): Evidence from Olivine-hosted and Plagioclase-hosted Melt Inclusions

Variations in Melt Productivity and Melting Conditions along SWIR (70°E–49°E): Evidence from Olivine-hosted and Plagioclase-hosted Melt Inclusions
Variations in Melt Productivity and Melting Conditions along SWIR (70°E–49°E): Evidence from Olivine-hosted and Plagioclase-hosted Melt Inclusions
Melt inclusion and host glass compositions from the eastern end of the Southwest Indian Ridge show a progressive depletion in light rare earth elements (LREE), Na8 and (La/Sm)n, but an increase in Fe8, from the NE (64°E) towards the SW (49°E). These changes indicate an increase in the degree of mantle melting towards the SW and correlate with a shallowing of the ridge axial depth and increase in crustal thickness. In addition, LREE enrichment in both melt inclusions and host glasses from the NE end of the ridge are compatible with re-fertilization of a depleted mantle source. The large compositional variations (e.g. P2O5 and K2O) of the melt inclusions from the NE end of the ridge (64°E), coupled with low Fe8 values, suggest that melts from the NE correspond to a variety of different batches of melts generated at shallow levels in the mantle melting column. In contrast, the progressively more depleted compositions and higher Fe8 values of the olivine- and plagioclase-hosted melt inclusions at the SW end of the studied region (49°E), suggest that these melt inclusions represent batches of melt generated by higher degrees of melting at greater mean depths in the mantle melting column. Systematic differences in Fe8 values between the plagioclase- and the olivine-hosted melt inclusions in the SW end (49°E) of the studied ridge area, suggest that the plagioclase-hosted melt inclusions represent final batches of melt generated at the top of the mantle melting column, whereas the olivine-hosted melt inclusions correspond to melts generated from less depleted, more fertile mantle at greater depths.
basalt, melt inclusions, olivine, plagioclase, Southwest Indian Ridge
0022-3530
1471-1494
Font, L.
03e5d779-9c16-4ded-a4bc-615631cd88b5
Murton, B.J.
9076d07f-a3c1-4f90-a5d5-99b27fe2cb12
Roberts, S.
f095c7ab-a37b-4064-8a41-ae4820832856
Tindle, A.G.
526107c8-b065-4e98-992a-0c15ed50ce7c
Font, L.
03e5d779-9c16-4ded-a4bc-615631cd88b5
Murton, B.J.
9076d07f-a3c1-4f90-a5d5-99b27fe2cb12
Roberts, S.
f095c7ab-a37b-4064-8a41-ae4820832856
Tindle, A.G.
526107c8-b065-4e98-992a-0c15ed50ce7c

Font, L., Murton, B.J., Roberts, S. and Tindle, A.G. (2007) Variations in Melt Productivity and Melting Conditions along SWIR (70°E–49°E): Evidence from Olivine-hosted and Plagioclase-hosted Melt Inclusions. Journal of Petrology, 48 (8), 1471-1494. (doi:10.1093/petrology/egm026).

Record type: Article

Abstract

Melt inclusion and host glass compositions from the eastern end of the Southwest Indian Ridge show a progressive depletion in light rare earth elements (LREE), Na8 and (La/Sm)n, but an increase in Fe8, from the NE (64°E) towards the SW (49°E). These changes indicate an increase in the degree of mantle melting towards the SW and correlate with a shallowing of the ridge axial depth and increase in crustal thickness. In addition, LREE enrichment in both melt inclusions and host glasses from the NE end of the ridge are compatible with re-fertilization of a depleted mantle source. The large compositional variations (e.g. P2O5 and K2O) of the melt inclusions from the NE end of the ridge (64°E), coupled with low Fe8 values, suggest that melts from the NE correspond to a variety of different batches of melts generated at shallow levels in the mantle melting column. In contrast, the progressively more depleted compositions and higher Fe8 values of the olivine- and plagioclase-hosted melt inclusions at the SW end of the studied region (49°E), suggest that these melt inclusions represent batches of melt generated by higher degrees of melting at greater mean depths in the mantle melting column. Systematic differences in Fe8 values between the plagioclase- and the olivine-hosted melt inclusions in the SW end (49°E) of the studied ridge area, suggest that the plagioclase-hosted melt inclusions represent final batches of melt generated at the top of the mantle melting column, whereas the olivine-hosted melt inclusions correspond to melts generated from less depleted, more fertile mantle at greater depths.

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More information

Published date: August 2007
Additional Information: Actually deposited by J. Conquer
Keywords: basalt, melt inclusions, olivine, plagioclase, Southwest Indian Ridge

Identifiers

Local EPrints ID: 49691
URI: http://eprints.soton.ac.uk/id/eprint/49691
ISSN: 0022-3530
PURE UUID: 051e6179-f2b9-4247-8462-ac95864aff39
ORCID for S. Roberts: ORCID iD orcid.org/0000-0003-4755-6703

Catalogue record

Date deposited: 22 Nov 2007
Last modified: 16 Mar 2024 02:37

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Contributors

Author: L. Font
Author: B.J. Murton
Author: S. Roberts ORCID iD
Author: A.G. Tindle

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