Systematic Variation of Sr-, Nd- and Pb-Isotopes with Time in Lavas of Mauritius, Reunion Hotspot

Nohda, Susumu; Kaneoka, Ichiro; Hanyu, Takeshi; Xu, Sheng; Uto, Kozo

doi:10.1093/petrology/egh085

Cited by 29 publications

(23 citation statements)

References 46 publications

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“…This mapping was done in 1999, during a joint Franco‐Mauritian project studying the detailed hydrogeologic setting of Mauritius. This map reveals more extensive outcrops of the Intermediate Series and more restricted, but still extensive outcrops of the Younger Series, whereas earlier maps [e.g., Baxter , 1975, 1976; Nohda et al , 2005] show limited exposures of the Intermediate Series (only to the SW tip of the island), and more extensive exposures of the Younger Series covering about three quarters of the island.…”

Section: Introductionmentioning

confidence: 66%

“…Shown for comparison are fields for Réunion [ Fisk et al , 1988; Albarède et al , 1997; Bosch et al , 1999; Luais , 2004; J. Blichert ‐ Toft, unpublished data] and CIR MORB [ Ito et al , 1987; Mahoney et al , 1989; Chauvel and Blichert‐Toft , 2001; Escrig et al , 2004]. Open symbols are previously reported data on Mauritius lavas [ Mahoney et al , 1989; Peng and Mahoney , 1995; Sheth et al , 2003; Nohda et al , 2005].…”

Section: Resultsmentioning

confidence: 99%

“…Réunion has been the subject of numerous geochemical studies [e.g., Upton and Wadsworth , 1966; McDougall , 1971; Oversby , 1972; Fisk et al , 1988; Albarède et al , 1997; Luais , 2004] while geochemical data on Mauritian basalts are unfortunately scarcer [ Norry , 1977; Mahoney et al , 1989; Sheth et al , 2003; Nohda et al , 2005]. We report concentrations for 36 trace elements and Sr, Nd, Pb, and Hf isotopic ratios of 30 basalt samples covering the three different volcanic series of Mauritius.…”

Section: Introductionmentioning

confidence: 97%

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Geochemistry of Mauritius and the origin of rejuvenescent volcanism on oceanic island volcanoes

Paul

White

Blichert‐Toft

2005

Geochem Geophys Geosyst

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[1] We report new trace element concentrations and Sr, Nd, Hf, and Pb isotopic ratios for basalts from the three lava series of Mauritius. Older Series lavas, which represent the shield-building phase of Mauritius, are isotopically similar to other lavas produced by the Réunion mantle plume. The Intermediate and Younger Series lavas, erupted after a hiatus of millions of years, have more depleted isotopic signatures than the Older Series. Incompatible element abundances and major element compositions suggest that the extent of melting was greatest for the Older Series, smallest for the Intermediate Series, and intermediate for the Younger Series. Volcanic evolution on Mauritius is thus broadly similar to the Hawaiian pattern, with lavas of the rejuvenescent phase being produced by small degrees of melting of a more depleted source than the shield phase. We propose that both shield and rejuvenescent phase magmas are derived from a lithologically heterogeneous or ''plum pudding'' mantle plume that consists of pods or veins of low-solidus-temperature material such as eclogite or pyroxenite embedded in peridotite matrix. The plums have a less depleted isotopic signature than the matrix. In the vertical stem of the plume, melting is zoned: at greatest depth, only the plums melt; at intermediate depth, both plums and matrix melt, and at shallowest depth, only the matrix melts. Shield stage magmas are hybrids of melts produced in all three zones. As the plume flattens out against the lithosphere and is dragged downstream of the stem, some melting continues due to buoyant lateral spreading of the plume. In this region, although both plums and matrix are melting, melts produced carry the isotopic signature of the matrix because incompatible elements in the plums were previously stripped during melting in the vertical stem of the plume. The relatively small degree melts produced in the melting tail, which give rise to rejuvenescent stage volcanism, thus carry the isotopic signature of the matrix. From a consideration of thermal and isotopic equilibrium, we judge the scale of heterogeneity to be about 10 2 m.

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Section: Introductionmentioning

confidence: 66%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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Geochemistry of Mauritius and the origin of rejuvenescent volcanism on oceanic island volcanoes

Paul

White

Blichert‐Toft

2005

Geochem Geophys Geosyst

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“…In contrast to the trace element characteristics, the helium and Sr‐Nd‐Pb isotope signatures of the hot spot component cannot be altered by melt removal alone. Therefore, Nauret et al [2006] previously concluded that the decrease in 87 Sr/ 86 Sr and 206 Pb/ 204 Pb ratios, and concomitant increase in 143 Nd/ 144 Nd observed in their study along the Gasitao Ridge requires mixing of Réunion hot spot material with MORB‐like mantle, and Sheth et al [2003] and Nohda et al [2005] proposed a similar scenario to explain the variations in Sr‐Nd‐Pb isotope compositions observed in Older Series, Intermediate Series, and Younger Series lavas from Mauritius. Furthermore, Intermediate series and Younger Series lavas from Mauritius and Rodrigues show 3 He/ 4 He ratios of 6.5 to 8.4 R A [ Hanyu et al , 2001].…”

Section: Discussionmentioning

confidence: 86%

Helium isotope variations between Réunion Island and the Central Indian Ridge (17°–21°S): New evidence for ridge–hot spot interaction

et al. 2011

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[1] We report new helium abundance and isotope results for submarine basaltic glasses from the Central Indian Ridge (CIR) between the Marie Celeste (16.7°S) and Egeria fracture zones (FZ) (20.6°S); the adjacent Gasitao, Three Magi, and Rodrigues ridges; and for olivine separates from lavas and cumulate xenoliths from the Mascarene Islands (Réunion, Mauritius, and Rodrigues). Helium isotope ratios in basaltic glasses range from 7.1 to 12.2 R A (where R A = air 3 He/ 4 He) and lie between values of Mid-Ocean Ridge Basalt (MORB) (8 ± 1 R A ) and samples from Réunion Island (11.5 to 14.1 R A ). The highest 3 He/ 4 He values (up to 12.2 R A ) are found in glasses recovered off axis from the Three Magi and Gasitao ridges. Along the CIR axis, MORB-like 3 He/ 4 He ratios are found near the Egeria FZ, and there is a marked increase to values of ∼11 R A between ∼19°and 20°S. The lowest 3 He/ 4 He values (<8 R A ) are found immediately south of the Marie Celeste FZ, where incompatible trace element ratios (e.g., La/Sm) are highest. These low 3 He/ 4 He ratios can be explained by closed system radiogenic 4 He ingrowth in either (1) a "fossil" Réunion hot spot mantle component, embedded into the subridge mantle when the CIR migrated over the hot spot at ∼34 Ma or (2) trace element enriched MORB mantle. In contrast, the high 3 He/ 4 He ratios observed on the CIR axis adjacent to the Gasitao Ridge, and along the off-axis volcanic ridges, are consistent with flow of hot spot mantle material from Réunion (∼1100 km to the west) toward the CIR.

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“…Like many oceanic islands, the formation of Mauritius is thought to be due to hotspotrelated volcanic activity. Using K- Ar dating, McDougall and Chamalaun [1969] and Nohda et al [2005] [Baxter, 1976]. Three distinct volcanic series can be identified as follows: the older (shield-building stage), the intermediate (post shield stage), and the younger (post erosional or rejuvenated stage) [Simpson, 1951;Baxter, 1975Baxter, , 1976Sheth et al, 2003].…”

Section: Introductionmentioning

confidence: 99%

The crustal structure beneath Mauritius from teleseismic P receiver functions: Oceanic or continental?

Singh

Kaviani

Rümpker

2016

Geophysical Research Letters

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It has recently been suggested that the volcanic island of Mauritius may be underlain by a remnant of continental origin termed “Mauritia.” To constrain the crustal thickness beneath Mauritius, we analyzed data from 11 land stations, 10 of which were deployed recently by the RHUM‐RUM project. From the recordings, we obtained 382 P receiver functions (RFs). By applying the H‐κ stacking technique, we derive crustal thicknesses of approximately 10–15 km. We observe a considerable variation in the Vp/Vs ratio caused by a lack of clear multiples. Using forward modeling of RFs, we show that the lack of clear multiples can be explained by a transitional Moho, where the velocity increases gradually. The modeling further indicates that the thickness of this gradient zone is estimated to be approximately 10 km. We argue that our findings suggest oceanic crust thickened by crustal underplating due to the mantle plume currently located beneath La Réunion.

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Systematic Variation of Sr-, Nd- and Pb-Isotopes with Time in Lavas of Mauritius, Reunion Hotspot

Cited by 29 publications

References 46 publications

Geochemistry of Mauritius and the origin of rejuvenescent volcanism on oceanic island volcanoes

Geochemistry of Mauritius and the origin of rejuvenescent volcanism on oceanic island volcanoes

Helium isotope variations between Réunion Island and the Central Indian Ridge (17°–21°S): New evidence for ridge–hot spot interaction

The crustal structure beneath Mauritius from teleseismic P receiver functions: Oceanic or continental?

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