Helium isotope variations in seafloor basalts from the Northwest Lau Backarc Basin: Mapping the influence of the Samoan hotspot

Lupton, J. E.; Arculus, R. J.; Greene, R. R.; Evans, L. J.; Goddard, Charlotte

doi:10.1029/2009gl039468

Cited by 47 publications

(126 citation statements)

References 27 publications

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“…It extends for at least 165 km more or less parallel to the Tonga Ridge, and approaches to within $40 km of the volcanic island of Ata in the Tofua Arc. In the northern basin, there is a short ridge segment north of PR called the Northern Lau Spreading Center (NLSC) and a three- Tables 1 and 2) are shown as red circles and other available 3 He/ 4 He data in the Lau Basin are shown as open circles (Poreda, 1985;Poreda and Craig, 1992;Poreda and Farley, 1992;Hilton et al, 1993;Honda et al, 1993;Bach and Niedermann, 1998;Lupton et al, 2009). Gray shade indicates areas shallower than 2000 m. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)…”

Section: Geological Background and Samplesmentioning

confidence: 99%

An overview of the volatile systematics of the Lau Basin – Resolving the effects of source variation, magmatic degassing and crustal contamination

Hahm

Hilton

Castillo

et al. 2012

Geochimica et Cosmochimica Acta

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Section: Geological Background and Samplesmentioning

confidence: 99%

An overview of the volatile systematics of the Lau Basin – Resolving the effects of source variation, magmatic degassing and crustal contamination

Hahm

Hilton

Castillo

et al. 2012

Geochimica et Cosmochimica Acta

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“…One would expect the helium isotopic signature in the hydrothermal fluids to agree with that in the volcanic rocks, since the vent fluid helium is extracted from the volcanic rocks or magma by hydrothermal circulation. Lupton et al [2009] reported 17.8 R a for one basalt sample collected from the summit of Lobster Caldera, while two additional samples on the flanks of Lobster reported previously by Poreda and Craig [1992] measured 21.9 and 22.1 R a . Thus the helium endmember estimate of 18.7-19.3 R a from the plume measurements at Lobster Caldera is in reasonable agreement with the basalt results.…”

Section: End-member Helium Isotope Compositionsmentioning

confidence: 99%

“…Lupton et al [2009] demonstrated that these elevated helium isotope ratios are not confined to the RR, but extend southward along the NWLSC to the Peggy Ridge. In contrast to the NWLSC-RR, the spreading centers of the northeast Lau Basin have typical MOR-type helium isotope ratios [Poreda and Craig, 1992;Hilton et al, 1993;Honda et al, 1993;Lupton et al, 2009]. Thus these elevated 3 He/ 4 He ratios appear to be confined to the NWLSC-RR system.…”

Section: Introductionmentioning

confidence: 99%

“…For example, Poreda and Craig [1992] measured elevated 3 He/ 4 He in three samples from the RR (up to 22 R a ), providing an early indication of the presence of a hot spot component in this backarc extensional zone. In a more extensive study of the same area, Lupton et al [2009] showed that a suite of 29 basalts dredged along the RR and NWLSC all had elevated 3 He/ 4 He (11 to 28 R a ), much higher than the ratio of 7 to 9 R a typically observed in MORBs [Graham, 2002]. Lupton et al [2009] demonstrated that these elevated helium isotope ratios are not confined to the RR, but extend southward along the NWLSC to the Peggy Ridge.…”

Section: Introductionmentioning

confidence: 99%

“…In a more extensive study of the same area, Lupton et al [2009] showed that a suite of 29 basalts dredged along the RR and NWLSC all had elevated 3 He/ 4 He (11 to 28 R a ), much higher than the ratio of 7 to 9 R a typically observed in MORBs [Graham, 2002]. Lupton et al [2009] demonstrated that these elevated helium isotope ratios are not confined to the RR, but extend southward along the NWLSC to the Peggy Ridge. In contrast to the NWLSC-RR, the spreading centers of the northeast Lau Basin have typical MOR-type helium isotope ratios [Poreda and Craig, 1992;Hilton et al, 1993;Honda et al, 1993;Lupton et al, 2009].…”

Section: Introductionmentioning

confidence: 99%

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Hydrothermal activity in the Northwest Lau Backarc Basin: Evidence from water column measurements

Arculus¹,

Massoth²,

Greene³

et al. 2012

Geochem Geophys Geosyst

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[1] The Northwest Lau Backarc Basin, consisting of the Northwest Lau Spreading Center (NWLSC) and the Rochambeau Rifts (RR), is unique in having elevated 3 He/ 4 He ratios (up to 28 R a ) in the erupted lavas, clearly indicating a hot spot or ocean island basalt (OIB)-type signature. This OIB-type helium signature does not appear in any other part of the Lau Basin. Water column plume surveys conducted in 2008 and 2010 identified several sites of active hydrothermal discharge along the NWLSC-RR and showed that the incidence of hydrothermal activity is high, consistent with the high spreading rate of $100 mm/year. Hydrocasts into the Central Caldera and Southern Caldera of the NWLSC detected elevated 3 He/ 4 He (d 3 He = 55% and 100%, respectively), trace metals (TMn, TFe), and suspended particles, indicating localized hydrothermal venting at these two sites. Hydrocasts along the northern rift zone of the NWLSC also had excess d 3 He, TMn, and suspended particles suggesting additional sites of hydrothermal activity. The RR are dominated by Lobster Caldera, a large volcano with four radiating rift zones. Hydrocasts into Lobster Caldera in 2008 detected high d 3 He (up to 239%) and suspended particle and TMn signals, indicating active venting within the caldera. A repeat survey of Lobster in 2010 confirmed the site was still active two years later. Plumes at Lobster Caldera and Central Caldera have end-member 3 He/ 4 He ratios of 19 R a and 11 R a , respectively, confirming that hot spot-type helium is also present in the hydrothermal fluids.Components: 9000 words, 12 figures.

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Evidence for a broadly distributed Samoan-plume signature in the northern Lau and North Fiji Basins

Price

Jackson

Blichert‐Toft

et al. 2014

Geochem. Geophys. Geosyst.

104

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Geochemical enrichment of lavas in the northern Lau Basin may reflect the influx of Samoanplume mantle into the region. We report major and trace element abundances and He-Sr-Nd-Hf-Pbisotopic measurements for 23 submarine volcanic glasses covering 10 locations in the northern Lau and North Fiji Basins, and for three samples from Wallis Island, which lies between Samoa and the Lau Basin. These data extend the western limit of geochemical observations in the Basins and improve the resolution of North-South variations in isotopic ratios. The Samoan hot spot track runs along the length of the northern trace of the Lau and North Fiji Basins. We find evidence for a Samoan-plume component in lavas as far West as South Pandora Ridge (SPR), North Fiji Basin. Isotopic signatures in SPR samples are similar to those found in Samoan Upolu shield lavas, but show a slight shift toward MORB-like compositions. We explain the origin of the enriched signatures by a model in which Samoan-plume material and ambient depleted mantle undergo decompression melting during upwelling after transiting from beneath the thick Pacific lithosphere to beneath the thin lithosphere in the northern Lau and North Fiji Basins. Other lavas found in the region with highly depleted isotopic signatures may represent isolated pockets of depleted mantle in the basins that evaded this enrichment process. We further find that mixing between the two components in our model, a variably degassed high-3 He/ 4He Samoan component and depleted MORB, can explain the diversity among geochemical data from the northern Lau Basin.

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Helium isotope variations in seafloor basalts from the Northwest Lau Backarc Basin: Mapping the influence of the Samoan hotspot

Cited by 47 publications

References 27 publications

An overview of the volatile systematics of the Lau Basin – Resolving the effects of source variation, magmatic degassing and crustal contamination

An overview of the volatile systematics of the Lau Basin – Resolving the effects of source variation, magmatic degassing and crustal contamination

Hydrothermal activity in the Northwest Lau Backarc Basin: Evidence from water column measurements

Evidence for a broadly distributed Samoan-plume signature in the northern Lau and North Fiji Basins

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