Lavas from Niuafo'ou Island, Tonga, Resemble Ocean–Floor Basalts

Reay, A.; Rooke, Joan M.; Wallace, Rod; Whelan, Peter

doi:10.1130/0091-7613(1974)2<605:lfnitr>2.0.co;2

Cited by 25 publications

(7 citation statements)

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“…These high 3 He/ 4 He ratios were confirmed recently by Lupton et al (2009). Niuafo'ou Island has moderately fractionated basalts with 49-50% SiO 2 , 5.1-7.2% MgO, and 1.4-1.8% TiO 2 (Reay et al, 1974). The Ni content is low (34-60 ppm) for this MgO range, as is Ba (35-68 ppm).…”

Section: A4 Seamountssupporting

confidence: 78%

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: A4 Seamountssupporting

confidence: 78%

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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“…Compared to the narrower central and southern parts of the basin, however, the northern Lau Basin (NLB) has a more complex tectonic setting. In addition to MORB‐like and arc‐like lavas, ocean island basalt (OIB)‐like lavas are erupted in NLB [e.g., Reay et al , 1974; Ewart , 1976; Volpe et al , 1988; Hawkins , 1995]. The presence of OIB‐like lavas is supported by the presence of anomalously high 3 He/ 4 He ratios (up to 28 R A , where R A = 3 He/ 4 He of air; MORB = 8 ± 1 R A ) in NLB basalts [e.g., Poreda , 1985; Poreda and Craig , 1992; Lupton et al , 2009; D. Hahm et al, An overview of the volatile systematics of the Lau Basin–resolving the effects of source variation, magmatic degassing and crustal contamination, submitted to Geochimica Cosmochimica Acta , 2011].…”

Section: Introductionmentioning

confidence: 99%

Major and trace element and Sr-Nd isotope signatures of the northern Lau Basin lavas: Implications for the composition and dynamics of the back-arc basin mantle

et al. 2011

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[1] We present new major element, trace element and Sr-Nd isotope analyses of volcanic glasses from Mangatolu Triple Junction (MTJ), Peggy Ridge (PR), Rochambeau Bank (RB), and Niuafo'ou Island (NF) within the northern Lau Basin (NLB). Lavas from MTJ range from tholeiitic basalts to basaltic andesites and andesites: such a lava series can be ascribed to fractional crystallization. Lavas from NF, RB and PR are mainly tholeiitic basalts save for two transitional basalts from RB. The lavas came from a compositionally heterogeneous mantle that exhibits compositional features similar to those of the mantle source of Indian mid-ocean basalt and bears the influence of both subduction and ocean island basalt (OIB) components. The subduction components consist mainly of fluid dehydrated from subducted oceanic crust and a minor amount of sediment melt. The geochemically enriched signature of enriched RB, PR and NF lavas comes from two OIB end-member components, most likely derived from enriched Samoan mantle plume materials leaking into NLB. The Rochambeau Rifts (RR)-RB corridor receives the greatest, although still variable, influence from the mantle source of Samoan shield magmatism whereas the outlying PR and NF regions experience a Samoan plume post-erosional type of magmatism. The relatively recent mixing of Samoan plume materials with the subduction-metasomatized Indian-type mantle may be responsible for some of the observed complex relationships between noble gases and other geochemical tracers in some NLB lavas.

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“…The KTJ lavas from northeast Lau are similar to N-MORB for all elements except the alkalis, which also are enriched, whereas the Niuafo'ou lavas have similarly enhanced alkali, Ba, and Pb abundances. In many respects, however, this oceanic island volcano is surprisingly MORB-like in its geochemistry (e.g., see also Reay et al, 1974).…”

Section: Composite Trace Element Comparisonsmentioning

confidence: 99%

Regional Geochemistry of the Lau-Tonga Arc and Backarc Systems

Ewart¹,

Bryan²,

Chappell³

et al. 1994

Proceedings of the Ocean Drilling Program

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Detailed comparison of mineralogy, and major and trace geochemistry are presented for the modern Lau Basin spreading centers, the Sites 834-839 lavas, the modern Tonga-Kermadec arc volcanics, the northern Tongan boninites, and the Lau Ridge volcanics. The data clearly confirm the variations from near normal mid-ocean-ridge basalt (N-MORB) chemistries (e.g., Site 834, Central Lau Spreading Center) to strongly arc-like (e.g., Site 839, Valu Fa), the latter closely comparable to the modern arc volcanoes. Sites 835 and 836 and the East Lau Spreading Center represent transitional chemistries. Bulk compositions range from andesitic to basaltic, but lavas from Sites 834 and 836 and the Central Lau Spreading Center extend toward more silica-undersaturated compositions. The Valu Fa and modern Tonga-Kermadec arc lavas, in contrast, are dominated by basaltic andesites. The phenocryst and groundmass mineralogies show the strong arc-like affinities of the Site 839 lavas, which are also characterized by the existence of very magnesian olivines (up to Fo 90 _9 2 ) and Cr-rich spinels in Units 3 and 6, and highly anorthitic plagioclases in Units 2 and 9.The regional patterns of mineralogical and geochemical variations are interpreted in terms of two competing processes affecting the inferred magma sources: (1) mantle depletion processes, caused by previous melt extractions linked to backarc magmatism, and (2) enrichment in large-ion-lithophüe elements, caused by a subduction contribution. Ageneral trend of increasing depletion is inferred both eastward across the Lau Basin toward the modern arc, and northward along the Tongan (and Kermadec) Arc. Numerical modeling suggests that multistage magma extraction can explain the low abundances (relative to N-MORB) of elements such as Nb, Ta, and Ti, known to be characteristic of island arc magmas. It is further suggested that a subduction jump following prolonged slab rollback could account for the initiation of the Lau Basin opening, plausibly allowing a later influx of new mantle, as required by the recognition of a two-stage opening of the Lau Basin.

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Lavas from Niuafo'ou Island, Tonga, Resemble Ocean–Floor Basalts

Cited by 25 publications

References 0 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

Major and trace element and Sr-Nd isotope signatures of the northern Lau Basin lavas: Implications for the composition and dynamics of the back-arc basin mantle

Regional Geochemistry of the Lau-Tonga Arc and Backarc Systems

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