Sr, Nd, O and H isotopic ratios in Ascension Island lavas and plutonic inclusions; cogenetic origin

Weis, Dominique; Demaiffe, Daniel; Cauet, Serge; Javoy, M.

doi:10.1016/0012-821x(87)90200-7

Cited by 50 publications

(21 citation statements)

References 59 publications

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“…The ICP-MS Tb, Er, and Tm were not included in the patterns because they caused small positive anomalies that are analytical in origin (i.e., patterns constructed using only the ICP-MS data do not have anomalies for these elements). The anomalies are greatest for Lanai lavas, which are an isotopic end-member for Hawaiian tholeiites [West et al, 1987]. They are similar to those of typical Hawaiian lavas (e.g., the U.S. Geological Survey Hawaiian basalt standard, BHVO-1)and those previously published for Loihi whole rock samples [Frey and Clague, 1983].…”

Section: Major Elementssupporting

confidence: 79%

An evaluation of temporal geochemical evolution of Loihi Summit Lavas: Results from Alvin submersible dives

Garcia¹,

Jorgenson²,

Mahoney³

et al. 1993

J. Geophys. Res.

107

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Stratigraphically controlled sequences of in situ lavas were collected from Loihi Seamount using the Alvin submersible to evaluate the volcano's temporal geochemical evolution. Three sections with up to 370 m of relief were sampled from the two pit craters at the summit of Loihi. All of the analyses were done on glass separates. Our results indicate that tholeiitic and alkalic volcanism at the summit of Loihi has been coeval. The tholeiitic and alkalic lavas have similar incompatible element patterns and O, Pb, Sr, and Nd isotope ratios but are distinct in some incompatible element ratios. These results are consistent with the different Loihi rock types being derived by variable degrees of melting from a common source. The crossing and light‐rare‐earth‐enriched rare earth element patterns and variable Sc/Yb ratios of the tholeiites indicate that their source was a garnet lherzolite. The relatively low δ18O values (∼4.9 ‰) for Loihi lavas are interpreted to be characteristic of the Hawaiian plume.

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Section: Major Elementssupporting

confidence: 79%

An evaluation of temporal geochemical evolution of Loihi Summit Lavas: Results from Alvin submersible dives

Garcia¹,

Jorgenson²,

Mahoney³

et al. 1993

J. Geophys. Res.

107

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“…8b) values, LREE/HFSE ratios (e.g., La/Zr, Fig. 8c) (Weis et al, 1987;Chiba et al, 1989;Mattey et al, 1994;Zheng, 1993). The group of VVP xenoliths that are characterized by δ 18 O ≤ 7.0‰, and for which the whole range of oxygen isotope variation is less than 1‰, thus plotting on almost vertical trends in the plots of δ 18 O and Na 2 O or TiO 2 contents, can be explained by simple Rayleigh oxygen isotope fractionation during partial melting (Figs.…”

Section: Discussionmentioning

confidence: 92%

Ultramafic xenoliths from the Veneto Volcanic Province (Italy): Petrological and geochemical evidence for multiple metasomatism of the SE Alps mantle lithosphere

et al. 2006

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Petrologic and geochemical characteristics of whole rocks and minerals may be explained by metasomatism of the local mantle lithosphere induced by both alkaline magmas upwelling to the surface (OIB-like mantle diapirism) and interaction with slab-derived material. In comparison with the geochemistry of xenoliths carried by alkaline magmas in typical withinplate tectonic environments, the Veneto xenoliths record a major heterogeneity of the local lithosphere. This appears to be related to a geodynamic scenario that was previously dominated by active continental collision, in which plume-like magmatism subsequently manifested itself.

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“…Sr isotopic data were acquired for 21 whole-rock samples and Nd isotopic data for 7 of them (Tables 2, 3; ULB Bruxelles; method described in Weis et al 1987). Sr isotopic composition was measured with a single collector Finnigan Mat 260 mass spectrometer, whereas Nd isotopic composition was measured with a multicollector VG Sector 54 spectrometer.…”

Section: Methodsmentioning

confidence: 99%

Geochemical signature of the Egersund basaltic dyke swarm, SW Norway, in the context of late-Neoproterozoic opening of the Iapetus Ocean

Bingen¹,

Demaiffe

1999

Norsk Geologisk Tidsskrift

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The Egersund basaltic dyke swarm is made up of 11 ESE-WNW-trending dykes in the Proterozoic crystalline basement of southwest Norway. Two types of dyke occur: porphyritic dykes with plagioclase phenocrysts and aphyric dykes. Limited magmatic differentiation occurred in the dykes during shallow level intrusion. The porphyritic dykes and one of the aphyric dykes have subalkaline to mildly alkaline compositions, whereas the other aphyric dykes have alkaline compositions. The most primitive magmas occur in the porphyritic dykes; they have Mg numbers of 56-61, TiO 2 contents of 2.0-2.1% and enriched incompatible trace element contents. Initial isotopic compositions, Sr i and e(Nd) i , are 0.7034-0.7039 and 2.0-3.1 respectively. The most evolved magmas in alkaline dykes are SiO 2 -poor (45-46%) ferrobasalts, very enriched in TiO 2 (3.2-3.4%), P 2 O 5 (2.0-2.5%) and incompatible trace elements. They have Sr i of 0.7058-0.7060 and e(Nd) i of 1.0. The compositions of the most primitive magmas and minerals suggest that the porphyritic dykes tapped a magma chamber situated at the crust-mantle boundary, at ca. 10 kbar. It is shown that one of the aphyric dykes is possibly related to the porphyritic dyke magma by a fractional crystallization process accompanied by limited crustal assimilation at this pressure. The alkaline dykes represent a distinct suite with a distinct mantle source. The 616 AE 3 Ma Egersund Swarm is placed in the geotectonic context of late-Neoproterozoic rifting leading to opening of the Iapetus Ocean. At the Baltoscandian passive margin of Baltica, there is a first order 'oceanwards' decrease in incompatible trace element contents and Sr i and an increase of e(Nd) i values of basaltic dyke swarms, from the Egersund Swarm in the continental basement, to the sheeted dyke complexes situated at the continent-ocean transition. This geochemical trend is interpreted as a change from high-pressure partial melting of garnet peridotite with residual garnet in a mildly depleted mantle, to lower-pressure partial melting of a depleted mantle. Norway, 7491 Trondheim, Norway (bernard.bingen@ngu.no); D. Demaiffe, Département des Sciences de la Terre et de l'Environnement, CP160/02, Université Libre de Bruxelles, 1050 Bruxelles, Belgium (ddemaif@ulb.ac.be). B. Bingen, Geological Survey of

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Sr, Nd, O and H isotopic ratios in Ascension Island lavas and plutonic inclusions; cogenetic origin

Cited by 50 publications

References 59 publications

An evaluation of temporal geochemical evolution of Loihi Summit Lavas: Results from Alvin submersible dives

An evaluation of temporal geochemical evolution of Loihi Summit Lavas: Results from Alvin submersible dives

Ultramafic xenoliths from the Veneto Volcanic Province (Italy): Petrological and geochemical evidence for multiple metasomatism of the SE Alps mantle lithosphere

Geochemical signature of the Egersund basaltic dyke swarm, SW Norway, in the context of late-Neoproterozoic opening of the Iapetus Ocean

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