Journal ArticleDOI
Chemistry of Tholeiites from the Galapagos Islands and Adjacent Ridges
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In this paper, the authors summarized the petrological evidence for a Galapagos mantle plume, present new data on basalts from the rift valley of the Galapago Ridge and discuss the origin and composition of the Cocos and Carnegie Ridges.Abstract:
Petrological evidence suggesting a mantle plume beneath Iceland has been presented1,2. Schilling1 gives geochemical data which indicate that the incompatible elements TiO2, P2O5, K2O and La decrease regularly southwards from Iceland along the Reykjanes Ridge axis to about 61° N. The rare earth element pattern for Icelandic tholeiites shows a high normalised La/Sm ratio which steadily decreases to less than 1 along the ridge. The crystallisation index (FeO*/ MgO) and the ratio of pyroxene/plagioclase among the phenocrysts also follow this trend. Campsie et al.2 noted that tholeiites all the way from Iceland to the Charlie Gibbs Fracture Zone retain chemical coherence in their major elements (except SiO2) and belong to a single pyroxene-tholeiite magma type. Here we summarise petrological evidence for a Galapagos mantle plume, present new data on basalts from the rift valley of the Galapagos Ridge and discuss the origin and composition of the Cocos and Carnegie Ridges.read more
Citations
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Journal ArticleDOI
Galapagos Hot Spot-Spreading Center System: 1. Spatial petrological and geochemical variations (83°W-101°W)
TL;DR: In this paper, the petrology and geochemistry of basalts dredged at 40-50 km intervals along the Galapagos Spreading Center, between 83/sup 0/W and 101/sup 1/W (40 stations), were reported.
Journal ArticleDOI
Rhyodacites, andesites, ferro-basalts and ocean tholeiites from the galapagos spreading center
TL;DR: This paper showed that the ferro-basalts correlate with the previously proposed zone of high magnetic anomaly amplitudes which flank the Galapagos hot spot, and are consistent with a genesis by shallow fractional crystallization.
Journal ArticleDOI
Rare earth, Fe and Ti variations along the Galapagos spreading centre, and their relationship to the Galapagos mantle plume
TL;DR: In this article, rare earths, Fe and Ti concentrations in basalts dredged along the Galapagos spreading center reveal that a juvenile mantle plume is welling up beneath the Galapeagos Islands and mixing with the depleted asthenosphere to the north-east and north-west beneath the ridge.
Journal ArticleDOI
Minor and trace element geochemistry of volcanic rocks dredged from the Galapagos Spreading Center: Role of crystal fractionation and mantle heterogeneity
TL;DR: In this article, a wide range of rock types (abyssal tholeiite, Fe-Ti-rich basalt, andesite, and rhyodacite) were dredged from near 95°W and 85°W on the Galapagos spreading center.
Journal ArticleDOI
Major element chemistry of Galapagos Rift Zone magmas and their phenocrysts
TL;DR: Basalts from the Galapagos Rift Zone between 85°W and 100°W were analyzed by electron microprobe to determine the chemistry of the glass exteriors and included phenocrysts, microphenocrysts and quench minerals as discussed by the authors.
References
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Journal ArticleDOI
Iceland Mantle Plume: Geochemical Study of Reykjanes Ridge
TL;DR: In this article, rare earth and minor element concentration variations in basalt recently erupted along the postglacial Reykjanes Ridge Axis and its northward extension over Iceland reflect the existence, spatial influence, and primordial nature of the Iceland hot mantle plume.
Journal ArticleDOI
Chemical Characteristics and Origin of Oceanic Ridge Volcanic Rocks
TL;DR: Oceanic ridge volcanic rocks alkali metal, alkaline earth, rare earth, nickel and major element content, observing partial melting as mentioned in this paper. But this is not the case for all volcanic rocks.
Journal ArticleDOI
Sea-Floor Evolution: Rare-Earth Evidence
TL;DR: In this paper, a systematic survey of rare-earth abundances in submarine tholeiitic basalts along mid-oceanic ridges has been made by neutron activation analysis.
Journal ArticleDOI
Igneous Rocks of the East Pacific Rise: The alkali volcanic suite appear to be differentiated from a tholeiitic basalt extruded from the mantle.
A. E. J. Engel,Celeste G. Engel +1 more
TL;DR: The apical parts of large volcanoes along the East Pacific Rise (islands and seamounts) are encrusted with rocks of the alkali volcanic suite, while the more submerged parts of the Rise are largely composed of a tholeiitic basalt which has low concentrations of K, P, U, Th, Pb, and Ti.