Large-scale chemical and thermal division of the Pacific mantle

Vlastelić, Ivan; Aslanian, Daniel; Dosso, Laure; Bougault, Henri; Olivet, Jean-Louis; Géli, Louis

doi:10.1038/20664

Cited by 63 publications

(31 citation statements)

References 29 publications

(33 reference statements)

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“…It contains material that varies laterally and vertically in density, viscosity, concentration of radioactive elements, and melt fraction. Broad spatial variability, perhaps coinciding with past geometries of continental rifting or subduction, may be the main reason why isotopic anomalies, for example, exist on a regional scale (e.g., Dupré and Allégre, 1983;Hart, 1984), including along the East Pacific Rise (Vlastélic et al, 1999), and why regional temperature differences (McNutt and Fischer, 1987;McNutt et al, 1996;Hillier and Watts, 2004) are linked to some of these anomalies (Staudigel et al, 1991).…”

Section: Accumulation Of Low-density Materials and Melt In The Asthenomentioning

confidence: 98%

Fissure control on volcanic action in the Pacific

Natland¹,

Winterer²

2005

Plates, Plumes and Paradigms

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Many modern linear volcanic chains on the Pacific plate can be backtracked to the general region of large Mesozoic seamount provinces in the far western Pacific, but those provinces differ in many ways from their younger counterparts in volcano arrangement, spacing, linearity, and age progression. Over the past 165 m.y., regions of volcanism have become narrower, more linear, and more consistently age-progressive. Rather than viewing this trend as a consequence of changes in the number, location, duration, and intensity of mantle plumes, we propose instead that five sets of stresses in the upper mantle combine to produce the patterns of great fissures and systems of fissures through the lithosphere along which seamount provinces and linear chains form. These are (1) lateral lithospheric contraction; (2) subduction-driven flow of the asthenosphere, which presently is antiparallel to Pacific plate motion, but which can be uneven in velocity and somewhat divergent in direction; (3) stresses in the plate produced by changes in patterns, relative orientations, and rates of subduction; (4) accumulation of low-density material and melt at places of lateral heterogeneity of density, viscosity, and composition in the asthenosphere; and (5) volcanic loading and redistribution of mass during differentiation at volcanic centers. Of these, the present direction of propagation of linear volcanic chains is most strongly controlled by contractive stresses and the pattern of subduction-driven asthenospheric counterflow, with volcanic spacing and volume arising from different combinations of the other stresses.Eruption of midplate seamounts results from buoyancy contrasts in the uppermost asthenosphere stemming from mantle heterogeneity, slightly variable temperature gradients, and the ponding of melt. Melt generally present in the low-velocity zone flows into shear gashes and then pools in traps beneath permeability barriers at the base of the lithosphere, with higher melt concentrations occurring above regions of greater mantle fertility and/or higher temperature. The lithospheric stress regime coupled with magma overpressure then induces lithospheric fracturing and eruption. Eruption, even above fertile mantle, may be stifled when the combination of lithospheric stresses is compressive, and fairly voluminous, even above refractory asthenosphere, when lithospheric stresses are extensional. Extremely voluminous volcanism occurs when a strongly extensional regime and/or a lithospheric thin spot coincides with asthenosphere having both high mantle fertility and higher temperature (e.g., oceanic plateaus at triple junctions). 687*on June 26, 2015 specialpapers.gsapubs.org Downloaded fromThe relative importance of the five sets of stresses has varied in the past. Assuming that linear island chains propagate mainly in the local direction of least principal stress in the underlying lithosphere, the changes in fissure patterns through time are probably related to the increasing proportion and distribution of subduction boundaries on the...

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Section: Accumulation Of Low-density Materials and Melt In The Asthenomentioning

confidence: 98%

Fissure control on volcanic action in the Pacific

Natland¹,

Winterer²

2005

Plates, Plumes and Paradigms

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“…The MORB data set was a compilation by A. Stracke from the work of Bach et al (1994), Chauvel and Blichert-Toft (2001), Dosso et al (1988Dosso et al ( , 1993Dosso et al ( , 1999Dosso et al ( , 1991, Douglass et al (1999), Fontignie and Schilling (1996), Frey et al (1993), Hamelin and Allègre (1985), Hamelin et al (1986), Hanan et al (1986), Hegner and Tatsumoto (1987), Ito et al (1987), Kempton et al (2000), Klein et al (1991Klein et al ( , 1988, MacDougall and Lugmair (1986), Mahoney et al (2002Mahoney et al ( , 1989Mahoney et al ( , 1994, Mertz et al (1991), Mertz and Haase (1997), Michard et al (1986), Newsom et al (1986), Price et al (1986), Pyle et al (1992), Rehkämper and Hofmann (1997), Salters (1996), Salters and Hart (1991), Salters and White (1998), Schilling et al (1994Schilling et al ( , 1999, Shirey et al (1987), Sims et al (2002), Vlastelic et al (1999), Wendt et al (1999), White et al (1987), and Yu et al...…”

Section: F Data Sourcesmentioning

confidence: 99%

A theoretical approach to understanding the isotopic heterogeneity of mid-ocean ridge basalt

Rudge

McKenzie

Haynes

2005

Geochimica et Cosmochimica Acta

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“…This geochemical heterogeneity is evidenced by the composition of basalts which erupted along mid-oceanic ridges, which reveals the existence of broad mantle isotopic domains (e.g., the DUPAL anomaly (Dupré and Allègre, 1983)). Each mantle domain is characterized by its intrinsic lithological and geochemical heterogeneity, suggesting different convective histories (Vlastelic et al, 1999;Hanan et al, 2004;Meyzen et al, 2007;Hamelin et al, 2011). At a local scale, basalt geochemical variations are interpreted to result from partial melting of a marble-cake upper mantle Morgan and Morgan, 1999;Stracke et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Atypically depleted upper mantle component revealed by Hf isotopes at Lucky Strike segment

et al. 2013

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International audienceThe Earth's upper mantle is commonly depicted as a "marble cake" assemblage of a refractory component mingled with varying amounts of geochemically diverse enriched components. This depleted component controls the major element composition of Mid-Oceanic Ridge Basalts (MORBs). It has long been considered a fairly uniform reservoir, depleted by early melting and well homogenized by subsequent convective stirring. We present new Hf, Nd, Pb and Sr isotopes and trace element data for basalts from the center of the Lucky Strike segment of the Mid-Atlantic Ridge (MAR). Despite the limited size of our sampling area (1.6 km along-axis by 5 km across), these data show a large range of isotopic compositions (similar to that of the whole MAR). It has recently been shown that part of the reason for not observing more segments with correlated Hf-Nd isotope systematics may be the lack of fine-scale sampling. Our data confirm this idea and show strong correlations between all isotope ratios. The systematics of Hf-Nd isotopes in Lucky Strike basalts define an atypical correlation, distinct from the global mantle array, with an anomalously high epsilon Hf for a given epsilon Nd. We illustrate that this atypical trend is the signature of an ancient refractory mantle rather than the product of kinetic processes during the melting event. The existence of this mantle component at Lucky Strike allows us to discuss the structure of the upper mantle around the Azores

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Large-scale chemical and thermal division of the Pacific mantle

Cited by 63 publications

References 29 publications

Fissure control on volcanic action in the Pacific

Fissure control on volcanic action in the Pacific

A theoretical approach to understanding the isotopic heterogeneity of mid-ocean ridge basalt

Atypically depleted upper mantle component revealed by Hf isotopes at Lucky Strike segment

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