Dunitification of mantle lithosphere below the society archipelago: Evidence for magma-mantle thermal and chemical transfers through xenoliths from the Papenoo Valley, Tahiti

Berger, E. T.; Weber, Bodo

doi:10.1016/0264-3707(91)90040-l

Cited by 4 publications

(1 citation statement)

References 51 publications

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“…We now suppose that dunitic material, aggregated in large quantities deep beneath the crustal root of an island, such as Hawaii (Clague and Denlinger, 1994), and present in the long column of lithosphere between the melt source and the base of the crust (Bohrson and Clague, 1988;Berger and Weber, 1991), might indeed sink and depress the lithosphere into the asthenosphere, especially while the reheated mantle is still warm and supple (cf. Jull and Kelemen, 2001;P.…”

Section: Volcanic Loading and Redistribution Of Mass During Differentmentioning

confidence: 99%

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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