The relationship between buoyant mantle flow, melt migration, and gravity bull's eyes at the Mid-Atlantic Ridge between 33°N and 35°N

Magde, Laura S.; Sparks, D. W.; Detrick, R. S.

doi:10.1016/s0012-821x(97)00039-3

Cited by 69 publications

(42 citation statements)

References 27 publications

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“…For ridge segments bounded by large tectonic offsets, the midsections often exhibit the shallowest bathymetry and thickest crust, while the segment ends exhibit wide, deep axial valleys and thin crust, as deduced from gravity (Detrick et al, 1995;Kuo and Forsyth, 1988;Lin et al, 1990) and seismic data (Canales et al, 2000b;Dannowski et al, 2011;Dunn et al, 2005;Hooft et al, 2000;Hosford et al, 2001;Purdy and Detrick, 1986;Sinha and Louden, 1983;Tolstoy et al, 1993). Melt focusing may occur due to mantle diapirism or by following the bottom of a freezing front at the base of the lithosphere that shallows near segment centers (Magde et al, 1997). Melt focusing may occur due to mantle diapirism or by following the bottom of a freezing front at the base of the lithosphere that shallows near segment centers (Magde et al, 1997).…”

Section: Spreading Rate Dependencementioning

confidence: 99%

Crust and Lithospheric Structure - Seismic Structure of Mid-Ocean Ridges

Dunn

Forsyth²

2015

Treatise on Geophysics

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Section: Spreading Rate Dependencementioning

confidence: 99%

Crust and Lithospheric Structure - Seismic Structure of Mid-Ocean Ridges

Dunn

Forsyth²

2015

Treatise on Geophysics

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“…Melt focusing in the presence of a permeability barrier has been studied in 2‐D [ Sparks and Parmentier , 1991; Spiegelman , 1993; Ghods and Arkani‐Hamed , 2000; Katz , 2008, 2010] and 3‐D [ Sparks et al , 1993; Magde et al , 1997; Gregg et al , 2009; Weatherley and Katz , 2010; Hebert and Montési , 2011] numerical models. In 3‐D, ridge segmentation induces melt focusing not only toward but also along the axis.…”

Section: Permeability Barriers As a Mechanism For Focusing Meltsmentioning

confidence: 99%

Controls on melt migration and extraction at the ultraslow Southwest Indian Ridge 10°–16°E

Montési¹,

Behn²,

Hebert³

et al. 2011

J. Geophys. Res.

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[1] Crustal thickness variations at the ultraslow spreading 10-16°E region of the Southwest Indian Ridge are used to constrain melt migration processes. In the study area, ridge morphology correlates with the obliquity of the ridge axis with respect to the spreading direction. A long oblique "supersegment", nearly devoid of magmatism, is flanked at either end by robust magmatic centers (Joseph Mayes Seamount and Narrowgate segment) of much lesser obliquity. Plate-driven mantle flow and temperature structure are calculated in 3-D based on the observed ridge segmentation. Melt extraction is assumed to occur in three steps: (1) vertical migration out of the melting region, (2) focusing along an inclined permeability barrier, and (3) extraction when the melt enters a region shallower than ∼35 km within 5 km of the ridge axis. No crust is predicted in our model along the oblique supersegment. The formation of Joseph Mayes Seamount is consistent with an on-axis melt anomaly induced by the local orthogonal spreading. The crustal thickness anomaly at Narrowgate results from melt extracted at a tectonic damage zone as it travels along the axis toward regions of lesser obliquity. Orthogonal spreading enhances the Narrowgate crustal thickness anomaly but is not necessary for it. The lack of a residual mantle Bouguer gravity high along the oblique supersegment can be explained by deep serpentization of the upper mantle permissible by the thermal structure of this ridge segment. Buoyancy-driven upwelling and/or mantle heterogeneities are not required to explain the extreme focusing of melt in the study area.

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“…1). Once at the ridge, material flows along the ridge gradient to the center of the ridge segment, the highest physical point, due to thermal uplift (e.g., Parmentier and Forsyth, 1985;Sleep, 1990;Lin and Morgan, 1992;Kincaid et al, 1996a,b;Magde et al, 1997). The thermal gradient at the ridge follows the basic physiographic gradient and directs material to the ridge and, when at the ridge, to center of the ridge segment.…”

Section: Ridge-hotspot Interactionsmentioning

confidence: 99%

Stress-induced seamount formation at ridge-transform intersections

Beutel

2005

Plates, Plumes and Paradigms

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Our current understanding of thermal and physiographic gradients at the ridge suggests that hotspot (or buoyant melt) will be directed to the center of ridge segments and away from the ridge-transform intersections (RTIs). However, hotspots located at RTIs can be found on almost every spreading ridge across the planet. Finite element models are used to demonstrate that increasing transform strength dramatically increases extensional stresses at RTIs. Several models are presented that suggest that increased extensional stress at RTIs may result in adiabatic melting, thinning of the lithosphere, and consequently a change in the physiographic and thermal gradient at the ridge. Whether this change results in the formation of a hotspot, the propagation of the ridge, or the formation of a new weak transform is dependent on a variety of factors. However, it appears that hotspot formation at RTIs may be the result of lithospheric processes rather than deep-seated mantle plumes.

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The relationship between buoyant mantle flow, melt migration, and gravity bull's eyes at the Mid-Atlantic Ridge between 33°N and 35°N

Cited by 69 publications

References 27 publications

Crust and Lithospheric Structure - Seismic Structure of Mid-Ocean Ridges

Crust and Lithospheric Structure - Seismic Structure of Mid-Ocean Ridges

Controls on melt migration and extraction at the ultraslow Southwest Indian Ridge 10°–16°E

Stress-induced seamount formation at ridge-transform intersections

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