Relationship between spreading rate and the seismic structure of mid-ocean ridges

Purdy, G. M.; Kong, Laura S. L.; Christeson, G. L.; Solomon, Sean C.

doi:10.1038/355815a0

Cited by 171 publications

(128 citation statements)

References 24 publications

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“…In this model, all the lower crust crystallized in the successively filled shallow melt lens, and then it flowed down and away from the melt lens, similar to the way that the ice in a glacier flows away from its source [Sleep, 1975; This accretion geometry was also found to be consistent with the observed pattern in the variation of the depth to the seismic lens with spreading rate: deepening of the melt lens with decreasing spreading rate [Purdy et al, 1992] and a sharp transition from a midcrust level lens to no lens for half spreading rate less than -20 mm/yr .…”

Section: Introductionsupporting

confidence: 69%

Thermal effects of gabbro accretion from a deeper second melt lens at the fast spreading East Pacific Rise

Chen¹

2001

J. Geophys. Res.

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Abstract. Motivated by recent observations, a ridge model has been developed which includes both a shallow melt lens and a second deeper melt lens above the Moho to assess the thermal effect of the gabbro accretion from the lower melt lens at the fast spreading East Pacific Rise. Modeling results argue for a limited role of the lower melt lens in constructing the layer 3 gabbros. If significant (>10%) amount of the layer 3 gabbros is emplaced near the Moho, then the liberated latent heat during crystallization would generate a large "molten" section of the lower crust due to the inability of cold seawater to penetrate into this hot/ductile region. A large molten section of the lower crust is not consistent with recent seismic tomographic results of the East Pacific Rise. Thus it is likely that the amount of the gabbro being emplaced from the lower melt lens at the EPR is significantly less than that suggested by Oman ophiolite studies, such a lower melt lens is short-lived, or a large portion of the sill intrusions observed at Oman was emplaced at a few kilometers off axis (>3-4 km).

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Section: Introductionsupporting

confidence: 69%

Thermal effects of gabbro accretion from a deeper second melt lens at the fast spreading East Pacific Rise

Chen¹

2001

J. Geophys. Res.

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“…If magma ponds at a thermal boundary, the observed variations in magma sill depth are due to changes in axial thermal structure. This concept is consistent with the observed decrease in average depth of the magma sill with increasing spreading rate ( Table 1, Purdy et al , 1992).…”

Section: Controls On the Depth Of The Magma Sillsupporting

confidence: 79%

“…The strongest evidence for a thermal control on the depth at which magma accumulates beneath mid-ocean ridges is the variation in depth of crustal magma chambers with spreading rate, first noted by Purdy et al (1992), and illustrated in Figure I. The hypothesis that the depth of magma bodies beneath mid-ocean ridges are primarily controlled by thermal processes has recently been tested quantitatively by Phipps Morgan and Chen (1993).…”

Section: Discussionmentioning

confidence: 95%

The influence of magma supply and eruptive processes on axial morphology, crustal construction and magma chambers

Hooft¹

1996

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“…Above the critical rate, the lens is quasi steadystate and about I km wide. As the spreading rate increases, geophysical results indicate that the width of the melt lens and its thickness are not visibly modified; the only' effect seems to make the lens shallower [Purdy et al, 1992]. This effect which should result in a more efficient cooling is taken into account by increasing Our results are summarized in Fig.…”

Section: Spreading Rate Dependence Of the Magma Lensmentioning

confidence: 50%

Crustal feeding in the Oman ophiolite: From the top and from the bottom? A thermal and mass balance model

Chenevez

Nicolas

1997

Geophysical Research Letters

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Abstract. The stability of the basalt melt lens identified below fast spreading ridges has been tested by a thermal and mass balance model in order to investigate how the generation of the crust by basaltic melt can be affected by spreading rate. The model is constrained using field information from the Oman ophiolite, the main piece of evidence dealing with the nature and structure of the root zone of sheeted dikes which acts as a thermal boundary la•ver between the melt lens below, and the hydrothermally cooled sheeted dike unit above. For a mass balance calculation we first assume that the gabbro unit is entirely created by the melt issued from the lens. We examine how the heat generated by crystallization of this mass can be evacuated through the boundary layer on top of the melt lens. A steady-state situation is found for a given spreading rate and ratio of the Nusselt number to the fielddeduced thickness of the boundary layer. If, as suggested by geophysical data, the melt lens exists only for spreading rates larger than 6 cm/yr, the boundary layer needs to be essentially conductive. With increasing spreading rates and increasing heat supply the system thermally adjusts itself until it must work in a new mode. Geological evidence suggests that this could be achieved by developing an additional feeding of the gabbro unit by a large number of sills being emplaced below the melt lens into the lower gabbros.

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Relationship between spreading rate and the seismic structure of mid-ocean ridges

Cited by 171 publications

References 24 publications

Thermal effects of gabbro accretion from a deeper second melt lens at the fast spreading East Pacific Rise

Thermal effects of gabbro accretion from a deeper second melt lens at the fast spreading East Pacific Rise

The influence of magma supply and eruptive processes on axial morphology, crustal construction and magma chambers

Crustal feeding in the Oman ophiolite: From the top and from the bottom? A thermal and mass balance model

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