Three-dimensional mantle convection beneath a segmented spreading center: Implications for along-axis variations in crustal thickness and gravity

Journal Article · Wed Dec 01 04:00:00 EST 1993 · Journal of Geophysical Research

DOI:https://doi.org/10.1029/93JB02397· OSTI ID:79467

Sparks, D W; Parmentier, E M; Morgan, J P ^[1]

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1. Lamont-Doherty Earth Observatory, Palisades, NY (United States)

Segmentation and along-axis variations within individual segments indicate the inherently three-dimensional nature of mantle upwelling and melting beneath oceanic spreading centers. Numerical convection experiments are used to explore the effects of local buoyancy forces on upwelling and melt production beneath a segmented spreading center. The experiments are conducted in a region consisting of a thermally defined rigid lithosphere and a uniform viscosity asthenosphere overlying a higher-viscosity mantle half-space. A periodic plate boundary geometry is imposed consisting of spreading segments and transform offsets. Buoyancy forces are caused by thermal expansion and the compositional density reduction due to the extraction of partial melt. The relative magnitudes of the buoyant and plate-driven components of mantle flow are controlled by the spreading rate and mantle viscosity, with buoyant flow more important at lower spreading rates and viscosities. Buoyant flow beneath the spreading axis amplifies along-axis variations in upwelling near a ridge-transform intersection, and distributes the variations along the entire spreading axis.

• Sponsoring Organization: USDOE
• OSTI ID: 79467
• Journal Information: Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: B12 Vol. 98; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CONVECTION
EARTH CRUST
MATHEMATICAL MODELS
PLATE TECTONICS
SOLIDS FLOW
VISCOUS FLOW