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Thermal structure of oceanic transform faults

Mark D. Behn^*,1, Margaret S. Boettcher^,1 and Greg Hirth¹

¹ Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, US

We use three-dimensional finite element simulations to investigate the temperature structure beneath oceanic transform faults. We show that using a rheology that incorporates brittle weakening of the lithosphere generates a region of enhanced mantle upwelling and elevated temperatures along the transform; the warmest temperatures and thinnest lithosphere are predicted to be near the center of the transform. Previous studies predicted that the mantle beneath oceanic transform faults is anomalously cold relative to adjacent intraplate regions, with the thickest lithosphere located at the center of the transform. These earlier studies used simplified rheologic laws to simulate the behavior of the lithosphere and underlying asthenosphere. We show that the warmer thermal structure predicted by our calculations is directly attributed to the inclusion of a more realistic brittle rheology. This temperature structure is consistent with a wide range of observations from ridge-transform environments, including the depth of seismicity, geochemical anomalies along adjacent ridge segments, and the tendency for long transforms to break into small intratransform spreading centers during changes in plate motion.

Key Words: oceanic transform faults • mid-ocean ridges • fault rheology • intratransform spreading centers

This article has been cited by other articles:

				J. J. McGuire Seismic Cycles and Earthquake Predictability on East Pacific Rise Transform Faults Bulletin of the Seismological Society of America, June 1, 2008; 98(3): 1067 - 1084. [Abstract] [Full Text] [PDF]