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Warping and cracking of the Pacific plate by thermal contraction
Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, USA
Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, USA
Lineaments in the gravity field and associated chains of volcanic ridges are widespread on the Pacific plate but are not yet explained by plate tectonics. Recent studies have proposed that they are warps and cracks in the plate caused by uneven thermal contraction of the cooling lithosphere. We show that the large thermoelastic stress produced by top-down cooling is optimally released by lithospheric flexure between regularly spaced parallel cracks. Both the crack spacing and approximate gravity amplitude are predicted by elastic plate theory and variational principle. Cracks along the troughs of the gravity lineaments provide conduits for the generation of volcanic ridges in agreement with new observations from satellite-derived gravity. Our model suggests that gravity lineaments are a natural consequence of lithospheric cooling so that convective rolls or mantle plumes are not required.
Received 16 March 2004; accepted 2 August 2004; published 26 October 2004.
Citation: (2004), Warping and cracking of the Pacific plate by thermal contraction, J. Geophys. Res., 109, B10411, doi:10.1029/2004JB003091.
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