Tectonic modification of axial crustal structure: Evidence from spectral analyses of residual gravity and bathymetry of the Mid-Atlantic Ridge flanks - Ecole Nationale du Génie de l'Eau et de l'Environnement de Strasbourg Accéder directement au contenu
Article Dans Une Revue Earth and Planetary Science Letters Année : 1998

Tectonic modification of axial crustal structure: Evidence from spectral analyses of residual gravity and bathymetry of the Mid-Atlantic Ridge flanks

Résumé

Bathymetry and gravity data of the northern Atlantic suggest that oceanic crustal structure on the flanks of the Mid-Atlantic Ridge is strongly modified by tectonic extension at spreading ridge segments. The seafloor along the zero-age isochron is systematically more elevated and the crust thicker near the segment midpoint than at the ends, suggesting focused magmatic accretion at segment centers. In contrast, seafloor older than 2-3 Ma is usually the shallowest at inside corners of ridge-offset intersections, where positive residual gravity anomalies indicate tectonically thinned crust. Coherence between residual gravity and bathymetry for zero-age crust is found at wavelength greater than ; 20 km, which reflects the characteristic length of ridge segments, and is consistent with an effective elastic plate thickness of 1-3 km. No significant coherence, however, is observed on isochron profiles at ages of 2.5 Ma and older at all wavelengths. Flow-line profiles display coherence at wavelength greater than ; 5 km, yielding an estimated effective elastic plate thickness of only 0.3-0.5 km. Synthetic fault models suggest that the flow-line coherence may be controlled by the relatively close spacing of fault-generated abyssal hills rather than reflecting the true elastic thickness of unfaulted lithosphere. Together these results indicate that the crustal structure of the zero-age crust is modified strongly by tectonic extension along the rift valley walls of the slow-spreading Mid-Atlantic Ridge. q 1998 Elsevier Science B.V.

Dates et versions

hal-02325926 , version 1 (23-10-2019)

Identifiants

Citer

Javier Escartin, Jian Lin. Tectonic modification of axial crustal structure: Evidence from spectral analyses of residual gravity and bathymetry of the Mid-Atlantic Ridge flanks. Earth and Planetary Science Letters, 1998, 154 (1-4), pp.279-293. ⟨10.1016/S0012-821X(97)00194-5⟩. ⟨hal-02325926⟩
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