Elastic thickness of the oceanic lithosphere beneath Tehuantepec ridge

Relationship between bathymetry and free-air gravity is analyzed by computing response function (admittance) for 7 shipborne profiles crossing the Tehuantepec ridge (TR). The age of the lithosphere at the time of bathymetric loading of the TR is deduced from the experimental admittance and the elastic thickness, Te. Admittance is interpreted in terms of isotropic elastic plate thickness. The oceanic lithosphere is assumed to behave as an elastic plate 10±5 km thick. Low admittances at low wave-numbers suggest that TR is isostatically compensated. We estimate a median value of 8 Ma (in the interval 2-17 Ma) for the age of oceanic lithosphere at the time of TR onset.