Mechanical behavior of the oceanic lithosphere at a corner area defined by an axial valley and a large offset transform fault: Case of the oceanographer transform fault

Elastic behavior of lithospheric plates is able to account for the return to the isostatic equilibrium level, observed at the corner where a mid-ocean ridge axial valley and a large offset transform fault intersect. The formalism is a generalization in two dimensions of the one-dimensional one, due to Kuo et al. [1986]. Good agreement of depth profiles of the oceanic platform can be obtained between models and data from the two corner areas, associated with the Oceanographer Transform Fault (OTF); a band 10 to 20 km wide, around the transform fault affected by shear faulting, has to be excluded from the elastic behavior and possibly also a band 20 to 30 km wide around the ridge axis, affected by normal faulting. A major result concerns the evaluation of the amount of the static contribution, due to anomalous crust, in the deepening of the crustal valley in the vicinity of the OTF, to a value in the range 50 to 70%; the residual 30 to 50% is attributed to an increase of the dynamical effect of the asthenospheric upwelling, feeding the lithospheric plates.