Erosion and flexural uplift along transform faults

Abstract

In all geodynamic settings (intracontinental, continent-ocean, intraoceanic), the main morphological feature of transform plate boundaries is a narrow and elongated valley bounded on at least one side by an uplifted shoulder. Several mechanisms have been proposed to explain this uplift: differential thermal subsidence, lateral heat transfer, extension perpendicular to the transform, but none can be used in all settings. We propose that the erosion of a lithospheric plate along the transform boundary may be an alternative mechanism that can be active in all geodynamic settings. Erosional unloading produces flexural uplift along the transform border, which does not exceed 35-40 per cent of the difference in height between the lithospheric plate and the transform valley. Our model perfectly fits the morphology of several examples in the continental lithosphere: the uplifted shoulder of the Dead Sea transform, as well as marginal ridges in continental transform margins. Along an oceanic transform fault, the erosion of the transform border only partially explains the uplift of the highest transverse ridges, but may amplify other mechanisms.