Passive Margin and Continental Basin: Towards a New Paradigm

Abstract

The existence of an unique thinning process generating passive continental margins must be considered for discussion: the diversity of their structural morphology is indeed related to tectonic heritage, geodynamic context and probably mantle heat segmentation. However, the recurrence of certain general features pleads in favour of common rules of the first-order. The commonly used models, like simple shear, pure shear or polyphase models, to explain the lithospheric stretching and consequent crustal thinning of passive continental margins, exclude exchanges between the lower continental crust and upper mantle, and are thus referred as conservational models. They imply large amount of horizontal movement and are not able to explain the observations collected in the most conjugate margins neither fit the kinematic constraints. Based on wide-angle seismic images on passive margins in the Mediterranean sea, the Central Atlantic, the Equatorial Atlantic, the Central segment of the South Atlantic and the Indian oceans, we are now able to propose a new paradigm.