Diagnostic criteria for mapping rifted margin architecture using seismic reflection profiles

Rifted margins result from the complex interaction between tectonic, magmatic and sedimentary processes. Conceptual models explaining their evolution have changed considerably over the last few decades, moving from simple stretching models to more complex polyphase rift models that distinguish between structural domains (proximal, necking, distal) and distinct rift modes. Advances in dynamic numerical modelling have made it possible to not only reproduce the predicted sequential evolution of rift modes and the related rift domains, but also to create complex 2D and even 3D computer-generated simulations, which must be compared with real world examples. While increasingly sophisticated 2D and 3D seismic images of rifted margins allow theoretically to rigorously test and calibrate the models, the problem resides that their geological interpretations are none unique. It is therefore more important than ever to develop a ‘protocol’ which allows for objective, verifiable, consistent and reproducible geological interpretations of seismic data.

 

Rifted margins present, indeed, first- and second-order diagnostic geometries and seismic facies that can be mapped on seismic reflection profiles. Our contribution aims to synthesise current knowledge on margin architecture and present a systematic approach to seismic interpretation, supported by representative “champion” seismic lines. For each domain, we describe the main structural and stratigraphic characteristics and provide diagnostic criteria commonly observable on seismic reflection profiles. Rather than revisiting the mechanisms of margin formation, we assess whether first- and second-order observational features capture the full range of architectures between existing endmember models. While using the magma-rich/magma-poor dichotomy aids communication, natural rift systems span a continuum of intermediate and hybrid configurations. Our approach accommodates this variability and promotes standardized, reproducible interpretations, allowing to close the loop between increasingly sophisticated modelling and imaging techniques and their testable, reproducible, across-scales coherent geological interpretation.