Abstract
Rifted margins are the result of the successful process of thinning and breakup of the continental lithosphere leading to the formation of new oceanic lithosphere. Observations on rifted margins are now integrating an increasing amount of multi-channel seismic data and drilling of several Continent-Ocean Transitions. Based on large scale geometries and domains observed on high-quality multi-channel seismic data, this article proposes a classification reflecting the mechanical behavior of the crust from localized to diffuse deformation (strong/coupled to weak/decoupled mechanical behaviors) and magmatic intensity leading to breakup from magma-rich to magma-poor margins. We illustrate a simple classification based on mechanical behavior and magmatic production with examples of rifted margins. We propose a non-exhaustive list of forcing parameters that can control the initial rifting conditions but also their evolution through time. Therefore, rifted margins are not divided into opposing types, but described as a combination and continuum that can evolve through time and space.
Highlights
Rifted margins are the result of the successful process of thinning and breakup of the continental lithosphere leading to the formation of new oceanic lithosphere
From the tilted blocks of the 1970′s, the detachments and mantle exhumation of the 1980′s–1990′s to the great variety of geometries seen[1], we revisit the classification of these margins
Other data collected o ffshore[14,15,16,17] and o nshore[18,19] in the Northern Atlantic led to the development of a model for Volcanic, or magma-rich, Rifted Margins (VRM)[20,21]. These margins are characterized by thick wedges, up to 20 km, of Seaward Dipping Reflectors (SDR)[22,23] mainly composed of basaltic flows interbedded with sediments and paleo-soils, all intruded by sills
Summary
Rifted margins are the result of the successful process of thinning and breakup of the continental lithosphere leading to the formation of new oceanic lithosphere. Alpine geologists highlighted the convergence with geological features observed in the Swiss Alps and developed original models integrating the complete evolution from the first increment of continental extension to oceanisation[7,8,9,10] From these combined studies arose the magma-poor model of rifted margins, characterized by limited volumes of syn-rift magmatic rocks and exhumation of continental lithospheric mantle in the COT11–13. Other data collected o ffshore[14,15,16,17] and o nshore[18,19] in the Northern Atlantic led to the development of a model for Volcanic, or magma-rich, Rifted Margins (VRM)[20,21]. The different observations did not allow sufficient convergence of ideas to reach a consensual model[26,27,28,29,30]
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