Unifying rift terminology in the northeast Atlantic: towards a harmonized framework

Rifted margins form through multi-phased periods of rifting, stretching and thinning of the continental lithosphere until breakup is complete and oceanic lithosphere is formed. It is widely accepted that rifted margins can be partitioned into distinct structural domains (proximal, necking, distal (hyperextended and exhumed), outer and oceanic), which are characterized by their architecture and associated rift stages. However, no consensus has been reached yet on how the different domain boundaries should be defined. As a result, the terminology used to describe rifted margin domains remains inconsistent across studies, hindering comparison between margins and limiting the development of a unified conceptual framework.

A key challenge for establishing robust nomenclature is the dependency of the domain boundary on the constraining data type. Structural, geophysical and magmato-stratigraphic data inherently result in different boundaries. The oversimplistic concept of a Continent Ocean Boundary (COB) is a classic example of this, where the definition is heavily dependent on the method and data utilized. A similar ambiguity is present for the various structural domains, such as the boundary between the necking and distal domains. The inconsistency in terminology highlights the need for unification of the nomenclature through a novel classification framework.

In this contribution, we compile and synthesize published contributions to construct this set of unifying definitions for rifted margin domain boundaries. Through an extensive literature review, we highlight the existing terminology discrepancies. We focus on the Northeast Atlantic region, including the NE Greenland & Norway and the SE Greenland & Faroe-Hatton-Rockall margins, as an ideal test laboratory for our work. The regional tectonic history captures a complete evolution from Devonian post‑orogenic collapse through multiple rifting phases and finally Cenozoic breakup and magmatism. The area has been extensively studied because of past hydrocarbon exploration, providing ample constraints. Finally, local complexities including microcontinents (e.g., Jan-Mayen), failed rift basins (e.g., Rockall Basin) and anomalous ridges (Greenland-Iceland-Faroe Ridge) ensure that our framework will capture the full spectrum of rifted margin architectures.

Our preliminary results confirm that domain boundaries shift systematically depending on the dataset used, reinforcing the need for a unifying classification approach. We present the foundations of a novel framework for defining rifted margin domain boundaries, showcasing its application to the NE Atlantic. This framework aims to bridge across the rifting terminology, ultimately improving cross‑margin comparisons and fostering greater consistency within the rifting community.