Influence of Tectonic Inheritance on the Extensional Architecture of the Iberia–Newfoundland Margins

The Variscan (~370–290 Ma)–Alleghanian (~335–265 Ma) orogen was fragmented during the Mesozoic opening of the Atlantic Ocean, resulting in a complex margin architecture shaped by both extensional processes and inherited tectonic structures. This complexity challenges orogen reconstruction, as current models often underestimate the influence of tectonic inheritance and superimposed rifting. Understanding the interaction between extension and inherited crustal features is therefore essential.

Remnants of this orogen occur offshore in the West Iberian Margin (WIM) and Newfoundland Margin (NM), which form conjugate margins with marked along-strike variability. We restore the marine domains to their pre-breakup configuration and examine how basement characteristics, inferred from geophysical data, controlled extension patterns. We quantify margin extension, its partitioning between upper and lower crust, and its balance with total crustal stretching.

Our reconstruction correlates onshore and offshore basement domains and proposes a new zoning of the Variscan–Alleghanian basement. Results indicate that Mesozoic rifting was oblique to the inherited orogenic architecture, providing new insights into the structural variability of the WIM–NM system. This highlights the role of lithological composition in the Variscan basement and Avalon terranes in shaping rift geometry.