Solving the western European Rheic Puzzle Through Orogenic Architecture Diagrams

The Rheic ocean is one of the many oceanic basins inferred to form part of the intricate puzzle of continents and microcontinents in the Paleozoic. It opened in the Early Ordovician, separating the microcontinent Avalonia from Gondwana, and subsequently closed in the late Paleozoic with the amalgamation of the supercontinent Pangea, playing a major role in the Variscan orogeny. The existence of the Rheic ocean is accepted and required in plate reconstructions. However, its actual width, along-strike length, and relationships with other oceans and seaways (e.g., the Rhenohercynian, Galicia-Moldanubian, Saxo-Thuringian oceans) are unconstrained and controversial.

To address these issues, we perform a detailed review of available data on lithostratigraphy, magmatism, geochronology, geochemistry, structural geology, and metamorphism of tectonostratigraphic units in Iberia and the British Isles, where the Variscan belt comprises accreted units of Gondwana, Avalonia and their intervening ocean(s). We compile these datasets in orogenic architecture diagrams, with the aim of objectively assessing the current state of knowledge on the paleogeographic limits and evolution of the Rheic ocean and on the nature and continuity of its suture. Through our preliminary compilation, we identify what data constitutes solid evidence for the existence of the Rheic ocean and whether gaps in the current knowledge exist that have been filled by interpretative work, and discuss tectonic implications and potential paths forward.