THE EARLY DEVONIAN INITIATION OF PANGEA AMALGAMATION: NEW INSIGHTS FROM PALEOMAGNETIC AND GEOLOGICAL DATA (Invited Presentation)

The mid-to-late Paleozoic Caledonian-Appalachian orogen resulted from subduction of the Iapetus and Rheic Oceans between Gondwana, Laurentia and Baltica. During this long-lived orogenic activity, the Laurentian margin preserves abundant geological evidence for the accretion of terranes prior to the amalgamation of Pangea. To help understand the profound role of Laurentia during Pangea amalgamation, we re-evaluated the tempo-spatial distribution of mid-to-late Paleozoic paleomagnetic data from Laurentia, Baltica and Gondwana with a new approach that takes into account of age error, spatial error and Q-factor of each of individual paleopoles. The resulting apparent polar wander (APW) path of Laurentia during 460-300 Ma largely resembles published ones but also reveals a robustly defined kink (i.e., a discontinuity of the APW path) between ca. 420-400 Ma, which is also revealed by the coeval segments of the Baltican and Gondwanan APW paths. By integrating these new APW paths with existing geological data and field relationships in the European Variscides, we show that the formation of Pangea was likely initiated by at least 400 Ma via the collision between Laurussia and a ribbon-like Gondwanan promontory mainly comprised of the Iberian, Armorican and Bohemian massifs. Our model suggests that Pangea’s amalgamation was accomplished by mostly orthogonal convergence between Gondwana and Laurussia, in contrast with existing models suggesting that the juxtaposition of Gondwana and Laurussia (Laurentia-Baltica) was achieved via long-lasting highly oblique convergence in the Late Paleozoic.