Iberian-Appalachian connection is the missing link between Gondwana and Laurasia that confirms a Wegenerian Pangaea configuration

Pedro Correia,J Brendan Murphy

doi:10.1038/s41598-020-59461-x

Abstract

The formation and subsequent breakup of the supercontinent Pangaea has dominated Earth’s evolution for the last 320 million years. Although its configuration at the time of breakup is widely accepted, there remains uncertainty about its configuration at the time of its amalgamation. The classic Pangaea-A model, widely known as “Wegenerian” configuration, implies that Pangaea did not deform internally between amalgamation and breakup. Palaeomagnetic studies suggest the possibility of a Pangaea-B configuration, in which Gondwana was located about 3000 km farther east relative to Laurasia compared its location in Pangaea-A. Here, we provide firm evidence of an Iberian-Appalachian connection in the Late Pennsylvanian (307–299 Ma) which confirms a Pangaea-A configuration for the relative locations of Gondwana and Laurasia in the late Palaeozoic, negating the possibility of Pangaea-B at that time. This evidence is based on palaeobotanical and biostratigraphic findings recently documented in the Carboniferous successions of Iberia (Douro Basin, Portugal). These new findings also precisely constrain the timing of uplift of the Appalachian and Iberian (Variscan) orogens and climatic changes during the amalgamation of Pangaea and final closure of the Rheic Ocean.

Highlights

Over the past 30 years, a broad consensus has emerged that repeated cycles of supercontinent amalgamation and dispersal have occurred since the end of the Archean, and these cycles have profoundly affected the Earth’s evolution[1,2]
Determination of the palaeogeography of Laurasia relative to Gondwana during the late Palaeozoic is hindered by the lack of palaeobiogeographic evidence linking both continents
We draw on recent discoveries in Carboniferous successions in the Iberian Massif (Douro Basin, Portugal)[14,15] that, for the first time, www.nature.com/scientificreports provide linkages between the ancient landmasses Laurentia and Iberia along the palaeoequatorial belt during the Late Pennsylvanian (307–299 Ma) (Fig. 1)

Summary

Gondwana and Laurasia that confirms a Wegenerian Pangaea configuration

The formation and subsequent breakup of the supercontinent Pangaea has dominated Earth’s evolution for the last 320 million years. We provide firm evidence of an Iberian-Appalachian connection in the Late Pennsylvanian (307–299 Ma) which confirms a Pangaea-A configuration for the relative locations of Gondwana and Laurasia in the late Palaeozoic, negating the possibility of Pangaea-B at that time This evidence is based on palaeobotanical and biostratigraphic findings recently documented in the Carboniferous successions of Iberia (Douro Basin, Portugal). Other reconstructions based on a wealth of faunal, lithological, stratigraphic, detrital zircon and palaeoclimatic data[20,21,22,23,24,25], imply that these terranes remained along the Gondwanan margin for the entirety of the Palaeozoic[26,27,28,29] In the latter scenario, Rheic Ocean closure resulted from continental collision of Laurasia with the northern Gondwanan margin, which began ca. On the basis of this evidence, we adopt the second scenario and our reconstructions showing a unified Iberia and Gondwana throughout the Palaeozoic

Palaeofloral and Biostratigraphic Evidence

Additional information