Pangea Migration. Issue 6 (7th June 2021)

• Record Type: Journal Article
• Authors: Le Pichon, Xavier; Jellinek, Mark; Lenardic, Adrian; Şengör, A. M. Celal; İmren, Caner
• Is Part Of: Tectonics. Volume 40:Issue 6(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-06-07
• Subjects: Geology, Structural -- Periodicals; 551.8
• DOI: 10.1029/2020TC006585
• Languages: English
• ISSNs: 0278-7407

Abstract

Abstract: We confirm the proposition of Le Pichon et al (2019, https://doi.org/10.1029/2018TC005445 ) that Pangea was ringed by a hemispheric subduction girdle from its formation 400 Ma to its dispersal 100 Ma. We quantify the northward migration, that we attribute to True Polar Wander (TPW), of its axis of symmetry, between 400 and 150 Ma, from southern latitudes to the equatorial zone. The spatial stabilizing within the equatorial zone of the axis of symmetry in a fixed position with respect to the lower mantle was marked by alternating clockwise and counterclockwise oscillations between 250 and 100 Ma that we relate to tectonic events. A subduction girdle is predicted to set up lateral temperature gradients from the relatively warm sub‐Pangean mantle to a cooler sub‐oceanic mantle. Over time, this effect acts to destabilize the Pangea landmass and its associated subduction girdle. Quantitatively, a scaling theory for the stability of the subduction girdle against the mantle overturn constrains the maximum magnitude of sub‐Pangean warming before breakup to be order 100 °C, consistent with constraints on the Pacific‐Atlantic oceanic crustal thickness differences. Our predictions are in line with the recent analyses of the Jurassic‐Cretaceous climate change and with the existing models for potential driving forces for a TPW oscillation of Pangea across the equator. The timing and intensity of the predicted sub‐Pangean warming potentially contributed to the enigmatically large Siberian Traps and CAMP flood basalts at 250 Ma and 201 Ma, respectively. Key Points: Plate tectonics of the stationary hemispheric equatorial Pangea was radically different from the present dispersed continental stage Hemispheric surrounding slab curtain led to fixity with respect to the mantle causing thermal isolation and a warm underlying upper mantle Consequences are sea level control, Pangea migration to equator and associated oscillations, fracturing, flood basalts, and finally, breakup