Gondwana\u2019s Apparent Polar Wander Path during the Permian-new insights from South America

Renata N. Tomezzoli,Hugo Tickyj,Farid Chemale,Ernesto O. Cristallini,Guadalupe Arzadún,Leandro C. Gallo,Augusto E. Rapalini

doi:10.1038/s41598-018-25873-z

Abstract

A long-standing debate regarding the configuration of Pangea during the Late Paleozoic has been going on among the paleomagnetic community concerning the validity of one of two significantly different Pangea reconstructions (Pangea A vs Pangea B) since the proposal of Pangea B. Although, Pangea B avoids any continental overlap marring classical Pangea A configuration (Wegener’s type), it requires a Carboniferous-Permian megashear of up to 1500 km to achieve the pre-Jurassic configuration. The existence of this megashear is controversial and has led to a wide range of hypotheses, in order to avoid Pangea A continental overlaps and consequently the need for major intra-Pangea movements and to accommodate the paleomagnetic database within a Pangea A reconstruction. We present paleomagnetic results from Permian volcanic rocks of the El Centinela, La Pampa, Argentina. Undeformed volcanic rocks are not affected by any inclination bias and are, therefore, ideal to test different paleogeographic models. The presence of two different paleopole positions, at the base and the top of the same stratigraphic sequence, makes this location optimal to constrain the track of the Gondwana’s path during the Late Paleozoic, which shows the transition from Pangea B during the Carboniferous-Permian, to Pangea A at the Permian – Triassic boundary.

Highlights

Along-standing debate regarding the configuration of Pangea during the Late Paleozoic has been going on among the paleomagnetic community concerning the validity of one of two significantly different Pangea reconstructions (Pangea A vs Pangea B) since the proposal of Pangea B
Despite the fact that zircons are rather rare in ultra potassic volcanic rocks, several attempts have been undertaken in order to collect zircon crystals for radiometric dating
On one of the successful occasions, a sample of 5 kg from the lava flow from the top of the sequence (Fig. 1b,c) was processed and two zircon crystals were separated for isotopic analysis

Summary

Wander Path during the Permiannew insights from South America

The presence of two different paleopole positions, at the base and the top of the same stratigraphic sequence, makes this location optimal to constrain the track of the Gondwana’s path during the Late Paleozoic, which shows the transition from Pangea B during the Carboniferous-Permian, to Pangea A at the Permian – Triassic boundary. Instead the difference in the declinations might be attributed to apparent polar wander (Fig. 3) The presence of these two paleopolar positions in the same continuous and undeformed volcanic stratigraphic sequence makes this location perhaps the best example in the world for the study of the paleogeography of Gondwana during the Late Paleozoic. With these poles it is possible to precisely track the APWP for South. The continents displacement relative to the geographic South Pole shows the transition from a Pangea B16 during the Carboniferous-Permian/Upper Permian (Fig. 4), to a Pangea A in the Permian-Triassic boundary[6]

Methods

Author Contributions

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