Avalonia, get bent! Paleomagnetism from SW Iberia confirms the Greater Cantabrian Orocline

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Authors

Bruno Daniel Leite Mendes, Daniel Pastor-Galán , Mark Dekkers, Wout Krijgsman

Abstract

The amalgamation of Pangea formed the contorted Variscan-Alleghanian orogen, suturing
Gondwana and Laurussia during the Carboniferous. From all swirls of this orogen, a double
curve stands out in Iberia, the coupled Cantabrian Orocline and Central Iberian Curve. The
Cantabrian Orocline formed subsequent to Variscan orogeny (ca. 315-295 Ma). The
mechanisms of formation for this orocline are disputed, with an Avalonian (Laurussia)
indenter of south-westernmost Iberia; and a change in the stress field that buckled the
orogen, as the most prominent. In contrast, the geometry and kinematics of the Central
Iberian curve are largely unknown. Whereas some authors defend both curvatures are
genetically linked, others support they are distinct and formed at different times. Such
uncertainty adds an extra layer of complexity into our understanding of the final stages of
Pangea formation. To solve these issues, we study the late Carboniferous kinematics of SW
Iberia with paleomagnetism. Our results show up to 70 ̊ counterclockwise vertical axis
rotations at late Carboniferous, coincident with the kinematics expected in the southern limb
of the Cantabrian Orocline. These results discard a concomitant formation of both
Cantabrian and Central Iberian curvature. The coherent rotation of both Gonwdanan and
Avalonian pieces of SW Iberia confirms the Greater Cantabrian Orocline hypothesis and
discards the Avalonian indenter as a mechanism of formation for the Cantabrian Orocline.
The Greater Cantabrian Orocline extended beyond the Rheic Ocean suture affecting both
Laurussia and Gondwana margins and probably formed due to a late Carboniferous change
in the stress field.

DOI

https://doi.org/10.31223/osf.io/evwc6

Subjects

Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure

Keywords

paleomagnetism, Central Iberian Curve, Greater Cantabrian Orocline, Pangea, Variscan orogeny

Dates

Published: 2020-01-29 03:02

Last Updated: 2020-02-09 20:31

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License

CC BY Attribution 4.0 International

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