Recumbent folding in the Upper Cretaceous Eaux-Chaudes massif: A Helvetic-type nappe in the Pyrenees?

Norbert Caldera*, Antonio Teixell, Albert Griera, Pierre Labaume, Abdeltif Lahfid

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

Abstract

We describe a singular structure in Upper Cretaceous rocks of the Eaux-Chaudes massif of the western Pyrenees, consisting of a kilometre-scale fold nappe with a sheared overturned limb. High ductile strain attests a deformation style rarely reported for the alpine Pyrenees, and peak temperature in Upper Cretaceous carbonates is estimated by Raman spectroscopy of carbonaceous material palaeothermometry in the lower greenschist facies (>300°C). The normal fold limb retains the original sedimentary textures, while the overturned limb shows calcite crystal-plastic deformation and dynamic recrystallization, with crystallographic preferred orientation. The observed ductility and metamorphic temperature bear similarities with the lower Helvetic nappes of the Alps, suggesting deep burial and/or possibly high geothermal gradient in this part of the Pyrenees.

Original languageEnglish
JournalTerra Nova
DOIs
Publication statusAccepted in press - 2020

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