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Communication Dans Un Congrès Année : 2016

Volcanosedimentary complex encompassing the Ediacaran- Cambrian boundary interval in the Oriental Pyrenees

Résumé

The Pyrenees are part of the northeastern margin of the Ibero- Armorican Variscan Arc. They possess one of the most complete uppermost Ediacaran–Cambrian successions in West Gondwana which has been classically divided into two principal lithostratigraphic units : the Canaveilles and Jujols Groups. In the southern flank of the Canigou massif (Puigmal Variscan tectonostratigraphic unit), a unique Fabert volcanic level is usually described at the top of the Cabrils Formation (uppermost Canaveilles Group) which was recently dated around ca. 570 Ma. The overlying Tregurà Formation (Jujols Group) is divided into a lower volcanoclastic breccia member with limestone olistoliths and strong thickness variations, and an upper limestone member. The Tregurà Formation has been considered to encompass the Ediacaran-Cambrian transition, however, until now, no geochronological data have supported this hypothesis. The present study has been aimed to provide an up-to-date and detailed facies analyzes of the Ediacaran- Cambrian formations from the Pyrenees, and to test previously published dating of above-mentioned volcanic and breccia levels through new LA-ICPMS U–Pb dating of zircons. Therefore, the so-called Fabert volcanic level have been sampled in the Fabert Village and the nearby Pic de la Clape, yielding respective ages at ca.559.5 +1.7/-1.3 Ma and ca.542.9 +5/-1.3 Ma. The Tregurà breccia, sampled at the Pic du Finestrelles and the Pic de la Clape, have respectively yielded maximum depositional ages of ca.556±7Ma and ca.532.9±6.1 Ma.. These new dating argue for a long-lasting volcanic episode with multiple pulses during the Ediacaran-Cambrian transition. As a consequence, an updated stratigraphic framework is proposed.
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Dates et versions

insu-01388549 , version 1 (27-10-2016)

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  • HAL Id : insu-01388549 , version 1

Citer

Maxime Padel, Javier Alvaro, Marc Poujol, Sébastien Clausen, Bernard Laumonier. Volcanosedimentary complex encompassing the Ediacaran- Cambrian boundary interval in the Oriental Pyrenees. 25 ème Réunion des sciences de la Terre (RST 2016), Société Géologique de France, Oct 2016, Caen, France. pp.250. ⟨insu-01388549⟩
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