French Guiana margin evolution: From Gondwana break‐up to Atlantic opening

Abstract

AbstractKnowledge of the Guiana Shield evolution during the Gondwana break‐up is key to a better understanding of craton dynamics and margin response to transtensional opening. To improve this knowledge, we investigated the dynamics and thermal evolution of French Guiana, using several low‐temperature thermochronology methods applied to basement rocks, including apatite and zircon (U‐Th)/He and apatite fission tracks. Inverse modelling of results allows us to reconstruct the Phanerozoic thermal history of French Guiana margin and to give a preview of the Guiana Shield evolution. Three main events are inferred: firstly, a long‐term period of relative stability since ~1.2 Ga, with no strong evidence for any erosional or burial event (>5–7 km); secondly, a heating phase between ~210 and ~140 Ma consistent with the Central Atlantic Magmatic Province‐related event. Finally, an exhumation phase between ~140 and ~90 Ma, triggered by the Equatorial Atlantic opening, brought samples close to the surface (<40°C).