Using Cosmogenic 3 He Dating of Fluvial Terraces for Estimating the Present Uplift of the Massif Central within the Northeastern Termination of the Cévennes Fault System
Résumé
In 2019, the rupture of the La Rouvière fault leads to the Mw 4.9 earthquake of Le Teil and awakens great interest among the scientific community. Located on the North-East termination of the Cévenol fault system (CFS), an intraplate domain with extremely low deformation rates, La Rouvière fault, just as most of the neighboring fault segments, was not considered as potentially active. This event logically called into question our knowledge of regional dynamics and the seismogenic potential of the CFS faults. In this work, we aim to estimate the incision rates, in the normal to the CFS Escoutay valley, using cosmogenic 3He dating. This dating method unravels exposure ages of surfaces and is applied on basaltic pebbles because of their mineralogy (Ol., Px.). Dating those terraces on both sides of the CFS allows constraining incision rates in the valley and potentially the changes in uplift rates on a regional scale. The long-term objective of this study is to understand the recent history of these faults and what processes are triggering such reactivation.
Domaines
Géophysique [physics.geo-ph]
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