Neogene exhumation history of the Bergell massif (southeast Central Alps).
Gweltaz Mahéo 1, Cécile Gautheron 2, Philippe-Hervé Leloup 1, Matthew Fox 3, Laurent Tassant-Got 4 and Eric Douville 5
1- Laboratoire de Science de la Terre, CNRS-UMR5570, Université Claude Bernard Lyon1, ENS Lyon, Université de Lyon, 69100
Villeurbanne, France, gweltaz.maheo@univ-lyon1.fr, phone : + 33 4 72 44 52 36
2- UMR Interactions et Dynamique des Environnements de Surface – CNRS-UPS 8148, Université Paris Sud, 91405 Orsay, France
3- ETH Zürich, Geologisches Institut, NO E49, Sonneggstr. 58092 Zurich, Switzerland
4- Institut de Physique Nucléaire, CNRS/IN2P3, Université Paris Sud, 91405 Orsay, France,
5- Laboratoire des Sciences du Climat et de l’Environnement - CNRS, Giff/Yvette, FranceAbstract:
The Bergell pluton is an elongated plutonic
body emplaced during Oligocene time along the Insubric line in the
central Alps. Reconstruction of its exhumation based on apatite
(U-Th)/He dating and one dimension thermal modeling, provide evidence
for a three steps history: (1) following initial fast exhumation from
>20-25 to ~17 Ma, slow down of the exhumation rate until ~10 Ma, (2)
quiescent phase from ~10 to ~5-6 Ma and (3) an apparent increase of
exhumation after ~5-6 Ma. The decrease of exhumation rate is related
with migration of thrusting south of the Bergell area in the Southern
Alps (Lombardic phase). Increase in exhumation rate after ~5-6 Ma is
possibly related with Messinian base level drop, enhanced climatic
variability (3-4 Ma) and intensification of glaciation (~0.87 Ma).
Terra Nova, vol. 25, n°2, p 110-118, 2013. doi: 10.1111/ter.12013, 2013.
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