Cretaceous folding in the Dévoluy mountains (Subalpine Chains, France): gravity-driven detachment at the European paleomargin versus compressional event

• DOI: 10.2113/gssgfbull.181.6.565
• Publication Date: 2011-01-05T22:21:01Z
• Authors: André Michard; Thierry Dumont; Louis Andreani; Nicolas Loget
• Keywords: Subaerial; Conglomerate; Escarpment; Massif; Syncline

Abstract Located in the southern Subalpine Chains, Dévoluy-Bochaine (D-B) area displays an “ante-Senonian” (Turonian) unconformity classically interpreted as result of a compressional event. We argue that D-B results from major synsedimentary collapse on slope European paleomargin. During Tithonian-Late Cretaceous interval, was located steep between platform (Vercors) and Vocontian basin SE France where mass-flows resedimented deposits accumulated. Under unconformity, Dévoluy folding affects Kimmeridgian-Cenomanian series detached Mid-Upper Jurassic marl-rich “Terres Noires”. Truncation top collapsed unit resulted normal faulting fragmentation poorly consolidated sediments their erosion by deep sea currents. Neither subaerial nor shallow water conglomerates occur at interface, fault scarp breccias are locally exposed. The subsequent, mostly Coniacian-Maastrichtian onlapping formation (“Calcaires en Lauzes”) consists channelized sandy calci-turbidites slumping events again. To conclude, massifs offer first example exposed External Western Alps comparable to Niger or Israel offshore study cases.