Huge
David
Besson1,
Olivier Parize1,
Robert W Dalrymple2,
Noel James2,
JeanYves Reynaud 3,
Jean-Loup Rubino
4 (1) Ecole Nationale Superieure des Mines de Paris, Fontainebleau Cedex, France
(2) Queen’s University, Kingston (3) Museum National d’Histoire Naturelle, Paris, France (4)
Total, Pau Cedex, France
Ten
depositional sequences can be recognized in the Miocene South East Alps
foreland basin. They belong to the Neogene cycle,
which evolved from peri-reefal environments to siliciclastic coastal and fluvial systems. Geometrical
relations of these sequences allow us to identify three huge IVSs, respectively dated Lower, Middle and Upper Miocene.
These huge IVSs (up to 100 km long and up to 300 m
deep) are related to geodynamic foreland basin evolution and constitute major
potential stratigraphics traps. The Lower Miocene IVS
cuts most of the East-West Middle Eocene (Provençal)
folds and are generally localized along Oligocene extensional structures. This
first IVS is linked to the basal foreland unconformity. It presents a compound
cool-water carbonates Incised-Valleys Fill (IVFs)with deep erosional sequence
boundaries underlined by diagenetic features. Lower
Miocene deposits were also inverted and the associated compound IVS was
re-incised between Burdigalian and Langhian. This younger incision stage occurs
perpendicularly to the first and is linked to a sea level drop, strongly
enhanced by regional uplift. This foreland basin uplift is explained by shortening
rate increase, shown by fold growing, coeval with the end of the