MASCLE, ALAIN, and PHILIPPE YANN, Institut Francais du Petrole, Rueil Malmaison, France

ABSTRACT: The Jura Thrust Belt and Its Foreland: Tectonic History and Petroleum Plays

The Jura thrust belt in eastern France is the accurate leading edge of the Alps, which developed in the Neogene as a thin-skinned wedge of imbricate sheets of Mesozoic calcareous and marly platform sediments. The basal decollement generally is hosted in middle and late Triassic evaporites and salt layers. The foreland to the west is the Bresse basin, a complex late Eocene-early Miocene north-south-elongated rift superimposed on the Mesozoic platform and on more locally distributed Stephanian and Permian troughs related to the post-compressional collapse of the Variscan chain.

Two main source rock intervals have been recognized so far in the whole area: coal measures and bituminous shales of the Stephanian-Autunian and marine black marls of the Toarcien.

Reservoirs and associated seals are distributed more randomly and include sandstones, limestones, and dolostones of the Triassic and Jurassic. Tiny gas fields were exploited at the Jura front in the past but have now been abandoned. Significant oil shows have been encountered recently in Triassic sandstones at the southern edge of the Jura mountains. They have boosted exploratory plays considerably and, as a result, about 50% of the Jura and Bresse area presently is covered by licenses and license applications.

AAPG Search and Discovery Article #90990©1993 AAPG International Conference and Exhibition, The Hague, Netherlands, October 17-20, 1993.