Abstract: Documentation for the Early and Middle Jurassic Sequence Cycle Chart of Western European Basins

Pierre C. De Graciansky, Thierry Jacquin, Peter R. Vail

The new sequence cycle chart for the Western European basins is based on well dated outcrop data (Subalpine France, Aquitaine, London-Paris basins) and also well dated subsurface data only from the Paris Basin. Three hierarchy of stratigraphic cycles are recognized for the Early and Middle Jurassic: one first-order cycle (Rhaetian-Aalenian), five transgressive-regressive second-order facies cycles and 37 third-order (short term) depositional sequence cycles.

Second-order cycle (no. 1) is Rhaetian to earliest Pliensbachian. The transgressive part is marked by overall backstepping. The regressive part comprises thick forestepping third-order sequences on the proximal Tethyan margin. Second-order cycle (no. 2) is Pliensbachian and (no. 3) is Toarcian to late middle Aalenian. The transgressive part of both is starved on the Tethyan margin due to rapid and extended transgression on the whole craton. The regressive part of both comprise thick third-order sequences on the Tethyan margin but attenuated third-order sequences within intracratonic basins. Second-order cycle (no. 4) is late middle Aalenian to middle Bathonian. The transgressive part shows aggrading carbonate platform in the Paris basin but is relatively starved in the Tethyan margin. The regressive part is often attenuated due to wide-scale intracratonic deformation. Second-order cycle (no. 5) is middle Bathonian to late Oxfordian. The transgressive part comprises extremely thick accumulation of black shales (third-order lowstands) in the proximal Tethyan margin but platform carbonates or shales in the intracratonic basins. The second-order cycles appear to be controlled by the successive phases of extension and subsidence that are related to the Tethyan rifting.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994