La Mancha Triassic and Lower Lias Stratigraphy, a well log interpretation

Abstract

The Stratigraphy of the Triassic Keuper and the lowermost Liassic sedimentary interval has historically attracted much less attention than the adjacent sediments of Muschelkalk and Buntsandstein, and Lower to Middle Lias. A twelve wells correlation, along a cross-section of the La Mancha area, has been prepared to demonstrate the arrangement of facies in these formations, as well as their respective ordering in sedimentary sequences. Well data show the existence of complex multistage thick evaporitic sequences in the lower and more saline K1 unit, and in the upper and relatively more anhydritic K4-K5 units. A clastic episode, K2-K3 units, extends across the zone with several sand rich fairways. The topmost Keuper K6 unit is a very good marker. Sedimentation continued upwards, lowermost Lias, with a thick evaporitic section, the Anhydrite Zone, which has a signifi cant halite episode in the central part of the cross-section. It is remarkable the good correlation existing between outcrops and well data, for these formations.