El tránsito Jurásico-Cretácico en la Cordillera Ibérica: relación tectónica-sedimentación y evolución paleogeográfica.

Abstract

Stratigraphycal and sedimentologycal analysis carried out in the so-called Tithonian-Eerriasian Sequence in the Iberian Cliain (northeast Spain), resulted in further information about the origin and evolution of the accommodation in the basin at this time span. The lower boundary of 4w sequence has been related to the uplift of the western marginal arcas (i.e., Meseta Massif), which also involved an important coastal sift basinwards. During Middle and Late Tithonian a low angle and homogeneous carbonate ramp developed in the central areas of the Chain. During Early and Middle Berriasian the ramp evolved into a mixed ramp, showing clastie units in southwestern areas of Ihe basin which grade to the East into carbonate facies. This increase of the cíastic input along with the coastal sift basinwards at 4w Jurassic-Cretaceous boundary are evidences for the tectonie uplift of the marginal arcas of the basin at this time span. The generation of some subsident sedimentary furrows developed in the central part of the basin at tlie onset of the Berriasian, are the result of an increase of the tectonic extensional deformation at this time span. Tcctonics extension from the Kimmeridgian and from the Tithonian onwards also involved the genesis of the Maestrat (to the East) and Cameros (to the Northwest) basinso- respectively. To this tectonic effect, may be superimposed a long term eustatic falí, as proposed by Haq et al. (1987). However, none of the intermediate third order cycles proposed in the Exxon curve at this time span were evidenced in the Iberian basin.