Las discontinuidades mayores del Jurásico de las Zonas Externas de las Cordilleras Béticas: análisis e interpretación de los ciclos sedimentarios.

Abstract

Tbe External Zones of tbe Betic Cordillera (Prebetie and Subbeíic Zones) constitute the meridional margin ofthe Iberian Mate. which corresponded during 4w Mesozoic to a transtensive margin. fis Jurassic historx represents the evolution of the rift that starved in tbe Trias aud also the beginning of the margin expansion ¿ter the Upper Jurassic. Eustatic. tectonic. sedimentary and climatic factors bave conditioned this evolution. A special attention is payed in this study to the Jurassic stratigraphic gaps: they are interpreted as the result of an interaction of sorne episodes of paleomargin fracture. eustatic falís and the end -or important diminutionof sedimentation. The most significant events in the Jurassic evolution (which are olten registred with gaps) are the following: 1 .--Lower Liassic: Generalized development of sballow water plarform carbonates (pre-rift period of the paleornargin). 2.--Middle Liassic: Individualization of the greal paleogeographieal realms: Prebetic Zone in the North and Subbetic Zone in 11w South. Begintung of the sinrifí period. In tbe Subbetic there is a generalization of (be pelagic facies after a gap and a differentiation of paleogeograpbic realnvs of troughs aud swells (External. Middle and Internal Suhbetic) 3.--Uppcr Liassic and Middle Jurassic: a) Prebetie Zone: The sedimentation of the shallow water platforrn goes on. Heginning of fracture al Ihe end of Middle Jurassic. It Subhetic Zone: Progressive differeníiation of the paleogeographic realms. Episodes of hlock movemenís with local emersions aud formation of greater gap s. 4.--Beginning of the Upper Jurassic: Generalization of the pelagie facies in the paleomargin as a result of t1w tectonoeustatic transgression of be begintung of the Atíantie and Ligur expansion. 5.--Jurassic-Cretaceous Boundary: a) Prebetie Zone: Increase in the fracture tectonies. Great development of ihe purbeck Iheles as a resull of dic uppcrmosí Jurassic regression. Ending of the Jurassic cycle in Ihe lower Valanginian as the shallow water purbeck plalfortus dic. b) Subbelic Zone: Progressive disminution in troughs and swells. Action of therrnic subsidence. l-leterochronological termination of the Jurassic cycle between dic Herriasian nod the Iower Valanginian.