Las facies evaporíticas y carbonatadas del tránsito Triásico-Jurásico (Morata de Jalón, Zaragoza): relación tectónica-sedimentación

Abstract

Facies analysis and geological mapping of the Triassic-Jurassic transition units (Cor tes de Tajuña and Lécera Fms) exposed in an area of 10 km2 around Morata de Jalón locality (Zaragoza province, North Iberian Range) allow the definition of two sedimentar y episodes controlled by normal faulting. During episode 1, a subsident coastal salina filled with Ca-sulphates was formed in the downthrown block of two normal faults. Erosion of the Upper Triassic units (Keuper facies and Imón Fm) and deposition of terrestrial facies (lutites, sandstones and polymict breccias), took place in the uplifted blocks. During episode 2, tectonic reactivation combined to long-term sea level rise, resulted in the setting of tidal flat facies, preserved as dolomitic breccias, cellular limestones and finelly-crystalline limestones. Deposition of shallow subtidal facies (mudstones and oolitic-peloidal and bioclastic packstones-grainstones) was favoured in the more subsident areas of downthrown blocks. Cracking and fracturing of the early lithified subtidal carbonates also originated the local deposition in these areas of calcareous breccias and rudites