Origen de las brechas de la base del Jurásico de Leitza (Cordillera Vasco-Cantábrica oriental, Navarra)

Abstract

ExtensionsI tectonic activity at the Triassic-Jurassic boundary in the eastern Basc-Cantabric Range (N Spain) in v o lv e d the generation o f a set o f semigraben basins. The largest basin appears related to the Leitza fault, which determined both the accumulation of a thick succession of a caothic and poorly sorted breccia and the upwelling of basalts. These breccias grade up into massive dolomites deposited in shallow to supratidal marine restricted environments. Sinemurian relative sea level rise involved the flooding of these basins and the setting of an extensive carbonate ramp