Ritmicidad de alta frecuencia en una plataforma mixta de alta energía tipo rampa (Tortoniense Superior, Cuenca de Guadix, Cordillera Bética)

Abstract

During the Late Tortonian the stacking of 29 rhythms (10 to 25 m thick each) constituted a succession of high-energy mixed platform deposits (about 500 m thick) attached to the southwestern margin of the Guadix Basin, one of the Neogene-Quaternary basins of the Betic Cordillera. The ramp platform sequences consist of two lithofacies intervals: burrowed silty marl and cross-stratified calcarenites and calcirudites. The high-frequency cyclicity in the succession is linked to changes reflecting the sum of climatic variations and tectonic subsidence. It is suggested two climatically-controlled models which could leave its signature on two different scales in the platform deposits: (1) Glacio-eustatic sea level changes and (2) Short period catastrophic events that cause instantaneous increase in carrying capacity of the rivers, erosion of coastal deposits and storm-dominated deposition on pelagic environments. Each rhythm must have been deposited in a very short time period controlled by fifth- or sixth-order cycles on the basis of the biostratigraphy of the succession.