Estudio sedimentológico y tectosedimentario de la Cubeta de Cervera del Río Alhama (La Rioja) durante la sedimentación del Grupo Urbión (Cretácico Inferior)

Abstract

The aim of ths work is the study of the evolution and infilling of an Early Cretaceous (Valanginian) basin characterized by the development of lacustrine depositional systems. Simultaneously with the deposition of the siliciclastic Urbion Group in the Cameros basin, shallow carbonated lakes were developed in the Cervera del Rio Alhama-Grávalos sector (La Rioja). The Urbion Group in this area has been divided into four lithostratigrafic units which have been sedimentologically characterized as follows:
- Lower Heterolithic Unit (HI): It represents a fluvio-Iacustrine complete cycle developed in a basin which was isolated of the Cameros Basin as a whole at the beginning of the deposition of Urbion Group.
- Cabreton Limestone Unit (Ce): It corresponds to the maximum developing of the carbonated lakes in this area.
- Transitional Heterolithic Unit (HT): It characterizes the transition from a lacustrine system to a fluvial one.
- Shales with Sandstones Unit (LA): This unit corresponds to a fluvial system which homogenizes the deposition in the studied area with the Cameros Basin as whole.
From all these stratigraphic and sedimentological data the Cervera del Rio Alhama Basin is proposed as a new tecosedimentary realm in the Cameros Basin as a whole. It can be characterized as a small basin controlled by the movement of a NW-SE trending half-graben 00 the basament.