Arquitectura fluvial de las «Areniscas del río Arandilla». Triásico de Molina de Aragón (Guadalajara)

Abstract

The outstanding outcrops of Upper Buntsandstein sediments (Middle Triassic) in Molina de Aragón (Guadalajara) area, allow a detailed study of their characteristics and their associations which are described here. The fluvial architecture of the section indicates four main depositional episodes. The two lowest episodes were laid down by a fluvial system characterized by frequent channel shifting, low sinuosity and wide shallow channels. The drainage basin was controlled by highly seasonal discharge. The middle episode evolved into a more distal systems, with smaller higher sinuosity channels and fine overbank deposits. The uppermost episode is related to an increase of slope in the basin. That increase is probably related to tectonic movements recorded in this area. An attempt has been made to correlate the above events to the global sea level fluctuations (Haq et al., 1987). So, the low stage that have been stated occurred during Early Anisian can be tentatively correlated with the uppermost episode in Areniscas del río Arandilla.