Características estructurales y estratigráficas del substrato Plioceno del Delta del Llobregat (Barcelona, España). Aplicación a los estudios hidrogeológicos

Abstract

The study of 71 mechanical bore-hole has allowed to characterize the pre-Quaternary substratum of the Llobregat delta, mainly composed by marine Pliocene clays. The Pliocene is divided in two depositional sequences. The first one is transgressive with a onlap device on the previous materials; the second are regressive with a offlap device on the previous one. The Plio-Quaternary limit (2,0±0, 1 Ma) constitute to discontinuity surface associated to the fini-pliocene marine regression. Three marine stabilization sea levels have been detected to ~ 80, 100-110 and ~ 150 m.b.s.l. The two regional faults systems identified (SW-NE and NNW-SSE) have their continuation in the Quaternary materials as growth faults. These systems produce the extensional compartimentation of the former basin, giving a relief of rising and deeping blacks that conditions the unequal volume of accommodation and rate of subsidence during the Quaternary. The consequence is o bigger thickness of sediments affected by marine intrusion in coastal areas and the desconection of Quaternary aquifer levels.