Los depósitos de la última secuencia deposicional de la plataforma continental del Golfo de Cádiz y del Mar de Alboránestudio comparado

Résumé

High resolution seismic profiles have been used to make a detailed comparative study of the Late Quaternary stratigraphic architecture of continental shelves of southern Spain (Gulf of Cadiz and Alboran Sea). A 4th-order Type 1 depositional sequence (100-110 kyr) composed of FWRST, LST, TST and HST has been determined in both areas. FWRST developed during the regressive interval of isotopic stage 3. LST is related to the onset of isotopic stage 2 when sealevel was around 120 m below its present level. TST is characterised by backstepping and agradational deposits developed between 14-6.5 ky. HST is composed of modern deltaic and infralittoral bodies developed during the last 6.5 ky. The Late Quaternary sedimentary evolution of the continental shelf was controlled by the last 4th order asymmetric relative sea-level cycle. The following considerations can be extracted: a) Volumetrically: the FRST and LST are the most important components of the sequence, b) RST, LST, and HST are characterised by low-energy prodeltaic facies and high-energy infralittoral prograding wedges, c) TST comprises a wide variety of coastal depositional. d) Isopachs maps of each system tract show a parallel distribution along the shelf, with a relatively homogeneous thickness.