Resumen de Cambios en la estructura sedimentaria de los depósitos Cuaternarios del Margen Continental Suribérico Atlántico

Francisco Javier Hernández Molina, Luis Somoza, Víctor Díaz del Río Español, Francisco José Lobo Sánchez, Juan Tomás Vázquez, Adolfo Maestro González, C. Roque, Antonio Barnolas Cortina

• A. significative change in the Plio-Quaternary strati graph ¡cal architecture of the Gulf of Cadiz continental margin between Cadiz City and San Vicente Cape has been evidenced by means of a seismic stratigraphy analysis. The change is observable in ail the physiographic domains of the continental margin: shelf, slope and especially in the Faro Drift. Pleistocene deposits are arranged into two main units: a) Lower unit, which is composed of vertically stacked aggrading depositional sequences, b) Upper unit. This unit overlies a discontinuity (RPM) of high amplitude and erosive character which is widespread all over the basin. It is internally composed by a set of 4th and 5th order shelf-break wedges with a progradational sigmoid configurations, which westward evolve to complex divergent sequences composed of hemipelagic and pelagic deposits and to aggrading/ prograding contouritic deposits in the Faro continental slope. This noticeable change in the structure of Pleistocene deposits could be attributed to the influence of the climatic changes which took place before and after the Middle Pleistocene Revolution. In this sense, the climatic/eustatic oscillations genérated by Milankovitch eccentricity cycles and which repeat and amplify considerably during the last 920.000 y. seem to have played á dominant role in determining the structuration of the tipper unit