A Liassic isolated platform controlled by tectonics: South Iberian Margin, southeast Spain

Abstract

The middle and upper members of the Gavilán Formation near Vélez-Rubio (Almería Province, southeast Spain) are interpreted as carbonate platform deposits. The studied outcrops form geologically part of the External Zones of the Betic Cordillera (South Iberian Palaeomargin). A genetic unit limited by intra-Sinemurian and intra-Upper-Carixian sedimentary breaks is defined. The evolution of the parasequence sets in the area, and the development of deeper sedimentation in its northern outcrops, suggest that this platform was isolated with regard to the South Iberian Margin. Three distinct parasequence sets are proposed: progradational parasequence set (only locally present), retrogradational parasequence set (middle member of the Gavilán Formation) and aggradational parasequence set (basically composed of the upper member of the Gavilán Formation). Sedimentary features (such as neptunian dykes, sharp lithological changes, thickness variations), the presence of palaeofaults and the subsidence history all lead to the conclusion of a significant regional tectonic influence in the genetic unit evolution. Normal extensional faulting has been proposed as a major control on sedimentation on this isolated platform. This regional factor has completely distorted the effect of the eustatic fluctuations for this period of time.