Transition from a Passive Continental Margin to an Active Margin Documented by Time-Facies Profiles and Geohistory Diagrams

Jeroen A. M. Kenter, John J. G. Reymer, Hendrik C. Van Der Straaten

The Upper Cretaceous to Neogene sediments in the northern part of the external zone of the Betic Cordilleras (southeast Spain) reflect the evolution of a passive continental margin into an active margin. Time-facies profiles and geohistory diagrams were constructed to identify and date tectonic events and sea level changes in the sedimentary record.

During Late Cretaceous to middle Eocene time, parallel-trending shallow marine facies belts at the edge of a slowly subsiding basin evidence a passive continental margin setting. The period from middle Eocene to early Miocene is rather poorly documented. After initial shallowing the whole area emerged and continental conditions prevailed from the late Eocene to early Miocene. The subareal exposure may have been caused by the compound effect of the worldwide Oligocene sea level drop and overall tectonic uplift. Miocene sediments reflect the compressional tectonic regime of an active margin. The parallel facies belts were disrupted and the area was segmented into several tectonic blocks, each displaying an individual sedimentary record due to differential vertical movement. During middl to late Miocene time a major compressional phase generated northeast-trending folds and activated strike-slip and thrust faults. This tectonic phase led to a highly differentiated topography, resulting in the development of local depocenters--each with a unique tectonic and depositional record.

AAPG Search and Discovery Article #91032©1988 Mediterranean Basins Conference and Exhibition, Nice, France, 25-28 September 1988.