THE ROLE OF TIDAL CURRENTS IN THE TORTONIAN ATLANTIC-MEDITERRANEAN CONNECTION (ONSHORE BETIC): IMPLICATIONS ON PALEOGEOGRAPHY AND RESERVOIR CHARACTERIZATION

Shallow-marine deposits in the Onshore Betic of the Tortonian Atlantic-Mediterranean connection are now revisited and interpreted in terms of tide-dominated environments. In spite of the favorable paleogeographic scenario... [ view full abstract ]

Shallow-marine deposits in the Onshore Betic of the Tortonian Atlantic-Mediterranean connection are now revisited and interpreted in terms of tide-dominated environments. In spite of the favorable paleogeographic scenario (i.e. amplification of tidal flows) the tide signature has been poorly regarded in the Tortonian Betic marine deposits.
The Tortonian Betic Basin is infilled by a marine succession characterized by an overall transgressive to tectonically-controlled forced-regressive trend punctuated by several regressive-transgressive minor cycles. The lower part of the succession (transgressive trend) consists of retrogradational to aggradational coastal systems (reefs, wave-dominated deltas) adjacent to a kilometric-scale, tide-dominated mixed ramp that distally evolved to a storm-dominated distal ramp and pelagic basin. The upper part of the succession (forced-regressive trend) consists of river-dominated deltas (reefs) and ramps.
The tidal signals are: (i) compound cross-bedding (tidal compound dunes), (ii) bi-directional small cross-strata, and ripples climbing the lee side of bars (tidal bars), (iii) bundling of siliciclastic to bioclastic laminae in dunes and delta foreset reflecting high-frequency tidal cycles and (iv) rhythmic lamination in fine-grained sediments of the distal or lateral reaches of the delta system.
Tide influence increased and wave influence decreased in the succession upward through time due to the retrogradational trend of the lower part of the succession. Then tide influence migrated to the north and river influence increased upward through time in the upper part of the succession due to the tectonically-controlled progradational trend (larger emerged terrains at the southern margin of the corridor).