Abstract

The Aptian deposits of the easternmost part of the Betic Cordillera in the Iberian peninsula are represented by shallow carbonate platform limestones and outer platform hemipelagic marly sediments deposited at a inner platform-to-outer platform transition zone. The lithostratigraphic and sedimentologic study of eight Aptian sections, and their correlation based on datations using ammonites, planktonic and benthic foraminifera, has allowed the establishment of a detailed stratigraphy of the Aptian deposits. Three formations: Llopis Formation, Almadich Formation and Seguili Formation, with notable lateral changes among them are described. The Aptian sedimentary evolution of the studied platforms consists of a succession of sedimentary processes, such as platform progradation, aggradation and drowning, bounded by discontinuities. The biostratigraphic study carried out demonstrate that the present resolution of biostratigraphy is not enough to make a precise time stratigraphic chart and fine dating of the sedimentary processes at the scale of 3rd or higher order sequences. The sequential analysis have led us to define six depositional sequences, which make up a second order transgressive-regressive cycle. The common features to these sequences are: rare development of lowstand deposits; poorly developed transgressive deposits; and well developed inner carbonate platforms during highstand conditions. Sequential correlation with other Aptian platforms and the Exxon cycle chart shows in general a good coincidence of the sequence boundaries, which would point to global or supra-regional factors as the cause of the sequences. Nevertheless, the internal configuration of each sequence, and events such as the main terrigenous input and the platform drowning seems to be controlled mainly by local tectonic.

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