Record of the oceanic anoxic event OAE1a (Lower Aptian) in a platform setting. Prebetic (Alicante province)

摘要

The Early Aptian was a time of major global events, being probably the most notable the Oceanic AnoxicEvent 1a. In this paper, we present the study of the record of the OAE1a in a platform setting, the PrebeticZone of the Betic Cordillera, which represents the shallow platform environments of the Southern IberianPalaeomargin during the Mesozoic. In this context, several events of global and regional character arerecorded, whose timing and relationships are extremely interesting to be clarified. The correlation betweenthe studied sections has permitted the establishment of the timing of the main sedimentary events. Thetransgressive general context recorded in the studied units, linked to the tectonic subsidence, resulted inseveral retrogradational pulses, leading finally to the drowning of the shallow platform, which was postdatedby the OAE1a event. The record of the OAE1a in a platform setting is explained as related to a localcombination of factors, as a transgressive general context, strong local subsidence rate, and importantinput of terrestrial organic matter in the platform, as has been supported by the data provided from theanalysis of the organic matter contained in the sediments