Understanding the Driving Factors of the Oceanic Anoxic Event 1A (Early Aptian) - The Continental and Neritic Perspective

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Ocean-wide anoxic events (OAEs) represent intensively investigated anomalies in the global carbon-cycle. The study of OAE-coeval shallow water settings is now increasingly seen as an interesting complementary approach, but one that is not without problems either. Whereas platform drowning characterizes the Early Aptian of the northern Tethyan margin, out-of-balance facies and ongoing shoalwater sedimentation at the southern Tethyan margin (Oman) bears important information on potential causes of C-cycle perturbations. In the first two project years, fieldwork focussed on outcrops in the central Tethys (Croatia, Istria) and the northern Tethys (France, Haute Savoie). Based on this project and previous studies, a latitudinal change in Lower Aptian shoalwater facies is observed with OAE1a-coeval Lithocodium-Bacinelladominated facies in Oman and Istria and Lithocodium-Bacinella-poor facies and platform drowning in France. The transition zone between these two end-member facies types is poorly constrained both geographically and lithologically. For the third project year, we here propose to investigate uppermost Barremian and Lower Aptian section in western Portugal (Atlantic domain) that share attributes of both platform modes (i.e., Lithocodium-Bacinella-dominated facies followed by platform drowning. It is proposed that the Portuguese sections provide important information on latitudinal changes in Lower Aptian shallow-water sedimentation.