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Oceanic Anoxic Event 2 (Cenomanian–Turonian) record in the northwestern part of the Adriatic Carbonate Platform (Istria and Kvarner, Croatia) – progress report and future directions

The well-documented, global Oceanic Anoxic Event 2 (OAE2, Bonarelli event) is generally manifested in shallow-marine carbonate depositional systems by a rather weak signal, which is also commonly masked by postdepositional diagenetic and tectonic modifications. This study includes investigation of the OAE2 record in the northwestern part of the former Adriatic Carbonate Platform (AdCP), in present- day Istria (Ćićarija, Barban) and Kvarner (Premuda), and also incorporates the results from earlier studies in Croatia (Dugi otok and Brač). In the focus of this research are intraplatform basin/drowned platform deposits, formed during positive eustatic changes at the Cenomanian–Turonian boundary (CTB), and their relationships with underlying and overlying shallow-marine deposits. To provide a more complete overview of depositional events and paleoenvironmental conditions, this study utilized the litho-, bio-, and microfacies analyses, as well as SEM, EDS, TOC, and stable isotope (δ13C and δ18O) analyses. The documented δ13C and δ18O values, TOC fluctuations, turnovers in benthic foraminifer’s assemblages, diversification and expansion of planktonic foraminifera and calcareous dinoflagellates, and the presence of hypoxic and/or anoxic conditions provide new insights into the character of the CTB interval in this part of the Tethyan realm. Synsedimentary tectonism reflects the dynamics and complexity of this area during the late Cenomanian and early Turonian, which was later overprinted by the uplift of the Dinarides and subsequent neotectonic movements. The research results so far encourage future applications of similar approaches to other AdCP areas, especially in its central part (e.g., the central Mt. Dinara area) in order to better understand the larger regional response of this carbonate platform to prominent global OAE2 perturbations.

Istria, Kvarner, OAE2, Cenomanian–Turonian, Adriatic Carbonate Platform (AdCP)

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