TY - JOUR
T1 - Cretaceous Oceanic Anoxic Event 2 in the Arobes section, northern Spain
T2 - Nannofossil fluctuations and isotope events
AU - Melinte-Dobrinescu, Mihaela C.
AU - Bernárdez, Enrique
AU - Kaiho, Kunio
AU - Lamolda, Marcos A.
N1 - Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.
PY - 2013
Y1 - 2013
N2 - The Cenomanian-Turonian boundary interval of the Arobes section, northern Spain, represents the maximum depth of a relatively shallow succession. The investigated section extends within the Rotalipora cushmani and Whiteinella archaeocretacea planktonic foraminiferal zones, and from UC3 up to UC8 nannofloral zones, respectively. The Oceanic Anoxic Event 2 (OAE2) is about 16 m thick and includes a positive δ13C excursion, from 3 up to 5.5‰. The first peak of δ13C is situated towards the upper part of the Rotalipora cushmani planktonic foraminiferal zone, while the second peak of δ13C is situated in the lower part of the Whiteinella archaeocretacea planktonic foraminiferal zone. The plateau, the youngest phase of OAE2, ends slightly above the first occurrence (FO) of the nannofossil Quadrum gartneri. Based on nannofloral fluctuation, an unstable environment is recognized from the last occurrence (LO) of the nannofossil Axopodorhabdus albianus up to the FO of the nannofossil Quadrum gartneri. Mesotrophic, eutrophic and oligotrophic nannofossils have successive peaks throughout the OAE2. In the lower part of OAE2, especially in the trough phase and second build-up, productivity increased. The calcareous dinoflagellate Thoracosphaera spp. peaks up to almost 30% in the lower part of the second build-up phase. The critical nannofloral turnover episode is characterized by impoverished calcareous nannofossil assemblages and temporary disappearances of high-fertility taxa, such as Biscutum constans and Zeugrhabdotus erectus. This shift in nannofloral assemblages starts in the last stages of OAE2; that is, towards the top of the second build-up phase and also covers the main part of the plateau phase of δ13C.
AB - The Cenomanian-Turonian boundary interval of the Arobes section, northern Spain, represents the maximum depth of a relatively shallow succession. The investigated section extends within the Rotalipora cushmani and Whiteinella archaeocretacea planktonic foraminiferal zones, and from UC3 up to UC8 nannofloral zones, respectively. The Oceanic Anoxic Event 2 (OAE2) is about 16 m thick and includes a positive δ13C excursion, from 3 up to 5.5‰. The first peak of δ13C is situated towards the upper part of the Rotalipora cushmani planktonic foraminiferal zone, while the second peak of δ13C is situated in the lower part of the Whiteinella archaeocretacea planktonic foraminiferal zone. The plateau, the youngest phase of OAE2, ends slightly above the first occurrence (FO) of the nannofossil Quadrum gartneri. Based on nannofloral fluctuation, an unstable environment is recognized from the last occurrence (LO) of the nannofossil Axopodorhabdus albianus up to the FO of the nannofossil Quadrum gartneri. Mesotrophic, eutrophic and oligotrophic nannofossils have successive peaks throughout the OAE2. In the lower part of OAE2, especially in the trough phase and second build-up, productivity increased. The calcareous dinoflagellate Thoracosphaera spp. peaks up to almost 30% in the lower part of the second build-up phase. The critical nannofloral turnover episode is characterized by impoverished calcareous nannofossil assemblages and temporary disappearances of high-fertility taxa, such as Biscutum constans and Zeugrhabdotus erectus. This shift in nannofloral assemblages starts in the last stages of OAE2; that is, towards the top of the second build-up phase and also covers the main part of the plateau phase of δ13C.
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U2 - 10.1144/SP382.7
DO - 10.1144/SP382.7
M3 - Article
AN - SCOPUS:84890088932
VL - 382
SP - 63
EP - 84
JO - Geological Society Special Publication
JF - Geological Society Special Publication
SN - 0305-8719
IS - 1
ER -