Palaeoenvironments and palaeoceanography changes across the Jurassic/Cretaceous boundary in the Arctic realm: case study of the Nordvik section (north Siberia, Russia)

• Published in: Polar Research
• Main Authors: Zakharov, V. A., Rogov, M. A., Dzyuba, O. S., Žák, K. (Karel), Košťák, M., Pruner, P. (Petr), Skupien, P., Chadima, M. (Martin), Mazuch, M., Nikitenko, B. L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2014
• Subjects: biodiversity; stable isotopes; J/K boundary; Arctic Realm; palaeoceanography; Arctic; Pacific; Siberia
• Online Access: https://doi.org/10.3402/polar.v33.19714; http://hdl.handle.net/11104/0233682

The Jurassic/Cretaceous transition was accompanied by significant changes in palaeoceanography and palaeoenvironments in the Tethyan Realm, but outside the Tethys such data are very scarce. Here we present results of a study of the most complete section in the Panboreal Superrealm, the Nordvik section. Belemnite δ18O data show an irregular decrease from values reaching up to +1.6> in the Middle Oxfordian and from +0.8 to −1.7> in the basal Ryazanian, indicating a prolonged warming. The biodiversity changes were strongly related to sea-level oscillations, showing a relatively low belemnite and high ammonite diversity during sea-level rise, accompanied by a decrease of the macrobenthos taxonomical richness. The most prominent sea-level rise is marked by the occurrence of open sea ammonites with Pacific affinities. Peak abundances of spores and prasinophytes correlate with a negative excursion in organic carbon δ13C near the J/K boundary and could reflect blooms of green algae caused by disturbance of the marine ecosystem.