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, Victor A., Rogov, Mikhail A., Dzyuba, Oksana S., Žák, Karel, Košt’ák, Martin, Pruner, Petr, Skupien, Petr, Chadima, Martin, Mazuch, Martin, Nikitenko, Boris L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Norwegian Polar Institute 2014
• Subjects: Biodiversity; stable isotopes; J/K boundary; Arctic Realm; palaeoceanography; Arctic; Pacific; Polar Research; Siberia
• Online Access: https://polarresearch.net/index.php/polar/article/view/3194; https://doi.org/10.3402/polar.v33.19714

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.Keywords: Biodiversity; stable isotopes; J/K boundary; Arctic Realm; palaeoceanography(Published: 25 March 2014)Citation: Polar Research 2014, 33, 19714, http://dx.doi.org/10.3402/polar.v33.19714