Integrated stratigraphy and new radiolaria bioevent constraints of Late Pliocene to Holocene sediments from the subpolar North Atlantic (IODP Site U1314)

Radiolarian biozonations constitute an important tool in Cenozoic stratigraphic studies in polar regions. Neogene-Quaternary radiolarian biostratigraphical schemes have been established mainly in low latitude regions, but only a few attempts have been carried out in the high-latitude North Atlantic. In this study, we quantitatively analyze a radiolarian zonation for the Late Pliocene-Holocene (3 Myr to present) at IODP Site U1314 (Gardar Drift, 56.36°N, -27.88°E, 2820 m water depth). The present study focuses on taxa of both stratigraphic importance and of limited occurrence. Specifically, we determined several radiolarian bioevents, some of which are the first time that they are found in the North Atlantic, such as the last occurrences of Druppatractus irregularis Popofsky and Cycladophora sakaii, and first occurrence of Cycladophora davisiana Ehrenberg. In addition, we described two new radiolarian species; Pseudocubus abruptus n.sp. and Spongasteriscus chiasmos n.sp., whose biostratigraphic ranges are also defined and have the potential to be used as biomarkers across the high-latitude North Atlantic Ocean.

In addition to the new radiolarian biostratigraphic record, on-board bio and magnetostratigraphy, refined relative paleointensity and physical property records, and published isotope stratigraphy and radiocarbon ages were used to construct an integrated chronostratigraphic framework at Site U1314 to constraint the new radiolarian bioevents. The stratigraphic distributions of these marker species indicates that the radiolarian scheme proposed herein has a potential to be applied in a broader region, from the mid-latitude North Atlantic, north of about 40°N to the Norwegian Sea. Furthermore, comparison of the radiolarian bioevents with other northern hemisphere datasets provides novel perspectives on the evolutionary dynamics, ecological adaptation and origins of radiolarian lineages.