CLIMATE CHANGE AND CARBON CYCLE PERTURBATIONS IN THE NORWEGIAN-GREENLAND SEAWAY DURING THE LATEST JURASSIC AND EARLY CRETACEOUS

During the Late Jurassic—Early Cretaceous, the humid climate of north-western Europe was punctuated by a widespread arid phase, but the temporal and geographic extent of this climatic shift is poorly understood. Clay mineralogical and palynological records reveal increasing aridity in the latest Jurassic and a transition to humid conditions in the early-mid Berriasian (earliest Cretaceous), widely believed to have occurred later at higher latitudes within the mid-late Berriasian. In order to assess the precise timing of this climatic shift, stratigraphic fidelity is critical.

This study aims to understand the exact timing and extent of the Early Cretaceous climatic shift. Here we use high-resolution age models for several sections from the Norwegian Continental Shelf, produced by bio-, cyclo- and chemostratigraphic correlation. Detrital kaolinite is a palaeoclimatic proxy; its presence and relative abundance in clay mineral assemblages indicates humidity. At ~30 °N in north-western Europe, kaolinite is known to have reappeared in the clay mineralogical record during the early-mid Berriasian. However, we find an absence of kaolinite at ~40 °N in the North Sea until the late Berriasian, confirming that initiation of the first humid phase in the Early Cretaceous was diachronous.

Our regional-scale correlation reflects a high correlation potential across significant distances and allows precise dating of climatic events in the Norwegian-Greenland Seaway. While physical properties or biostratigraphic data alone usually do not allow precise correlation, we have constructed high-resolution age models by an integrated approach. This has provided an excellent opportunity to study the precise timing of climatic impacts during the Late Jurassic‒Early Cretaceous in a N-S transect of the Norwegian-Greenland Seaway, and therefore improve stratigraphic integrity in the area.