| dc.description.abstract | Sedimentation in the North Atlantic Ocean underwent fundamental changes during the Cretaceous.
From a Late Jurassic restricted basin regime, characterized by a large influx of siliciclastics, to a Mid –
Late Cretaceous widening basin with open circulation and a prominent biogenic component. A
systematic analysis of sediment and mineral composition of the Cretaceous cores in IODP sites was
made. The study covers; Moroccan offshore, Iberian offshore, Celtic Sea Basin, Grand Banks, Blake
Bahama Basins, and Demerara Rise Basins. This dissertation aims to enhance the understanding of
the effect of climatic and oceanographic changes on the general sedimentary infill of the North
Atlantic during the Cretaceous.
The western and eastern Early Cretaceous North Atlantic commenced as wet and humid, the
northern North Atlantic was prone to strong terrigenous deposition. Aptian large eustatic sea level
rise, shoaling CCD and heating climate led to widespread clay deposition. The climatic and
oceanographic changes led to OAE formation, from the Aptian onward. The western and
southeastern margins behave differently. Continued warming climate, eustatic sea level rise and
shoaling CCD were responsible for the continued shale deposition and carbonate deposition on the
eastern margin influenced by upwelling. Turonian change to a ventilated margin caused by the deep
water connection to the South Atlantic and cooling climate led to a carbonate dominated western
North Atlantic and a zeolitic clay dominance in the southeastern North Atlantic. The Late Cretaceous
was characterized by marl deposition in the western margin, and clay deposition in the southeastern
North Atlantic. The western and northern continental humidity, continental weathering and high
temperatures created optimum surface for high oceanic primary production. Ventilated oceans on
the southeastern North Atlantic margin led to adverse conditions; less nutrient input and shoaling
CCD leading to large-scale clay deposition. | |
