The time-transgressive initiation of boreal ice-caps: continental and oceanic evidence reconciled
Abstract Oxygen isotope analyses of planktonic foraminifera and organic carbon 13C measurements of the sediment at DSDP Site 116, compared with planktonic foraminiferal counts and sedimentological investigations previously published by Poore and Berggren, indicate: (1) that the Hatton-Rockall Basin did not undergo any significant temperature change 3.1 Ma ago, when the first boreal ice-caps were established on the western side of the North Atlantic; (2) that the ice-rafted detrital grains appeared close to 2.7 Ma ago, still without noticeable change in the growth temperature of the plankton; and (3) that the major cooling took place at about 2.3 Ma and can be correlated with the Pretiglian first cold phase in northern Europe. Thispattern of climatic change shows the existence of a lag in the initial glaciation of the western and eastern shores of the Atlantic and can be explained by the persistence of the North Atlantic drift between 3.1 and 2.3 Ma in the northeastern Atlantic Ocean.