Palynological evidence for Miocene climatic cooling in eastern Iceland about 9.8 Myr ago

Abstract

The processes which led to the Pleistocene glaciations in the Northern Hemisphere are presently known only from fragmentary evidence of major Tertiary climatic cooling events1,2. Although there is good evidence3 for glacial intervals in Alaska 10–9 Myr, most terrestrial records4,5 which suggest a corresponding high-latitude climatic cooling in the north-east Atlantic are poorly dated, and North Atlantic palaeoceanographic records contain large erosional hiatuses2,6. We have obtained new palynological data from eastern Iceland, from clastic units between lava formations dated by K–Ar and palaeomagnetic methods7,8. We now report that these data record a floral succession which suggests that a temperature decrease of ∼10°C occurred in Iceland between 10 and 9.5 Myr.