Miocene climate evolution of northern Europe: A palynological investigation from Denmark

A palynological investigation has been conducted on Lower–Upper Miocene sediments from Jylland, Denmark, corresponding to the time interval of about 19 to 8 Ma. The sediments, derived from the Sdr. Vium drill core, were deposited in marine to marginal-marine environments, as shown by the relatively high abundance of dinoflagellate cysts in all samples. Nevertheless, rich and diverse pollen assemblages occur throughout the succession and the palynological analysis reveals that coastal areas of the study area were during the Miocene dominated by Taxodium swamp forests that also hosted terrestrial angiosperms such as Nyssa, Betula, Alnus and elements of the Myricaceae. Further inland, a mixed deciduous–evergreen forest prevailed. In areas with better drained soils, or on elevated areas, gymnospermous conifer forests prevailed including taxa such as Pinus, Sequoia and Sciadopitys. Overall, the climate in the study area was warm temperate during major parts of the Miocene with mean annual temperatures between 15.5 and 20 °C. By employing the Coexistence Approach combined with the method of allocating taxa into standardized climatic groups, four different climatic Miocene events are detected within the studied succession correlated to the coeval climate record of northwestern Europe. The oldest event is a cooling during the earlier Burdigalian, at approximately 19 Ma, coinciding with the MBi-1 oxygen isotope excursion. At ca. 18.5 Ma (in mid-Burdigalian) a warming phase is reconstructed, characterized by the highest precipitation rates observed in the sedimentary succession. A warming trend, starting in the latest Burdigalian, corresponds to the globally recognized Middle Miocene Climatic Optimum (MMCO) while a longer-term late Neogene cooling was initiated in the mid Serravallian, about 13 Ma.