Upper bathyal trace fossils document palaeoclimate changes

Marine trace fossils were investigated in a 102-m cored section that covers −14.379 to −14.142 Ma (Middle Miocene). Long-term climate trends are perfectly reflected by changing trace fossil communities of the upper bathyal (−200 to −300 m). The community structure is expressed in abundance of taxa based on probabilities of time concordance between the deposition of the sediment and the time, when the traces were produced. Changes in community structure precisely parallel the increasing δ¹³C isotopes during the Middle Miocene climate transition and perfectly mirror oscillations in solar insolation in both amplitudes and phase. Furthermore, the density stratification of the seawater caused by wind-induced currents is reflected in trace fossil communities. Additionally, the dependence of ichnotaxa abundance from threshold values in the sedimentation rate could be demonstrated.