Dislocation of Eemian peat in a deglaciation succession: stratigraphical implications for the Neubrandenburg area

A large gravel pit 30 km north of the Pomeranian ice margin has been investigated. Besides gravel, sand, fines and diamicton, several deposits of organic material are present, some of them showing a typical Eemian Pollen- and macroflora. Previous interpretations assume that the sediments below the Eemian peat belong to the Saalian, and those above the peat to the Weichselian. Sorted sediments in the central part of the pit are interpreted as Elsterian and Saalian glacifluvial channel fills. This study shows that all sediments in the pit belong to the last deglaciation and that none of the peat layers are in situ. Rafts of older sediments, including peat and older tills, have been dislocated during an ice advance and finally deposited in a dead-ice environment during the retreat of the last ice sheet. The dominating gravel and sand deposits in the central part of the pit are interpreted as an intermediate braided river system in the dead-ice landscape. Debris-rich dead-ice melted down and melt-out material as well as mass-movement deposits were deposited. Pollen assemblages from the different organic materials suggest both Eemian and Tertiary origin. All of them are re-deposited. Since Eemian and Tertiary peat are not in situ in this open section, organic material from drill holes in the vicinity may also be re-deposited and might not serve as stratigraphical marker horizons. Thus, stratigraphical marker horizons such as peat cannot be accepted unconditionally, but must be proved in their sedimentological, stratigraphical and structural context.