Refining the timing of Middle Pleistocene ( MIS 12 to MIS 6) ice advances into northern central Europe: Sedimentological analysis and single‐grain luminescence dating of glaciotectonic complexes and tunnel‐valley fills

The timing of the Middle Pleistocene ice advances into northern central Europe is still disputed. In this study, we summarize the current state of knowledge on the age of the Middle Pleistocene Saalian and Elsterian ice advances into northern central Europe and provide new single‐grain luminescence ages of related meltwater deposits. Twenty‐five samples for luminescence dating were taken from five different Saalian ice‐marginal positions and (upthrusted) Elsterian tunnel‐valley fills in northern Germany. The sampled Elsterian deposits mainly comprise subaqueous fan and delta sediments, which were deposited in glacial lakes that formed in underfilled tunnel valleys and their marginal areas. The estimated luminescence ages range between >578 and 346±98 ka, probably correlating with Marine Isotope Stage (MIS) 12, although an older and/or younger age (MIS >14 to MIS 8) cannot be excluded. During MIS 6, four different ice advances are recorded from the study area. During the maximum extent of the first and second Saalian Drenthe ice advances, large ice‐dammed lakes formed along the Fennoscandian ice sheets, which catastrophically drained during ice‐margin retreat. Further north, glaciofluvial fans and/or larger glaciofluvial distributive systems formed along the ice sheets. The first Saalian Drenthe ice advance probably occurred during MIS 6e‐d. However, the estimated luminescence ages range between 293±59 and 209±37 ka, and therefore, we cannot rule out an earlier Saalian pre‐Drenthe ice advance into the north‐eastern part of the study area. After a phase of ice‐sheet retreat, fluvial erosion and soil formation, the second Saalian Drenthe ice advance probably occurred during late MIS 6c. The estimated luminescence ages range between 172±38 and 123±18 ka. Meltwater deposits that are related to the third Saalian Drenthe (Hondsrug ice stream) and/or Warthe ice advances have luminescence ages of 128±19 to 123±22 ka, correlating with MIS 6b‐a. The glaciotectonic complexes partly have a multiphase development related to the different Saalian ice advances. Smaller composite ridge systems with shallow detachments (20–60 m deep) evolved in areas with tunnel‐valley fills, probably controlled by the rheological contrasts between sandy meltwater deposits and underlying fine‐grained deposits of the uppermost Elsterian tunnel‐valley fills (Lauenburg Clay Complex). In contrast, larger glaciotectonic complexes with deep detachments (>100 m deep) formed further south (‘Rehburg line’) where large tunnel valleys are absent.