Fluvial system response to Middle and Upper Pleistocene climate change in the Meurthe and Moselle valleys (Eastern Paris Basin and Rhenish Massif)

Research in the Meurthe and Moselle valleys downstream from the Vosges Massif has resulted in the definition of the terrace system, and in the recognition of the climatic influence on its formation. Eight alluvial terraces were recognized at less than 100 m relative height. An absolute chronology was established for the youngest alluvial terraces, based on infrared optically stimulated luminescence and radiocarbon dating. This provides evidence that each terrace corresponds to a single glacial–interglacial cycle. This result is confirmed by the study of numerous sections, which present a constant succession of lithofacies in each valley part. Four alluvial sequences were also defined along the Meurthe and Moselle valleys, reflecting Middle and Late Pleistocene climate change: their upper basin, developed in the Vosges Massif, was actually covered by glaciers during the Pleistocene cold periods. The differences between these four alluvial sequences are attributed to the unequal expansion of ice in the upper basins of the Meurthe and Moselle rivers, and their tributaries.In spite of these differences, the sequences show important similarities: main aggradation events correlate with cold periods (Pleniglacial and Lateglacial), whereas erosional phases occurred at the warm-to-cold transitions, and secondarily at the Pleniglacial–Lateglacial transitions. This evolution is comparable with those already described in other northwestern European valleys, especially since the Upper Saalian.