Magnetic polarity and enviromagnetic stratigraphy of Early Pleistocene terrace deposits of the Lower Moselle: towards a robust chronology of the Main Terraces Complex (MTC) of the Rhenish Massif (RM)

Controlled solely by the Earth's core, Earth's Magnetic Field reverses its polarity aperiodically on time scales of 104 to 106 years. This process is recorded by magmatic rocks and by sediments of a wide range of depositional environments, providing a Magnetic Polarity Stratigraphy (MPS). In combination with climate sensitive magnetic and sedimentological parameters, MPS forms the backbone of Neogene magnetic time scales yielding a temporal resolution of c. 104 years.Here, we combine for the first time the methodologically independent approaches of MPS with cosmogenic depth profile and burial isochron dating in order to improve the chronology of the MTC of the Lower Moselle using up to date methods. Magnetic polarity data from terrace accumulations and their sandy-silty cover beds reveal clear polarity changes from reversed (old) to normal (young) accompanied by climate indicative magnetic and sedimentological characteristics. Taking into account relative terrace elevations and age constraints from cosmogenic dating, a chronostratigraphic assignment of the MTC to an age interval ranging from c. 1.3 to 0.78 Ma is proposed. This period is characterized by increasing uplift of the RM marking the end of the trough valley period and antedating the onset of the formation of the entrenched valleys. The palaeomagnetically dated increase in subsidence of the Upper Rhine Graben at about 1 to 1.2 Ma ago (Scheidt et al., 2015) coincides with the magnetic dating of the end of the trough valley period in the RM suggesting a common cause of a fundamental change in western European crustal stress fields.