New insights into the age of aeolian sand deposition in the northern Upper Rhine Graben (Germany)

Abstract

Generally, it is assumed that deposition of aeolian sands in the northern Upper Rhine Graben (URG) occurred in multiple phases during the Würm glaciation with the main period linked to the Younger Dryas. But the age of the aeolian sands was mainly based on stratigraphic evidence and its location relative to the Rhine and Neckar rivers. Moreover, previous studies about the landscape evolution in the URG suggested that deposition of loess and aeolian sand happened simultaneously. Interestingly, a simultaneous deposition in the study area has never been confirmed, due to lack of geochronological research regarding the aeolian sands. To overcome this and to provide new numerical ages we studied aeolian sands and loess from the northern URG near Darmstadt. The depositional age of the aeolian sands and loess was determined using optically stimulated luminescence dating (OSL). Sand samples were collected from a trench that was dug during the construction of a gas pipeline and samples from loess deposits were taken from outcrops in the western Odenwald. Our results show that deposition of loess took place from 42 to 17 ka ago and aeolian sand from 17 to 10 ka ago confirming a deposition during the end of the Würm glaciation. However, older sand deposits might exist in the study area but could not be reached for sampling. Additionally, our results indicate a younger period of anthropogenic induced redisposition of aeolian sands at around 4 ka. Overall, our results show that aeolian sand activity in the study area continued after loess deposition ended at around 17 ka.