Sea-level markers in West and South Greenland detected in fossil beach deposits using ground-penetrating radar

Abstract:

Melting of the Greenland ice sheet contributes to global sea-level change and results in uplift of the Greenland lithosphere due to unloading. The result of these processes has left fossil raised beach ridge systems several tens of meters above present sea-level. These beach ridge systems were formed during the Holocene, and they represent a proxy for the establishment of relative sea-level curves for this important time period.

Here, we present ground-penetrating radar images of fossil raised beach ridge systems from western and southern Greenland. The radar images show the overall beach ridge system development and show traces of processes, as for example solifluction, which have disturbed the original beach deposits. Moreover, we interpret the transition from beach face deposits to upper shoreface deposits based on the radar images. The markers obtained in this way probably represent a level close to sea-level at the time of formation of the beach ridge deposits, and thus we suggest to use these markers to form the basis for construction of relative sea-level curves over time. We discuss our interpretation in the light of previous findings from other (micro-tidal) environments in southwest Scandinavia, where the tidal range is much smaller.

Finally, advantages of using ground-penetrating radar images collected across beach ridge systems for estimation of relative sea-level fluctuations during the Holocene are discussed and the methodology is compared to other methods, for example isolation basin or beach ridge surface morphology studies, which have traditionally been widely used in Greenland.