Biostratinomy of dune tracks in sub-0 °C temperature

Abstract

Trackways left in dune sand spark intrigue with their ephemeral nature. Small animals (arthropods and vertebrates) leave their footprints in eolian sands but such tracks do not last long. Wind and avalanching may re-mobilize sand grains and obliterate their footprints, ultimately preventing them from entering fossil record. Some of these fleeting tracks are lucky enough to survive at the parting surfaces between sedimentary layers. This paper highlights the possible role that sub-0 °C temperatures play in the biostratinomy of eolian tracks. Water combined with sub-0 °C temperatures may create short-lasting ice cementation within the very top of an active sand layer—mm-scale crust. The temporal cement stabilizes the surface, inhibits the re-mobilization of sand particles and hinders the obliteration of footprints. Such crust may provide a brief time window of enhanced preservation potential, protecting tracks until incoming sand buries them. On the contrary, if the ice-cement crust forms before the passage of a small and light trackmaker, no tracks are formed at all. This is because the crust is impenetrable to the tiny feet of light animals. Therefore, sub-0 °C temperatures apparently may play both, positive and negative roles in the biostratinomy of eolian tracks.