The formation of flute fields in glacial environments

Understanding the processes at glacier beds is crucial as they regulate ice flow, basal sediment dynamics, and meltwater routing, which collectively control glacier stability and response to climate change. Flute fields are a vital archive of subglacial processes, widespread in both terrestrial and marine glacial environments, whereby sediments are fashioned subglacially into lineations at different scales. The assemblages are highly variable in both environments, yet models to explain this are outstanding, and aspects of preservational bias are rarely entertained. Integrating observations from modern Alpine forefields (Austria) with exceptionally preserved Late Ordovician and Late Paleozoic examples in Africa and Arabia, we interrogate terrestrial and glaciomarine flute fields. Flutes, megaflutes, and diamictons occur in both settings, but architecture is strongly context-dependent. Terrestrial flutes degrade rapidly under surface meltwater and rainfall, whereas marine flute fields are commonly preserved beneath fine-grained shales, recording stacked lobate sediments with superimposed mega-scale glacial lineations, metre-scale flutes, and centimetre-scale soft-sediment striae. Oversteepened subaqueous flutes collapse laterally, forming fan-shaped deposits, and lateral margins exhibit scalloped surfaces that record focused subglacial meltwater discharge. We propose a conceptual model in which metre- and centimetre-scale lobes act as miniature grounding zone wedges, forming through simultaneous deposition and shearing beneath tidewater glaciers. This framework reveals how subglacial processes are recorded in preserved landforms and demonstrates that integrating modern and ancient records is essential to understanding glacier–bed interactions.