Geologos, 2019, 25, 1

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The interpretative significance of ripple-derived sedimentary structures within an upper Neogene fluvial succession of central Poland
(Wydawnictwo Naukowe UAM, 2019-04) Maciaszek, Piotr; Chomiak, Lilianna; Wachocki, Robert; Widera, Marek
Sedimentary structures discussed in the present study are genetically linked to ripples that consist of pure sand or al- ternating sand and mud layers. All types of ripple-related structures, such as climbing-ripple cross-lamination and het- erolithic bedding, i.e., flaser, wavy and lenticular (nodular), have been identified for the first time in fluvial strata that have been characterised previously as commonly massive. These small-scale bedforms, produced by migrating ripples, have been documented in a fluvial channel of late Neogene age in central Poland. The abundance and co-occurrence of the structures discussed and their spatial distribution provide evidence of their formation under very low-energy conditions, when flow velocity changed markedly, but was often significantly less than 0.5 m/s. Therefore, these rip- ple-derived sedimentary structures are here recognised as typical of channel fills of an anastomosing river.