Biogenic structures of organics‐poor siliciclastic sediments: Examples from Paleogene variegated shales, Polish Carpathians

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Abstract
The chiefly red and green (variegated), muddy to clayey sediments of the Polish Carpathian flysch display low diversity assemblages of macroscopic biogenic sedimentary structures (trace fossils). Plano‐lites and Chondrites are the most common distinctive traces in these sediments. A restricted food supply for tracemakers and low shear strength of sediments inhabited by them are suggested as the chief factors responsible for the low diversity of biogenic structures. Because of temporal fluctuations in rates of sediment accretion and/or changes in food supply some bioturbation occurred cyclically in what we are now the variegated shales.