Sole structures as a tool for depositional environment interpretation; a case study from the Oligocene Cergowa Sandstone, Dukla Unit (Outer Carpathians, Slovakia)

摘要

Sole structures, typically developed on basal bedding surfaces of turbidite sandstones, are commonly used as palaeocurrent indicators and indicators of the current ability to erode. Detailed analysis of types and frequency of sole structures in the 128-m-thick succession of Lower Oligocene Cergowa Sandstone (Outer Western Carpathians) also shows their potential as an indicator of flow properties during the deposition. The massive and amalgamated sandstones, predominantly containing load structures and minor grooves with unidirectional orientation, are suggested to be deposited by high-density turbidity currents and debris flows. A wide range of sole structures in thick and medium thick-bedded sandstones, suggesting oblique and reverse flows compared to the main palaeoflow direction, implies deposition from density-stratified flows where the lower, denser part has a tendency to deflect when hits a basin floor obstacle. The upper, less dense part has an ability to come over the obstacle and shows only small scatter in the palaeocurrent direction.