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

Dirnerová D., Janočko J.

Geological Quarterly

2014

Vol. 58, No. 1

41--50

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 Early Oligocene Cergowa Sandstone (Outer Western Carpathians) also shows their potential as an indicator of flow condition during the deposition. The massive and amalgamated sandstones, predominantly containing load casts and minor flutes and grooves with unidirectional orientation, are suggested to be deposited by highly turbulent flow after reaching hydraulic jump behind the topographic obstacle. High range of sole structures in thick and medium thick sandstones, suggesting inferior oblique and reverse flows, implies deposition from density stratified flows where lower, denser part has a tendency to deflect when hit the 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.

Sedimentary record of the Dukla Basin (Outer Carpathians, Slovakia and Poland) and its implications for basin evolution

Dirnerová D., Prekopová M., Janočko J.

Geological Quarterly

2012

Vol. 56, No 3

547--560

The Late Cretaceous to Oligocene strata of the Dukla Nappe, which is a part of the accretionary wedge formed in front of the Carpathian orogen, record a history of the basin development from remnant to foreland basin stages. The lower part of the succession indicates the first stage of basin evolution characterized by turbidite systems fed from the E (NE) to W (SW). The system encompasses deposits of the Łupków and Cisna formations deposited in a channel-lobe transition (Łupków Fm.) and in sandstone-rich channelized lobes (Cisna Fm.) The transitional phase is represented by deposits of the Submenilite Formation derived from two different sources (SE and N) and deposited in a submarine slope/ramp environment. The third stage of basin evolution is marked by the advancing front of the Carpathian orogen resulting in peripheral foreland basin development. Increased tectonic activity led to a switch in sediment source from the SE to the NW, more complex topography of the basin and a change in sediment distribution. The initial phase of this stage is characterized by low-density turbidites and suspension fall-out sediments of the Menilite Fm. Discrete tectonic pulses are recorded by the thick Cergowa sandstones, mostly deposited by hybrid flows and high-density turbidity currents. A decrease in tectonic activity is suggested by heterolithic deposits of the Krosno Fm. capping the sedimentary succession.