Refining the late Silurian sea-level history of the Prague Syncline—a case study based on the Přídolí GSSP (Czech Republic)

A 50-m-thick section in the Požáry quarry, Prague Syncline (Czech Republic) spanning the upper Silurian (uppermost Ludlow and Přídolí) to the lowermost Devonian (Lochkovian) has been studied using sedimentological and physical stratigraphical (gamma-ray spectrometry) methods combined with conodont biostratigraphy. Conodont data demonstrate the presence of local conodont biozones: “ Ozarkodina” crispa (uppermost Ludlow)— Zieglerodina zellmeri (base of Přídolí)— Zieglerodina ivochlupaci — Delotaxis detorta —“ Ozarkodina” eosteinhornensis s.s.— Zieglerodina klonkensis — Icriodus hesperius - optima (lowermost Lochkovian). The studied section represents a transgressive–regressive facies succession characterized by a transition from distal calciturbidites deposited in a distally steepened carbonate platform during transgression and sea-level highstand ( crispa to lower ivochlupaci zones) to mixed calciturbidites/coarse-grained bioclastic limestones (falling-stage systems tract, upper ivochlupaci to lower klonkensis zones). The upper part of the succession consists of bioclastic limestones corresponding to a subtidal setting between storm-wave and fair-weather wave base (lowstand systems tract in upper klonkensis and hesperius - optima zones). This interpretation corresponds to the late Silurian global sea-level pattern as recorded in other regions. Thus the depositional system is interpreted as mostly driven by eustasy with short-lived periods of influence from local tectonics.