Carbonate-clastic sediments of the Dudziniec Formation in the Koscieliska Valley (High-Tatric series, Tatra Mountains, Poland): role of syndepositio nal tectonic activity in facies development during the Early and Middle Jurassic

摘要

Sediments of the Dudziniec Formation (Lower Jurassic Aalenian) outcropping in the Koscieliska Valley (autochthonous unit of the High-Tatric series) are represented by a range of mixed carbonate-clastic deposits. Seven lithofacies have been distinguished based on lithology, sedimentary structures, colour and composition of intra-and extraclasts, with sandstones and crinoidal limestones as end members of a continuous spectrum of fades. The study area represents a shallower part of the sedimentary basin located in the vicinity of source areas, as compared to the Chochotowska Valley region located in the west. Fades characteristics and distribution were controlled mainly by synsedimentary tectonic activity, with sandy varieties representing periods of faulting with enhanced influx of extraclasts, and with crinoidal limestones corresponding to intervals of relative tectonic stability. Such influence of synsedimentary tectonics on the deposition in the Early Jurassic strongly resembles the Middle Jurassic development in the High-Tatric area. Neptunian dykes cutting the Dudziniec Formation, and most probably filled by Lower Jurassic sediments, are yet another indication of tectonic instability of the area in the Early Jurassic.