Fossil karst in the Jurassic of Kościuszko Mound in Kraków (southern Poland)

Abstract

Study of four boreholes (each 100 mdeep) drilled in the St. Bronisława Hill (a part of the horst of the Wolski Forest, Kraków area) indicated that within the Oxfordian limestone occur claystones with calcareous rubble (detritus), filling the fossil karst forms. The claystones, that in some cases show planar stratification, contain assemblages of Late Cretaceous (Campanian–Maastrichtian) foraminifers. The Middle Miocene planar laminated limestones have also been found in cavities formed in the Middle Oxfordian limestones. Miocene deposits of this type, filling the fossil karst, were not previously known from the area of Kraków. Both the Upper Cretaceous and the Middle Miocene deposits document probably marine sedimentation that resulted in the filling of the karst system. This type of karst was probably formed before the transgression of the Upper Cretaceous sea and the subsequently before the transgression of the Middle Miocene sea into the area of present horst of the Wolski Forest.