Ordovician through earliest Devonian development of the Holy Cross Mts. (Poland): constraints from subsidence analysis and thermal maturity data

Abstract

The Lysogóry Block (LB) exposed in the northern Holy Cross Mts. (HCMts.) reveals subsidence and thermal development consistent with the pattern observed in adjoining East European Craton (EEC) areas. This evidence, in addition to previously reported similarities in sedimentation and deep crustal structure, contradicts the Pożaryski's hypothesis that the Lysogóry Block represents a terrane within the Caledonian orogen. This area is here interpreted as the part of a Late Silurian foredeep basin which developed on the Baltica margin in response to terminal phases of collision with Eastern Avalonia. The development of the continuous Late Silurian foredeep basin along the EEC margin from the Peri-Tornquist Basin in the north-west to the present northern HCMts. implies that the North German-Polish Caledonides orogen had its NE continuation near the present Holy Cross area. The southern HCMts. comprise the northern margin of the Malopolska Massif (MM). The Ordovician-Silurian subsidence development of this area, its thermal history and crustal structure point to a stable cratonic setting. Existing similarities in sedimentary succession (mostly Ordovician and Lower Silurian) as well as clearly Baltic palaeobiogeographic affinities indicate a close spatial connection between the MM and Baltica during the analysed time interval. The juxtaposition of the MM against the LB area can be explained assuming that the MM is a part of Baltica detached from its margin due to right-lateral strike-slip after late Ludlow and before Emsian time.