Lithostratigraphy and regional significance of the Nowa Słupia Group (Upper Silurian) of the Łysogóry Region (Holy Cross Mountains, Central Poland)

Abstract

The Ludlovian-Lochkovian succession of the Łysogóry Region of the Holy Cross Mountains (Central Poland) represents an infill of a Caledonian foreland basin situated at the SW margin of the East European Craton (EEC). The facies pattern and transport directions indicate that the source area was located westward from the basin and was separated from the Baltica mainland by the epicratonic sea. The 2.5 km thick succession, defined here as the Nowa Słupia Group, has been subdivided into 9 formations (from bottom to top: Trzcianka, Trochowiny, Winnica / Rachtanka, Sarnia Zwola / Bronkowice, Podchełmie, Rudki and Bostów formations). Arevised lithostratigraphic scheme has been constructed. The lower part of the Nowa Słupia Group (Trzcianka and Trochowiny formations) represents the underfilled stage of the basin development and is composed of flysch-like sediments. The upper part of the group represents the filled to overfilled stage of the basin. In the latter stage the lateral migration of two main facies: red continental deposits (represented by the Rachtanka and Podchełmie formations) and open shelf hemipelagic sediments (represented by the Sarnia Zwola and Rudki formations and referred here to the Podlasie facies), is observed. The lateral facies migrations probably resulted fromeustatic fluctuations. The twomain facies zones are separated by a narrowbelt of neritic sediments (represented by the Winnica, Bronkowice and Bostów formations), which are known for their rich benthic fauna. The facies trends observed show that during the latest Ludlovian through early Pridolian, the boundary between the continental and marine facies in the Łysogóry Region was oriented parallel to the Baltica margin (NNW-SSE).