Depositional environment and provenance of the pre-glacial Słopiec Formation, Holy Cross Mountains (Poland)

Abstract

The pre-glacial, autochthonous deposits of the Słopiec Formation represented by the Jabłonna and Radzików members, were identified in two new boreholes – Jabłonna UJK-1 and Słopiec UJK-2 – which were drilled in the Słopiec Basin in the Holy Cross Mountains. Their sedimentary environment, provenance, and environmental conditions were determined using sedimentological, mineralogical-petrographic, geochemical, geophysical and palynological methods. The boundaries of the Słopiec Formation are well defined. It lies on the Paleozoic bedrock and is overlain by glacial deposits, the precise chronostratigraphic position of which remains under discussion. The basal Jabłonna Member comprises lacustrine deposits (muds; silts and silts with interlayers of sands and with organic detritus, which overlie gravels), while the overlying Radzików Member consists of fluvial (fluvio-aeolian) deposits (sands and sands with gravels). Deposition took place in karst lakes, probably meromictic, in a cold climate. The source material came from the local weathering covers (Paleozoic, Mesozoic and Paleogene-Neogene). Palynological analysis (7 samples) revealed the presence of 118 taxa, including 23 cryptogam taxa, 20 gymnosperm taxa, 51 angiosperm taxa and 24 phytoplankton taxa, indicating significant mixing and repeated redeposition of palynomorphs from various sources. The final phase of deposition of the Jabłonna Member occurred during the Quaternary Period. The results described provide the first detailed description of pre-glacial deposits in the Holy Cross Mountains and will serve as an important reference for future regional and extra-regional lithostratigraphic correlations.