Warunki temperaturowe w czasie diagenezy piaskowców pensylwanu w rejonie Morza Bałtyckiego
Abstract
Thermal conditions during diagenesis of Pennsylvanian sandstones in the Baltic Sea area.
A b s t r a c t. The purpose of this study is to reconstruct the temperature conditions in the sediment during the diagenesis history of Pennsylvanian sandstones drilled in three deep boreholes in the Baltic Sea. These sandstones are represented by quartz and sublithic arenites and wackes, cemented by matrix and autigenic minerals. Among the autigenic minerals: quartz, clay minerals (kaolinite, dickite, illite) and carbonates (calcite, dolomite, ankerite) are the temperature indicators. The presence of dickite in the sediments indicates a temperature of about 120°C. Quartz and carbonate crystallization temperatures, based on the analysis of fluid inclusions, are estimated to be in the range of 70–180°C. The K/Ar age of the fibrous illite that forms at the final stage of diagenesis (above 100°C), was determined at 262_+2 to 247_+4 My, i.e. from the Middle Permian to the Early Triassic. It determines a length of the post-deposition period, when the deposits were permeable for pore fluids
A b s t r a c t. The purpose of this study is to reconstruct the temperature conditions in the sediment during the diagenesis history of Pennsylvanian sandstones drilled in three deep boreholes in the Baltic Sea. These sandstones are represented by quartz and sublithic arenites and wackes, cemented by matrix and autigenic minerals. Among the autigenic minerals: quartz, clay minerals (kaolinite, dickite, illite) and carbonates (calcite, dolomite, ankerite) are the temperature indicators. The presence of dickite in the sediments indicates a temperature of about 120°C. Quartz and carbonate crystallization temperatures, based on the analysis of fluid inclusions, are estimated to be in the range of 70–180°C. The K/Ar age of the fibrous illite that forms at the final stage of diagenesis (above 100°C), was determined at 262_+2 to 247_+4 My, i.e. from the Middle Permian to the Early Triassic. It determines a length of the post-deposition period, when the deposits were permeable for pore fluids