Piaskowce i zlepieńce plejstoceńskie w dolinie dolnej Wisły
Abstract
PLEISTOCENE SANDSTONES AND CONGLOMERATES IN THE LOWER VISTULA RIVER VALLEY
Summary
Pleistocene sandstones and conglomerates forming stratified irregular patches from a few cm to 6 m thick are found in several places on slopes of valleys of the Lower Vistula River and its tributaries. These patches occur everywhere at the same altitude, 50 m a.s.l., and stratigraphic position, that is in the top of intermorainic sands and gravels and below the second (counting from the surface of morainic till layer which records early-Midle-Würm advance of Scandinavian ice-sheet in this area (5). The studies showed that cement of these deposits is formed by either plateau or microcrystalline calcite. The present authors relate cementation processes to fluvial subglacial environment and stagnant crypto-areally decaying ice. In this environment, disintegration of ice resulted in origin of local hydrodynamic and thermic gradients. These gradients stimulated intense migration and concentration of CO2 supplied under high pressure from melting ice masses as well as CaCO3 from dissolution of carbonate rock debris present in morainic material. The concentrations of CO2 and CaCO3 were originatin in areas of disintegration of ice, where expansion of subglacial waters and escape of CO2 to atmosphere were taking place. This resulted in cementating precipitation of CaCO3.
Summary
Pleistocene sandstones and conglomerates forming stratified irregular patches from a few cm to 6 m thick are found in several places on slopes of valleys of the Lower Vistula River and its tributaries. These patches occur everywhere at the same altitude, 50 m a.s.l., and stratigraphic position, that is in the top of intermorainic sands and gravels and below the second (counting from the surface of morainic till layer which records early-Midle-Würm advance of Scandinavian ice-sheet in this area (5). The studies showed that cement of these deposits is formed by either plateau or microcrystalline calcite. The present authors relate cementation processes to fluvial subglacial environment and stagnant crypto-areally decaying ice. In this environment, disintegration of ice resulted in origin of local hydrodynamic and thermic gradients. These gradients stimulated intense migration and concentration of CO2 supplied under high pressure from melting ice masses as well as CaCO3 from dissolution of carbonate rock debris present in morainic material. The concentrations of CO2 and CaCO3 were originatin in areas of disintegration of ice, where expansion of subglacial waters and escape of CO2 to atmosphere were taking place. This resulted in cementating precipitation of CaCO3.