Episodes of intense chemical weathering recorded in the Hettangian profiles from Holy Cross Mts margin (new research results)

Abstract

Results of new mineralogical and geochemical research on clay deposits of the Rhaetian-Hettangian successions from the Holy Cross Mts. margin (south-eastern part of the epicontinental Polish basin) are presented. The clay mineral assemblages were mostly controlled by climatic conditions and weathering regime. Reworking of ancient sediments and the early diagenesis could modify the clay mineral composition. Some levels of the high kaolinite content at the Triassic-Jurassic boundary suggest intense continental weathering in the humid-subtropical to tropical climate related to the global warming episodes that were recorded on isotope curves from a number of sections in the world