What do the K-Ar ages of illite tell us about the diagenesis of Rotliegend sandstones of the Fore-Sudetic Monocline, SW Poland?

Abstract

The all available K-Ar data of authigenic illite from Rotliegend aeolian sandstones of the Fore-Sudetic Monocline, including the results from six samples examined in the present study, are reviewed in terms of their geological meaning, relation to diagenetic processes occurring in the sandstones, and implications for a petroleum system. The majority of ages fall in the range between 195 and 150 Ma, i.e. they correspond to Jurassic times. The results may be grouped in several time intervals, which are almost identical to those identified for Rotliegend sandstones of central and western Europe, and which are interpreted as pulses of intensive illite growth. The K-Ar data corroborate the long-held assumption that throughout the entire Southern Permian Basin Jurassic illite growth was triggered by the same, large-scale underlying processes, which manifested themselves in enhanced heat flow. These processes may also have caused the expulsion of hydrocarbons from source rocks.