Sedimentology of the late cretaceous and early tertiary (tuffaceous) chalk of Northwest Europe

Abstract

The Tuffaceous Chalk of South Limburg (The Netherlands), a friable, porous, bioclastic carbonate sandstone, became subject of scientific interest in 1770, when workers found a large skull of Mososourus comperi in the subterranean quarry of Mount St. Pieter near Maastricht. After Dumont (1849) had considered the Tuffaceous Chalk of Maastricht to represent the youngest Cretaceous deposits, many investigations were carried out conceming the taxonomy of the fossils and the bio- and lithostratigraphy of the type section of the subtropiC<'11 shallow marine deposits of the "systeme de Maestricht", exposed at Mount St. Pieter. The Tuffaceous Chalk is part of a 200 m thick Late Cretaceous-Early Tertiary, transgressive-regressive succession of dm-m thick, laterally continuous layers. The basis of tllis succession consists of Santonian-Campanian (glauconitic) quartz sands and smectitic clays, which cover the abraded and karstified Paleozoic sediments of the gently dipping, block-faulted northem flank of tlle Ardennes Massif. The middle part is foroled by Campanian-Ma..'1strichtian cOCCOlitllic mudstones (Chalk) with flint nodule layers tllat gradually chrUlge upwards into the upper part tllat consists of Maastrichtian-Danian bioclastic sandstones (Tuffaceous Chalk) with hardgrounds. In this thesis attention is paid to the sedimentology of tlle Maastrichtian-Danian coarsening upwards (Tuffaceous) Chalk sequences of Ma..'1Stricht, the Gironde Estuary (France) and Stevns Klint (Denmark). TIle vertical rhythmic variation of grain size, structures and authigenic mineral concentrations has been measured and analyzed and is explained using numerical models that allow tlle simulation of tlle genesis of bedding in (Tuffaceous) Chalk.