Cyclicité climatique à la limite Dévonien-Carbonifère et configuration orbitale de l'évènement de Hangenberg en Belgique

Abstract

In order to better understand the climatic change between the Devonian (greenhouse climate) and the Carboniferous (icehouse climate) and the duration of the phenomena that led to the Hangenberg crisis, we conducted a cyclostratigraphic study on the Chanxhe sections, in south-eastern Belgium. These sections, dated to the Upper Famennian and Lower Tournaisian, show rhythmic limestone/shale alternations deposited on a continental shelf in an open neritic environment. In addition, they expose the Hangenberg Black Shale and the Hangenberg Sandstone. Supported by lithological and geochemical analysis, spectral analysis has revealed nine to ten short eccentricity cycles and precession cycles grouped by 6 to 8. The total duration of the sections is estimated to be 1-1.05 Myr and the Hangenberg Black Shale duration to be about 130 kyr.