The Dinantian (Mississippian) succession of southern Belgium and surrounding areas: stratigraphy improvement and inferred climate reconstruction

The interactions between sea-level changes, local and global tectonics, and palaeoclimates have influenced the sedimentary deposition and the stratigraphy of the Belgian Dinantian. This paper emends the Belgian Dinantian sequence stratigraphy pattern and the third-order sequence 4 is divided into two sequences (4A, 4B). We also confirm that the sudden sea-level drop corresponding to the Hangenberg Sandstone at the Devonian-Carboniferous transition does not correspond to a third-order sequence boundary, but to an out-of-sequence event. The stratigraphy of the Tournaisian in the Namur, South Avesnois and Vesdre-Aachen sedimentation areas is clarified and leads to restrict the latter area to the Aachen vicinity only. The shape of the Namur-Dinant basin is revised and shows a migration of the depocenter northward during Dinantian times. During the Tournaisian, precession cycles are well developed and correspond to alternations of monsoon and dryer climates, without marked changes in the sea level. However, superimposed on these alternations, the Tournaisian third-order sequences recorded higher sea-level variations, which are considered to be due to glacioeustatism, indicating long-duration period of ice formation. The very strong fall in the sea-level at the Tournaisian-Visean boundary is considered to record the development of an ice-cap and to a heralding change to the Carboniferous climate with glaciations. From that time (sequence 5), marked eccentricity parasequences developed during the Visean, recording alternating shorter interglacial-glacial periods. Thus, the onset of the Carboniferous glaciations is as early as the Early Visean and not in the Late Visean as usually considered.