PALEOENVIRONMENTAL RECONSTRUCTION OF THE MIRWART FORMATION (PRAGIAN) IN THE LAMBERT QUARRY (FLAMIERGE, ARDENNE, BELGIUM).
Geological Survey of Belgium, Royal Belgian Institute of Natural Sciences, Jenner Street, 13, B-1000 Brussels, Belgium. E-mail: Eric.Goemaere@naturalsciences.be;
Geological Survey of Belgium, Royal Belgian Institute of Natural Sciences, Jenner Street, 13, B-1000 Brussels, Belgium. E-mail: Leon.Dejonghe@naturalsciences.be
Abstract
This paper describes the palaeoenvironments of the Mirwart Formation in the Belgian Ardenne. A tectonical, petrological and sedimentological study of the Lambert Quarry (Flamierge commune, Bertogne entity) has been carried out. Criteria are discussed that may be used in interpreting ancient sedimentary environments in the central Ardenne area. Distinctive sedimentological structures pointed out that the very fine sands, coarse silts and muds originated in a tidal flat environment. Tidal channels, mud flat, mixed flats and sand flats sub-environments are vertically stacked. Mud/Sand flats represented extended surfaces with very low relief areas without any sandy barrier to protect tidal flat environments from the open sea. These large surfaces are an answer to the transgression over large flood- and delta plain flat environments. In comparison with equivalent present-day environments, the unusual thickness of tidal deposits is related to a continuous subsidence and a regular and constant influx of clastics through a well-developed fluvial system. Clastics derived from the northern Old Red Sandstone Continent, trough alluvial and deltaic environments situated northerly of the studied area. Muddy islands, above the tidal range, occasionally fell dry and allowed the development of paleosoils and plant communities.