ABSTRACT
A thick upper Carboniferous sequence was deposited in the Netherlands and adjacent areas. Despite intense erosion during the late Carboniferous and early Permian, it has been preserved beneath the unconformably overlying successions. The preserved thickness locally exceeds 5500 m. The sequence comprises almost exclusively siliciclastic sediments, deposited in a cratonic-molasse basin that formed as a result of the collision of the northward drifting Gondwana continent against Laurussia.The Variscan orogenic belt, the axis of this collision, provided the sediment source for the southern part of the basin. Sediments in the north were sourced from the older Caledonian mountains, which had already formed as the result of the collision of Laurentia, Baltica and Avalonia in Silurian-Devonian times. The lithology ranges from claystone, siltstone and sandstone up to conglomerate size. The units were initially deposited in a predominantly marine basin flanked by deltas, grading into a paralic basin with alluvial plains and -fans, and finally in a largely fluvial red-bed environment. Thick and extensive peat layers were formed from the Yeadonian (Early Pennsylvanian) until the early Asturian (Middle Pennsylvanian) in deltaic and paralic floodplain environments. The coal beds, which formed when this peat became deeply buried, were mined in the southern Netherlands from medieval times up until 1974 and have been the main driver for the industrial revolution in Western Europe. Combustible gas, generated from Carboniferous coals, has been the most important exploration target of the petroleum industry in the Netherlands. Since the discovery of gas in the upper Carboniferous reservoirs of the Coevorden field in 1951, numerous other discoveries have been made in the east and northeast of the Netherlands from the 1950s onward, as well as offshore from 1974 to the present.
