COAL BASINS IN THE CANTABRIAN MOUNTAINS, NORTHWESTERN SPAIN

The Cantabrian Mountains, containing about 70% of the total coals of t he country and 95% of the anthracitic and bituminous resources, is the most important coal-mining district of Spain. Coal-bearing succession s are Late Carboniferous in age and their deposition took place in a s yn-orogenic context during the Hercynian activity, mainly in three dif ferent time-successive locations: foreland basins, intrathrust basins and intramontane fault-controlled basins. Foreland deposition occurred in strongly asymmetrical basins located ahead of thrust sheets units. Intrathrust basins resulted from folding and tightening of these unit s during or after their emplacement. Intramontane and fault-controlled basins were developed along lineaments with strike-slip movements and as a result of fold and fault reactivation. Peat mires in foreland an d intrathrust coal basins mainly occupied broad areas on abandoned del ta and fan delta lobes. Coals in intramontane and fault-controlled bas ins were related with alluvial fan and lacustrine environments. Coal r anks vary from high volatile bituminous coals to anthracite, depending on the structural location of the coalfields. Hydrothermal activity s eems to be the most important factor in coal evolution.