The Carboniferous rocks of Spain crop out mainly in the Iberian Massif, which occupies almost half of the Iberian Peninsula. There are additionally a number of smaller Carboniferous inliers, separated by a Mesozoic and Tertiary cover, exposed in the Iberian Ranges, Pyrenees, Catalonian Coastal Ranges, Minorca and the Betic Cordillera (Fig. 7.1). Variscan and sometimes Alpine tectonism has variously overprinted these Carboniferous outcrops, commonly obscuring their original relationships.
During the Carboniferous period, sedimentation was coeval with the Variscan orogeny, in contrast to earlier Palaeozoic sedimentation in a rift to passive margin setting. The strong tectonic control on Variscan sedimentation resulted in mobile, unstable basins, with sedimentary successions that show rapid temporal and spatial changes in lithofacies and thickness. This has promoted a proliferation of stratigraphic units of only local importance, making regional correlations difficult.
The Carboniferous successions in Spain are generally dominated by siliciclastic rocks that vary from deep water turbidite successions to shallow marine, coal-bearing coastal and fully continental formations. Deep water turbidite successions are in many places referred to as the ‘Culm’, a term coined by Fiege (1936), although the Culm successions of the Iberian Variscan Belt are not always Early Carboniferous in age as in the original definition. In some areas limestones are locally important or even dominant and thin, condensed units of limestones or shales are widespread during Tournaisian and Visean times. An exception to the dominantly sedimentary record is provided by volcanic and volcaniclastic rocks which are abundant in the southern