Coal facies and depositional environments of the Aurora and Cabeza de Vaca Units, Peñarroya–Belmez–Espiel Coalfield (Cordoba, Spain)

Abstract

The Peñarroya–Belmez–Ezpiel Coalfield (Cordoba, Spain) is a narrow strip, 1 km wide and 50 km long, parallel to the Precambrian and lower palaeozoic structures of Central Iberian and Ossa–Morena zones. The strip corresponds to an intramontane basin, the Peñarroya Basin, infilled with lower Westphalian continental sediments. The Aurora and Cabeza de Vaca Units, situated in central–eastern part, correspond to the second major sedimentary event, mainly represented by fluvial and lacustrine sequences including several coal-bearing units. The petrographic study of coals seams from the Aurora Unit (seams 6, Sucia and Candelaria) and the Cabeza de Vaca Unit (seams 1, 3 bis, 4 and 5) indicates a vitrinite-rich composition, despite the high content of detrital mineral matter in the majority of coals. Liptinite and inertinite present a very irregular distribution, being liptinite (mainly sporinite) dominant over inertinite. Apart coals with very high proportions of carbominerite+minerite, vitrite is the dominant microlithotype. Nevertheless, clarite and duroclarite constitute very important microlithotypes in some coal seams. The paleomire systems deduced from petrographic composition and plots in coal facies diagrams vary from fen and swamps mainly associated with marginal lacustrine and alluvial and floodplain environments for seams 1, 4, 5, 6 and Sucia to more protected palaeomire systems for seams 3 bis and Candelaria.