Fusulinoidean characterization of the uppermost Moscovian-Gzhelian (upper Pennsylvanian) synorogenic depositional sequences from northern Picos de Europa Unit (Spain)

Abstract

Late Pennsylvanian succession of the Picos de Europa Unit (Cantabrian Mountains, NW Spain) constitutes one of the few exposed marine strata of this age in Western Europe. It consists of synorogenic deposits that accumulated in piggy-back basins developed during the latest stages of the Variscan orogeny. The 11 mappable 3rd, 4th–5th order depositional sequences that form the succession were subdivided in higher-order cycles (5th order) and grouped into two sequence sets. Fusulinoidean faunas have allowed dating of these strata (late Myachkovian-Gzhelian) and to characterize each depositional sequence. Sequence stratigraphy, coupled with sedimentological and paleontological analysis have enabled the reconstruction of a sea level curve that may shed light on Late Pennsylvanian global events and faunal migrations. These studies suggest potential correlations between late Moscovian cycles recognized both in the Cantabrian Mountains and in the Moscow Basin. Sudden appearances of early Dorogomilovian and early Gzhelian fusulinoideans could indicate migrations within the Paleotethys, probably favoured by global sea level rises and highstands.