New data (smaller foraminifers and correlation with depositional sequences) on the Las Llacerias section (Late Pennsylvanian, Cantabrian Mountains, NW Spain)

Abstract

New sedimentological and paleontological information on the uppermost Moscovian and Kasimovian strata of the Las Llacerias section, a succession exposed in the Picos de Europa region (Cantabrian Mountains) that is considered to bear interest for the global correlation of the Upper Pennsylvanian subsystem, are presented. Based on sedimentological studies, three stratigraphic intervals can be established which record three successive episodes in the evolution of the carbonate platform. The study of the environmental evolution and sea-level fluctuations, as well as biostratigraphic fusulinoidean information, allow the correlation of this section with the synorogenic deposits of the Gamonedo-Cabrales area (northern Picos de Europa region). It is recognized that in the Las Llacerias strata, 7 of the 11 depositional sequences of the latter area are represented. The taxonomy and distribution of smaller foraminifers, a fossil group never studied before in this section, have been analysed. Data obtained show the presence of, at least, 30 genera. In some cases (Syzrania aff. bulbosa, Tezaquina, Mesolasiodiscus, Pseudotaxis and Hemidiscus), their record in the Las Llacerias section significantly extends the stratigraphic genus or species range. The potential role of Protonodosaria and Nodosinelloides species, as well as the acme of Hemigordius schlumbergeri for the correlation of the Kasimovian deposits is reinforced within this study.