Microplankton from three Palaeozoic formations in the province of León, NW-Spain

In the Lower Palaeozoic where true palynological microfossils become rare, much use can be made of other acid-resistant microfossils such as acritarchs and chitinozoans. This study gives some of the results of an investigation on the presence of acritarchs and chitinozoans in three essentially Lower Palaeozoic formations of the Province of León in northwest Spain, viz. the Formigoso, the San Pedro, and the La Vid Formations. They range from Upper Llandoverian to the middle part of the Emsian. The techniques used to prepare the samples are discussed. The vertical distribution of the most common acritarchs and chitinozoans in the region investigated are given, as well as the changes of frequency in the associations of some selected groups of acritarchs from a number of sections of the San Pedro and the La Vid Formations. Most formgroups show characteristic changes of frequency providing the possibility of detailed correlation within the formations. The most common forms of acritarchs and chitinozoans used for correlation purposes are described. A list of species may be found on pages 280 and 337. Most of these forms had not yet been recorded.