Abstract
Detailed geological mapping (1:10000 scale) has been carried out in the area of Salento surrounding Copertino village (Lecce). The aim is to clarify the stratigraphy of Oligo-Miocene sediments which crop out widely in the area and were referred to the Pietra leccese and Andrano Calcarenite formations in the last edition of the Geologic Map of Italy. This study suggests a different stratigraphic scheme for the Copertino area with the occurrence of two different lithostratigraphic units--the Galatone Formation (Upper Oligocene) and the Lecce Formation (Lower Miocene)--between the Upper Cretaceous Altamura Limestone Formation and the Lower to Upper Miocene Pietra leccese formation. The Galatone Formation is characterized by whitish-greyish micritic limestone interbedded with centimetre-scale layers of whitish limestone and laminated yellowish calcareous marls. Their thickness commonly ranges from a few centimetres to several decimetres with frequent dominating plane laminae and stromatolitic structures. Fossils are abundant, represented mainly by gastropoda and ostracoda. Moreover, a new important outcrop referred to the Galatone Formation, 30 metres thick, has been identified. It is of interest because of the presence of a paleosol, varying from a few centimetres to around 50 cm thick, represented by brown sandy clays devoid of fossils. The upper surface of the paleosol is undulating and in places is intersected by mud cracks. The paleosol underlies a characteristic marly horizon, around 70 cm thick, rich of Hydrobiidae. This stratigraphical datum could constitute an element of correlation with the type section of the Galatone Formation (Bossio et alii, 1999). The characters described are therefore distinctive of lagoonal sediments with continental intervals. The Lecce formation is made of shallow marine deposits characterized mostly by whitish massive calcarenites with more or less distinct decimetre-scale stratification, interbedded with rare greyish marly and micritic limestone. Macrofossils are rare and represented by Cardium sp., gastropoda and macroforaminifera such as Operculina sp.. These two units were previously included either in the Andrano Calcarenite formation and in the Pietra leccese formation, inducing problems for the interpretation of the stratigraphic evolution of the area. Thus it is stressed that the attribution of Miocene deposits, reported in the Geological Map of Italy in other areas of Salento, should be checked.
