PRELIMINARY PALEONTOLOGICAL AND GEOLOGICAL NOTES ABOUT AN ABANDONED QUARRY NEAR MANDURIA (SALENTO PENINSULA, SOUTHERN ITALY)

A collection of fossil vertebrates from the Salento Peninsula (Italy), and housed at the Natural History Museum of Verona, prompted new fieldwork in the area. The attention was focused on the northern sector of the Salento Peninsula, and led to the study of an abandoned quarry near Manduria (Taranto, Italy). The preliminary results of this investigation are reported here. The original quarry operations had exposed about 8 meters of Upper Cretaceous “platten-kalke”-type deposits, containing interesting and quite peculiar palaeontological and geological features. A high-resolution litho-biostratigraphic analysis was performed. The lithotypes outcropping in the quarry are dominated by the cyclic alternation of: i) mm- to cm-thick, dome-shaped, cyanoalgal laminites, sometimes presenting mud-cracks; ii) “vuggy” layers made of prismatic-to-discoidal voids, related to evaporitic salts dissolution; and iii) pedogenetic horizons (terre rosse). The facies analysis suggests a supratidal depositional setting for these “fenestral” and laminated mudstones, under hypersaline evaporitic conditions. A unique, oligotypic, and mostly well-preserved thanatocoenosis characterizes the stratigraphic framework, adding further constraining information about the depositional environment. The macrofauna is strictly oligotypic, and is represented by articulated fish remains, coprolites, regular sea urchins and few specimens of Chondrodonta sp.; the echinoids and their spines are preserved as “phantoms”, since the original high-Mg calcite of the tests is not preserved, and the spines are always found disarticulated. The preferential orientation of the echinoid spines provides some evidence about the paleocurrents that affected the area. The microfauna is missing, possibly as a result of the extreme conditions of the depositional environment and/or because of postmortem dissolution. The colonization of supratidal environments by benthic organisms and fishes could be related to periodical and ephemeral flooding of the area by normal-salinity seawater.