RICERCHE STRATIGRAFICHE SUI SEDIMENTI MIOCENICI DEL BACINO DI CAMERINO (MARCHE CENTRO-MERIDIONALI)

Abstract

Severa! stratigraphic sequences are recognized in the Miocene Basin of Camerino. These are described from a litostratigraphic, biostratographic and chronostratigraphic point of vìew. Although the lower terms (Le. Bisciaro and Schlier) are almost identica! in ali sequences, considerable differences appear in the upper terms, especial!y in the turbidìte bodies that follow the Schlier. These dif­ferences reflect the complex history of the basin, which was affec­ted by a strong synsedìmentary tectonics since the Middle Torto­nian. This led to the development of two subbasins: the «Collamato Subbasin» in the northwesternmost part of the origina! basin, and the «Matelica-Fiegni Subbasin)), which takes up the remaining part. The stratigraphic sequences are distinct in the two subbasins, but also show differences within each of these. Thus, two different areas with their own characteristics can be distinguìshed in the <,Collamato Subbasin», while the «Matelica-Fiegni Subbasin» has been subdivided into a northern, a centra!, and a southern area. The biostratigraphic and chronostratigraphic definìtion of the different units has allowed correlations among the sequences of the above mentioned areas to be made. In addìtion, combining such correlatìons with field data allowed the basin paleoenvironmental evolution during the Miocene to be reconstructed. In particular, the biostratigraphic study is based on the analy­sis of a large number of samples covering the interval between the top of the Scaglia cinerea and the evaporite deposits which close the sequence. The micropaleontological assemblages have allowed the definition of some biostratigraphical intervals to be made, in fairly good agreement with known Lower and Middle Miocene schemes. For the Upper Miocene, a new scheme was determined; its relation­ship with the scheme of D'ONOFRIO and others (1975) is outlined.