BLACK SHALES, A HIGH-RESOLUTION CHRONOLOG ICAL TOOL - CASE-STUDY OF THE ALBIAN FROM THE UMBRIA-MARCHE BASIN (CENTRAL ITALY)

An analysis of the cyclostratigraphic potential of black shales is pro posed from the study of the Albian part of the Marne a Fucoidi Formati on of the Umbria-Marche basin (Central Italy). The succession, about 6 5 tn thick, is constituted by marl-limestone alternations in which are intercalated numerous black shales (150). Firstly, the spatial arrang ement of black shales was studied on an interval approximatively 42 m thick along a 40 km transect in order to verify the homogeneity of the succession. Secondly, a cyclostratigraphic approach was applied on th e temporal distribution of black shales. The genetic significance of b lack levels was discussed from their petrologic characteristics (miner alogic, palynologic and geochemical).The depositional model obtained w as compared with the model of deposition for the Mio-Pliocene sapropel s of the Mediterranean. A temporal significance of black shales is the n advanced. A potential use of the spatio-temporal distribution of the se singular levels in pelagic realm is purposed.