Organic matter characterisation of the Selli Level (Umbria-Marche Basin, central Italy)

The Selli Level is a marker-bed in the Umbria-Marche Apennines that represe nts the regional sedimentary expression of the Lower Aptian Oceanic Anoxic Event la. This one to three-metre-thick interval shows a remarkable uniform ity on a regional scale, with a green to grey marry lower part overlain by black shales. Bulk geochemical studies and an examination of palynofacies w ere carried out on three sections in order to characterise the distribution and nature of the organic matter in the Selli Level which has been poorly known hitherto. The organic content is medium (0.5 to 2.9% TOC) in the basa l part and higher (4.5% on average, and up to 18% TOC) in the black shares. Pyrolysis and palynological data indicate that the organic matter is mainl y of marine origin. The geochemical characteristics of the Selli Level are compared to other, more or less organic-rich marker-beds in the Cretaceous succession of the Umbria-Marche Apennines. (C) 1998 Academic Press Limited.