Source rock potential and spatial distribution of the stratigraphic formations in the central Mediterranean Ridge: Evidence from mud volcanic deposits and 2D seismic data

Due to the lack of deep wells in the broader region, the mud volcanic deposits (mud breccia) are the only source of direct information for the deep stratigraphic units of the Mediterranean Ridge (MR), in the eastern Mediterranean. The study of this material, combined with the available seismic data, can improve the geological understanding of this frontier exploration area. In this paper, biostratigraphic and geochemical studies are performed on mud breccia deposits from five Mud Volcanoes (MVs) in the central MR, aiming to define the sediments' stratigraphic origin and assess the source rock potential of the individual formations. In addition, regional seismic data is used to reveal the spatial distribution of the major lithostratigraphic formations in the subsurface. Results indicate an Eocene-Miocene origin for the mud breccia of Gelendzhik, Nice, Moscow and Dublin MVs, whereas a Paleocene (?) and Cretaceous origin is suggested for the Toronto MV deposits. Most clasts represent hemipelagic mudstones/marlstones. Regarding the source rock potential of the area, it is considered that: (a) nine clasts of Miocene, Eocene and undetermined age, reflect the presence of immature and early mature, gasprone source rocks of poor to moderate potential; (b) a small clast discovered in the matrix of Dublin MV originates from an excellent quality oil-prone source rock; and (c) the discovered solid hydrocarbons and oil droplets point to an active petroleum system in the region. Seismic interpretation defines the spatial distribution of the Post-Evaporite, Evaporite and Pre-Evaporite formations. The burial depth of the Pre-Evaporite formation (source layers of MV deposits) significantly varies from 20 to 4970 m inside the study area and is largely dependent on Evaporite thickness.