Petrology of Late Jurassic-Early Cretaceous ophiolites from Timpa delle Murge (Southern Apennines, Italy): insights from fragments of Tethyan oceanic crust

Abstract

On the Timpa delle Murge hill, located in the Lucania region close to Mt. Pollino (southern Apennines, Italy), Upper Jurassic – Lower Cretaceous metaigneous and metasedimentary rocks crop out, which are believed to represent fragments of Tethys oceanic crust obducted on continental crust during the Apennine orogenic phases. This ophiolitic sequenceincludes, from base upward: gabbros, pillow lavas, pillow breccias, and a pelagic sedimentary pile made up of radiolarian cherts, red and green shales, quartz-arenites and black shales. A few kilometers apart, the Episcopia - S. Severino Mélange includes serpentinized peridotites, likely representing fragments of an upper mantle portion. The radiolarian cherts were dated at 161 Ma based on their microfossil content, and this age is believed to be the end of oceanic crust generation in that area. Both serpentinites and the whole oceanic crust sequence were affected by subduction-related HP/LT metamorphism, marking a burying and exhumation episode occurred during the Late Oligocene-Early Miocene Apennine orogenesis. Only few literature data are available on the petrology of these rocks, thus a modern petrologic investigation is needed in order to better characterize this ophiolitic sequence, and shed light on the nature and history of this part of the Tethyan oceanic crust. In this contribution, major oxide and trace element geochemistry data will be illustrated forrepresentative shales and wackes from the Timpa delle Murge and Crete Nere formations. Geochemical modeling using compositional data of these metasedimentary rocks will be presented in order to find a possible link between the oceanic crust which was subducted during the Tethys closure, and subduction-related Tertiary-Quaternary volcanism of southern Italy.