 Journal of Mediterranean Earth Sciences 9 (2017), 203-206 Journal of Mediterranean Earth Sciences Miocene sedimentary sequences of the Sardinian Graben System as possible analogue for the Upper Jurassic Rogn Formation of the Norwegian Continental Shelf Donatella Telesca a , Sergio G. Longhitano a , Rikke Bruhn b , Domenico Chiarella c a Dipartimento di Scienze Geologiche, Università della Basilicata, Potenza, Italy b DONG E&P Norge, Veritasveien 25, 4007 Stavanger, Norway c Royal Holloway, University of London, Department of Earth Sciences, Egham, Surrey, TW20 0EX, UK Keywords: Sardinian Graben System; Miocene, outcrop analogue; Rogn sandstone; tidal sedimentology. 1. INTRODUCTION Te Rogn Fm is an Oxfordian to Volgian (Late Jurassic) sand-rich interval recognised in the ofshore subsurface of the Norwegian Continental Shelf (Gjelberg et al., 1987, Dalland et al., 1988). In its type well the formation is up to 60 m thick and exhibits a coarsening-upward trend (Provan 1992) (Fig. 1). Te Rogn Fm, which has found encased in shelf fnes or adjacent to the fanks of structural highs, consists of well-sorted coarse-grained sandstones, made up of sub-angular clasts, difusely cross laminated, and also including siltstones and shales (e.g., Elliott et al., 2015) (Fig. 1). Te Rogn Fm has become even more renowned thanks to its good reservoir properties (P=29%; K=8 Darcy; N/G=0.7) and because it provided promising oil discoveries in the last twenty years. Te more accepted interpretation on the depositional genesis of the Rogn Fm is the derivation from the erosion of several hundred of meters of pre-Permian to Upper Jurassic successions from the uplifed Frøya High, and the subsequent accumulation in sheltered coastal zones and/or in more distal ‘shelf’ environments, tectonically shaped into narrow-elongate depocenters (Provan 1992). Te recurrent motif of cross-bedding observable in the Rogn sandstones point out towards a general control exerted by tractional fows, whose strength was possibly infuenced by lateral constrictions, generating a series of current-infuenced subaqueous bedforms (i.e. in the southern-east Frøan Basin) or transported towards further to north on the Halten Terrace. However, a number of uncertainties related to the sub-seismic depositional architectures or lateral facies changes of the Rogn Fm call for evaluable outcrop- analogue studies, useful to constrain or revise preliminary interpretations and, thus, to increase the exploitation potential of the Rogn Fm. Te tectonic evolution and the type of sedimentation that characterised the Norwegian Continental Shelf during the Late Jurassic seems well matching the geological history of the Sardinian Graben System (SGS) in the western Mediterranean, during the Miocene. For this reason, a feld-based study was promoted focused on two main representative outcrop areas belonging to this extensional basin. 2. THE SARDINIAN GRABEN SYSTEM AND THE ROGN FM OUTCROP-ANALOGUE AREAS Te Sardinian Graben System (SGS) was an N-S-striking elongate basin, developed in a back-arc setting from the Late Oligocene onwards (Cherchi et al., 2008). Te SGS was progressively flled by continental and marine extra- basinal clastics and intra-basinal carbonates during at least three main complete cycles of relative sea-level changes (Casula et al., 2001; Oggiano et al., 2009). Te feld study, based on a detailed facies analysis, logging of stratigraphic sections, grain size lab analyses and mineralogical tests, has been focused on two main areas (Fig. 2) belonging to the SGS: (i) an Early Miocene ca. 10-km-wide palaeo- embayment, whose deposits are presently exposed in the center of the island, and (ii) an Early-Middle Miocene, 10-km-wide and 20-km-long half-graben, namely the Logudoro Basin located in the northern Sardinia. Both these areas resemble the two end-member settings invoked for the deposition of the Rogn Fm (i.e., embayment vs. confned shelf) and point out towards a general control on the sedimentation exerted by a specifc oceanographic circulation deriving from the amplifcation of bottom (tidal currents) fowing across epicontinental restrictions (i.e., seaways and straits) (Chiarella et al., 2012, 2016; Longhitano, 2013; Longhitano et al., 2012, 2014).