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Late Cretaceous Extensional Tectonics and Intraplatform Basin Formation: Insights from Soft-sediment Deformation in the Sorrento Peninsula

Alessandro Iannace, Mariano Parente, Stefano Tavani, Stefano Mazzoli, Monica Girundo, Christoph Strauss, and Chadia Volery

The platform carbonates of southern Italy host the reservoir of the reservoirs of Basilicata area, which represent the largest onshore oil and gas accumulations in Europe. The up to several km’s thick reservoir units of lowporosity Mesozoic fractured carbonates of the Apulian Platform. The upper part essentially consists of Upper Cretaceous rudist-rich limestones, deposited in open platform and ramp environments. The lower part is mainly represented by Aptian-Cenomanian, partly dolomitized limestones of restricted platform facies. Oil was sourced by finely laminated Albian–Cenomanian organic-rich dolomites that formed in intraplatform basins. Little is known about these basins, as no analogue structures have been reported until now.

We present evidences of syn-sedimentary tectonics in the Albian platform carbonates of the Sorrento Peninsula (Naples, Italy), which seemingly represent the best surface analogue for the Albo-Cenomanian dolomitized limestones of the Southern Apennines oilfields. The studied outcrop includes two bodies of dolomitized breccias in the hanging wall of two, major NE-SW to NNE-SSW striking faults. The area between these two extensional master faults hosts a small basin filled by organic-rich laminated dolomites, offset by NE-SW and NW-SE striking minor faults. The synsedimentary nature of extensional faults is supported by the observation of layer thickening and occurrence of widespread soft-sediment deformation, both features supporting the conclusion that the observed extensional system was controlled by NE-SW striking faults. These, once the post-Cretaceous vertical axis rotations are removed, provide a N-S oriented stretching direction, likely compatible with data from the intraplatform basins of the subsurface oilfields Further studies are required to unequivocally confirm the presence of a mid-Cretaceous, roughly N-S oriented stretching in the southern portion of Adria. However, a review of the literature shows evidence of mid-Cretaceous tectonics with comparable paleo-orientation in further sectors of the Adriatic carbonate platforms.

AAPG Search and Discovery Article #90161©2013 AAPG European Regional Conference, Barcelona, Spain, 8-10 April 2013