Integration of Sandbox Analogue Modelling and 2-D Structural Restoration as a Supplementary Tool to Exploration: Case Histories in Extensional, Transcurrent and Compressional Settings

Salvi, Francesca ¹; Cappelletti, Alessio ¹; Meda, Marco ²; Testi, Dorina ²; Cavozzi, Cristian ³; Nestola, Yago ³; Chowdhury, Baishali Roy ³; Argnani, Andrea ⁴; Tsikalas, Filippos ¹; Magistroni, Corrado ²; Dalla, Stefano ¹; Roveri, Marco ³; Bevilacqua, Nicola ²
(1) GEOLAB, eni E&P Division, San Donato Milanese - Milano, Italy. (2) GEBA, eni E&P Division, San Donato Milanese - Milano, Italy. (3) Earth Science Department, University of Parma, Parma, Italy. (4) ISMAR, CNR, Bologna, Italy.

By combining a series of 3D sandbox analogue models and 2D structural restoration of geological regional transects, the structural evolution of three case-histories, namely, in extensional (South Atlantic rifted continental margins), transcurrent (northern Nile Delta area) and compressional (upper Assam valley, NE India) settings, have been investigated with particular emphasis on exploration issues. The extensional sandbox analogue models were performed at full lithospheric setup-scale, considering a series of different rheological layering (strength-depth functions) for crust and mantle to investigate the pre-, syn- and late-rifting stages. The study elucidates the structural elements and features reflecting the syn-rift basin evolution and the processes that governed the pre-breakup lithospheric extension of a rifted continental margin. The transcurrent setting sandbox analogue models successfully reconstructed and refined a coherent pre-Messinian structural and kinematics evolution of the Nile Delta area; provided insights on the interaction between deformation and sedimentation, outlining the tectono-stratigraphic evolution of the area; and finally, resolved specific details, in time and space, of the structures in the vicinity of the three main regional structural lineaments/features (to the south the E-W trending Nile Delta Hinge Zone, to the east the NW-SE Bardawil/Temsah fault system, and to the west the NE-SW Rosetta fault). Close integration of structural restoration and sandbox modelling in the Nile Delta area was able to provide valuable support in decreasing the exploratory risk. The compressional sandbox analogue models focused on the structural evolution of the Naga Thrust (upper Assam valley, NE India), the youngest structure located in the frontal part of the Assam-Arakan thrust-and-fold belt. Analogue modelling investigated the geometry and the rheological behaviour of the detachment levels, and also addressed the possible interaction between the deeper extensional structures and the nucleation of the shallow thrusts, together with the effects of syn-tectonic sedimentation in the foreland. The study led to better constrain the relative chronology of the main tectonic structures (Naga and previous thrusts) and the geometry and role of the source rock strata as detachment level during the deformation, allowing considerations about both timing of hydrocarbon maturity and possible hydrocarbon charge migration routes.

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.