Reservoir Scale Modulation of Turbidite Architecture Related to Paleo-gradients Generated by Syn-sedimentary Structural Growth and Segmentation of an Overfilled Foreland Basin System: The Marnoso-arenacea Formation at the Coniale Anticline, Northern Apennines, Italy

The link between tectonics and sedimentation is arguably best exemplified in deep-marine foreland basin systems where structural deformation is contemporaneous with turbidite sedimentation. The distribution and modulation of sedimentary attributes defining Deepwater sedimentation regions record changes in paleo-gradient framed by five orders of tectonic deformation. Second-order foreland basin systems consist of third-order wedge-top, foredeep, forebulge, and back-bulge structural domains. Fourth-order structural growth of a submarine anticline segments and transforms the third-order foredeep into the wedge-top structural domain. The Coniale anticline manifests a fourth-order structure containing attendant fifth-order mass-transport-deposits defining four sedimentation regions represented by pre- and syn- kinematic turbidite distributions across the structure.

Tabular lobes and fine-grained carbonate drapes are the dominant sedimentary bodies in an overfilled basin, where lateral expansion of large turbidity currents scale to the basin width. Consequently, sedimentation units are equivalent to sedimentary bodies, simplifying the number of sedimentary attributes required for analysis. Wavy stratification is moderately subordinate to structureless sandstone in pre-kinematic turbidite sedimentation units which contain thinner mudstone caps, but separated by thicker calcareous mud drapes. There is more uniformity in these attributes across the structure (~5 km distance). By contrast, syn-kinematic turbidites show more variation in component facies, sedimentation unit thickness, and cyclic modulation of sedimentary bodies across the structure, including the addition of mass-transport deposits on the east flank of the structure.

Paleo-gradients of fourth- and fifth- order tectonic surfaces are determined from a partial 3D restoration of the structure and correlate structural growth to turbidite distribution and modulation. Fourth-order structural growth segments foreland domains and combined with fifth-order structure-generated surfaces explains changes in the four sedimentation regions. This suggests that lower resolution structural features can be used to assess smaller reservoir-scale architecture relevant to subsalt prediction in the Gulf of Mexico.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California