Depositional and Diagenetic Factors Affecting the Development of Bed-Parallel, Burial-Related Structures in Oligo-Miocene Ramp Carbonates (Maiella Mountain, Central Italy)

Rustichelli, Andrea ¹; Tondi, Emanuele ¹; Agosta, Fabrizio ²; Giorgioni, Maurizio ³; Invernizzi, Chiara ¹
(1)Geology Division, School of Science and Technology, University of Camerino, Camerino, Italy. (2) Department of Geology, Basilicata University, Potenza, Italy. (3) Shell Italia E&P, Rome, Italy.

In several geological contexts rocks are characterised by both diffused and localized strain, which can be represented by background deformation and fault zones, respectively. The combination of diffused and localised deformation may form a discontinuity network of structural elements that may strongly affect the hydraulic rock properties.

With regards to background deformation, the progressive burial of sediments subsequently to their deposition is responsible for the progressive change of the boundary conditions (i.e. stress field, pressure and temperature, fluid composition) and rock rheology, therefore, for the development of compressive structures within the rock under lithification. In carbonate rocks, these structures, oriented parallel to bedding, may consist on pressure solution seams and/or compaction bands. It has been documented how this bed-parallel elements often represent mechanical interfaces controlling the frequency and distribution of subsequent structural elements.

In this contribution, we present the results of a study conducted in the Maiella Mountain, Central Italy. The study focused on the Oligo-Miocene Bolognano Formation, which is made up of several lithofacies ranging from shallow-water skeletal grainstones to hemipelagic mudstones. These carbonates were deposited in a non-tropical carbonate ramp belonging, at the time of deposition, to the Apulian platform realm. With the objective to assess the control exerted by environmental, sedimentological, diagenetic and petrophysical features on the development of bed-parallel pressure solution seams and compaction bands, we integrate the results obtained from stratigraphic, sedimentological and structural field analyses with those obtained in the laboratory through optical microscopy and digital image analyses.

On the basis of the results we obtained, we propose a conceptual model of the control exerted by intrinsic rock features on the development of bed-parallel, burial-related structures in carbonates. By knowing the following factors: (i) depositional environment, (ii) biota evolution, (iii) depositional processes, (iv) diagenesis, (v) rock components and (vi) petrophysical rock properties, it is possible to infer both type and distribution of the structural discontinuities pertaining to the background deformation. As a consequence, the hydraulic properties of the carbonate rock masses crosscut by burial-related, bed-parallel structures can be inferred.

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