Structural and Kinematic Analyses Across the Dinarides Mountain Chains in the Mediterranean Orogen: Inferences on the Petroleum Potential

Abstract

The Dinarides orogen can be characterized as a structurally complex fold-and-thrust belt. These type of mobile belts have a structural system with the potential to host considerable petroleum reserves and therefore serve as sufficient exploration and production targets. One of the most common observation in these types of orogens is the migration of contractional deformation and associated slabs in space and time towards external areas by lower plate crustal accretion. This migration is generally accommodated by back-arc extension, which significantly overprints older contractional deformation and makes difficult understanding the overall kinematics of accretion. The Dinarides orogen is one of the few places where the sequence of contractional deformation, affecting the lower continental plates during subduction and collision, can be optimally studied, and where a remnant of the subducted slab is presently observed in a far external position. In order to derive the kinematic sequence of deformation, we have constructed two large scale profiles, in particular focused on the less known External Dinarides of Montenegro, Croatia and Bosnia & Herzegovina. The construction of the profiles was aided by kinematic mapping of key areas affected by deformation along the chosen orogenic transects. The results demonstrated a long-lived Late Jurassic - Quaternary evolution of shortening that affected the Dinarides lower orogenic plate. While the Late Jurassic-Earliest Cretaceous deformation was associated with an earlier obduction moment, the latest Cretaceous onset of collision has gradually focused deformation at inherited rheological weakness zones, such as the oceanic suture zone, nappe contacts or inherited extensional grabens. We show for the first time that a period of Miocene extension has affected all areas of the Dinarides and was unlikely to be related to back-arc mechanics driven by slab roll-back. Our findings demonstrate a more continuous crustal accretion mechanism than previously thought, which is still active at present.

The new kinematic analyses of the profiles gave the ability to balance and restore them into their pre-orogenic configuration, to constrain the main episodes of structural deformation. This will give the ability to perform a basin model and to constrain the source rock maturation and fluid flow migration of this area for the first time. This methodology can be considered as an example for similar orogenic collisional systems worldwide.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018