Coupled kinematic and thermal modelling of collisional orogens: Implications for subsurface geo-resources assessment in the external Dinarides

Abstract

The thermal evolution of collisional orogens is largely controlled by their kinematic and burial/exhumation history, where sedimentation and erosion rates, as well as shear heating and deep heat flow supply conditions for the temperature distribution, fluid flow and the associated fluid-rock interactions. The aim of our research is to understand this coupled kinematic and thermal evolution to ultimately infer the conditions favourable for subsurface geo-resources. We achieve this aim by means of numerical modelling and its application to one of the best available orogenic indentation examples, which is the Dinarides Mountains chain in Central Europe. Based on the analysis and modelling of an integrated onshore and offshore geological cross-section, we quantified the shortening, erosion/exhumation and sedimentation/burial rates, maturity of potential petroleum source rocks and the gross potential for sustainable geothermal resources. The coupled kinematic/thermal modelling revealed a general pattern of heat flow variations associated with crustal deformations. The hanging-wall and upper parts of the footwalls show increased conductivity and heat flow during episodes of thrusting, whereas the deepest parts of footwalls have lower heat flow values. Fluids are observed to migrate towards the foreland during the latest Cretaceous – Early Oligocene thrusting. The largest amounts of post-Middle Miocene shortening took place in the SE external parts of the orogen, where deep-sourced fluid ascent took place towards the foreland. In this region, significant footwall burial enhanced the maturation of potential source rocks. Modelling results infer a considerable hydrocarbon potential for the Dalmatian unit and the South Adriatic basin. The kinematic and thermal model combined with geothermal well design and well performance calculations infer a viable geothermal energy potential for the Dalmatian and High-Karst units. Results of this novel workflow allowed to quantify the orogenic kinematic and thermal history, and its bearing on conventional and sustainable geo-resources.