Quantification of fracturing within fault damage zones affecting Late Proterozoic carbonates in Svalbard

Abstract

The Cenozoic activity of the De Geer transform fault, which releases the relative movements between of the North Atlantic and the Arctic Ocean, produced a wide deformation zone that presently affects the western coast of the Svalbard (Spitsbergen Island) as testified in the extended rock exposure along the West Spitsbergen fold and thrust belt. In particular, the still ongoing tectonic activity along this transform is responsible for the formation of fault strands characterized by highly fractured damage zones (DZs). These DZs represent hydraulic conduit that steer the pathway of deep fluids (e.g., oil and gas). Understanding the fracturing evolution in fault DZs represent a key factor to model potential reservoirs in the arctic region (and in the Barents Sea area) for various purposes including natural resources development (oil/gas production), gas storage (CO2) as well as nuclear waste disposal. In the present work, we analyze two faults representative of the status of brittle deformation of Vendian carbonates in Svalbard where it was possible to study the fracturing in their DZ. The intensity of brittle deformation was quantified and its spatial variation within the DZ was modeled through an empirical/physical approach that allowed to develop a predictive model to quantify fracturing. This model was prepared by comparing field measurements with an empirical equation taking into account the main fracturing and sealing processes operating during the fault activity. Results can be successfully applied to other carbonate rocks, including the Svalbard analogues of the carbonate reservoirs in the Barents Sea.