Fluid flow and diagenesis in carbonate dominated ForelandFold and Thrust Belts: petrographic inferences from field studies of late-diagenetic fabrics from Albania, Belgium, Canada, Mexico and Pakistan

Abstract

Five different Foreland Fold and Thrust Belt (FFTB) systems have been studied with the aim of reconstructing the fluid flow history through time and to deduce the primary processes affecting reservoir units. By placing the diagenetic history into its kinematic framework, a database is generated allowing to predict diagenetic processes in FFTBs. Particular attention is paid to the late diagenetic processes since petrographical and geochemical data indicate that several of these processes reflect nonequilibrium conditions with respect to their host rocks. Some of these systems involve channeled fluid flow where the system is, to some extent, water dominated (e.g. hydrothermal karstification, MVT mineralisation, zebra dolomitization and cooling of formation water). Other processes are less fluid prone, but here cooling of entire thrust sheets by thrusting and recrystallisation of dolomite by layer parallel shortening during tectonic compression are processes proposed to explain the diagenetic alteration of some reservoirs.