Influence of inherited structures as fluid-thermal conduits applied to the formation of uranium mineralisation in the Athabasca Basin, Canada
Résumé
Ore deposit formation requires the synchronisation of multiple processes with transportation of fluids and heat. Ancient inherited structures found within the basement of the Athabasca Basin were formed as a result from of orogenic processes (i.e nucleation and accretion processes). It is established that their reactivation played a significant role for the formation of the unconformity-related uranium deposits. The time gap between the inherited structures' inception and mineralisation event is sufficient for any traces of hydrothermal systems to reach steady state. The aim of this study is to determine the role for these inherited structures affecting the hydrothermal dynamics, by using a pre-existing tectonic structure generated from a thermo-mechanical study and incorporating fluid-thermal processes until steady-state conditions. The models are then experimented with permeability fields of increasing complexity in three types of tectonic scenarios. Results indicate that deep-seated structures operate as fluid-thermal conduits that bring fluids and heat towards the upper portions of the crust. In addition, thermal convection occurs at favourable permeability conditions. The experimentation of models in different permeability fields provides a general framework for the Athabasca Basin suggesting the transportation of basement-associated fluids and heat to the surface.