A Two-Stage, Transient Heat and Mass Transfer Model for the Granodiorite Intrusion at Seriphos, Greece, and the Associated Formation of Contact Metasomatic Skarn and Fe-ore Deposits

Abstract

At Seriphos, Cyclades, Greece, the shallow intrusion of a granodiorite pluton produced a contact metamorphic aureole and extensive contact metasomatic skarn and Fe-ore deposits. Based on geological evidence a simplified, one-dimensional, two-stage mathematical model is developed describing the coupled transfer of heat and mass during the thermal evolution of the intrusive system. The model encompasses the magmatic as well as the post-magmatic stages of the intrusive event. The magmatic stages are modelled by assuming convection in the melt and conductive heat transfer into the surrounding contact aureole. The post-magmatic stages are treated by simulating the advective outflow of hydrothermal solutions from the (high temperature-high fluid pressure) plutonic heat and fluid source into its (lower temperature-lower fluid pressure) environment.

By using model parameters obtained from experimental data as well as from observed mineral assemblages, oxygen isotope results and fluid inclusion studies, sufficient information is obtained to construct a model that agrees well with the field evidence. The model results, in their turn, give an indication of the complex time-temperature interrelations between the major processes that accompanied the intrusion of the granodiorite. The model, in addition, permits a quantitative evaluation of the post-magmatic, metasomatic mass exchanges. For instance, the total amount of Fe that can be modelled to precipitate in the skarn and Fe-ore deposits is well in accordance with the field estimations.