Spatio-temporal scales of fluid transport and reaction during ore formation

The formation of ore deposits includes complex interaction of fluid pathways, advection and diffusion of matter and temperature, mixing of fluids, as well as reactions that include replacement as well as new growth of material. Even though fluids are often modelled as having a certain chemical composition, eventually, every locality in an ore deposit, down to small scales, can have a different fluid composition. Incoming fluids or existing pore fluids may initially have constant compositions, but these will change locally due to mixing and as soon as reactions take place, the host rock is dissolved into the fluid, new material precipitates and the fluid chemistry changes. Even a simple crack around which reactions take place will become a multi-component system with complex chemical and transport interactions on the grain scale.

 

This research project investigates spatio-temporal patterns in ore-formation on the small to outcrop scale with numerical simulations. The models will be calibrated with natural examples and used to develop proxies for the related processes and their scales. 

 

In this project, we will model reactions and related fluid changes to be able to capture the full complexity of ore formation on the small scale. We will then quantify the developing patterns as a function of incoming and pore fluid chemistries as well as host rock properties and extrinsic variables like depth and temperature. In addition, we will attain complete geochemical cross-sections of alteration zones and ore zones around specific fluid pathways in our model field systems. These will be compared with the numerical patterns to develop a predictive tool for alteration zone and ore formation.