Effects of Fluid Pressure Development on Hydrothermal Mineralization via Cellular Automaton Simulation

Abstract

The behavior and evolution trajectory of hydrofracture, which show a close relationship with the hydrothermal mineralization process, is greatly influenced by fluid flow and fluid pressure. However, further investigation is needed to achieve an in-depth understanding of the formation and evolution mechanisms behind the link between the rate of fluid pressure development and the occurrence of induced hydrofracture and mineralization process. We considered different fluid pressure development rates as the initial data for a cellular automaton model. With the increase in the fluid pressure increase rates, the corresponding hydrofracture became more focused, changing in scale from a large number of small-scale hydrofractures to a small number of large-scale hydrofractures. Episodes of fluid pressure fluctuation induced by either low or high fluid pressure increase rates were shown to trigger mineral precipitation and further contribute to the generation of strong spatially structured and enriched geochemical patterns. Moreover, the correlation length at the percolation threshold, which is of great significance to the degree and scale of mineralization, increased with the increasing fluid pressure increase rates. It was concluded that computational grids with high fluid pressure increase rates are much more prone to produce enriched geochemical patterns with strong spatial structures than grids with low fluid pressure increase rates owing to a larger correlation length at the percolation threshold. These results suggest that the way of fluid pressure development is a key factor for quantifying the behavior of hydrofracture and mineralization process.