Koehn, D., Kelka, U., Toussaint, R., Siegel, C., Mullen, G., Boyce, A. and Piazolo, S. (2022) Outcrop scale mixing enhanced by permeability variations: the role of stationary and travelling waves of high saturation indices. Geological Magazine, 159(11-12), pp. 2279-2292. (doi: 10.1017/S001675682200070X)
![[img]](https://eprints.gla.ac.uk/style/images/fileicons/text.png) |
Text
297995.pdf - Published Version Available under License Creative Commons Attribution. 1MB |
Abstract
To study the ore mineralization at the outcrop scale we merge an advection–diffusion simulation with the geochemical software iphreeqc to model the mixing of two realistic fluids. We simulate the infiltration of a metal-rich fluid into a rock that is saturated with pore fluid. We test the feedback effects with a number of scenarios based on an outcrop-scale 5 × 5 m model consisting of two high-permeable vertical faults within a low-permeable host rock that lead into a permeable layer. The hot metal-rich fluid enters the model through the faults from below. We solve the advection–diffusion equation for 12 chemical species and temperature, and use iphreeqc to determine the resulting properties of local fluid domains as well as related saturation indices for minerals. The faults in the model act as pathways for the metal-rich fluid, with the infiltrating fluid displacing the pore fluid. Mixing in the model takes place as a function of advection along permeable faults coupled with diffusion of chemical species at the interface between two fluids, while heat diffusion is fast enough (103 times faster) to equilibrate temperature. Simulations show a high saturation index of mixing-derived minerals such as barite at the interface between the two fluids as a result of fluid mixing. Fast fluid pathways (i.e. faults) show travelling waves of high saturation indices of barite, while low-permeability zones such as fault walls and areas below less permeable layers experience stationary waves of high saturation indices. Our results show that, depending on the dominant transport process (advection or diffusion), mineralization will localize next to permeability contrasts in zones where local diffusion dominates.
| Item Type: | Articles |
|---|---|
| Additional Information: | This research was part of the project “Integrated geophysical-structural-kinematic analysis of the fault patterns in Northern Bavaria” funded by the Bayerisches Landesamt für Umwelt (LfU) and the Bavarian Ministry of Science and Art (StMWK) of the Geothermal Alliance Bavaria (GAB). GM, AB and DK acknowledge funding by the Natural Environment Research Council (Case Studentship grant no. NE/R007772/1, title: “Predicting ore mineralization using quantitative forward modelling and high resolution analytical data”). CS acknowledges MinEx CRC phase 1 for funding the acquisition of microXRF maps. RT acknowledges the support of the CNRS INSU CESSUR programmes and the Research Council of Norway through its Centre of Excellence funding scheme (project no. 262644). The authors also acknowledge the support of ITN FlowTrans, the European Union’s Seventh Framework Programme for research (grant no. 316889). |
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Boyce, Professor Adrian and Mullen, Gary |
| Authors: | Koehn, D., Kelka, U., Toussaint, R., Siegel, C., Mullen, G., Boyce, A., and Piazolo, S. |
| College/School: | College of Science and Engineering College of Science and Engineering > Scottish Universities Environmental Research Centre |
| Journal Name: | Geological Magazine |
| Publisher: | Cambridge University Press |
| ISSN: | 0016-7568 |
| ISSN (Online): | 1469-5081 |
| Published Online: | 13 October 2022 |
| Copyright Holders: | Copyright © 2022 The Authors |
| First Published: | First published in Geological Magazine 159(11-12):2279-2292 |
| Publisher Policy: | Reproduced under a Creative Commons License |
University Staff: Request a correction | Enlighten Editors: Update this record
Funder and Project Information
Funder and Project Information