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Mineralium Deposita

, Volume 39, Issue 5–6, pp 622–631 | Cite as

Numerical investigation of salinity in controlling ore-forming fluid transport in sedimentary basins: example of the HYC deposit, Northern Australia

  • Jianwen Yang
  • Stuart Bull
  • Ross Large
Article

Abstract

This paper presents the first hydrogeological model that fully couples transient fluid flow, heat and solute transport associated with the formation of the HYC SEDEX deposit in the McArthur Basin, northern Australia. Numerical results reveal that salinity plays an important role in controlling hydrothermal fluid migration. In particular, it appears that it is the distribution of evaporitic units within a given basin, rather than their absolute abundance, that controls the development of free convection. Relatively saline conditions at the seafloor strengthen the thermally-induced buoyancy force and hence promote free convection of basinal solutions; whereas high salinities at the bottom counteract the thermal function of natural geothermal gradient and suppress the development of convective hydrothermal fluid circulation. In the latter case, higher thermal gradients are required to initiate substantial free convective fluid flow.

Numerical experiments also suggest the position of an ore body with respect to its vent system may be controlled by the spatial and temporal salinity distributions in the basin. Vent-distal ore formation, a result of exhalation of brines that are denser than seawater and hence can flow away from the vent region, is promoted by moderate salinity at the seafloor and higher salinity in the aquifer. Vent-proximal ore accumulation, a result of pluming upon exhalation of brines less dense than seawater, is favored by the highest salinity conditions occurring near the level of the seafloor.

Keywords

Basinal brine flow Heat transport Solute transport Buoyancy force Numerical modeling 

Notes

Acknowledgments

This research was supported by the Australian Research Council (ARC)’s Research Centres Program and by the Natural Sciences and Engineering Research Council of Canada (NSERC) through a Discovery Grant (RGPIN 261283) to JY. The authors are grateful to Alison Ord and Georges Beaudoin for their constructive reviews.

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Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  1. 1.Department of Earth SciencesUniversity of WindsorWindsorCanada
  2. 2.Centre for Ore Deposit ResearchUniversity of TasmaniaHobartAustralia

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