Role of fluid mixing in deep dissolution of carbonates

M. Corbella, C. Ayora

Abstract


The presence of cavities filled with new minerals in carbonate rocks is a common feature in oil reservoirs and lead-zinc deposits. Since groundwater equilibrates rapidly with carbonates, the presence of dissolution cavities in deep carbonate host rocks is a paradox. Two alternative geochemical processes have been proposed to dissolve carbonates at depth: hydrogen sulfide oxidation to sulfuric acid, and metal sulfide precipitation. With the aid of geochemical modeling we show that mixing two warm solutions saturated with carbonate results in a new solution that dissolves limestone. Variations in the proportion of the end-member fluids can also form a supersaturated mixture and fill the cavity with a new generation of carbonate. Mixing is in general more effective in dissolving carbonates than the aforementioned processes. Moreover, mixing is consistent with the wide set of textures and mineral proportions observed in cavity infillings.

Keywords


Hydrothermal karst; MVT deposits; Reactive transport; Fluid mixing; Carbonate dissolution.

Full Text:

PDF


DOI: https://doi.org/10.1344/105.000001618

Refbacks

  • There are currently no refbacks.




Creative Commons License
This work is licensed under a Creative Commons Attribution-ShareAlike License.

                                                                                                            
            Facultat de Ciències de la Terra                       Geociències Barcelona                           Institut de Diagnosi Ambiental                    Universitat Autònoma de Barcelona           
                Universitat de Barcelona                                                                                          i Estudis de l'Aigua (CSIC) 
 
 
Geologica Acta (ISSN-1695-6133)
Biblioteca de Ciències de la Terra (UB-CSIC) | Facultat de Ciències de la Terra, Martí i Franquès s/n 08028 Barcelona | Spain
Phone: +34 93 403 19 89 | E-mail: geologica-acta@ictja.csic.es
RCUB RCUB Declaració ètica Avís Legal Centre de Recursos per a l'Aprenentatge i la Investigació Universitat de Barcelona