Hydrogeology of an arsenic-mineralized fractured phyllite, and implications for groundwater arsenic dispersion

Massimo Gasparon, V Ciminelli, G Duarte, Jack Ng

    Research output: Contribution to conferencePaperpeer-review

    1 Citation (Scopus)

    Abstract

    The hydrogeology of the Paracatu area in Minas Gerais, Brazil, was assessed by a combination of pumping tests, natural hydrogeological tracers (oxygen and hydrogen stable isotopes, and 222Rn), and trace element water geochemical analyses. The area's geological basement is a fractures phyllite hosting a significant gold deposit, with gold being associated with arsenopyrite and quartz boudins. Hydraulic conductivity in both mineralized and non-mineralized areas was low, ranging from 2 × 10- 6 to 1 × 10- 5 cm/sec. Pervasive kaolinite filling was observed in the fractures. 222Rn levels were very variable, ranging from ∼8 to ∼110 Bq/L, and stable isotope data also indicated multiple water sources and complex mixing patters. Arsenic levels were typically below 1 μg/L, with some exceptions found in both impacted and non-impacted areas. Despite the fracturing and jointing, the geological substrate has low hydraulic permeability, limiting the mobility of As released from the rock mineralization. Extensive analytical results have confirmed the good quality of groundwater in the Paracatu region.

    Original languageEnglish
    Pages74-75
    Number of pages2
    DOIs
    Publication statusPublished - 16 Aug 2012
    Event4th International Congress on Arsenic in the Environment -
    Duration: 22 Jul 2012 → …

    Conference

    Conference4th International Congress on Arsenic in the Environment
    Period22/07/12 → …

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