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TitreThe Lake St. Martin bolide has a big impact on groundwater fluoride concentrations
AuteurLeybourne, M I; Peter, J M; Johannesson, K H; Boyle, D R
SourceGeology vol. 36, no. 2, 2008 p. 115-118, https://doi.org/10.1130/G24135A.1
Année2008
Séries alt.Commission géologique du Canada, Contributions aux publications extérieures 20060582
ÉditeurGeological Society of America
Documentpublication en série
Lang.anglais
DOIhttps://doi.org/10.1130/G24135A.1
Mediapapier; en ligne; numérique
Formatshtml; pdf
ProvinceManitoba
SNRC62O/09; 62O/10; 62O/15; 62O/16
Lat/Long OENS -98.8833 -98.3333 51.8167 51.5500
Sujetsressources en eau souterraine; aquifères du substratum rocheux; géologie du substratum rocheux; géologie du socle; lithologie; roches métamorphiques; roches granitiques; roches vertes; cratères météoriques; brèches; fractures; structures flui dales; roches sédimentaires; carbonates; grès; bassins sédimentaires; couches rouges; évaporites; gypse; régimes des eaux souterraines; géochimie des eaux souterraines; puits d'eau; qualité de l'eau; salinité; sulfate; fluorures; réseaux de pH; sodium; chlorure; bore; lithium; oxydes de fer; alumine; capacité d'échange cationique; perméabilité; dangers pour la santé; analyses géochimiques; géochimie de l'eau; géochimie des roches totales; Structure d'impact de Lake St. Martin ; Grès de Winnipeg ; eau potable; hydrogéologie; géochimie; Phanérozoïque; Crétacé; Trias; Paléozoïque; Dévonien; Silurien; Ordovicien; Précambrien
Illustrationssketch maps; plots
ProgrammeGovernment of Manitoba, Funding Program
ProgrammeProgramme de cartographie des eaux souterraines
Résumé(disponible en anglais seulement)
The majority of residents of Manitoba (Canada) outside of the capital, Winnipeg, rely on groundwater for their drinking water. Between lakes Winnipeg and Winnipegosis, most aquifers occur in Paleozoic carbonate lithologies. Proximal to the town of Gypsumville, however, lithologies associated with the Lake St. Martin impact structure and younger basin-fi lling red bed and evaporite ( gypsum/anhydrite) sedimentary rocks complicate the hydrology and hydrochemistry.
Here, domestic wells have elevated salinities (up to 8000 mg/L total dissolved solids), elevated sulfate (up to 4000 mg/L), and elevated fl uoride concentrations that are in excess of health limits (F- up to 15.2 mg/L, with 20% over 1.5 mg/L). Groundwaters with elevated fl uoride occur exclusively within the impact structure. The impact melt rocks and younger red beds consistently have the highest fl uoride abundances, up to 2160 ppm. Groundwater pH values are alkaline, ranging up to 10.7, with highest groundwater pH from wells in the impact melt rocks. The spatial associations of impact melt rocks and red beds with elevated fl uoride, strong positive correlations between fl uoride and pH, sodium, chloride, sulfate, boron and lithium, greater Fe2O3 and Al2O3 concentrations of the host rocks, and cation exchange capacity (CEC) all indicate that fl uoride concentrations in groundwaters are enhanced as a result of anion exchange wherein OH- and CO3 2- displace F- adsorbed onto Fe- and Al-oxyhydroxide surfaces. Thus, the elevated fl uoride contents of groundwaters at Gypsumville are a consequence of the composition of the impact melt rocks and enhanced permeability and grain-size reduction produced by bolide impact.
GEOSCAN ID223336