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Tailings and Mine Waste Conference
Geological, hydrological, and geochemical framework for Questa Logsdon, Mark J.
Abstract
The Questa Weathering and Stability Study included detailed earth-science characterization of hydrothermally-altered igneous rock-pile and analog materials and associated groundwater. Radiometric dating demonstrates that natural weathering processes and their mineralogical outcomes have been active at Questa over a million years or more. Dissolution of pyrite, calcite, and silicate minerals is the predominant geochemical reaction that results in low-pH, high-TDS seepage and precipitation of gypsum, jarosite, and iron hydroxide minerals. Silicate minerals in the Questa rock piles dissolve congruently, without producing clay minerals. Seepage waters are thermodynamically under-saturated with respect to all silicate minerals (including clay minerals), sulfides, and carbonates, but are saturated with respect to jarosite, ferric oxides, and gypsum. Clay minerals at Questa formed under hydrothermal, not weathering, conditions. Secondary precipitates predicted from water chemistry are directly observed, and locally they act to cement rock fragments in rock piles and debris flows. [All papers were considered for technical and language appropriateness by the organizing committee.]
Item Metadata
Title |
Geological, hydrological, and geochemical framework for Questa
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Creator | |
Contributor | |
Date Issued |
2011-11
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Description |
The Questa Weathering and Stability Study included detailed earth-science characterization of hydrothermally-altered
igneous rock-pile and analog materials and associated groundwater. Radiometric dating demonstrates
that natural weathering processes and their mineralogical outcomes have been active at Questa over a million
years or more. Dissolution of pyrite, calcite, and silicate minerals is the predominant geochemical reaction that
results in low-pH, high-TDS seepage and precipitation of gypsum, jarosite, and iron hydroxide minerals. Silicate
minerals in the Questa rock piles dissolve congruently, without producing clay minerals.
Seepage waters are thermodynamically under-saturated with respect to all silicate minerals (including clay
minerals), sulfides, and carbonates, but are saturated with respect to jarosite, ferric oxides, and gypsum. Clay
minerals at Questa formed under hydrothermal, not weathering, conditions. Secondary precipitates predicted
from water chemistry are directly observed, and locally they act to cement rock fragments in rock piles and
debris flows.
[All papers were considered for technical and language appropriateness by the organizing committee.]
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Genre | |
Type | |
Language |
eng
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Date Available |
2011-10-18
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
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DOI |
10.14288/1.0107715
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URI | |
Affiliation | |
Peer Review Status |
Unreviewed
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Scholarly Level |
Other
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Rights URI | |
Aggregated Source Repository |
DSpace
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Item Citations and Data
Rights
Attribution-NonCommercial-NoDerivatives 4.0 International