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Concentrations of weathering products in streams often show relatively little variation compared to changes in discharge, both at event and annual scales. In this study, several hypothesized mechanisms for this “chemostatic behavior� were evaluated, and the potential for those mechanisms to influence relations between climate, weathering fluxes, and CO2 consumption via mineral weathering was assessed. Data from Loch Vale, an alpine catchment in the Colorado Rocky Mountains, indicates that cation exchange and seasonal precipitation and dissolution of amorphous or poorly crystalline aluminosilicates are important processes that help regulate solute concentrations in the stream; however, those processes have no...
This paper investigates injection of CO2 into non-dome-shaped geological structures that do not provide the traps traditionally deemed necessary for the development of artificial CO2 reservoirs. We have developed a conceptual and two numerical models of the geology and groundwater along a cross-section lying approximately NW?SE and in the vicinity of the Hunter power station on the Colorado Plateau, Central Utah and identified a number of potential sequestration sites on this cross-section. Preliminary modeling identified the White Rim Sandstone as appearing to offer the properties required of a successful sequestration site. Detailed modeling of injection of CO2 into the White Rim Sandstone using the reactive chemical...
The Summitville Au?Ag?Cu deposit is a classic volcanic dome-hosted high-sulfidation deposit. It occurs in the Quartz Latite of South Mountain, a composite volcanic dome that was emplaced along the coincident margins of the Platoro and Summitville calderas at 22.5�0.5 Ma, penecontemporaneous with alteration and mineralization. A penecontemporaneous quartz monzonite porphyry intrusion underlies the district and is cut and overlain by pyrite?quartz stockwork veins with traces of chalcopyrite and molybdenite. Alteration and mineralization proceeded through three hypogene stages and a supergene stage, punctuated by at least three periods of hydrothermal brecciation. Intense acid leaching along fractures in the quartz...
With the increased importance of water resources in the western United States and many areas worldwide, the remediation of impacts from historical mining becomes ever more important. A possible process of making decisions about remediation for a catchment might include identification of principal sources of metals in the catchment, classification of the sources as natural or anthropogenic, and simulations to evaluate different options for removal of anthropogenic sources. The application of this process is based on understanding the pre-mining conditions in the catchment, so that remediation goals appropriately correct for the impacts of mining. A field experiment in Redwell Basin, Colorado, provided a setting to...
Carbonate mineral phases were investigated with respect to distribution and isotopic composition from core holes in the Green River Formation, Wyoming, an ancient lake complex. Mineral distribution data suggest dolomite genesis on a carbonate mudflat surrounding a central lake facies with transportation and subsequent later alteration in the lacustrine facies. Calcite was the dominant carbonate mineral deposited in the lacustrine facies. Samples, investigated by stable isotopes, representing each member of the Green River Formation, displayed isotopic values for ?13C of from ? 1.3 to + 7.5? and for ?18C of ? 6.0 to ?0.8?. Isotopic values representing modern and paleolacustrine sequences were compared. ?13C-values...
A closed-system model is used for predicting the ?18O of formation waters in the deep portions of the northern Green River basin, Wyoming. ?18Ocalcite is calculated from this modeled water and compared with the ?18O of measured calcites to help interpret diagenesis in the basin. The modification of 18Owater, which may be caused by diagenetic reactions at elevated temperatures, is modeled from two mass-balance equations. Three diagenetic reactions used to modify ?18Owater include: detrital limestone� calcite cement; detrital quartz? quartz cement; and detrital clay � authigenic illite/smectite. A weighted average ?18Owater and ?18O of calcite, quartz and illite/smectite in equilibrium with this water are calculated...