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Reactions between CO2-charged brines and reservoir minerals might either enhance the long-term storage of CO2 in geological reservoirs or facilitate leakage by corroding cap rocks and fault seals. Modelling the progress of such reactions is frustrated by uncertainties in the absolute mineral surface reaction rates and the significance of other rate limiting steps in natural systems. Here we use the chemical evolution of groundwater from the Jurassic Navajo Sandstone, part of a leaking natural accumulation of CO2 at Green River, Utah, in the Colorado Plateau, USA, to place constraints on the rates and potential controlling mechanisms of the mineral–fluid reactions, under elevated CO2 pressures, in a natural system....
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Patterns of deformation within the Upheaval Dome structure, Utah, provide important clues for assessing its possible impact origin. The complex structure of the innermost part of the dome, in particular of the White Rim Sandstone (WRS), indicated almost complete loss of internal coherence during deformation. The WRS displays extreme thickness variations, blind terminations and frequent embranchments at nodular-like points. This, together with discordant contacts to the country rock, shows that WRS builds up a dike network that was emplaced and injected during formation of the central dome. Microstructural analysis reveals that the macroscopically ductile appearance is achieved by distributed cataclastic flow. Beside...
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Using multiple isotope systems, we examine the complex effects of drainage reorganization in the Laramide Foreland in the context of stable isotope paleoaltimetry. Strontium, oxygen and carbon isotopic data from lacustrine carbonates formed in the southwestern Uinta Basin, Utah between the Late Cretaceous and late Middle Eocene reveal a two stage expansion in the drainage basin of Lake Uinta beginning at ~Â 53Â Ma culminating in the Mahogany highstand at 48.6Â Ma. A marked increase in 87Sr/86Sr ratios of samples from the Main Body of the Green River Formation is interpreted as the result of water overflowing the Greater Green River Basin in Wyoming and entering Lake Uinta from the east via the Piceance Creek Basin...
Fluid transport in the earth's crust is either extremely rapid, or extremely slow. Cracks, dikes and joints represent the former while tight crystalline rocks and impermeable fault gouge/seals represent the latter. In many cases, the local permeability can change instantaneously from one extreme to the other. Instantaneous permeability changes can occur when pore pressures increase to a level sufficient to induce hydro-fracture, or when slip during an earthquake ruptures a high fluid pressure compartment within a fault zone. This 'toggle switch' permeability suggests that modeling approaches that assume homogeneous permeability through the whole system may not capture the real processes occurring. An alternative...
This study is the first to employ spectral analysis to examine meter-scale sedimentary cyclicity in the Wilkins Peak Member of the lower Eocene Green River Formation of Wyoming. Generally regarded as the classic example for orbital forcing of lacustrine sediments at eccentricity and precession time scales, this long-standing interpretation was recently contested, with a much shorter duration (≤ 10 ky) inferred for the dominant cyclicity. Earlier work lacked adequate age control or spectral analysis or both. Our analysis is based upon an evaluation in the frequency domain of oil-yield values from four boreholes, accuracy estimation for suggested orbital interpretations, and comparison to independent geochronology....
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Field and microstructural observations from Upheaval Dome, in Canyonlands National Park, Utah, show that inelastic strain of the Wingate Sandstone is localized along compactional deformation bands. These bands are tabular discontinuities (b0.5 cm thick) that accommodate inelastic shear and compaction of inter-granular volume. Measurements of porosity and grain size from nondeformed samples are used to define a set of capped strength envelopes for the Wingate Sandstone. These strength envelopes reveal that compactional deformation bands require at least ca. 0.7 GPa (and potentially more than 2.3 GPa) of effective mean stress in order to nucleate within this sandstone. We find that the most plausible geologic process...
    map background search result map search result map Compactional deformation bands in Wingate Sandstone; additional evidence of an impact origin for Upheaval Dome, Utah Dike formation, cataclastic flow, and rock fluidization during impact cratering: an example from the Upheaval Dome structure, Utah The effect of drainage reorganization on paleoaltimetry studies: An example from the Paleogene Laramide foreland Dike formation, cataclastic flow, and rock fluidization during impact cratering: an example from the Upheaval Dome structure, Utah Compactional deformation bands in Wingate Sandstone; additional evidence of an impact origin for Upheaval Dome, Utah The effect of drainage reorganization on paleoaltimetry studies: An example from the Paleogene Laramide foreland