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Heat Flow in Western Canada 总被引:1,自引:0,他引:1
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Numerical Modeling of Perched Water Under Yucca Mountain, Nevada 总被引:1,自引:0,他引:1
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The Barry Granodiorite is a weakly deformed I‐type, and the Sunset Hills Granite is a moderately deformed S‐type, granite. Both granites were passively intruded into an already foliated greywacke and volcanic sequence. Emplacement may have been facilitated by faults related to the oblique opening of the late Early Silurian Hill End Trough. The granites display a dominant foliation which formed during the late Middle Devonian and subsequently was reoriented during the Early Carboniferous. The Barry Granodiorite and Sunset Hills Granite are on the margin of north‐south ductile shear zones related to the Wyangala Batholith. These granites and the adjacent Carcoar Granodiorite have undergone reorientation during movement on ductile shear zones either due to megakinking during late‐stage north‐south shortening, or southeastward movement of the southern margin of the west‐northwest‐trending Lachlan Transverse Zone. 相似文献
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C. A. Kennedy W. C. Lennox 《Stochastic Environmental Research and Risk Assessment (SERRA)》2001,15(4):325-340
The advection-dispersion equation (ADE) is inadequate for describing tails in solute breakthrough curves. Re-examination
of solute breakthrough curves from one-dimensional experiments in porous media and channel flow literature shows a consistent
discrepancy compared with solutions to the ADE. The leading tail of breakthrough curves is sharper, and the trailing tail
is longer and smoother, than best fitting, least-squares ADE solutions. A random particle simulation exercise shows that the
ADE may firstly be erroneous because of the assumption of time steps over which random solute movements are considered independent.
Definition of such time steps hinges upon the slowest random movements, such as those predominantly by molecular diffusion.
A second potential source of error is the highly skewed nature of the inverse distribution of underlying, micro-scale velocities,
which causes slow convergence to normality under the central limit theorem. 相似文献
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Diffusion parameters have been estimated for K-feldspar in and adjacent to mylonite shear zones in the Wyangala Batholith. The parameters obtained suggest that deformation during mylonitisation would have caused argon systematics to reset because diffusion distances were reduced by cataclasis, deformation and/or recrystallisation. However, the mineral lattice remained sufficiently retentive to allow subsequently produced radiogenic argon to be retained. 40Ar/39Ar geochronology is thus able to constrain operation of these biotite-grade ductile shear zones to the period from ca 380 Ma to ca 360 Ma, at the end of the Tabberabberan Orogeny. 相似文献
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Brent Lennox Ian Spooner Timothy Jull William P. Patterson 《Journal of Paleolimnology》2010,43(1):15-27
A high-resolution, multi-proxy lake sediment record was used to establish the timing of Holocene environmental change in Canoran Lake, southwest Nova Scotia, Canada. Proxies include %C, δ15N, δ13C, HI, magnetic susceptibility, and pollen. Canoran Lake is a small, shallow (11 m) lake with two ephemeral inlets and an outlet. The site was deglaciated at ca. 15,300 cal (calibrated) year BP and elevated %C values indicate the establishment of a productive aquatic environment that is consistent with Allerød warming. The Allerød was interrupted by rapid air temperature cooling during the Younger Dryas (ca. 12,900–11,600 cal year BP). The Early Hypsithermal (ca. 11,600–8,500 cal year BP) was relatively warm and wet. A slight increase in clastic input occurred between 9,100 and 8,500 cal year BP but δ15N, δ13C, and HI values imply that the lithostratigraphic response may not be indicative of climate-induced change. The strong proxy response between 8,500 and 8,000 cal year BP was likely due to cooling and drying coincident with the 8.2 k year event. The climate was relatively warm and dry during the Late Hypsithermal (ca. 8,000–3,500 cal year BP). None of the proxies’ exhibit notable change during the 5,500 cal year BP hemlock decline, indicating that ecological change was likely due to a pathogen attack. Post-Hypsithermal (modern) climate was characterized by an increase in precipitation and a decrease in air temperatures from ca. 3,500 to 700 cal year BP (top of core). 相似文献