Floodplain storage of mine tailings in the belle fourche river system: A sediment budget approach     

Donna C. Marron 《地球表面变化过程与地形》1992,17(7):675-685

Arsenic-contaminated mine tailings that were discharged into Whitewood Creek at Lead, South Dakota, from 1876 to 1978, were deposited along the floodplains of Whitewood Creek and the Belle Fourche River. The resulting arsenic-contaminated floodplain deposit consists mostly of overbank sediments and filled abandoned meanders along White-wood Creek, and overbank and point-bar sediments along the Belle Fourche River. Arsenic concentrations of the contaminated sediments indicate the degree of dilution of mine tailings by uncontaminated alluvium. About 13 per cent of the 110 × 10⁶ Mg of mine tailings that were discharged at Lead were deposited along the Whitewood Creek floodplain. Deposition of mine tailings near the mouth of Whitewood Creek was augmented by an engineered structure. About 29 per cent of the mine tailings delivered by Whitewood Creek were deposited along the Belle Fourche River floodplain. About 60 per cent of that sediment is contained in overbank deposits. Deposition along a segment of the Belle Fourche River was augmented by rapid channel migration. The proportions of contaminated sediment stored along Whitewood Creek and the Belle Fourche River are consistent with sediment storage along the floodplains of perennial streams in other, similar sized watersheds.  相似文献   

Trace metals in sediments from Torres Strait and the Gulf of Papua: concentrations,distribution and water circulation patterns   总被引：3，自引：0，他引：3  

Haynes D  Kwan D 《Marine pollution bulletin》2002,44(11):1309-1313

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True polar wander     

Donna M. Jurdy   《Tectonophysics》1981,74(1-2)

A re-evaluation of the existence of true polar wander (TPW) since the Late Cretaceous and a comparison among the various approaches are made using updated paleomagnetic, hotspot and relative motion datasets. Previous attempts to determine the existence of TPW had resulted in different conclusions: comparison of hotspot locations and paleomagnetic poles required significant pole motion, although lithospheric plate displacement analysis yielded insignificant motion. However, these earlier determinations cannot be directly compared to find the reason for the discrepancies, because each used different datasets. For this study the different approaches are applied to a single updated model with three alternative relative motions of East and West Antarctica. Although the results are model-dependent, in general there was not significant motion of the pole relative to the lithosphere (1–5°) since the early Tertiary, but a large motion (10–12°) relative to the hotspot framework. It is unlikely that errors in the determinations could account for this disagreement: the A₉₅ of the plate reconstruction is about 3°, the uncertainty in Antarctica motion is estimated to no larger than 3°, and cumulative errors in the relative plate motions may also amount to 3°. Only if all these errors are present in the maximum estimated amount, and in the same direction, could they account for the 10–12° gap between the two approaches. This conclusion of pole motion relative to the hotspots, but not the lithosphere, may indicate an independent shift of the mesosphere relative to the lithosphere (or “mantle roll” of Hargraves and Duncan).  相似文献   

The halo mass function from the dark ages through the present day     

Darren S. Reed  Richard Bower  Carlos S. Frenk  Adrian Jenkins  Tom Theuns 《Monthly notices of the Royal Astronomical Society》2007,374(1):2-15

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The stellar mass content of distant galaxy groups     

Michael L. Balogh  Dave Wilman  Robert D. E. Henderson  Richard G. Bower  David Gilbank  Richard Whitaker  Simon L. Morris  George Hau  J. S. Mulchaey  A. Oemler  Jr    R. G. Carlberg 《Monthly notices of the Royal Astronomical Society》2007,374(3):1169-1180

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Resolved spectroscopy of a gravitationally lensed L* Lyman-break galaxy at z∼ 5     

A. M. Swinbank  R. G. Bower  Graham P. Smith  R. J. Wilman  Ian Smail  R. S. Ellis  S. L. Morris  J.-P. Kneib 《Monthly notices of the Royal Astronomical Society》2007,376(2):479-491

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Garnet polycrystals and the significance of clustered crystallization     

Donna L. Whitney  Nicholas C. A. Seaton 《Contributions to Mineralogy and Petrology》2010,160(4):591-607

Polycrystalline garnets are common in metamorphic rocks and may form as a result of close spacing of nuclei (if clustering is early) or impingement of larger grains (if clustering occurs later in the growth history). The timing of clustering relative to garnet growth is relevant to understanding the formation and evolution of porphyroblasts and evaluating the significance (if any) of clustering. Electron backscattered diffraction (EBSD) analysis of garnet-bearing metamorphic rocks reveals the presence of polycrystalline garnet in nine localities examined in this study: the northern Appalachians (Vermont, Maine, New York, USA); North American Cordillera (North Cascades Range, Washington; Snake Range, Nevada, USA); western Rocky Mountains (British Columbia, Canada); southern Menderes Massif (Turkey); Santander Massif (Colombia); and the Sanandaj–Sirjan zone (Hamadan, Iran). In some samples, polycrystals comprise ~20–30% of garnets analyzed, and chemical and textural evidence suggests that early coalescence of garnet polycrystals is common. Some early-coalescing polycrystals exhibit growth zoning that is concentric about the geometric center of the polycrystal. In thin section, these garnets may be undetectable as polycrystals based on morphology or zoning. In some polycrystals, zoning is unrelated to the location of internal grain boundaries; in others, Fe–Mn–Mg zoning has a different pattern than that of Ca; zoning patterns may vary on the scale of a single thin section. In addition, some polycrystals are characterized by high-angle misorientation boundaries that may be in special (non-random) orientations, an observation that indicates that these polycrystals are not random clusters of grains. The presence of internal grain boundaries may affect diffusion pathways and length scales, and may facilitate communication of porphyroblast interiors with matrix phases, thereby influencing reaction history of the rock and the composition/zoning of garnet.  相似文献   

ACE‐2 multiple angle micro‐pulse lidar observations from Las Galletas, Tenerife, Canary Islands     

Donna M. Powell  John A. Reagan  Manuel A. Rubio  Wayne H. Erxleben  James D. Spinhirne 《Tellus. Series B, Chemical and physical meteorology》2000,52(2):652-661

Multiple‐angle micro‐pulse lidar (MPL) observations were made at Las Galletas on Tenerife, Canary Islands during the Aerosol Characterization Experiment‐2 (ACE‐2) conducted June–July, 1997. A principal objective of the MPL observations was to characterize the temporal/spatial distributions of aerosols in the region, particularly to identify and profile elevated Saharan dust layers which occur intermittently during the June–July time period. Vertical and slant angle measurements taken 16 and 17 July characterize such an occurrence, providing aerosol backscatter, extinction, and optical depth profiles of the dust layer between 1 and 5 km above mean sea level (MSL). Additionally, horizontal measurements taken in Las Galletas throughout the 6‐week period provide a time profile of the varying aerosol extinction at the surface. This profile exhibits the alternating periods of clean maritime air and pollution outbreaks that typified the region. Horizontal measurements also provide some evidence suggesting the possible influx of Saharan dust from the free troposphere to the surface. This paper presents estimates of aerosol optical properties retrieved from the multi‐angle MPL measurements in addition to an outline of the methodologies employed to obtain these results.  相似文献   

A panoramic Hα imaging survey of the  z= 0.4  cluster Cl 0024.0+1652 with Subaru     

Tadayuki Kodama  Michael L. Balogh †  Ian Smail  Richard G. Bower  Fumiaki Nakata 《Monthly notices of the Royal Astronomical Society》2004,354(4):1103-1119

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Revisiting the cosmic cooling crisis     

Michael L. Balogh  Frazer R. Pearce  Richard G. Bower  Scott T. Kay 《Monthly notices of the Royal Astronomical Society》2001,326(4):1228-1234

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