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1.
Ryszard Kryza Jolanta Muszer Joanna Haydukiewicz Czesław August Marta Jurasik Nickolay Rodionov 《International Journal of Earth Sciences》2011,100(6):1227-1235
A Lower Carboniferous platform sedimentary sequence (the Paprotnia Beds) in the Bardo Unit of the central Sudetes (NE part
of the Bohemian Massif, SW Poland) is biostratigraphically well dated, based on rich macro- and micro-fossil evidence, as
Late Viséan (late Asbian, crenistria, Go III α zone). The beds contain several bentonite layers, one of which was dated using the U–Pb SHRIMP method on volcanic
zircons and yielded an age of 334 ± 3 Ma. This date fits well to the recently established chronostratigraphic limits of the
Viséan, and is consistent with the newest isotopic age constraints of 336.5–332 Ma for the Asbian boundaries. 相似文献
2.
Yuyu Zhou Yeqiao Wang Arthur J. Gold Peter V. August Thomas B. Boving 《GeoJournal》2014,79(2):155-166
In this study, we investigated the relationship between watershed characteristics and hydrology using high spatial resolution impervious surface area (ISA), hydrologic simulations and spatial regression. We selected 20 watersheds at HUC 12 level with different degrees of urbanization and performed hydrologic simulation using a distributed object-oriented rainfall and runoff simulation model. We extracted the discharge per area and ratio of runoff to base flow from simulation results and used them as indicators of hydrology pattern. We derived percentage of ISA, distance from ISA to streams, and stream density as the watershed characteristics to evaluate the relationship with hydrology pattern in watersheds using ordinary least square, spatial error and spatial lag regression models. The comparison indicates that spatial lag regression model can achieve better performance for the evaluation of relationship between ratio of runoff to base flow and watershed characteristics, and that three models provide similar performance for the evaluation of relationship between discharge per area and watershed characteristics. The results from regression analyses demonstrate that ISA plays an important role in watershed hydrology. Ignorance of spatial dependence in analyses will likely cause inaccurate evaluation for relationship between ISA and watershed hydrology. The hydrologic model, regression methods and relationships between watershed characteristics and hydrology pattern provide important tools and information for decision makers to evaluate the effect of different scenarios in land management. 相似文献
3.
Polished sections of 5 enstatite chondrites have been irradiated with 30 MeV 4He ions to produce the alpha-radioactive nuclei 211At and 210Po from 209Bi and 208Pb, respectively. The distribution of alpha activity can be mapped, using cellulose nitrate as an alpha track detector, to give the corresponding Bi or Pb distributions in the meteorite. No strong localization of Bi or 208Pb was found; relatively uniform track distributions were observed. In particular, metal or sulfide grains are not enriched in Bi or Pb (relative to bulk), which is in agreement with the predictions of nebular condensation calculations. While the track distributions appear uniform, the results of detailed, track-by-track mappings of the Bi detectors indicate that the Bi is not totally randomly distributed; the statistical fluctuations in the observed track density are different for the cases where the Bi is totally randomly distributed and where the Bi is localized in point sources. Assuming that the Bi in a given sample is localized in identical point sources which are uniformly distributed throughout the sample, the observed relative population densities of clusters (‘stars’) of small numbers of tracks (2–5) corresponds to Bi being localized, with ~90% in grains with about 10?16g-Bi (~3 × 105Biatoms), and with ~10% in 4 × 10?14 g-Bi sources. If these are elemental Bi, as predicted theoretically, they are ~ 102 Å and 103 Å in size, respectively. 相似文献
4.
A distributed object-based rainfall–runoff simulation (DORS) model with incorporation of detailed impervious surface-area (ISA) data, derived from digital true-color orthophotography data with high spatial resolution, was developed. This physically based model simulates hydrologic processes of precipitation interception, infiltration, runoff, evapotranspiration, change of soil moisture, change of water-table depth, runoff routing, groundwater routing, and channel-flow routing. The modeling processes take objects based on land-cover types as fundamental spatial units in order to reduce data volume, increase computational efficiency, strengthen representation of watersheds, and utilize the data in variable scales. US Geological Survey stream-gaging data were used to validate the temporal variation of simulated discharge within two watersheds in Rhode Island State. The ratio of absolute error to the mean and the Nash coefficient in the validation period are 7.2% and 0.90 for the first watershed, and 8.0% and 0.77 for the second watershed, respectively. The results indicate that the DORS model is able to capture the relationship between rainfall and runoff in the study area, and that it is applicable in the further study of ISA impacts on the water cycle and associated pollution problems. The results also demonstrate that the performance of the hydrologic simulation is improved with ISA data with high spatial resolution. 相似文献
5.
John F. Paul Jane L. Copeland Michael Charpentier Peter V. August Jeffrey W. Hollister 《Marine Geodesy》2003,26(1):63-72
Geographic information systems (GIS) tools are now considered integral in estuarine monitoring and assessment research. A synopsis is presented of our estuarine applications of GIS in the Northeast region of the U.S. The applications discussed cover sample site selection, support for field sampling activities, quality assurance of data, spatial display of geographic referenced information, quantitative spatial analysis of data, and communication of results. 相似文献
6.
The Moon: A Taylor perspective 总被引：1，自引：0，他引：1
S. Ross Taylor G. Jeffrey Taylor L. August Taylor 《Geochimica et cosmochimica acta》2006,70(24):5904-5918
We address several current lunar problems. The data suggest that the Moon likely possesses an Fe-rich metallic core a few percent of lunar volume, although definitive proof is lacking. Refractory elements appear to be enriched relative both to the composition of the primordial solar nebula (CI) and the Earth. Very volatile elements appear to be depleted uniformly at high levels. We adopt the single-impact hypothesis for lunar origin, which formed a high-temperature silicate vapor disk, mostly of metal-poor silicate material from an impactor (Theia) that was already depleted in volatiles. We speculate that the curious lunar bulk-composition resulted from condensation from high-temperature vapor at around a few Earth radii. This could produce an enriched refractory-element composition that cut off below 1000 K, producing a uniform depletion in very volatile elements. 相似文献
7.
Shiran Havivi Doron Amir Ilan Schvartzman Yitzhak August Shimrit Maman Stanley R. Rotman Dan G. Blumberg 《地球表面变化过程与地形》2018,43(6):1229-1240
It is generally held that subtle changes in sandy environments are very difficult to detect in imagery. Nonetheless, this study demonstrates how synthetic aperture radar (SAR) interferometric decorrelation can be used to identify changes in individual sand dunes. The use of coherence maps over time facilitates the analysis of dune dynamics, both temporally and spatially. The Ashdod‐Nizzanim coastal dunes, along the southern coastal plain of Israel, were chosen as an illustrative example of the analysis of dune dynamics. High‐resolution TerraSAR‐X (TSX) radar images covering the entire research area were acquired for the period February to July 2012, together with meteorology data (wind and rain) for the area. The coherence results enabled the stability of individual dunes to be described as a function of time. It was found that the dune crests were more stable than the windward slopes and that the degree of stability was dependent on the distance of the dune from the sea. The results of this study show the potential of using interferometric synthetic aperture radar (InSAR) decorrelation for aeolian studies, even in areas characterized by low coherence. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
8.
9.
Barbara Wohlfarth Francesco Muschitiello Sarah L. Greenwood August Andersson Malin Kylander Rienk H. Smittenberg Margret Steinthorsdottir Jenny Watson Nicola J. Whitehouse 《Boreas: An International Journal of Quaternary Research》2017,46(2):143-161
The Last Termination (19 000–11 000 a BP) with its rapid and distinct climate shifts provides a perfect laboratory to study the nature and regional impact of climate variability. The sedimentary succession from the ancient lake at Hässeldala Port in southern Sweden with its distinct Lateglacial/early Holocene stratigraphy (>14.1–9.5 cal. ka BP) is one of the few chronologically well‐constrained, multi‐proxy sites in Europe that capture a variety of local and regional climatic and environmental signals. Here we present Hässeldala's multi‐proxy records (lithology, geochemistry, pollen, diatoms, chironomids, biomarkers, hydrogen isotopes) in a refined age model and place the observed changes in lake status, catchment vegetation, summer temperatures and hydroclimate in a wider regional context. Reconstructed mean July temperatures increased between c. 14.1 and c. 13.1 cal. ka BP and subsequently declined. This latter cooling coincided with drier hydroclimatic conditions that were probably associated with a freshening of the Nordic Seas and started a few hundred years before the onset of Greenland Stadial 1 (c. 12.9 cal. ka BP). Our proxies suggest a further shift towards colder and drier conditions as late as c. 12.7 cal. ka BP, which was followed by the establishment of a stadial climate regime (c. 12.5–11.8 cal. ka BP). The onset of warmer and wetter conditions preceded the Holocene warming over Greenland by c. 200 years. Hässeldala's proxies thus highlight the complexity of environmental and hydrological responses across abrupt climate transitions in northern Europe. 相似文献
10.
August Kumm 《International Journal of Earth Sciences》1920,10(4-8):183-233
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