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High‐resolution stratigraphy of Scandinavian coastal archaeological settlements: the case of Håkonshella,W Norway 
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下载免费PDF全文 Arnald Puy Andrea L. Balbo Camilla Zinsli Morten Ramstad 《Boreas: An International Journal of Quaternary Research》2016,45(3):508-520
The stratigraphy of Scandinavian open‐air archaeological settlements is usually characterized as homogeneous, highly enriched in decomposing organic matter and poor in biogenic carbonates such as shells or bones. As a result, stratigraphies are often difficult to read in the field and settlement sequences may pass unnoticed by archaeologists. Here we show how the integration of bulk analyses, soil micromorphology, X‐ray fluorescence (XRF) core scanning and multivariate statistics can help in overcoming such limitations. We use the case study of Håkonshella 8, a Mesolithic hunter‐fisher‐gatherer settlement located in Bergen (W Norway). Fluctuations in the organic matter content, geochemical proxies (mainly P, Ga, Ti and the Si/Al ratio) and redoximorphic features highlight four cycles of site occupation and abandonment in an otherwise massive anthropogenic deposit. Following these settlement sequences, the site was covered by colluvium from nearby slopes over which a waterlogged soil formed. The approach used in Håkonshella has the potential to improve our capacity to interpret organically enriched anthropic deposits formed in coastal Scandinavia and in similar climatic regions. 相似文献
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The uptake of a chemical species by an aquatic microorganism is modelled considering two kinds of sites where Langmuirian adsorption is followed by first order internalisation kinetics. Simpler models, such as only one internalisation route (while most of the adsorption takes place on non-internalising sites) or a linear isotherm for adsorption on one or both sites, become limiting cases of this double-Langmuirian model. The model considers the sites located on the spherical (or semi-spherical) surface of the organism, and takes diffusion from the medium into explicit account. The numerical solution for the internalisation flux shows a maximum. We provide an estimate for the time needed to reach a certain proximity to steady state. The transient solution confirms that the analytical expressions for the steady-state flux are usually valid and that the accumulated amounts reflect the impact of the short-time uptake. The Instantaneous Steady-State Approximation (ISSA), where an intercept of the linear regression of accumulated amount as a function of time is interpreted as an adsorbed amount, can be critically assessed with the transient numerical code for two cases: (i) when the total burden of metal on the cell is the input data and (ii) when an extraction procedure provides further information on the adsorbed and internalised amount. 相似文献
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The Lugo gneiss dome, in the NW Iberian Massif (Spain) is a Variscan structure developed during late stages of orogenic collapse. Crustal extension was mainly accomplished by two kilometre-scale conjugate extensional shear zones and by the late development of the dome and a huge normal fault. These structures overprint previous contractional recumbent folds and a thrust fault. The Lugo dome and its southward continuation, the Sanabria dome, are the site of the conspicuous Eastern Galicia Magnetic Anomaly (EGMA), a N–S band, 50 km wide and 190 km long, with a maximum amplitude of 190 nT. Integrated potential field modelling of the EGMA and its corresponding gravity signature have been carried out aided by constraints provided by the measurement of c. 900 magnetic susceptibilities and by previous geophysical data, mainly seismic refraction and reflection profiles. Results suggest that a large volume of low-density migmatites and associated inhomogeneous granites are the main source of the magnetic anomaly. Small massifs of basic and ultrabasic rocks inside the migmatites and high-susceptibility iron ore bodies sparsely distributed in low-grade Middle Ordovician slates are also thought to contribute to the anomaly but to a minor extent. Although otherwise similar to other gneiss domes, the Lugo dome is accompanied by a striking magnetic anomaly whose origin is discussed in terms of the tectonic evolution of this structure and the provenance of the magnetite-bearing migmatites and inhomogeneous granites that core it. 相似文献
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对泰安台水平摆和垂直摆倾斜仪长期观测资料进行了分析,通过对M2波潮汐因子变化和矢量图进动轨迹的分析发现,汶川地震前存在异常现象. 相似文献
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Y. Wiaux L. Jacques G. Puy A. M. M. Scaife P. Vandergheynst 《Monthly notices of the Royal Astronomical Society》2009,395(3):1733-1742
Radio interferometry probes astrophysical signals through incomplete and noisy Fourier measurements. The theory of compressed sensing demonstrates that such measurements may actually suffice for accurate reconstruction of sparse or compressible signals. We propose new generic imaging techniques based on convex optimization for global minimization problems defined in this context. The versatility of the framework notably allows introduction of specific prior information on the signals, which offers the possibility of significant improvements of reconstruction relative to the standard local matching pursuit algorithm CLEAN used in radio astronomy. We illustrate the potential of the approach by studying reconstruction performances on simulations of two different kinds of signals observed with very generic interferometric configurations. The first kind is an intensity field of compact astrophysical objects. The second kind is the imprint of cosmic strings in the temperature field of the cosmic microwave background radiation, of particular interest for cosmology. 相似文献
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Effects of mantle upwelling in a compressional setting: the Atlas Mountains of Morocco 总被引：1，自引：0，他引：1
Antonio Teixell Puy Ayarza Hermann Zeyen Manel Fernàndez María-Luisa Arboleya 《地学学报》2005,17(5):456-461
We discuss the implications of a lithospheric model of the Moroccan Atlas Mountains based on topography, heat flow, gravity and geoid anomalies, taking into account the regional geology. The NW African cratonic lithosphere, some 160–180 km thick, thins to c. 80 km beneath the Atlas fold-thrust belts, in contrast with the shortening regime prevailing there since the early Cenozoic. This fact explains several geological and geophysical features as high topography with modest tectonic shortening, the occurrence of alkaline magmatism contemporaneous to compression, the absence of large crustal roots to support elevation, the scarce development of foreland basins, and a marked geoid high. The modelled lithosphere thinning is related to a thermal upwelling constrained between the Iberia–Africa convergent plate boundary and the Saharan craton. 相似文献
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