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Calpionellids and chitinoidellids were identified from exotic limestone clasts occurring in flysch deposits of the Early Cretaceous to Oligocene age from the Silesian and Subsilesian nappes of the Polish Outer Carpathians. They represent the remnants of carbonate sedimentation along the northern and southern margin of the Severin-Moldavidic Basin, areas which are no longer preserved on the surface. Chitinoidellid and calpionellid assemblages characterize the Chitinoidella, Crassicollaria and Calpionella zones (latest early Tithonian–early Berriasian). The calpionellid zonation for the Western Carpathians was used for the present study, but some difficulties were encountered resulting from the application of this zonation. Cathodoluminescence imaging (CL) was useful for the identification of these microfossils in samples containing sparse and poorly preserved specimens, especially in the studied shallow-water limestone (the so-called Štramberk-type limestones). 相似文献
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Waldo Sven Lavado Casimiro Josyane Ronchail David Labat Jhan Carlo Espinoza Jean Loup Guyot 《水文科学杂志》2013,58(4):625-642
Abstract We present a procedure for estimating Q95 low flows in both gauged and ungauged catchments where Q95 is the flow that is exceeded 95% of the time. For each step of the estimation procedure, a number of alternative methods was tested on the Austrian data set by leave-one-out cross-validation, and the method that performed best was used in the final procedure. To maximise the accuracy of the estimates, we combined relevant sources of information including long streamflow records, short streamflow records, and catchment characteristics, according to data availability. Rather than deriving a single low flow estimate for each catchment, we estimated lower and upper confidence limits to allow local information to be incorporated in a practical application of the procedure. The components of the procedure consist of temporal (climate) adjustments for short records; grouping catchments into eight seasonality-based regions; regional regressions of low flows with catchment characteristics; spatial adjustments for exploiting local streamflow data; and uncertainty assessment. The results are maps of lower and upper confidence limits of low flow discharges for 21 000 sub-catchments in Austria. 相似文献
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Melanie Brandmeier 《国际地球制图》2013,28(8):629-648
A combined approach to detect hydrothermal alteration zones and their mineral distribution is proposed for a relatively remote area around the Carhuarazo volcanic complex in southern Peru encompassing 2222 km2. In this region, tertiary volcanic structures associated with hydrothermal alteration are well known to host epithermal ore deposits. We make an attempt to detect and to quantify alteration minerals based on spectral analysis using ASTER reflectance data product provided by LP-DAAC. Besides commonly used ratio images, mineral indices (MI) and relative band depth images (RBD), we also extracted endmember spectra using Pixel-Purity-Processing preceded by minimum noise fraction transformation. These spectra are thought to represent the spectrally purest pixel of the image and show the typical absorption features of the main constituents. Based on this assumption, we used different spectral analysis methods in order to extract the most important alteration minerals for such an environment. These minerals were then used for matched filter processing in areas showing high values in MIs and RBDs. Using this method, we detected and mapped argillic alteration and variations in the distribution of important minerals like alunite, kaolinite or nacrite. There were no indications for the presence of propilitization at ASTER spatial resolutions. Our method can be applied easily to any ASTER scene and provides information about the intensity of alteration and the character of alteration zones. The intensity is highest in the centre of the Carhuarazo volcanic complex and is mostly argillic with a high content of alunite, dickite and other clay minerals. 相似文献
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Susan W. Beatty 《自然地理学》2013,34(1):44-52
The origin of soil heterogeneity found in Adenostoma fasciculatum and A sparsifolium chaparral was investigated in the Santa Monica Mountains, California. Possibilities were that geologic and genetic processes created inherent variability in surface soils, and/or that chaparral vegetation generated this variability. Fourteen soil properties were assessed under 17 pairs of the two shrub species before (1984) and after (1985) a wildfire. Hypotheses were that, although magnitudes of soil properties may change with fire, the inherent soil patterns would remain, while vegetation-influenced patterns might either be accentuated or obliterated. All but one of the 14 soil properties changed after fire, and 8 of these changed in the same direction for both shrub species. Different magnitudes of change, as well as opposite changes in 5 soil properties, led to an elimination of most spatial heterogeneity after fire. Eleven soil properties showed significant pre-burn differences between shrub species, while only 3 did so after fire. Vegetation influence was responsible for the spatial soil heterogeneity in the mature stand of chaparral, apparently developing over one regeneration period of about 40 years. With the obliteration of fine-scale soil differences during each fire cycle, soil heterogeneity cannot play a role in determining vegetation regeneration patterns. The creation of a more uniform substrate after fire, however, may favor sprouting over seeding strategies in postfire succession. [Key words: chaparral, fire ecology, soil properties, California.] 相似文献
107.
剥蚀型汇聚板块边缘大地震成因机理研究:来自国际综合大洋钻探344航次的报告 总被引:3,自引:0,他引:3
旨在探究剥蚀型汇聚板块边缘大地震成因机理的国际综合大洋钻探(IODP)344航次于2012年10月23日至12月11日在中美洲地震频发的哥斯达黎加西部海域实施钻探。介绍了钻探区域的大地构造特征、该航次的主要科学目标、执行情况、所取得的初步成果以及对航次后研究工作的展望等。航次后更多深入细致的研究工作正在进行中,所取得的研究成果将集中在2014年南京召开的航次后学术研讨会上汇报、交流、集成、总结,从而提升对剥蚀型汇聚板块边缘大地震起源机理的认识。 相似文献
108.
AbstractDivergent and convergent margins actualistic models arc reviewed and applied to the history of the western Alps. Tethyan rifting history and geometry are analyzed : (he northern European margin is considered as an upper plate whereas the southern Apulian margin is a lower plate; the Bréche basin is regarded as the former break-away trough; the internal Bríançonnais domain represents the northern rift shoulder whilst the more external domains are regarded as the infill of a complex rim basin locally affected by important extension (Valaisan and Vocontian trough).The Schistes lustres and ophioliles of the Tsaté nappe are compared to an accretionary prism : the imbrication of this nappe elements is regarded as a direct consequence of the accretionary phenomena already active in early Cretaceous; the Gels/Simme complex could originate from a more internal part of the accretionary prism. Some eclogitic basements represent the former Apulian margin substratum (Sesia) others (Mont-Rose) are interpreted as the former edge of the European margin. The history of the closing Tethyan domain is analyzed and the remaining problems concerning the cinematics, the presence/absence of a volcanic arc and the eoalpine melamorphism are discussed. 相似文献
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Fred Pollitz Paramesh Banerjee Kelly Grijalva B. Nagarajan R. Bürgmann 《Geophysical Journal International》2008,173(1):189-204
The 2004 M = 9.2 Sumatra–Andaman earthquake profoundly altered the state of stress in a large volume surrounding the ∼1400 km long rupture. Induced mantle flow fields and coupled surface deformation are sensitive to the 3-D rheology structure. To predict the post-seismic motions from this earthquake, relaxation of a 3-D spherical viscoelastic earth model is simulated using the theory of coupled normal modes. The quasi-static deformation basis set and solution on the 3-D model is constructed using: a spherically stratified viscoelastic earth model with a linear stress–strain relation; an aspherical perturbation in viscoelastic structure; a 'static' mode basis set consisting of Earth's spheroidal and toroidal free oscillations; a "viscoelastic" mode basis set; and interaction kernels that describe the coupling among viscoelastic and static modes. Application to the 2004 Sumatra–Andaman earthquake illustrates the profound modification of the post-seismic flow field at depth by a slab structure and similarly large effects on the near-field post-seismic deformation field at Earth's surface. Comparison with post-seismic GPS observations illustrates the extent to which viscoelastic relaxation contributes to the regional post-seismic deformation. 相似文献