Taphonomic phenomenon of ancient hair from Glacial Beringia: perspectives for palaeoecological reconstructions          下载免费PDF全文

Irina V. Kirillova  Johannes van der Plicht  Stanislav V. Gubin  Oksana G. Zanina  Olga F. Chernova  Elena G. Lapteva  Svetlana S. Trofimova  Eugeny V. Zinovyev  Anton A. Zharov  Elena O. Fadeeva  Thijs Van Kolfschoten  Fedor K. Shidlovskiy  Alexey A. Kotov 《Boreas: An International Journal of Quaternary Research》2016,45(3):455-469

An accumulation of mammoth hair, discovered in the Bol'shaya Chukochya River valley (northeast Yakutia, Russia), was found to contain remains of terrestrial and aquatic organisms, including plants, insects, crustaceans, birds and mammals. Radiocarbon dating indicated that this post‐mortem taphocoenosis represented multiple time periods. The mammoth hair was dated to older than 45 ka BP, the plants were dated to 12 750±50 a BP (which corresponds to a shift in the environmental conditions and landscapes during the formation of thermokarst in northeastern Russia) and the bird feathers were dated to 4115±40 a BP. A scenario of the formation of this fossil assemblage is proposed, covering the MIS 3‐1 time range. The hair also yielded various Arctic branchiopod crustaceans, which inhabit shallow temporary water bodies and therefore are important for reconstruction of palaeoenvironments. The cladoceran subgenus Daphnia (Ctenodaphnia), currently absent from the Asian part of Beringia, is reported from this region for the first time. The study demonstrates that the discovered permafrost‐preserved hair is a unique repository of Ice Age organisms.  相似文献   

A Europe–South America network for climate change assessment and impact studies     

Jean-Philippe Boulanger  G. Brasseur  Andrea Fabiana Carril  Manuel de Castro  Nicolas Degallier  Carlos Ereño  H. Le Treut  Jose Antonio Marengo  Claudio Guillermo Menendez  Mario Nestor Nuñez  Olga C. Penalba  Alfredo Luis Rolla  Matilde Rusticucci  Rafael Terra 《Climatic change》2010,98(3-4):307-329

The goal of the CLARIS project was to build an integrated European–South American network dedicated to promote common research strategies to observe and predict climate changes and their consequent socio-economic impacts taking into account the climate and societal peculiarities of South America. Reaching that goal placed the present network as a privileged advisor to contribute to the design of adaptation strategies in a region strongly affected by and dependent on climate variability (e.g. agriculture, health, hydro-electricity). Building the CLARIS network required fulfilling the following three objectives: (1) The first objective of CLARIS was to set up and favour the technical transfer and expertise in earth system and regional climate modelling between Europe and South America together with the providing of a list of climate data (observed and simulated) required for model validations; (2) The second objective of CLARIS was to facilitate the exchange of observed and simulated climate data between the climate research groups and to create a South American high-quality climate database for studies in extreme events and long-term climate trends; (3) Finally, the third objective of CLARIS was to strengthen the communication between climate researchers and stakeholders, and to demonstrate the feasibility of using climate information in the decision-making process.  相似文献   

Young circumnuclear disks in elliptical galaxies     

Olga K. Sil’chenko 《Astrophysics and Space Science》2009,320(1-3):51-54

By means of integral-field spectroscopy with the Multi-Pupil Field/Fiber Spectrograph of the Russian 6-m telescope we have studied the central parts of NGC 759 and NGC 83— regular (non-interacting, without strong nuclear activity) round red luminous (M _B =?20.8–?21.6) elliptical galaxies which are however known to possess molecular gas. In both galaxies we have found central stellar disks with the extension of 1–2 kpc along the radius which are evidently being formed just now.  相似文献   

Paleoproterozoic,High-Metamorphic,Metasedimentary Units of Siberian Craton     

Lena URMANTSEVA  Olga TURKINA 《《地质学报》英文版》2009,83(5):875-883

Abstract: Sensitive, high-resolution ion microprobe zircon U–Pb ages of Paleoproterozoic, high-grade, metasedimentary rocks from the south-western part of the Siberian Craton are reported. Early Precambrian, high-grade complexes, including garnet–biotite, hypersthene–biotite, and cordierite-bearing gneisses compose the Irkut terrane of the Sharyzhalgay Uplift. Protoliths of studied gneisses correspond to terrigenous sediments, ranging from greywacke to shale. The paragneiss model Nd ages of 2.4–3.1 Ga indicate Archean-to-Paleoproterozoic source provinces. Zircons from gneisses show core-rim textures in cathodoluminescence (CL) image. Round or irregular shaped cores indicate detrital origin. Structureless rims with low Th/U are metamorphic in origin. The three age groups of detrital cores are: ≥2.7, ~2.3, and 1.95–2 Ga. The ages of metamorphic rims range from 1.86 to 1.85 Ga; therefore, the sediments were deposited between 1.95 and 1.86 Ga and derived from Archean and Paleoproterozoic source rocks. It should be noted that Paleoproterozoic metasedimentary rocks of the Irkut Block are not unique. High-grade metaterrigenous sediments, with model Nd ages ranging from 2.3 to 2.5 Ga, are widely distributed within the Aldan and Anabar Shields of the Siberian Craton. The same situation is observed in the North China Craton, where metasedimentary rocks contain detrital igneous zircon grains with ages ranging from 3 to 2.1 Ga (Wan et al., 2006). All of these sedimentary units were subjected to Late Paleoproterozoic metamorphism. In the Siberian Craton, the Paleoproterozoic sedimentary deposits are possibly marked passive margins of the Early Precambrian crustal blocks, and their high-grade metamorphism was related to the consolidation of the Siberian Craton.  相似文献   

On an application of cluster analysis for classification of valley cross profiles using special orthonormal functions     

Olga J. Waelder 《Central European Journal of Geosciences》2009,1(2):232-239

Morphometric approaches deal with obtaining quantitative parameters of relief forms. In particular, such parameters can be used for the classification of diverse relief forms. There is a noticeable demand for such approaches in geosciences. For example, the differentiation of valley forms belongs to the research field of geomorphology. A valley form includes important information with respect to the valley genesis. It is assumed that the U-shape probably corresponds to a glacier-induced valley, but the V-shape reflects the fluvial genesis of a valley. A prior generalisation of valley cross-profiles is necessary in order to obtain their morphometric parameters. These parameters contribute to the valley differentiation. The conventional generalisation approaches are based on the approximation of such cross-profiles using a special function. This function can be a catenary curve, a special polynomial or a set of polynomials. An alternative model is the GPL model. In this paper we propose a new generalisation approach, which uses special orthonormal functions. Based on these functions, form coefficients can be obtained for use in cluster analysis, resulting in the shape classification of valley cross profiles. An application of our approach for a real data set is presented.  相似文献   

Cyclone life cycle characteristics over the Northern Hemisphere in coupled GCMs   总被引：4，自引：1，他引：3  

Ulrike Löptien  Olga Zolina  Sergey Gulev  Mojib Latif  Vladimir Soloviov 《Climate Dynamics》2008,31(5):507-532

Cyclone activity and life cycle are analysed in the coupled GCMs ECHAM5/OM and ECHAM4/OPYC3. First, the results for the present climate (1978–1999) are compared with ERA-40 and NCEP/NCAR reanalyses, showing a drastic improvement in the representation of cyclone activity in ECHAM5/OM compared to ECHAM4/OPYC3. The total number of cyclones, cyclone intensity, propagation velocity and deepening rates are found to be much more realistic in ECHAM5/OM relative to ECHAM4/OPYC3. Then, changes in extra tropical cyclone characteristics are compared between present day climate and future climate under the emission-scenario A1B using ECHAM5/OM. This comparison is performed using the 20-year time slices 1978–1999, 2070–2090 and 2170–2190, which were considered to be representative for the various climate conditions. The total number of cyclones does not undergo significant changes in a warmer climate. However, regional changes in cyclone numbers and frequencies are evident. One example is the Mediterranean region where the number of cyclones in summer increases almost by factor 2. Some noticeable changes are also found in cyclone life cycle characteristics (deepening rate and propagation velocity). Cyclones in the future climate scenario tend to move slower and their deepening rate becomes stronger, while cyclone intensity does not undergo significant change in a warmer climate. Generally, our results do not support the hypothesis of enhanced storminess under future climate conditions.  相似文献   

Water-soluble organic and nitrogen levels in cloud and rainwater in a background marine environment under influence of different air masses     

Adriana Gioda  Olga L. Mayol-Bracero  Gabriel J. Reyes-Rodriguez  Gilmarie Santos-Figueroa  Jeffrey L. Collett Jr. 《Journal of Atmospheric Chemistry》2008,61(2):85-99

Chemical characterization was performed on cloud and rainwater samples collected as part of the Rain In Cumulus over the Ocean Experiment (RICO). This experiment took place at a mountaintop site (East Peak) in Puerto Rico from December 2004 to March 2007 in order to determine water-soluble organic and nitrogen fractions in a marine background environment. For cloud water, similar average concentrations of 1.0 (±0.3) mg/L were found for total organic carbon (TOC) and total nitrogen (TN) and an average concentration of 0.8 (±0.2) mg/L was found for dissolved organic carbon (DOC). In rainwater, these concentrations were lower, ranging from 0.3 to 0.5 (±0.1) mg/L. Changes in the concentrations of these species were observed in periods under the influence of anthropogenic, African dust, and volcanic ash air masses. In these periods the concentrations of TOC, DOC, and TN were 2 to 4 times higher than in periods under the influence of trade winds. The insoluble organic material arriving during African dust events showed total carbon (TC) concentrations on averaging 1.5 mg/L for cloud water. The TC was composed mainly of organic carbon with polar compounds from low to high molecular weight (MW). The polar compounds with high MW were probably associated with pollution (e.g., fossil fuel combustion) from other regions. Crustal species (Al and Fe) dominated particles associated with dust episodes, confirming the soil origin. Our results suggested that a fraction (40–80%) of TOC and (<100%) of TN in Puerto Rican cloud/rainwater could be originated from long-range transport of dust, ash and/or pollution.  相似文献   

A simplified method for assessing landslide damage indices   总被引：1，自引：0，他引：1  

Olga Petrucci  Giovanni Gullà 《Natural Hazards》2010,52(3):539-560

  相似文献   

Parameterizing a hydrological model using a short-term observational dataset to study runoff generation processes and reproduce recent trends in streamflow at a remote mountainous permafrost basin     

Nataliia Nesterova  Olga Makarieva  David Andrew Post 《水文研究》2021,35(7):e14278

Recent decades have seen a change in the runoff characteristics of the Suntar River basin in the mountainous, permafrost, hard-to-reach region of Eastern Siberia. This study aims to investigate and simulate runoff formation processes, including the factors driving recent changes in hydrological response of the Suntar River, based on short-term historical observations of a range of hydrological, climatological and landscape measurements conducted in 1957–1959. The hydrograph model is applied as it has the advantage of using observed physical properties of landscapes as its parameters. The developed parametrization of the goltsy landscape (rocky-talus) is verified by comparison of the results of simulations of variable states of snow and frozen ground with observations carried out in 1957–1959. Continuous simulations of streamflow on a daily time step are conducted for the period 1957–2012 in the Suntar River (area 7680 km², altitude 828–2794 m) with mean and median values of Nash–Sutcliff criteria reaching 0.58 and 0.67, respectively. The results of simulations have shown that the largest component of runoff (about 70%) is produced in the high-altitude area which comprises only 44% of the Suntar River basin area. The simulated streamflow reproduces the patterns of recently observed changes, including the increase in low flows, suggesting that the increase in the proportion of liquid precipitation in autumn due to air temperature rise is an important factor in driving streamflow changes in the region. The data presented are unique for the vast mountainous parts of North-Eastern Eurasia which play an important role in the global climate system. The results indicate that parameterizing a hydrological model based on observations allows the model to be used in studying the response of river basins to climate change with greater confidence.  相似文献   

Mapping groundwater‐dependent ecosystems using remote sensing measures of vegetation and moisture dynamics          下载免费PDF全文

Olga V. Barron  Irina Emelyanova  Thomas G. Van Niel  Daniel Pollock  Geoff Hodgson 《水文研究》2014,28(2):372-385

Protection of groundwater‐dependent ecosystems (GDEs) is an important criterion in sustainable groundwater management, particularly when human water consumption is in competition with environmental water demands; however, the delineation of GDEs is commonly a challenging task. The Groundwater‐dependent Ecosystem Mapping (GEM) method proposed here is based on interpretation of the land surface response to the drying process derived from combined changes in two multispectral indices, the Normalised Difference Vegetation Index and the Normalised Difference Wetness Index, both derived from Landsat imagery. The GEM method predicts three land cover classes used for delineation of potential GDEs: vegetation with permanent access to groundwater; vegetation with diminishing access to groundwater; and water bodies that can persist through a prolonged dry period. The method was applied to a study site in the Ellen Brook region of Western Australia, where a number of GDEs associated with localised groundwater, diffuse discharge zones, and riparian vegetation were known. The estimated accuracy of the method indicated a good agreement between the predicted and known GDEs; Producer's accuracy was calculated as up to 91% for some areas. The method is most applicable for mapping GDEs in regions with a distinct drying period. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献