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1.
Variation in morphological characters used to distinguish the three sympatric species ofPalaemonetes, i.e.,P. pugio, P. intermedius, andP. vulgaris, is suggestive of natural hybridization. Interspecific crosses among the species and intraspecific crosses of allopatric populations ofP. pugio were made to determine whether hybridization was feasible and to evaluate taxonomic characters of the juveniles. No interspecific matings produced larvae in the laboratory. Larvae, from intraspecific matings ofP. pugio andP. vulgaris were reared to 40 days of age. Larval survival rates, development time, and postlarval length ofP. pugio andP. vulgaris were not different, but juveniles ofP. pugio at 40 days after hatching were larger than those ofP. vulgaris. At 40 daysP. pugio had developed adult diagnostic features. However,P. vulgaris displayed sufficient variation in adult diagnostic features to resembleP. pugio in some cases. The intraspecific matings ofP. pugio from widely separated populations were fertile, but there was some indication of reduced reproductive compatibility in crosses involving Virginia females and Florida males relative to intrapopulational controls. *** DIRECT SUPPORT *** A01BY019 00002 相似文献
2.
The taxonomic status of specimens referred to Tarchia kielanae, T. gigantea, and Minotaurasaurus ramachandrani has been contested. The holotype of T. kielanae, Zaklad Paleobiologii (Institute of Paleobiology)-Polish Academy of Sciences (ZPAL) MgD I/111, is redescribed. It has features common to both Palaeontological Institute-Russian Academy of Sciences (PIN) 3142/250, long considered Tarchia, and to M. ramachandrani but which are lacking in Saichania chulsanensis. The specimen PIN 3142/250 is not referable to Saichania but instead represents a new species, Tarchia teresae sp. nov. Similarly, the holotype skull of M. ramachandrani is not referable to T. kielanae, so Minotaurasaurus is a valid taxon. Tarchia is more derived than either Saichania or Minotaurasaurus while sharing features of both. 相似文献
3.
Extended Hückel molecular orbital theory (EHT) and simple, approximate Self-Consistent-Field MO methods are employed to explain the geometries of nontransition metal bearing minerals and inorganic compounds. The spectra of such minerals and the electronic structure of transition metal oxidic minerals are explained using the Self-Consistent-Field X α MO method. EHT provides an objective algorithm for rationalizing and correlating bond length and angle data for insular and polymerized TO 4 ?n tetrahedral oxyanions where T=Be, B, Al, Si, P, S, Ge, As and Se. Calculated bond overlap populations n(T-O), correlate linearly with the observed T-O bond lengths with shorter bonds tending to involve larger n(T-O) values. Such calculations show that n(T-O) is strongly dependent upon the average of the three O-T-O angles associated with a common bond, larger n(T-O) values involving wider angles. Calculations of n(T-O) as a function of the T-O-T angles in T 2O 7 ?n ions, indicate that the n(T-O) values for the bonds to the bridging oxygen atoms increase nonlinearly with increasing T-O-T angle whereas those the nonbridging oxygens decrease slightly as the angle widens. In agreement with the experimental data, these results predict that shorter T-O bonds should involve wider O-T-O and T-O-T angles. The SCF-X α MO cluster model is then applied to silica and FeO. The calculations yield a satisfactory interpretation of the visible, UV and X-ray emission and X-ray photoelectron spectra of these materials. Theoretical and empirical MO diagrams are constructed and the electronic structures of the materials are discussed. 相似文献
4.
A cross-correlation analysis is conducted to determine the impacts of the heterogeneity of hydraulic conductivity Ks, soil cohesion c′ and soil friction angle (tan φ′) on the uncertainty of slope stability in time and space during rainfall. We find the relative importance of tan φ′ and c′ depends on the effective stress. While the sensitivity of the stability to the variability of Ks is small, the large coefficient of variation of Ks may exacerbate the variability of pore-water pressure. Therefore, characterizing the heterogeneity of hydraulic properties and pore-water distribution in the field is critical to the stability analysis. 相似文献
5.
《Applied Geochemistry》2005,20(3):455-464
In order to characterize the H isotopic compositions of individual lipid compounds from different terrestrial depositional environments, the δD values of C-bound H in individual n-alkanes from typical terrestrial source rocks of the Liaohe Basin and the Turpan Basin, China, were measured using gas chromatography–thermal conversion–isotope ratio mass spectrometry (GC–TC–IRMS). The analytical results indicate that the δD values of individual n-alkanes in the extracts of terrestrial source rocks have a large variation, ranging from −140‰ to −250‰, and are obviously lighter than the δD of marine-sourced n-alkanes. Moreover, a trend of depletion in 2H(D) was observed for individual n-alkanes from different terrestrial depositional environments, from saline lacustrine to freshwater paralic lacustrine, and to swamp. For example, the δD values of n-alkanes from a stratified saline lacustrine environment vary from −140‰ to −200‰, δD for n-alkanes from swamp facies range from −200‰ to −250‰, while those from freshwater paralic lacustrine–lacustrine environments fall between the δD values of the end members. The shift toward lighter δD from saltwater to freshwater environments indicates that the source water δD is the major controlling factor for the H isotopic composition of individual compounds. In addition, H exchange between formation water and sedimentary organic matter may possibly be important in regard to the δD of individual n-alkanes. Therefore, other lines of geochemical evidence must be considered when depositional paleoenvironments of source rocks are reconstructed based on the H isotopic composition of individual n-alkanes. 相似文献
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7.
Scaling properties of earthquake populations bear the major information on the physics of the source process of an earthquake. To determine scaling properties, source spectra of more than 400 earthquakes of Kamchatka were determined in a frequency range 0.1–30 Hz using materials of digital registration of PET station, and characteristic frequencies of earthquakes were estimated. The range of magnitudes is 4–6.5, the range of distances is 80–220 km. To enable reduction of a spectrum to the source, attenuation properties of the medium around PET were determined beforehand. It is revealed that source spectra show several corner (characteristic) frequencies: f c1, f c2 and f c3; where the spectral trend changes: from f 0 to f ?1, from f ?1 to f ?2, and from f ?2 to f ?3, respectively. Although in some cases f c1 ≈ f c2 in agreement with the usual ω?2 spectral model, the main part of spectra has more complicated character. For a large part of the studied earthquakes a source-controlled upper cutoff of acceleration spectrum, or corner frequency f c3, is observed. This is an important fact, as the existence of f c3 (source-controlled f max) is not recognized in the bulk of the seismological literature. For f c1, the observed scaling agrees with the usual hypothesis of similarity of the earthquake sources of different size (magnitude); it is close to f c1 ～ M 0 ?1/3 , where M 0 is seismic moment. For f c2, scaling is close to f c2 ～ M 0 ?0.17 ～ f c1 0.5 , that indicates an expressed violation of similarity. For f c3, scaling is close to f c2 ～ M 0 ?0.08 ～ f c1 0.25 , so that similarity is broken even sharper in this case. Hypotheses about possible causes of the observed scaling are discussed. 相似文献
8.
采用国际照明委员会CIE LAB色度坐标,定量描述了翡翠的绿色,分析了颜色的分布情况,总结其分布规律,建立起翡翠绿色L*、a*、b*、C*、hab的分布关系。当明度较小时,色调角几乎不变,彩度和明度呈现近似的线性相关;当明度变大时,色调角的变化幅度稍大,彩度值在明度中等偏低时变为最大。这些信息将在很大程度上对翡翠绿色分级的细化起到积极作用,可以用来指导翡翠色卡的制备。 相似文献
9.
M. A. Ustinova 《Stratigraphy and Geological Correlation》2009,17(2):204-217
The distribution of calcareous nannofossils and foraminifers occurring in the Callovian-Oxfordian deposits in the southwest of Moscow is studied. Nannoplankton-bearing beds and foraminiferal zones are distinguished. The Retecapsa incompta Beds correspond in range to the Ophthalmidium sagittum-Epistomina volgensis and Ophthalmidium strumosum-Lenticulina brestica foraminiferal zones as well as the lower part of Epistomina uhligi-Lenticulina russiensis Zone. The Watznaueria manivitae, Crepidolithus perforata, and Watznaueria fossacincta (lowermost part) beds span interval of the Epistomina uhligi-Lenticulina russiensis Zone. The Watznaueria fossacincta Beds are concurrent to the Lenticulina ponderosa-Flabellamina lidiae Zone of the foraminiferal scale. 相似文献
10.
An ammonite fauna from the upper Abderaz Formation of Kuh-e-Bul in the northwestern part of the Koppeh Dagh (Iran) is described and illustrated. The collection of 30 specimens is assigned to seven species, all of which are recorded from Iran for the first time: Pseudophyllites indra (Forbes, 1846), Pachydiscus (Pach.) haldemsis (Schlüter, 1867), Patagiosites stobaei (Nilsson, 1827), Menuites wittekindi (Schlüter, 1876), Glyptoxoceras retrorsum (Schlüter, 1872), Lewyites elegans (Moberg, 1885) and Trachyscaphites spiniger (Schlüter, 1872). This fauna is of a typical Boreal character, with all taxa having been described from northwest Europe originally. The stratigraphic range indicated by the ammonites is lower upper Campanian, below the first occurrence of Nostoceras (Bostrychoceras) polyplocum (Roemer, 1841) and probably above the last occurrence of Hoplitoplacenticeras (H.) vari (Schlüter, 1872). A nannofossil sample from the ammonite-bearing interval corresponds to the upper Campanian nannofossil zone UC15/CC22. Thus, on the basis of both ammonites and calcareous nannofossils, the upper Abderaz Formation is shown to be younger than assumed previously. 相似文献
11.
《地学前缘(英文版)》2018,9(6):1639-1648
Cohesion(c) and friction angle(φ) of rock are important parameters required for reliability analysis of rock slope stability. There is correlation between c and φ which affects results of reliability analysis of rock slope stability. However, the characterization of joint probability distribution of c and φ through which their correlation can be estimated requires a large amount of rock property data, which are often not available for most rock engineering projects. As a result, the correlation between c and φ is often ignored or simply assumed during reliability studies, which may lead to bias estimation of failure probability. In probabilistic rock slope stability analysis, the influence of ignoring or simply assuming the correlation of the rock strength parameters(i.e., c and φ) on the reliability of rock slopes has not been fully investigated. In this study, a Bayesian approach is developed to characterize the correlation between c and φ, and an expanded reliability-based design(RBD) approach is developed to assess the influence of correlation between c and φ on reliability of a rock slope. The Bayesian approach characterizes the sitespecific joint probability distribution of c and φ, and quantifies the correlation between c and φ using available limited data pairs of c and φ from a rock project. The expanded RBD approach uses the joint probability distribution of c and φ obtained through the Bayesian approach as inputs, to determine the reliability of a rock slope. The approach gives insight into the propagation of the correlation between c and φ through their joint probability into the reliability analysis, and their influence on the calculated reliability of the rock slope. The approaches may be applied in practice with little additional effort from a conventional analysis. The proposed approaches are illustrated using real c and φ data pairs obtained from laboratory tests of fractured rock at Forsmark, Sweden. 相似文献
12.
Inoceramid bivalves of the upper Albian and lower Cenomanian of the United States Western Interior are revised, Eleven species-level taxa and three genera are described. Two new species, Gnesioceramus mowriensis, characterizing the Mowry Shale of the early, but not the earliest, Cenomanian, and Posidonioceramus merewetheri, of the lower Cenomanian, and on new genus, Posidonioceramus, are recognised. The Western Interior inoceramid species from this interval are strongly endemic and are not good tools for long-distance correlations, although they are very effective in regional dating.In terms of the inoceramid biostratigraphy, middle and upper parts of the upper Albian can be referred to the Gnesioceramus Biozone, represented by G. comancheanus (Cragin) and G. bellvuensis (Reeside). These taxa are endemic to the Western Interior and some adjacent areas (Gulf Coast; Greenland?), but are closely allied to the cosmopolitan species, Gnesioceramus anglicus (Woods). At approximately the Albian-Cenomanian boundary, the endemic clade of ‘Inoceramus’ nahwisi appears, now referred to the newly erected Posidonioceramus, resulting in a distinct P. nahwisi biozone. This zone corresponds to the lower part of the ammonite Neogastroplites’ stratigraphic range. Gnesioceramids re-appear in the early Cenomanian. Close to base of the Cenomanian, for the first in the Western Interior, the genus Inoceramus, represented by Inoceramus irenensis Warren and Stelck, 1958, apparently immigrated into the Western Interior Basin.The Western Interior inoceramids do not allow for direct correlation to chronostratigraphic standard subdivision. The Albian-Cenomanian boundary, as earlier recognized on geochronologic correlations and confirmed, to some extent, based on ammonites, may approximately be located close to the appearance level of the genus Posidonioceramus. 相似文献
13.
V. V. Arkad’ev T. N. Bogdanova S. V. Lobacheva E. D. Kalacheva I. I. Sey 《Stratigraphy and Geological Correlation》2008,16(4):400-422
Biostratigraphy of the Berriasian Stage in the Crimean Mountains is specified and substantiated. Fragments of all the standard stage zones (jacobi, occitanica, and boissieri) are distinguished based on the found index species, and position of the Jurassic-Cretaceous boundary is targeted. According to verified distribution of ammonites, the jacobi Zone is divided into the jacobi and grandis subzones crowned by the Malbosiceras chaperi Beds. The Tirnovella occitanica-Retowskiceras retowskyi Beds and overlying Dalmasiceras tauricum Subzone are recognized in deposits of the occitanica Zone. The upward succession of biostratigraphic units established in the boissieri Zone includes the Euthymiceras-Neocosmoceras Beds, Riasanites crassicostatus Subzone, Symphythyris arguinensis and Jabronella sf. paquieri-Berriasella callisto Beds. The last biostratigraphic unit is suggested in this work instead the former Zeillerina baksanensis Beds. Except for the jacobi Zone, the substantiated ammonoid zonation is practically identical to the Berriasian biostratigraphic scale of the northern Caucasus, although the Berriasian-Valanginian boundary has not been defined in the Crimean Mountains based on ammonites. Several marker levels of bivalve mollusks and four biostratigraphic subdivisions of brachiopod scale are distinguishable here. As for the latter, these are (from the base upward) the Tonasirhynchia janini, Belbekella airgulensis-Sellithyris uniplicata, Symphythyris arguinensis, and Zeillerina baksanensis beds. 相似文献
14.
《Tectonophysics》1999,301(1-2):159-171
A new classification scheme based on the degree of fluctuation in the geometry of different layers of a multilayered fold is suggested. The classification scheme uses the degree of fluctuation in geometry in terms of the standard deviation (σn) of the thickness parameters tα′ (orthogonal thickness parameter) and Tα′ (axial plane parallel thickness parameter) for n number of layers, and dip angle α. The degree of fluctuation in the geometry of a multilayered fold can be represented by σn(tα′) or σn(Tα′) versus α plots on a Cartesian plane. In the proposed classification scheme, multilayered folds have been divided into two broad categories, namely `isodeviatoric' and `anisodeviatoric'. Isodeviatoric folds have a constant fluctuation in the geometry of different layers recorded in terms of σn(tα′) or σn(Tα′) for α>10°. A special type of isodeviatoric fold is recognised as `analogous fold' in which each layer exhibits identical geometry [σn(tα′) or σn(Tα′)=0]. Plots of isodeviatoric folds lie parallel to the abscissa (α) and those of analogous folds lie along the abscissa in the σn(tα′) or σn(Tα′) (ordinate) versus α (abscissa) diagram. Analogous folds have been divided into ten varieties (1A1, 1A2, 1A3, 1B, 1C, 2, 3A, 3B, 3C and composite-analogous types). The anisodeviatoric folds do not exhibit constant fluctuation (deviation) in the geometry of different constitutive layers. Such folds have been subdivided into `peri-analogous', `sub-analogous', `sub-non-analogous', `non-analogous' and `strongly non-analogous' types. This classification scheme is applied to folds developed in low-grade metasedimentary rocks of the Mahakoshal Group and low- to medium-grade rocks of the Chhotanagpur Granite Gneiss Complex in central India. 相似文献
15.
C. M. Holl J. R. Smyth H. M. S. Laustsen S. D. Jacobsen R. T. Downs 《Physics and Chemistry of Minerals》2000,27(7):467-473
Natural witherite (Ba0.99Sr0.01CO3) has been studied by single-crystal X-ray diffraction in the diamond anvil cell at eight pressures up to 8 GPa. At ambient pressure, cell dimensions are a?=?5.3164(12) Å, b?=?8.8921(19) Å, c?=?6.4279(16) Å, and the structure was refined in space group Pmcn to R(F)?=?0.020 from 2972 intensity data. The unit cell and atom position parameters for the orthorhombic cell were refined at pressures of 1.2, 2.0, 2.9, 3.9, 4.6, 5.5, 6.2, and 7.0 GPa. The volume-pressure data are used to calculate equation of state parameters K T0?=?50.4(12) GPa and K′?=?1.9(4). At approximately 7.2 GPa, a first-order transformation to space group P3¯1c was observed. Cell dimensions of the high-pressure phase at 7.2 GPa are a?=?5.258(6) Å, c?=?5.64(1) Å. The high pressure structure was determined and refined to R(F)?=?0.06 using 83 intensity data, of which 15 were unique. This high-pressure phase appears to be more compressible than the orthorhombic phase with an estimated initial bulk modulus (K 7.2GPa) of 10 GPa. 相似文献
16.
17.
Dayong WangYongchen Song Weiguo LiuMinglong Zhao Tian Qi 《International Journal of Coal Geology》2011,87(1):33-40
This study presents a numerical investigation of the effect of volatilization and the supercritical state of pore water on maturation of organic matter in host rocks based on the heat flow models assuming the instantaneous and finite-time intrusion mechanisms of magma. A 15 m thick, well-dated basic sill in the DSDP 41-368 hole near Cape Verde Rise, eastern Atlantic is selected as an example due to the sufficient thermophysical parameters of rocks and the definite burial and thermal history of the shale host rocks. Results indicate: (1) The effect of the temperature-dependent thermal properties of pore water at a hydrostatic pressure of 414 bar on the predicted vitrinite reflectance (Rr) is less than 0.1% no matter which intrusion mechanism of magma is assumed and can hence be ignored reasonably; (2) The consideration of volatilization of pore water can reduce the predicted Rr of host rocks significantly. In case of the instantaneous intrusion mechanism, the maximum deviation of the predicted Rr caused by pore-water volatilization reaches 1.3% at the location of half the sill thickness away from the contact (i.e. X/D = 0.5), and the deviation above 0.5% can occur in the region from 0.3 to 1.0 in the form of X/D. In case of the finite-time intrusion mechanism, the maximum deviation of the predicted Rr due to pore-water volatilization attains 1.15% at X/D = 0.25, and the region where the deviation is larger than 0.5% lies between 0.15 and 0.6 in the form of X/D; (3) If hydrothermal convection in the host rocks is allowed for, the predicted Rr of the overlying host rocks is less than that of the underlying host rocks at the same X/D in the inner region of the contact aureole of igneous intrusions, whereas the phenomenon is converse in the outer region. In contrast, the measured Rr profile shows that at the same X/D, Rr of the overlying host rocks is totally higher than that of the underlying host rocks. Thus, it is not the hydrothermal convection in the overlying host rocks that resulted in the asymmetry of the current Rr profiles below and above the sill; (4) The predicted Rr based on the heat conduction model assuming the finite-time intrusion mechanism and pore-water volatilization matches well with the measured one out of the region where the Rr geothermometer is unreliable due to the effect of volatilization of pore water. This demonstrates that the finite-time intrusion mechanism of magma, together with pore-water volatilization, possibly represents natural conditions. 相似文献
18.
Michael Zech Nikolai Pedentchouk Katharina Leiber Slobodan B. Markovi? 《Geochimica et cosmochimica acta》2011,75(17):4917-4928
During the last decade, compound-specific hydrogen isotope analysis of plant leaf-wax and sedimentary n-alkyl lipids has become a promising tool for paleohydrological reconstructions. However, with the exception of several previous studies, there is a lack of knowledge regarding possible effects of early diagenesis on the δD values of n-alkanes. We therefore investigated the n-alkane patterns and δD values of long-chain n-alkanes from three different C3 higher plant species (Acer pseudoplatanus L., Fagus sylvatica L. and Sorbus aucuparia L.) that have been degraded in a field leaf litterbag experiment for 27 months.We found that after an initial increase of long-chain n-alkane masses (up to ∼50%), decomposition took place with mean turnover times of 11.7 months. Intermittently, the masses of mid-chain n-alkanes increased significantly during periods of highest total mass losses. Furthermore, initially high odd-over-even predominances (OEP) declined and long-chain n-alkane ratios like n-C31/C27 and n-C31/C29 started to converge to the value of 1. While bulk leaf litter became systematically D-enriched especially during summer seasons (by ∼8‰ on average over 27 months), the δD values of long-chain n-alkanes reveal no systematic overall shifts, but seasonal variations of up to 25‰ (Fagus, n-C27, average ∼13‰).Although a partly contribution by leaf-wax n-alkanes by throughfall cannot be excluded, these findings suggest that a microbial n-alkane pool sensitive to seasonal variations of soil water δD rapidly builds up. We propose a conceptual model based on an isotope mass balance calculation that accounts for the decomposition of plant-derived n-alkanes and the build-up of microbial n-alkanes. Model results are in good agreement with measured n-alkane δD results. Since microbial ‘contamination’ is not necessarily discernible from n-alkane concentration patterns alone, care may have to be taken not to over-interpret δD values of sedimentary n-alkanes. Furthermore, since leaf-water is generally D-enriched compared to soil and lake waters, soil and water microbial n-alkane pools may help explain why soil and sediment n-alkanes are D-depleted compared to leaves. 相似文献
19.
Setumi Miyamura 《Tectonophysics》1982,84(1):47-55
To describe an individual earthquake or the seismicity of a region, simple parameters such as magnitudes are necessary. In seismicity studies observations for as long as possible time intervals should be at disposal and subsequently the continuity of the parameters' quality should be guaranteed. MGR or MS can be such parameters. mb(sp) of USGS and ISC is another one, but it has been accumulated only since the 1960s. An international proposal to introduce or revive classical mb asks to change the traditional procedure of measuring the P maximum within a few seconds from the P onset. Some confusion appears to exist for recent mb-data in EDR of USGS. It is strongly hoped that the traditional procedure of USGS for mb(sp)-determination will not be discontinued and that the new mb will be introduced only as an additional parameter. 相似文献
20.
Evolutionary properties of the radial distribution of the gas density in the envelopes of 12 Galactic planetary nebulae are discussed. An evolutionary relationship between the maximum gas density n(r)max and the radius of the ionized segment of the nebula r c is derived. The ionized-gas masses in the envelopes of these nebulae M i /M ⊙ are determined. The relationship between the mass M i /M ⊙ and radius of the nebula is derived. The value of M i /M ⊙ changes by approximately a factor of 275 during a nebula’s evolution, ranging from 0.0038M ⊙ for “young” nebulae (IC 5117) to 1.05M ⊙ for “old” nebulae (NGC 7293). Distances to the nebulae are determined based on calculated photoionization models. These distances are in good agreement with those obtained independently byMalkov and with the distance to the planetary nebula K648 in the Galactic star cluster M15. 相似文献