岩石综合物性差异与变化的特征   总被引：2，自引：0，他引：2       下载免费PDF全文

于萍  冯永革 《地震学报》2001,23(5):541-547

从岩石物性与化学元素原子结构的关系出发，从密度、弹性、电性和放射性等诸方面，论述了岩石综合物性差异与变化的特征；并结合实例，得出岩石综合物性参数发生变化反映了组成岩石的原子、分子、矿物和结构发生了变化，且各参数之间具有某种相关性的结果．   相似文献   

适于窄线三维地震资料的面炮方法   总被引：4，自引：6，他引：4  

陈树民  刘洪  李幼铭 《地球物理学进展》2001,16(3):58-67,T002

用小孔径波动方程叠前深度偏移完成大面积数据的成像，不仅总的计算量较大，而且成像畸变较严重。为了进行大孔径波动方程叠前深度偏移，必须将实际的小孔径资料合成大孔径资料，并解决大孔径资料的成像方法。AMO等合成孔径方法，数据合成方式简单，但成像方法是近似的且较复杂。面炮方法从理论上讲数据合成方法较简单，成像方法是精确的且较简单，但其应用适用于远道振幅比近道弱很多的情况。在窄线三维地震资料情况，其联络测线方向不易满足面炮应用条件。针对这种情况，本文将最小二乘原理应用于波场成像，提出适用窄线三维地震资料的面炮方法。为了解三维波动方程叠前深度偏移的面炮方法解决复杂油气藏的可行性、所需计算资源和成像效果，我们利用大庆SW地区三维地震资料进行了实验研究。通过研究，我们获得了面炮方法的实际效果，获得了所需计算资源的测试数据。对实际效果的分析对比表明，面炮方法是一种三维波动方程叠前深度偏移的快速方法，有较好应用前景。  相似文献   

Characterization of Estonian Kukersite by spectroscopy and pyrolysis: Evidence for abundant alkyl phenolic moieties in an Ordovician, marine, type II/I kerogen     

S. Derenne  C. Largeau  E. Casadevall  J.S. Sinninghe Damst  E.W. Tegelaar  J.W. de Leeuw 《Organic Geochemistry》1990,16(4-6)

The kerogen of a sample of Estonian Kukersite (Ordovician) was examined by spectroscopic (solid state ¹³C NMR, FTIR) and pyrolytic (“off-line”, flash) methods. This revealed an important contribution of long, linear alkyl chains in Kukersite kerogen. The hydrocarbons formed upon pyrolysis are dominated by n-alkanes and n-alk-1-enes and probably reflect a major contribution of selectivity preserved, highly aliphatic, resistant biomacromolecules from the outer cell walls of Gloeocapsomorpha prisca. This is consistent with the abundant presence of this fossilized organism in Kukersite kerogen. In addition high amounts of phenolic compounds were identified in the pyrolysates. Series of non-methylated, mono-, di- and trimethylated 3-n-alkylphenols, 5-n-alkyl-1,3-benzenediols and n-alkylhydroxybenzofurans were identified. All series of phenolic compounds contain long (up to C₁₉), linear alkyl side-chains. Kukersite kerogen is, therefore, an aliphatic type II/I kerogen, despite the abundance of free phenolic moieties. This study shows that phenol-derived moieties are not necessarily associated with higher plant-derived organic matter.The flash pyrolysate of Kukersite kerogen was also compared with that of the kerogen of the Guttenberg Oil Rock (Ordovician) which is also composed of accumulations of fossilized G. prisca. Similarities in the distributions of hydrocarbons and sulphur compounds were noted, especially for the C₁–C₆ alkylbenzene and alkylthiophene distributions. However, no phenolic compounds were detected in the flash pyrolysate of the Guttenberg kerogen. Possible explanations for the observed similarities and differences are discussed.  相似文献   

半干旱半湿润地区洪水预报模型适用性研究   总被引：1，自引：0，他引：1       下载免费PDF全文

刘郁  赵兰兰  马丁 《水文》2016,36(1):32-36

针对半干旱半湿润地区的流域特性和产汇流特点,比较了河北雨洪模型和新安江模型的模型原理和模型特性,以滦河支流老牛河流域为例,开展了洪水预报适用性研究。结果表明,河北雨洪模型的预报精度较高,更适用于半干旱半湿润地区的洪水预报。  相似文献   

Estimation of river discharge from non-trapezoidal open channel using QuickBird-2 satellite imagery/Utilisation des images satellites de Quickbird-2 pour le calcul des débits fluviaux en chenaux ouverts non-trapézoïdaux     

《水文科学杂志》2013,58(2)

Abstract

Abstract River discharge is traditionally acquired by measuring water stage and then converting the water stage to discharge by using a stage–discharge rating curve. The possibility of monitoring river discharge by satellite has not been adequately studied hitherto, because of the difficulty in making sufficiently precise measurements of the water surface. Since the successful launch of commercial satellites with very-high-resolution sensors, it has become possible to derive ground information from satellite data. To determine river discharge in a non-trapezoidal open channel, an efficient approach has been developed that uses mainly satellite data. The method, which focuses on the measurement of surface water width coupled with river width–stage and ?remote? stage–discharge rating curves, was applied to the Yangtze River (Changjiang) and an accurate estimate of river discharge was obtained. The method can be regarded as ancillary to traditional field measurement methods or other remote sensing methods.  相似文献   

Temporal scaling in river flow: can it be chaotic? / L’invariance d’échelle de l’écoulement fluvial peut-elle être chaotique?     

《水文科学杂志》2013,58(3)

Abstract

Abstract Identification of the presence of scaling in the river flow process has been a challenging problem in hydrology. Studies conducted thus far have viewed this problem essentially from a stochastic perspective, because the river flow process has traditionally been assumed to be a result of a very large number of variables. However, recent studies employing nonlinear deterministic and chaotic dynamic concepts have reported that the river flow process could also be the outcome of a deterministic system with only a few dominant variables. In the wake of such reports, a preliminary attempt is made in this study to investigate the type of scaling behaviour in the river flow process (i.e. chaotic or stochastic). The investigation is limited only to temporal scaling. Flow data of three different scales (daily, 5-day and 7-day) observed in each of three rivers in the USA: the Kentucky River in Kentucky, the Merced River in California and the Stillaguamish River in Washington, are analysed. It is assumed that the dynamic behaviour of the river flow process at these individual scales provides clues about the scaling behaviour between these scales. The correlation dimension is used as an indicator to distinguish between chaotic and stochastic behaviours. The results are mixed with regard to the type of flow behaviour at individual scales and, hence, to the type of scaling behaviour, as some data sets show chaotic behaviour while others show stochastic behaviour. They suggest that characterization (chaotic or stochastic) of river flow should be a necessary first step in any scaling study, as it could provide important information on the appropriate approach for data transformation purposes.  相似文献   

Stochastically conditioned flow paths and travel time distribution in highly heterogeneous synthesized aquifers / Chemins d’écoulement et distribution des temps de parcours au sein d’aquifères synthétiques hautement hétérogènes sous conditions stochastiques     

《水文科学杂志》2013,58(6)

Abstract

Abstract Characterization of heterogeneity at the field scale generally requires detailed aquifer properties such as transmissivity and hydraulic head. An accurate delineation of these properties is expensive and time consuming, and for many if not most groundwater systems, is not practical. As an alternative approach, stochastic representation of random fields is used and presented in this paper. Specifically, an iterative stochastic conditional simulation approach was applied to a hypothetical and highly heterogeneous pre-designed aquifer system. The approach is similar to the classical co-kriging technique; it uses a linear estimator that depends on the covariance functions of transmissivity (T), and hydraulic head (h), as well as their cross-covariances. A linearized flow equation along with a conditional random field generator constitutes the iterative process of the conditional simulation. One hundred equally likely realizations of transmissivity fields with pre-specified geostatistical parameters were generated, and conditioned to both limited transmissivity and head data. The successful implementation of the approach resulted in conditioned flow paths and travel-time distribution under different degrees of aquifer heterogeneity. This approach worked well for fields exhibiting small variances. However, for random fields exhibiting large variances (greater than 1.0), an iterative procedure was used. The results show that, as the variance of the ln[T] increases, the flow paths tend to diverge, resulting in a wide spectrum of flow conditions, with no direct discernable relationship between the degree of heterogeneity and travel time. The applied approach indicates that high errors may result when estimation of particle travel times in a heterogeneous medium is approximated by an equivalent homogeneous medium.  相似文献   

Utility of high-resolution climate model simulations for water resources prediction over the Korean Peninsula: a sensitivity study / Utilité de simulations de modèle climatique à haute résolution pour la prévision des ressources en eau dans la Péninsule Coréenne: étude de sensibilité     

《水文科学杂志》2013,58(1)

Abstract

Abstract The utility of simulations of Global Climate Models (GCMs) for regional water resources prediction and management on the Korean Peninsula was assessed by a probabilistic measure. Global Climate Model simulations of an indicator variable (e.g. surface precipitation or temperature) were used for discriminating high vs low regional observations of a target variable (e.g. watershed precipitation or reservoir inflow). The formulation uses the significance probability of the Kolmogorov-Smirnov test for detecting differences between two distributions. High resolution Atmospheric Model Intercomparison Project-II (AMIP-II) type GCM simulations performed by the European Centre for Medium-Range Weather Forecasts (ECMWF) and AMIP-I type GCM simulations performed by the Korean Meteorological Research Institute (METRI) were used to obtain information for the indicator variables. Observed mean areal precipitation and temperature, and watershed-outlet discharge values for seven major river basins in Korea were used as the target variables. The results suggest that the use of the climate model nodal output from both climate models in the vicinity of the target basin with monthly resolution will be beneficial for water resources planning and management analysis that depends on watershed mean areal precipitation and temperature, and outlet discharge.  相似文献   

Multiple P–T–d–t paths reveal the evolution of the final Nuna assembly in northeast Australia     

Silvia Volante  Amaury Pourteau  William J. Collins  Eleanore Blereau  Zheng-Xiang Li  Matthijs Smit  Noreen J. Evans  Adam R. Nordsvan  Chris J. Spencer  Brad J. McDonald  Jiangyu Li  Christina Günter 《Journal of Metamorphic Geology》2020,38(6):593-627

The final assembly of the Mesoproterozoic supercontinent Nuna was marked by the collision of Laurentia and Australia at 1.60 Ga, which is recorded in the Georgetown Inlier of NE Australia. Here, we decipher the metamorphic evolution of this final Nuna collisional event using petrostructural analysis, major and trace element compositions of key minerals, thermodynamic modelling, and multi-method geochronology. The Georgetown Inlier is characterised by deformed and metamorphosed 1.70–1.62 Ga sedimentary and mafic rocks, which were intruded by c. 1.56 Ga old S-type granites. Garnet Lu–Hf and monazite U–Pb isotopic analyses distinguish two major metamorphic events (M1 at c. 1.60 Ga and M2 at c. 1.55 Ga), which allows at least two composite fabrics to be identified at the regional scale—c. 1.60 Ga S1 (consisting in fabrics S1a and S1b) and c. 1.55 Ga S2 (including fabrics S2a and S2b). Also, three tectono-metamorphic domains are distinguished: (a) the western domain, with S1 defined by low-P (LP) greenschist facies assemblages; (b) the central domain, where S1 fabric is preserved as medium-P (MP) amphibolite facies relicts, and locally as inclusion trails in garnet wrapped by the regionally dominant low-P amphibolite facies S2 fabric; and (c) the eastern domain dominated by upper amphibolite to granulite facies S2 foliation. In the central domain, 1.60 Ga MP–medium-T (MT) metamorphism (M1) developed within the staurolite–garnet stability field, with conditions ranging from 530–550°C at 6–7 kbar (garnet cores) to 620–650°C at 8–9 kbar (garnet rims), and it is associated with S1 fabric. The onset of 1.55 Ga LP–high-T (HT) metamorphism (M2) is marked by replacement of staurolite by andalusite (M2a/D2a), which was subsequently pseudomorphed by sillimanite (M2b/D2b) where granite and migmatite are abundant. P–T conditions ranged from 600 to 680°C and 4–6 kbar for the M2b sillimanite stage. 1.60 Ga garnet relicts within the S2 foliation highlight the progressive obliteration of the S1 fabric by regional S2 in the central zone during peak M2 metamorphism. In the eastern migmatitic complex, partial melting of paragneiss and amphibolite occurred syn- to post- S2, at 730–770°C and 6–8 kbar, and at 750–790°C and 6 kbar, respectively. The pressure–temperature–deformation–time paths reconstructed for the Georgetown Inlier suggest a c. 1.60 Ga M1/D1 event recorded under greenschist facies conditions in the western domain and under medium-P and medium-T conditions in the central domain. This event was followed by the regional 1.56–1.54 Ga low-P and high-T phase (M2/D2), extensively recorded in the central and eastern domains. Decompression between these two metamorphic events is ascribed to an episode of exhumation. The two-stage evolution supports the previous hypothesis that the Georgetown Inlier preserves continental collisional and subsequent thermal perturbation associated with granite emplacement.  相似文献   

Tectonometamorphic evolution of an intracontinental orogeny inferred from P–T–t–d paths of the metapelites from the Rehamna massif (Morocco)          下载免费PDF全文

P. Wernert  K. Schulmann  F. Chopin  P. Štípská  D. Bosch  M. El Houicha 《Journal of Metamorphic Geology》2016,34(9):917-940

New petrographic and microstructural observations, mineral equilibria modelling and U/Pb (monazite) geochronological studies were carried out to investigate the relationships between deformation and metamorphism across the Rehamna massif (Moroccan Variscan belt). In this area, typical Barrovian (muscovite to staurolite) zones developed in Cambrian to Carboniferous metasedimentary rocks that are distributed around a dome‐like structure. First assemblages are characterized by the presence of locally preserved andalusite, followed by prograde evolution culminating at 6 kbar and 620 °C in the structurally deepest staurolite zone rocks. This Barrovian sequence was subsequently uplifted to supracrustal levels, heterogeneously reworked at greenschist facies conditions, which was followed locally by static growth of andalusite, indicating heating to 2.5–4 kbar and 530–570 °C. The ²⁰⁶Pb/²³⁸U monazite age of 298.3 ± 4.1 Ma is interpreted as minimum age of peak metamorphic conditions, whereas the ages of 275.8 ± 1.7 Ma and 277.0 ± 1.1 Ma date decompression and heating at low pressure, in agreement with previous dating of Permian granitoids intruding the Rehamna massif. The prograde metamorphism occurred during thickening and associated horizontal flow in the deeper crust (S1 horizontal schistosity). The horizontally disposed metamorphic zones were subsequently uplifted by a regional scale antiform during ongoing N–S compression. The re‐heating of the massif follows late massive E–W shortening, refolding and retrograde shearing of all previous fabrics coevally with regionally important intrusions of Permian granitoids. We argue that metamorphic evolution of the Rehamna massif occurred several hundred kilometres from the convergent plate boundaries in the interior of continental Gondwanan plate. The tectonometamorphic history of the Rehamna massif is put into Palaeozoic plate tectonic perspective and Late Carboniferous reactivation of (Devonian)–Early Carboniferous basins formed during stretching of the north Gondwana margin and formation of the Palaeotethys Ocean. The inherited heat budget of these magma‐rich basins plays a role in the preferential location of this intracontinental orogen. It is shown that rapid transition from lithospheric stretching to compression is characterized by specific HT type of Barrovian metamorphism, which markedly differs from similar Barrovian sequences along Palaeozoic plate boundaries reported from Variscan Europe.  相似文献