金平白马寨铜镍矿床综合信息成矿预测模型   总被引：4，自引：0，他引：4  

宋立军  朱杰勇 《云南地质》2003,22(2):161-169

系统研究哀牢山造山带金平白马寨铜镍矿床的地质、地球物理及地球化学特征。提出本矿床为含矿基性—超基性岩浆熔离—结晶分异和矿浆依次脉冲式贯入的铜镍硫化物矿床成矿模式，最终建立本区铜镍矿床的综合信息成矿预测模型。  相似文献   

滑坡地段隧道变形机理的模型试验研究   总被引：9，自引：2，他引：9  

陶志平  周德培 《工程地质学报》2003,11(3):323-327

通过室内地质力学模型试验,研究了滑坡地段坡体变形与隧道的相互作用机理、围岩和衬砌压力的变化规律以及坡体和隧道的变形特征,着重研究了滑带土浸水软化及发生蠕变时坡体变形与隧道的相互作用关系。本文的成果可为该类病害的预测预报和有效整治提供科学依据。  相似文献   

Gold occurrence in Central Italy—the Ponte San Pietro mineralization     

G. De Casa  A. Manni  G. Saviano  M. Violo 《Ore Geology Reviews》2003,23(3-4):99-105

Gold mineralization related to a sulphide-bearing quartz vein within Triassic phyllites has been identified in a former study of an abandoned Cu–Zn–Pb mine in southern Tuscany–northern Latium. The vein-hosted mineral assemblage includes pyrite, sphalerite, chalcopyrite, galena, arsenopyrite, and tetrahedrite; the gold content reaches up to 20 ppm. The mineralization was related to fluids characterised by moderate temperatures and moderate salinities (5–15% NaCl equivalent) and represents the highest grade of Au in the ore deposits of southern Tuscany. The difference in the estimated values of Te of primary, L+V, pseudo-secondary L+V, secondary L+V fluids inclusions reflects different components present in the solutions.Based on these results one can conclude that euhedral quartz and pyrite deposition was related to fluids having variable salinity and chemical components.The origin of gold in Ponte San Pietro (PSP) deposit may be related to leaching of metapelites/phyllites derived from pelitic rocks containing some amount of sulphur-bearing organic matter; it is worthy noting that quartz–marcasite bearing lenses, interstratified in Triassic phyllites, contain significant amount of visible gold. The Co, Ni, Mn, as well as the δ³⁴S data, suggest a different origin for the phyllite-hosted marcasite, the PSP quartz-vein hosted pyrite, and for gold occurrences.  相似文献   

从滨里海盆地上古生界油气探讨中国海相碳酸盐岩油气勘探的科学思路   总被引：6，自引：0，他引：6  

张景廉  王新民  李相博  于均民  周晓峰 《海相油气地质》2002,7(3):50-58

中国海相碳酸盐岩油气勘探“久攻不克”,其中碳酸盐岩有机质丰度和油气运移是两大难题。滨里海盆地上古生界油气储量的地质成藏条件分析提供了一种碳酸盐岩油气成藏模式,即碳酸盐岩油气生成与地幔流体以及与中地壳的低速、高导层有关。原油、沥青、干酪根的 Pb、Sr、Nd 同位素组成、碳酸盐岩矿物与含水矿物的高温、高压实验、热液条件下 HCO_3~-与 H_2的实验均证实了上述认识,油气可以通过无机反应生成。根据这一油气生成模式,应该重新审视中国油气勘探的方针。近期可在西部三大克拉通盆地(塔里木盆地、四川盆地、鄂尔多斯盆地)及南方海相碳酸盐岩地区以“碳酸盐岩—生物礁(白云岩化)—膏盐”的岩性结构为模式有望找到大型、超大型油气田,关键是对生物礁的勘探及识别技术的突破、白云岩孔洞、裂缝储层的识别、预测及膏盐层钻井技术的改进。  相似文献   

The Bayesian approach applied to GPS ambiguity resolution. A mixture model for the discrete–real ambiguities alternative     

M. C. de Lacy  F. Sansò  G. Rodriguez-Caderot  A. J. Gil 《Journal of Geodesy》2002,76(2):82-94

 The problem of phase ambiguity resolution in global positioning system (GPS) theory is considered. The Bayesian approach is applied to this problem and, using Monte Carlo simulation to search over the integer candidates, a practical expression for the Bayesian estimator is obtained. The analysis of the integer grid points inside the search ellipsoid and their evolution with time, while measurements are accumulated, leads to the development of a Bayesian theory based on a mathematical mixture model for the ambiguity. Received: 29 March 2001 / Accepted: 3 September 2001  相似文献   

Response spectrum predictions for potential near-field and far-field earthquakes affecting Hong Kong: rock sites   总被引：1，自引：0，他引：1  

N. T. K. Lam  A. M. Chandler  J. L. Wilson  G. L. Hutchinson 《Soil Dynamics and Earthquake Engineering》2002,22(1)

To realistically assess the seismic risk relating to built infrastructures in Hong Kong and in the neighbouring coastal cities of southern Guangdong province, it is necessary to predict ground shaking induced by different earthquake scenarios with good accuracy. A companion paper has described the modelling of the spatial and temporal distribution of the diffused seismic activities in the region, based on the newly-developed ‘Expanding Circular Disc’ (ECD) method. Representative Magnitude–Distance (M–R) combinations for both near-field and far-field earthquakes (in relation to Hong Kong) have been derived using the ECD method. The present paper describes the modelling of the response spectrum on rock sites associated with the predicted M–R combinations, using the Component Attenuation Model (CAM) that was also developed recently by the authors, based on stochastic simulations of the seismological model. The significant effects of soil resonance on the response spectrum are described in a separate publication.The accuracy of CAM in modelling ground motion properties on rock sites has been tested here by comparisons with (i) strong motions recorded in Taiwan and South China from the 1999 ‘Chi-Chi’ earthquake in Taiwan (M=7.6), (ii) motions recorded in South China from another earthquake occurring in the southern Taiwan Strait in the same year (M=5.1), and (iii) historical seismic intensity data obtained within South China. The overall capability of CAM in modelling both near-field and far-field attenuation has been shown to be unmatched by existing empirical models. Results of the comparison studies confirm the accuracy of CAM, particularly within an epicentral distance of 300–400 km.This study shows that the developed serviceability response spectra (i.e. at short return periods) are controlled mainly by the earthquake recurrence behaviour of major distant seismic sources. In contrast, the ultimate response spectra (i.e. at long return periods) relate to events with magnitudes close to the maximum credible earthquake (MCE) limit, the effect of which may also be represented by the Characteristic Response Spectrum (CRS). Both types of earthquake scenario can be significantly affected by the regional crustal properties. The proposed response spectrum envelopes have been compared with previously developed recommendations, and a critical review has been conducted. The intrinsic advantages of the ECD–CAM modelling approach have been highlighted, emphasising its directness and transparency when compared with the more complex process required to implement traditional Probabilistic Seismic Hazard Assessment (PSHA).  相似文献   

Nonlinear surface ground analysis via statistical approach     

Izuru Takewaki  Nobuyoshi Fujii  Koji Uetani 《Soil Dynamics and Earthquake Engineering》2002,22(6)

A statistical approach is proposed for nonlinear surface ground analysis. In contrast to the conventional method which deals with only a single ground motion for equivalent linearization of soil properties, a design response spectrum defined at the upper level (bottom of the surface ground) of an engineering bedrock can be handled as the target design earthquake in the present paper. The effective shear strain in each soil layer is evaluated by means of a statistical procedure in which the mean peak shear strain is computed in terms of its standard deviation and the corresponding peak factor. The stiffness and damping ratio of each soil layer are obtained iteratively from the nonlinear relation of stiffness reduction factors and damping ratios with respect to the strain level. After the evaluation of the equivalent stiffness and damping ratio of every soil layer, the ground surface response spectrum is transformed from the design response spectrum defined at the upper level of the engineering bedrock via the one-dimensional wave propagation theory. The reliability and accuracy of the proposed analysis method is examined through the comparison with the results by the conventional method (represented by the program) for many simulated spectrum-compatible ground motions.  相似文献   

Aerosol optical thickness retrieval over the Atlantic Ocean using GOES imager data     

M Moula  J Verdebout  H Eva 《Physics and Chemistry of the Earth》2002,27(35):1525-1531

An algorithm based on simulated satellite signal calculated by the 6S radiative transfer model has been developed in order to retrieve the aerosol optical thickness of dust over the Atlantic ocean. The algorithm is applied to the visible channel of Geostationary Operational Environmental Satellite (GOES 8) images. The inversion uses a look-up table giving the satellite signal intensity as a function of surface albedo, viewing geometry, solar illumination and the optical properties of the aerosols. The study consists of assessing the feasibility of monitoring and mapping the transport of suspended particles across the Atlantic from the Sahara to the Caribbean. The study area is between 10 and 25 N and 30 and 65 W. The optical thickness of aerosols has been calculated over a period of 11 days between 10th and 20th of June 1997 for the 14:15 UT GOES image acquisition. The calculated aerosol optical thickness ranges from 0.0 to 0.81 with an important event of dust presence occurring between 13th and 16th of June. The retrieved aerosol optical thickness is in good agreement with the values obtained between 14h UT and 15h UT from ground based sun photometer measurements on the island of Guadeloupe, and a coefficient correlation (R²) of 0.88 has been found between the data sets.  相似文献   

Impact of a Saturation-Dependent Dissipation Source Function on Operational Hindcasts of Wind-Waves in the Australian Region     

Jose Henrique G. M. Alves  Diana J. M. Greenslade  Michael L. Banner 《Journal of Atmospheric & Ocean Science》2002,8(4):239-267

The impact of a modified parametric form of the dissipation source function S ds on the skill of an operational spectral wind-wave model is investigated. Numerical experiments are made with a version of the WAM model presently used operationally by the Australian Bureau of Meteorology to produce sea-state forecasts within the Australian region. Performances of wave hindcasts obtained using several alternative forms of this newly proposed dissipation source function are compared to those produced with forms of S ds commonly used operationally. A new ad hoc technique to compare modelled and observed wave spectra is introduced to assess the quality of calculated one-dimensional frequency spectra.

Our results indicate that wave model performance in terms of integral spectral parameters, such as the significant wave height H s , may benefit from improved parameterisations of the dissipation source term S ds . On the other hand, we also found that model performance was relatively poor in terms of predictions of the one-dimensional frequency spectrum, regardless of the chosen form of S ds . These results suggest that further refinements of the dissipation source term are strongly dependent on improved parametrisations of the nonlinear interactions source term S nl .  相似文献   

New evidence for a relation between wind stress and wave age from measurements during ASGAMAGE   总被引：7，自引：0，他引：7  

W.A. Oost  G.J. Komen  C.M.J. Jacobs  C. Van Oort 《Boundary-Layer Meteorology》2002,103(3):409-438

Data from the 1996 ASGAMAGE experiment, performed in the southern North Sea at research platform Meetpost Noordwijk (MPN), are analysed for the parameters affecting the momentum flux. The stress turns out to be quadratically related to the 10-m wind speed and linearly to the wind speed at a wavelength related level. The Charnock parameter (dimensionless roughness length) shows a pronounced correlation with wave age. This implies, due to a coupling between wave age and the steepness of the waves, a connection between the stress and the steepness. We find that our North Sea results are consistent withopen ocean observations. For a given wind speed the mean stress at MPN turns out to be higher because the wave age there is in general lower. We define and give an expression for a drag coefficient at a wavelength related level that can be calculated straightforwardly from the wave age and then reduced to a standard level.  相似文献