Finite Element-Analysis of an Overfold Using the Viscous Fluid Model

Symmetrical folding of a single layer and folding process of an overfold are analyzed by using the finite element method. In the analysis, the constituent substances are assumed to be isotropic and incompressible and to behave as Newtonian fluids. The penalty function method is used to deal with incompressibility, The results of the analysis are compared with the data measured in the field and with those obtained by the elastopla(?)e finite element analysis, It shows that the overfold geometry may be well simulated by using the viscous fluid model. Thus, a possible mechanism of the formation of overfold is proposed.     

A Comparison Study of Synkinematic Illite Isolation,Quantitative X-ray Powder Diffraction,and K-Ar Dating for Direct Fault Gouge Analyses

K-Ar dating of synkinematic illite is increasingly recognized as a central method to constrain the timing of shallow crustal faulting. Methods of efficient sample preparation and quantitative identification of illite polytypes are critical to acquiring K-Ar isotope data for authigenic clays. In this respect, we compared the commonly used clay size separation method through centrifugation with vacuum filtration technology, showing that the former is prone to extract fractions with finer particle ...     

有机质差热分析在有机地球化学中的应用和解释

The present paper primarily deals with DTA data on organic matters in carbonate rocks. In combination with analyzes of organic carbon and bituminous substances as well as infrared absorption spectra, an explanation of the features with respect to oil-generating carbonate roeks has been made. The results are summarized as fellows: (1) If the degree of hydrocarbonization ef organic matters in carbonate rocks is high, DTA exothermic pre-peaks will be expected at lower temperatures. (2) Insoluble organic matters in carbonate rocks, would crack up into soluble organic matters (light hydroearbons) during the meso-catagenetic stage. (3) Evolution of liquid hydrocarbons produced in the preto-eatagenetic stage is recognizable during the meso-eatagenetie stage.     

Subsidence Analysis and Burial History of the Late Carboniferous to Early Jurassic Soutpansberg Basin, Limpopo Province, South Africa

The subsidence history of the Soutpansberg Basin was reconstructed by a tectonic subsidence analysis coupled with backstripping calculations based on data of newly interpreted sequence boundaries. Furthermore,burial and time plots were constructed in order to understand the burial and thermal history of the basin. Input data were based on facies,lithostratigraphic models and tectonic interpretations. The studied succession is up to 1000 m and is underlain by the Achaean Limpopo Mobile Belt. The subsidence within the basin supports the primary graben system which must have been centred within the present basins,and later became a region of faulting. The subsidence and burial history curves suggests two phases of rapid subsidence during the Early-Late Permian(300–230 Ma) and Middle Triassic(215–230 Ma). The areas of greater extension subsided more rapidly during these intervals. Two slow subsidence phases are observed during the Late Triassic(215–198 Ma) and Early Jurassic(198–100 Ma). These intervals represent the post-rift thermal subsidence and are interpreted as slow flexural subsidence. Based on these observations on the subsidence curves,it is possible to infer that the first stage of positive inflexion(300 Ma) is therefore recognised as the first stage of the Soutpansberg Basin formation.     

Technology and Its Application： MIS with Geographical Information

Despite the constant expansion of the application of GIS, in recent years, the data process-ing ability of the application system developed with GIS_Tool is quite limited. Management information system with the geographical information can not only be used to deal with data commonly, but also deal with digitized maps as GIS_Tool does. Thus it can help the user develop an application system high-qual-ified both in maps and traditional data. This paper, by taking the method of integrated MapInfo in the application of Visual Basic as an example, mainly illustrates two technological problenm-integrated map technology and the multiuserization of Maplnfo geographical information. And also the concrete solu-tions to the problems are provided.     

Development of Geological Data Warehouse

Data warehouse (DW), a new technology invented in 1990s, is more useful for integrating and analyzing massive data than traditional database. Its application in geology field can be divided into 3 phrases: 1992-1996, commercial data warehouse (CDW) appeared; 1996-1999, geological data warehouse (GDW) appeared and the geologists or geographers realized the importance of DW and began the studies on it, but the practical DW still followed the framework of DB; 2000 to present, geological data warehouse grows, and the theory of geo-spatial data warehouse (GSDW) has been developed but the research in geological area is still deficient except that in geography. Although some developments of GDW have been made, its core still follows the CDW-organizing data by time and brings about 3 problems: difficult to integrate the geological data, for the data feature more space than time; hard to store the massive data in fifferent levels due to the same reason; hardly support the spatial analysis if the data are organized by time as CDW does. So the GDW should be redesigned by organizing data by scale in order to store mass data in different levels and synthesize the data in different granularities, and choosing space control points to replace the former time control points so as to integrate different types of data by the method of storing one type data as one layer and then to superpose the layers. In addition, data cube, a wide used technology in CDW, will be no use in GDW, for the causality among the geological data is not so obvious as commercial data, as the data are the mixed result of many complex rules, and their analysis needs the special geological methods and software; on the other hand, data cube for mass and complex geo-data will devour too much store space to be practical. On this point, the main purpose of GDW may be fit for data integration unlike CDW for data analysis.     

Genetic Modeling of GIS-Based Cell Clusters and Its Application in Mineral Resources Prediction

This paper presents a synthetic analysis method for multi-sourced geological data from geo-graphic information system (GIS). In the previous practices of mineral resources prediction, a usually adopted methodology has been statistical analysis of cells delimitated based on thoughts of random sam-pling. That might lead to insufficient utilization of local spatial information, for a cell is treated as a point without internal structure. We now take “cell dusters“, L e. , spatial associations of cells, as basic units of statistics, thus the spatial configuration information of geological variables is easier to be detected and utilized, and the accuracy and reliability of prediction are improved. We build a linear multi-discriminating model for the dusters via genetic algorithm. Both the right-judgment rates and the in-class vs. betweewclass distance ratios are considered to form the evolutional adaptive values of the population. An application of the method in gold mineral resoerces prediction in east Xinjiang, China is presented.     

High pressure equation of state for molten CaCO3 from first principles simulations

Carbonate melts are important active metasomatic agents and efficient transport agents; their thermodynamic properties at high temperatures and pressures are therefore of considerable interest for various geochemica applications. However, due to the extreme challenges in relevant experiments, current knowledge of even the density of carbonate melts is limited. In this study, we provide high quality volumetric data of Ca CO3-melt from firs principles at high temperatures and pressures(up to3,500 K and 60 GPa). The accuracy of these data is demonstrated through comprehensive comparison with available experimental data and a thorough discussion of the predictability of the re-scaling method proposed in this study. Based on the simulations, an equation of state has been established that is critical to relevant highly disputed questions such as the decomposition and solidification boundaries of Ca CO3 melts, the latter of which is briefly discussed in this study with a newly derived ab initio melting curve to high pressures.     

A Study on Identification of Conglomerate Reservoir Parameters and Oil/Water Beds in Ke82 Well Areas of Junggar Basin

This paper is mainly about the calculation of reservoir parameters and the interpretation method for identifying oil/water beds in Ke82 well areas of Junggar basin. It is difficult to determine the reservoir parameters with common logging methods such as core calibration log because of the diversity of minerals and rocks and the complexity of pore structures in the conglomerate reservoir of Junggar basin. Optimization logging exploration is a good method to determine the porosity by establishing the multi-mineral model with logging curves based on the integration of geological, core and well testing data. Permeability is identified by BP algorithm of neural network. Hydrocarbon saturation is determined by correlating Archie‘s and Simandoux formulas. Comparing the exploratory result and core data, we can see that these methods are effective for conglomerate logging exploration. We processed and explained six wells in the Ke82 well areas. And actual interpretation has had very good results, 85 % of which conform to well testing data. Therefore, this technique will be effective for identifying conglomerate parameters.     

Groundwater contaminant source identification based on QS-ILUES

When groundwater pollution occurs,to come up with an efficient remediation plan,it is particularly important to collect information of contaminant source(location and source strength)and hydraulic conductivity field of the site accurately and quickly.However,the information can not be obtained by direct observation,and can only be derived from limited measurement data.Data assimilation of observations such as head and concentration is often used to estimate parameters of contaminant source.As for hydraulic conductivity field,especially for complex non-Gaussian field,it can be directly estimated by geostatistics method based on limited hard data,while the accuracy is often not high.Better estimation of hydraulic conductivity can be achieved by solving inverse groundwater problem.Therefore,in this study,the multi-point geostatistics method Quick Sampling(QS)is proposed and introduced for the first time and combined with the iterative local updating ensemble smoother(ILUES)to develop a new data assimilation framework QS-ILUES.It helps to solve the contaminant source parameters and non-Gaussian hydraulic conductivity field simultaneously by assimilating hydraulic head and pollutant concentration data.While the pilot points are utilized to reduce the dimension of hydraulic conductivity field,the influence of pilot points’layout and the ensemble size of ILUES algorithm on the inverse simulation results are further explored.     

Effect of saltwater intrusion on groundwater environment in Weihe River downstream,Shandong Province,China

Based on the geological and hydrogeological conditions along with dynamic changes of groundwater level,this paper analyzes the hydrodynamic characteristics of saltwater intrusion in the study area.According to monitoring data of groundwater quality,the distribution characteristics of macro component are analyzed,and then fuzzy comprehensive evaluation method is adopted to evaluate the impact of saltwater intrusion on groundwater environment.Concerning the influence degree of groundwater environment,the study area is divided into brine area,seriously influenced area,moderately influenced zone,slightly influenced zone and uninfluenced zone.The results can offer references for prevention and control of saltwater intrusion as well as the protection of water resources.     

Quantitative Method of Classification and Discrimination of a Porous Carbonate Reservoir Integrating K-means Clustering and Bayesian Theory

Reservoir classification is a key link in reservoir evaluation. However, traditional manual means are inefficient,subjective, and classification standards are not uniform. Therefore, taking the Mishrif Formation of the Western Iraq as an example, a new reservoir classification and discrimination method is established by using the K-means clustering method and the Bayesian discrimination method. These methods are applied to non-cored wells to calculate the discrimination accuracy of the reservoir...     

弓长岭富磁铁矿床成因的地球化学模型

Based upon geological and geochemical data on the genesis of Gongchangling rich magnetite deposit, it is suggested that the deposit is of multigenesis, and a three-stage geochemical model for the genesis of the deposit is proposed : (1) Depositional stage : the deposition of banded low-grade ores (magnetite-quartzite) was accompanied by high-grade magnetite (hematite)-siderite ores which are intercalated with magnetite-quartzites as lenses or stratoid shoots. (2) Metaamorphic stage: In response to metamorphism, siderite was decomposed into magnetite and graphite with decreasing fo2 and increasing PCO2. On the margin of magnetitc-siderite ores or within the thin intercalated layers where fO2, was high relative to PCO2 were formed graphite-free rich magnetite ores. (3) Hydrothermal stage: As a result of later hydrothermal process diffusive metasomatism between the shoots and host rocks anti silica leaching took place, thus giving rise to the rich magnetite ores of metasomatic type, and altered rocks.     

Free Radicals in Organic Matter for Thermal History Reconstruction of Carbonate Succession

Geothermometer is one of the most useful methods to reconstruct the thermal history of sedimentary basins. This paper introduces the application of free radicals concentration of organic matter as a thermal indicator in the thermal history reconstruction of carbonate succession, based on anhydrous thermal simulation results of type I and H1 kerogen. A series of free radicals data are obtained under thermal simulation of different heating temperatures and times, and quantitative modds between free radical concentration （Ng） of organic matter and time-temperature index （TTI） for types I and type H1 kerogen are also obtained. This Ng.TTI relation was used to model the Ordovician thermal gradients of Well TZ12 in the Tarim Basin. The modeling result is corresponding to the results obtained by apatite fission track data and published data. This new method of thermal history reconstruction will be benefit to the hydrocarbon generation and accumulation study and resource assessment of carbonate succession.     

Non-parametric machine learning methods for interpolation of spatially varying non-stationary and non-Gaussian geotechnical properties

Spatial interpolation has been frequently encountered in earth sciences and engineering.A reasonable appraisal of subsurface heterogeneity plays a significant role in planning,risk assessment and decision making for geotechnical practice.Geostatistics is commonly used to interpolate spatially varying properties at un-sampled locations from scatter measurements.However,successful application of classic geostatistical models requires prior characterization of spatial auto-correlation structures,which poses a great challenge for unexperienced engineers,particularly when only limited measurements are available.Data-driven machine learning methods,such as radial basis function network(RBFN),require minimal human intervention and provide effective alternatives for spatial interpolation of non-stationary and non-Gaussian data,particularly when measurements are sparse.Conventional RBFN,however,is direction independent(i.e.isotropic)and cannot quantify prediction uncertainty in spatial interpolation.In this study,an ensemble RBFN method is proposed that not only allows geotechnical anisotropy to be properly incorporated,but also quantifies uncertainty in spatial interpolation.The proposed method is illustrated using numerical examples of cone penetration test(CPT)data,which involve interpolation of a 2D CPT cross-section from limited continuous 1D CPT soundings in the vertical direction.In addition,a comparative study is performed to benchmark the proposed ensemble RBFN with two other non-parametric data-driven approaches,namely,Multiple Point Statistics(MPS)and Bayesian Compressive Sensing(BCS).The results reveal that the proposed ensemble RBFN provides a better estimation of spatial patterns and associated prediction uncertainty at un-sampled locations when a reasonable amount of data is available as input.Moreover,the prediction accuracy of all the three methods improves as the number of measurements increases,and vice versa.It is also found that BCS prediction is less sensitive to the number of measurement data and outperforms RBFN and MPS when only limited point observations are available.     

Sequential Gaussian simulation for geosystems modeling: A machine learning approach

Sequential Gaussian Simulation(SGSIM)as a stochastic method has been developed to avoid the smoothing effect produced in deterministic methods by generating various stochastic realizations.One of the main issues of this technique is,however,an intensive computation related to the inverse operation in solving the Kriging system,which significantly limits its application when several realizations need to be produced for uncertainty quantification.In this paper,a physics-informed machine learning(PIML)model is proposed to improve the computational efficiency of the SGSIM.To this end,only a small amount of data produced by SGSIM are used as the training dataset based on which the model can discover the spatial correlations between available data and unsampled points.To achieve this,the governing equations of the SGSIM algorithm are incorporated into our proposed network.The quality of realizations produced by the PIML model is compared for both 2D and 3D cases,visually and quantitatively.Furthermore,computational performance is evaluated on different grid sizes.Our results demonstrate that the proposed PIML model can reduce the computational time of SGSIM by several orders of magnitude while similar results can be produced in a matter of seconds.     

Authigenetic K—feldspars and Their Relations to Sn—polymetallic Mineralization in the Dachang Ore Field

Sn-polymetallic ores at Dachang,Guangxi Autonomous Region,China,are hosted in Middle-Upper Devonian reef limestones,siliceous rocks,banded and lenticular limestones,etc.Two types of orebodies can be distinguished according to their telations to the bedding:one is distributed along the bedding and the.other cuts across the bedding.Sn and sulfide orebodies associated with K-feldspare are mostly characterized by laminated ore structure. Microscopic examinations of K-feldspar-bearing rocks,in conjunction with X-ray diffraction,chemical composiion and cathodoluminescence data for K-feldspars,as well as their telations to mineralization,the authors consider that the K-feldspare are of authigenic origin,subordinate to the epigenetic stage of diagenesis,They resulted from the reaction of mixed,deep-seated,circulating underground hot waters rich in K,Al and Si with argillaceous carbonates during the Indo nesian orogenic movement.It is suggested more attention should be paid to the effect of authigenic K-feldspars on Sn mineralization.In the meantime the event related to circulating underground hot waters should also be taken into account so as to provide new clues to blind ore prospecting.     

Rare—Earth Elements and Genesis of Lamprophyres in the Laowangzhai Gold Orefield,Yunnan Province

The Laowangzhai super-large gold orefield,which is situated in northern Mt.Ailao tectonic zone,Yunnan Province,is a typical gold orefield where lamprophyres are temporally and spatially related to gold mineralization.Major element data show that lamprophyres in the orefield are of alkalic series and can be divided into potassic and K-rich calc-alkaline lamprophyres.The rocks are enriched in rare-earth elements as compared with the primary mantle and mid-ocean ridge basalts(MORB).Modelled calculations by the least squares method of Petrological Mixing show that the mantle-source for the lamprophyres in enriched in rarc earth elemeots.The geotectonic development of western Yunnan,Sr and Nd isotopic compositions,incompatible element patterns and linear programing calculations indicate that the fluids were derived from dehydration of submaine sediments which are enriched in ALK,LREE and incompatible elements and then were carried to mantle wedges as a result of plate subduction.That is the main factor leading to the formation of a metasonatic fertile mantle in the area studied.     

Estimation on organic carbon content of source rocks by logging evaluation method as exemplified by those of the 4th and 3rd members of the Shahejie Formation in western sag of the Liaohe Oilfield

One of the most important tasks of evaluating natural resources of petroliferous basins is to determine the organic matter abundance of source rocks in the basin.The usual method for assessing the organic carbon content of source rocks is based on laboratory analyses.There is a deviation in calculating organic carbon content due to the heterogeneous distribution of organic matter and the artificial factors when sampling.According to the continuous characteristics of information logging,the conventional logging curves(mainly acoustics and resistivity,etc.) were calibrated with the organic carbon experimental data of cores,cuttings or sidewall cores.The organic carbon content of source rocks of the 4 th(Es 4) and 3 rd(Es 3) members of the Shahejie Formation in western sag in the Liaohe depression was estimated directly by a great amount of continuous data including resistivity and acoustic logging,etc.Comparison between the results from computer processing and lab analysis of logging data shows that the organic carbon contents derived from the computer processing of logging data have the same reliability and accuracy as the lab analysis results.The present data show that this method is suitable to evaluate the source rocks of western sag in the Liaohe depression and has great potential in evaluating natural resources of sedimentary basins in the future.On the basis of logging data of source rocks,experimental data and existing geochemical analyses of the Liaohe Oilfield,the corresponding total organic carbon(TOC) isograms of source rocks were plotted.The source rocks of Es 4 and Es 3 of the Shahejie Formation are thought to be beneficial to hydrocarbon accumulation due to the high TOC.     

天然水中氘的测定方法及某些天然水样和矿物包裹体水的δD测定结果

A method for preparing hydrogen gas in the determination of stable isotope composition of hydrogen in natural water using metal uranium as a reducing agent is described. The isotope fractionation daring the experimental process is discussed in detail The data on δD from some mineral deposits in China are presented as well.