In order to find concealed iron deposits in western Beishan of Gansu Province, the authors studied in detail 1:50 000 aeromagnetic data of the Gubaoquan iron ore district, performed 1:5 000 surface magnetic survey at the key area based on anomalies delineated by aeromagnetic survey, divided the anomalous area into two anomaly zones, delineated C1-C8 geomagnetic anomalies, and then made deduction, interpretation and engineering verification for these eight anomalies, which led to the discovery of the Gubaoquan iron deposit. Based on an analysis of the corresponding relationships between aeromagnetic anomalies, geomagnetic anomalies and ore bodies, the authors hold that there are still some aeromagnetic anomalies in the outskirt of the ore district which deserve further work.

The prospecting target of the polymetallic ore deposit in Errenshan-Huangshipogou area was delineated based on geological characteristics of the gold and silver polymetallic ore belt in combination with enrichment, assemblages, zoning of anomaliesy of the mineralized sediments, and electrical characteristics of ores and rocks. Using the EH4 conductivity imaging system, the authors detected the vertical extension and the attitude of the ore-bearing fractured zone, thus obtaining fairly satisfactory ore prospecting results.

In this study,the authors tried to carry out metallic active state prospecting test of the Chengmenshan copper polymetallic deposit along the lower Yangtze reaches metallogenic belt. The results show that, in the Chengmenshan ore district within the humid mountain landscape, Au mainly exists as organic Au, and Cu exists as organic Cu and Fe-Mn oxides. Above the ore body,the rate of active state reachs more than 30%, which can fairly effectively reflect deep mineralization information. This method can locate the concealed deposit. Organic Au and Cu can well reflect latent mineralization information. The Lianmeng silver-gold mineralization spot was found by using this method in southern Chengmenshan in the subsequent soil survey.

Based on such characteristics of the contact metasomatic skarn copper deposit as strata, intrusive bodies, ore-control structure, alteration zones and mineral geology and geochemistry, in combination with element associations, primary anomalies and zoning regularity of element anomalies, the authors have summed up three kinds of geochemical exploration criteria for the skarn deposit, i.e., rock body evaluation, erudition degree and concealed ore prognosis, which provide scientific basis for the exploration of this kind of ore deposits.

The Baguamiao gold deposit is the largest gold deposit in Shaanxi Province. The geochemical anomalies played a key role in the discovery and preliminary exploration of this ore deposit, and gave important clues to finding gold ore body. This paper deals with the characteristics and roles of geochemical anomalies in the exploration of the Baguamiao gold deposit for the purpose of providing references for future prospecting.

Based on a comprehensive study of the geotectonic background reflected by the aeromagnetic data, this paper made a prediction of the ore-search prospect along the Qinghai-Tibet railway. According to geological background of mineralization, tectonic-magmatic-hydrothermal environment and characteristics of magnetic anomalies, combined with the tectonic position, the authors divided the area into 7 metallogenic belts, and delineated 125 prospective areas of iron, copper, lead, zinc, gold, silver, chromite and polymetallic resources, in which 49 belong to first grade areas.

Qiongdongnan basin fault zone is one of the marker faults for fault partition and one of the central depression downthrown fault zones. Regional studies show that the central depression has a good hydrocarbon potential, so the area has been considered to be a favorable oil and gas exploration area. However, due to the formation of large sets of deposited shale resulting from drastic changes and rapid progress of water depth and slope, it is difficult to determine the velocity in this area, so the velocity problem constrains the exploration of the slope break in Qiongdongnan basin and becomes a difficult problem. In this study, the authors first analyzed the quality of the speed spectra available so as to understand the overall variation trend of the velocity, followed by considering the velocity obtained by drilling results; in combination with stratigraphic variation information, the velocity interpretation was carried out, and the energy in the center was used to explain the standards of velocity interpretation. Finally, on the basis of careful velocity interpretation, the forward model of two-dimensional velocity profile analysis confirmed the existence of a target structure.

Density and seismic wave velocity of volcanic rock generally higher than the sedimentary rock at same depth,it possesses more obvious density and velocity differences with surrounding rock.Interface shape and occurrence between volcanic rocks and surrounding rock are complex,resulting in seismic wave imaging difficulties.The authors discuss the seismic technology suitable for prospecting deep metal mine under volcanic cover combing with seismic exploration in Lishui volcanic basin.It helps to obtain the reflected wave formed by volcanic rock internal and its underlying strata interface using acquisition pattern of small group interval,long spread,high fold,shooting at volcanic rock top interface or internal volcanic rocks.

A high-order rotated staggered grid scheme (RSG) has been implemented to simulate the shear-wave splitting in tilted transversely isotropic (TTI) media. The high-order RSG can simulate wave propagation in media that contain high-contrast discontinuities like cracks more precisely than the standard staggered grid scheme (SSG) by avoiding the unstableness of the staggered grid scheme (SSG). The authors conducted a study of zero-offset S-wave splitting with the high-order RSG. The S-wave splitting study was mainly focused on fractured media which, on the scale of seismic wavelength, could be regarded as transversely isotropic (TI) media. The results of numerical modeling show that the high-order RSG scheme can be used to simulate waves' propagation in general anisotropic media. The perfect matched layer (PML) absorbing boundary condition combined with the high order RSG scheme can well attenuate reflections from the artificial boundary. The S-wave splitting is mainly affected by the angle between polarization direction of incoming wave and strike of the TTI media, and the energy of fast and slow shear waves is also associated with this angle. The dipping angle of TTI media may affect time lag between the fast and slow waves, which may result in variation of arrival time of waves from the same interface. Thus, the analysis of energy distribution of the fast and slow waves and the variation of arrival time may help detect the strike and dipping angle of the fracture. Besides, when propagating in the media that contain more than one layer of TTI media, the S-wave splitting will occur more than once.

Single lithology or property parameters can not satisfy the need of complicated oil and gas reservoirs. Based on a study of statistics of logging rock physics parameters, the authors found several sensitive parameters which are linked intimately with oil and gas characteristics. Based on pre-stack seismic elastic parameters inversion results, the authors explored the fluid detection method by a borehole-seismic comprehensive technique. Practices show that the results obtained by the authors obviously improve the multi-solution problem of post-stacked inversion, and can achieve good applied effect in the oilfield.

A method for the determination of antimony (Ⅲ) and antimony (Ⅴ) in geological samples (stream sediments) by hydride generation-atomic fluorescence spectrometry was developed in the paper. 4.8 mol/L HCl could be used as the extractant with ultrasonic-assisted extraction. In the medium of 0.24 mol/L hydrochloric acid, antimony (Ⅲ) could be alternatively determined with 6 g/mL sodium citrate as the masking agent for Sb (V). Then antimony (Ⅴ) could be figured out by the subtraction method. The detection limit of the method was 0.075×10^-6 for Sb (Ⅲ) and 0.097×10^-6 for Sb (Ⅴ), and the relative standard deviation was 1.1% and 0.64% (n＝11) for 40 ng/mL Sb (Ⅲ) and 40 ng/mL Sb(Ⅴ) standard solution. The proposed method was applied to the determination of antimony (Ⅲ) and antimony (Ⅴ) in geological samples, and a comparison between the extraction results and the aqua regia dissolution results shows that the extraction rate of antimony was higher than 80%, the recoveries were in the ranges of 83%~107% and 98%~114% for Sb (Ⅲ) and Sb (V) respectively.

In view of the facts that the near-region terrain correction is very important for gravity survey and there exists no other better terrain correction method, this paper analyzed the labor, equipment, accuracy, and integrated efficiency of four methods, i.e., visual estimation, laser range finder, forest compass and RTK, and then summarized the advantages and disadvantages of these four methods. The results of this experimental study provide a better application and demonstration effect for the near-region terrain correction.

The induced polarization sounding curve inversion is based on the resistivity inversion, using the equivalent resistivity. There are three methods for induced polarization inversion, i.e., linear inversion, formalism inversion and non-linear inversion. Through calculation and analysis by means of programming the horizontally layered model, the authors made a comparative study of the time-consuming conditions and effects of these three inversion methods. It is considered that the non-linear inversion method is the best inversion method in theory, whereas the linear inversion method can be satisfactorily used in actual production.

In the survey of the airborne gravity system, high frequency vibration caused by aircraft engine and airborne environment affects the precision of airborne gravity system measurement seriously, and this problem could be solved by the method of vibration reduction system. Therefore, the suppression effect of vibration reduction system and its modal parameters (natural frequency, damping ratio and model shape) constitute the very important basis of the structural design and evaluation of the vibration reduction system. Aimed at solving the problems existent in the airborne gravity vibration reduction system, the authors made several vibration tests, and the result shows that the natural frequency can avoid the periodic vibration frequency of aircraft engine. In the frequency band of 100—500 Hz, the vibration transmissibility for the measuring point 1 is from -18 to -38 dB, and the vibration reduction effect is quite obvious.

In order to improve the management of magnetic prospecting, ensure the quality of field work and adapt the management to the development of science and technology, especially to the improvement and enhancement of magnetic instruments, it is necessary to make timely revision of the relevant technical regulations or operational standards, which should agree with the actual conditions. It means that the regulations should be clearly determined and easily executed by subordinate production units. This paper discusses the safety separation distance between probes during the noise testing of magnetometers before the operation mentioned in "Technical Regulations of High Precision Grounded Magnetic Measurement" based on certain detailed field experiments. In combination with related technical regulations and the requirements of the textbooks as well as special test results, the authors propose some suggestions for revising the above regulations after the comparison and analysis of the results.

Induction type magnetic sensor is being used effectively in electromagnetic prospecting and earthquake prediction, which is very important for the investigation of earthquake precursors. In this paper, a new means of frequency compensation is discussed for inductive magnetic sensor in the electromagnetic disturbance instrument. This paper deals with its equivalent circuit, compensating circuit, main technical specifications and performance test method. This sensor can be used to detect a natural electromagnetic disturbance with the variation ranging from 0.1 to 10 Hz electromagnetic disturbance.

The theory of Hilbert-Huang transform is described in this paper. Exemplified by the measured GPR profile of the tunnel leading to the factory of the Heijunfeng Pumping Energy Storage Power Station, the authors applied the EMD method to eliminate partial noises, used the Hilbert-Huang transform to calculate the complex signal of GPR profile, and extracted three parameters, i.e., the instantaneous oscillation amplitude, the instantaneous phase and the instantaneous frequency. On such a basis, the mutually independent instantaneous parameters profiles could be drawn up. Multiple parameters integrated interpretation was conducted according to different geological conditions. The results show that this method can avoid the explanation error caused by using single time distance profile analysis, and can better reflect the anomaly information, thus improving the GPR data analysis precision.

Multiple wave interference is usually existent in the signals recorded by the ground penetrating radar receiving antenna with ultra-wide band. To eliminate the multiple wave interference and improve the signal-to-noise ratio, this paper puts forward ground penetrating radar signal processing based on waveform removal deconvolution, describes its basic principles and implementation method, and analyzes its application range and conditions. To testify this method, the authors carried out a model test, in which PVC pipes 100 mm in diameter were used as calibration models and were embedded in sand. The results show that the multiple interference and random disturbance to the radar signals are apparently suppressed after disposal, the image becomes "clear", and the quality of image is obviously improved.

The elastic parameters inverted from PP-wave data couldn't reflect the variation of the lithology and the fluid in pore adequately,which results in large uncertainty in the interpretation of oil reservoir.If the information of PS-wave data is added as the constraint,the interpretation ambiguity could be reduced effectively and the stability of inversion could be improved considerably.The method of the joint inversion presented in this paper uses the theory of GLI(generalized linear inversion) to invert P-wave velocity,S-wave velocity and density iteratively based on the exact Zoeppritz equation.And the precision of S-wave velocity inverted from the joint inversion is improved largely compared with that of inversion by only using PP-wave data.

In the oil field development stage,water or gas injection mining will change reservoir properties and the fluid inside the reservoir,which may provide a possiblity for time-lapse seismic monitoring.Mainly based on Gassmann equation,the authors discussed in detail the variation regularity of seismic velocity and density when the reservoir pore fluid is replaced,and established a seismic geological model for water saturation variation according to the forecast result.Through analyzing and optimizing the amplitude attributes extracted from the model,the sensitive time-lapse seismic attributes suitable for this area was finally found.The result provides a basis for predicting the distribution of remaining oil.

This paper proposes PML absorbing boundary based on Cerjan attenuation function based on the study of Cerjan absorbing boundary and PML absorbing boundary.Wave field modeling calculations by using two absorbing boundary conditions show that PML absorbing boundary based on Cerjan attenuation function can perform absorption much more clearly and absorb the boundary reflection from various angles.Besides,its operation is easy,the calculation time is short, and it is suitable to seismic wave numerical modeling in two-dimensional situation.

It is more difficult to predict the low porosity and low permeability tight reservoir than to predict the regular reservoir.The authors therefore tentatively applied kernel principal component analysis and support vector machine,called KPCA-SVM model,to solve this problem.Through the polynomial kernel function of the KPCA,the model can obtain the nonlinear feature extraction.Then the Gaussian kernel function in the SVM is chosen to perform optimization again.Finally,reservoir identification is implemented in the SVM.As the model incorporates the advantages of kernel function,principal component analysis and support vector classification,it can better solve the problem of nonlinear small sample,eliminate the noise of the data and reduce the dimension without missing valid information.In addition,it can achieve the prediction function quickly and accurately.The model was employed to predict the reservoir in x856 well block,which belongs to Xu2 member gas reservoir of the Xinchang gas field.The prediction results show the superiority of this model,which can be used as an optional method in tight reservoir prediction.

Coal transient electromagnetic exploration is often conducted around a coal mine where man-made interference is stronger and noise in a secondary induction field signal-level is mostly rather high, and hence it is difficult to carry out the work of processing and interpretation. In order to eliminate the electromagnetic interference in data, the authors used the average and variance statistics of slope as mechanisms of interference discrimination according to the morphological characteristics of the decay curve and by refering to the properties of neighboring measuring points without suffering from interference, quickly and easily suppressed the interference and restored the original signal satisfactorily. The theoretical data and measured data obtained by this method were used to make processing and interpretation, which proved the effectiveness of this method. This method was used in the detection of the mined-out area of the coal mine, the anomaly interpretation through curve inversion after interference suppression was highly consistent with the data available, and hence the result in agreement with the reality was obtained.

At home and abroad,during the process of the channel tunnel construction, TSP has been used to detect small structures such as fault, collapse column.Because the fault plane and collapse column interface is undulating, the received energy of the reflected wave is weak, therefore it is difficult to image ahead of the tunnel. The scattered topography method based on Huygens-Fresnel principle can take full advantage of the information of the full wave field seismic signals. Scattered wave offers a new image method for TSP due to the good migration effect. In this particle, Building exploring tunnel model to study the effect of scattered topography, and prove the feasibility of the scattered topography used in the TSP.

The distribution and modes of occurrence of Cu, Pb, Zn, Cd and Hg in the soil and their content in the water were analyzed in this paper. It is found that the soil and water of the study area have been heavily polluted by Cu, Pb, Zn, Cd, Hg and other heavy metals. According to the National Environmental Quality Standards for Soil, no places in Baiyin has attained grade Ⅰ of quality of Cd in surface soil, while places of grade Ⅲ,Ⅳ account for 82.39% of the study area, so Cd pollution is very serious. The percentages of grade Ⅲ and above grade Ⅲ of quality of Hg, Pb, Zn and Cu account for 7.35%, 5.59%, 14.67% and 5.71% respectively. A comparison of the average content of heavy metal elements between 2000 and 2007 in Baiyin City reveals that the growth rate of Cu, Pb, Zn, Cd, Hg contamination was significantly and gradually growing. An investigation was made on the sources of Cu, Pb, Zn, Cd and Hg, which shows that the major sources of pollution are non-ferrous metal smelting, processing and heavy chemical industry, followed by coal, garbage and car exhaust emissions.

In view of the special site conditions of the Mengshan mined-out area in Taiyuan City, i.e., the considerable terrain fluctuation and the need of curved line measurement, the authors propose the integrated geophysical methods that combine the array-form measurement of high-density resistivity method with the single-point measurement of Transient Electomagnetic Method (TEM).The former has relatively high resolution for two-dimensional anomaly inversion, which can remedy the shallow survey blind area of the transient electromagnetic method, whereas the latter has the advantage of detecting greater depth and, by adopting the one-dimensional inversion method,it can make up for the defects of the high-density resistivity method caused by the spread of the section broken line and terrain fluctuation, thus realizing the complementary advantages of the two kinds of geophysical methods. With the integrated geophysical methods, the location and the distribution of the mined-out area are detected, and later drilling verified that the integrated geophysical methods are effective. The combination pattern of integrated geophysical methods provides a meaningful reference for detecting other mined-out areas with similar conditions.

As a new numerical computational method based on the principle of variation, the meshfree method has maintained a rapid development in recently years. It has been widely used to study the problem of mechanics and electromagnetics because of avoiding the onerous mesh generation. In this paper, two-dimensional magnetotelluric response was calculated by the meshfree method. The basis of the meshfree method was explicitly described and the particular meshless calculating formulas were deduced through the generalized variational principle. The program is verified by comparison with the analytic response of a symmetrical ladders model and with the finite difference results of laterally inhomogeneous model.

The key problem that airborne gravimetry has to solve is how to separate the disturbing accelerations generated by aviation from the total acceleration observed by gravimeter. The GPS technology is one of the methods to solve the problem. With it, we can get the position, velocity, acceleration and any other parameters of the aircraft carrier with high accuracy which can be used to make the necessary correction of the total acceleration. The authors have developed the GPS post-processing software system for airborne gravimetry, which is called EGPS, on the basis of the concept of software architecture. The software is the integration of different functional components according to certain interactive mode. EGPS uses the method of pseudo-range difference to get the position, and employs the method of Doppler frequency shift to get the velocity of the aircraft carrier with high accuracy. This paper presents the processing results of actual airborne gravimetry GPS data using EGPS. The data support a conclusion that EGPS has basically met the requirement of airborne gravimetry for GPS post-processing.

The definition and calculation of the apparent resistivity are not the same because of the difference of excitation field sources, working devices and working environments. The calculation methods for apparent resistivity in early-time, late-time and all-time with varying magnetic sources of TEM and different working devices were summarized and reviewed in this paper, and the whole-space apparent resistivity in tunnel and mine TEM in consideration with the turn off time were discussed. Some conclusions and suggestions were proposed based on an analysis of apparent resistivity combined with the development and application of TEM.

A multi-profile dynamic geogas survey was employed in search for a new favorable ore-prospecting target in an integrated exploration area of a certain lead-zinc mine in western Yunnan Province. The assemblage characteristics and REE patterns of geogas anomalies above the known ore body and unknown area were extracted and compared with each other. In combination with the high-power induced polarization data from previous work and according to a comprehensive analysis and study of new geogas anomalies, a new valuable ore-prospecting target site in western exploration area was delineated in the end.

A study of the geogas field was carried out in Huangshaping of Hunan Province and Dachang of Guangxi, two areas with typical significance in Nanling ore concentration area. The aim is to find the relationship between the geogas field and the ore body. Through a systematic analysis, the characteristics of ore-induced geogas anomalies were studied. The results show that the statistics of component proportions in the geogas anomaly can be used to judge the components of the concealed ore body and, what is more, some information about surrounding rocks and magmatic activities can be extracted according to the element association of the geogas anomaly.

A series of geogas models were built to study the element transportation regularity in the lead-zinc ore and its surrounding rocks under the action of ascending gas flows. The amount of elements transferred out of the simulated ore and rock layer were determined by ICP-MS. Then, the transportation rates of various elements were estimated. The experimental results indicate that the elements transferred out of the ore and rock layer can continually accumulate in the above catcher under the action of ascending gas flows. The transportation rates of elements are different from each other, varying in the range of 0.006~4 000 ng/d. A large concentrations of ore-forming elements in the ore body would inevitably result in high rates of transportation, forming geogas anomalies above the ore body. The result obtained by the authors provides a theoretical basis for the prospecting of concealed deposits with geogas anomaly.

In Changpai uranium exploration area of Guangdong Province, the authors obtained content data of more than ten kinds of elements in soils, such as Cu, Pb, Zn, As and Sr, by means of X-ray fluorescence rapid measurement of the soil samples. According to the resultant diagram based on the measurement results, the indicative function of these elements for the concealed granite-type uranium deposit is discussed is this paper. The results show that the anomaly of the concealed granite-type uranium deposit can be found by using the portable X fluorescence spectrometer for soil sample survey.

In order to automatically control the gas flow in dynamic geogas sampling and monitor the environmental parameters of the samping points,a intelligent dynamic geogas sampling device based on STM32F103RBT6 Micro-controller is designed so as to make effective control and scientific evaluation to the quality of the samples.It can extract geogas in field work at a accurate pumping velocity according to the given flow value, measure the parameters of temperature and humidity at the sampling site and draw up the dynamic flow curve,what's more,storage the flow curve and the parameters of temperature and humidity to SD card.

In view of the uranium prospecting characteristics in Changpai uranium exploration area of Guangdong Province, such as low ore grade, small ore body, and great depth, the authors employed improved dynamic geogas survey. During sampling, a couple of capturing agents were serially connected. On the basis of the premise of stationary sampling time, the sampling quantity of geogas was improved by approximately 50%. Before ICP-MS analysis, all geogas samples were concentrated from 40 mL to 5 mL, which improved the element concentrations in samples by 3~11 times. On the basis of this improvement, the elements with lower concentrations in geogas could be easily detected, and the analycial error was reduced effectively. The experimental results show that the improved measures can result in higher detection sensitivity of dynamic geogas survey and can further improve the prospecting effect of geogas survey.

With No. 95 zinc-opper ore body over 800 m in depth in the Dachang zinc-copper deposit of Guangxi as the research object, the authors carried out experiment on geogas survey by using dynamic geogas sampling device and ICP-MS analysis technology for exploration of large depth concealed polymetallic deposit. The results show that the geogas anomaly values of Zn, Cu elements above the ore body are 3 times higher than their background values, and Pb, As, Cd, Bi, Co, Cs, Mo, Rb and other elements also show significant anomalies. These data prove that using geogas survey to explore the large depth concealed ore bodies whose depth exceeds 800 m is completely feasible.

The experimental study of geogas was carried out in granite uranium exploration area of northern Guangdong. Through quickly sampling of No.4 and No.19 exploration line in exploration District, the authors acquired information from the 38 elements of U, Cu, Pb, Zn, Mn, Sr, REE, summarized exceptional characteristics through cluster analysis, pearson relativity, LREE partition, Eu exceptional judge and so on. The results show that geogas anomalies of U, Mn, Sr, Zn have different display above the ore body or border position. Anomalies of U have good correlation with Mn, Sr, Eu, Cu, Pb, Zn, Ho. Geogas anomaly area above the ore body have similar REE patterns and negative Eu anomalies. These characteristics can be used to judge mineralize geogas abnormal of concealed uranium.