Grounded-source transient electromagnetic method (TEM) has many advantages such as deep exploration, flexible arrangement in rough terrain and high working efficiency. Recently it has got much attention and a series of new methods are available, ranging from surface to airborne and borehole method. In this paper, the authors review the research history of long-offset TEM (LOTEM), short-offset TEM (SOTEM), multi-channel TEM(MTEM), grounded-source semi-airborne TEM and grounded-source surface to borehole TEM, and summarize their research status in forward modeling, system design, inversion, imaging and field working. The results show that, as a well-developed grounded-source TEM, LOTEM has accumulated many research achievements. Although some progress has been made, the researches on other grounded-source TEMs are still in a primary stage and still need further improvement. Valuable research results in LOTEM, for example, noise suppression technology, high dimensional inversion and point interpretation, can be introduced to these newly developed electromagnetic methods, which can help provide solutions for high working efficiency and high resolution deep exploration.

This paper has summed up the progress of the ERI method over the past decade of years as well as its future development trend in the following aspects: ① A comparison of the performances of the main ERI instruments used at present shows that the ERI instruments tend to develop in the multi-channel, multi-parameter, multi-functional, high-power direction; ② ERI measurement environment has changed from surface measurement to water surface, underwater and cross-hole measurements, with the last three kinds of measurements analyzed in this paper; ③ On the basis of analyzing ERI data processing method and inverse development status, this paper describes three-dimensional and four-dimensional inversion theory of ERI with practical examples; ④ ERT applications are summed up, and several new applications are introduced. It is concluded that, with the improvement of the probing depth and observation precision as well as the diversification of the observation models, the application field of ERI will become broader and broader, and this technique will surely have wide development prospect.

Studying the occurrence of natural gas hydrates (NGHs) is of profound significance for NGH exploration. The evaluation of the NGH saturation mainly relies on the Archie equation using the electrical parameters of rocks. The key to accurately calculating the NGH saturation is to select corresponding values of rock electrical parameters for different geological environments, especially the porosity index (m) and the saturation index (n). However, it is still a challenge to select the optimal m and n values for NGH evaluation in resistivity logging. To ascertain the relevant resistivity regularity of NGHs and the determination method of rock electrical parameter values in the Archie equation, this study systematically reviewed relevant references and summarized the resistivity influencing factors of NGHs. Moreover, this study analyzed the influencing factors for the accurate evaluation of the NGH saturation based on the Archie equation. Accordingly, this study generalized the resistivity characteristics of NGH-bearing sediments and proposed the application research direction of the Archie equation.

There is a lack of selection bases in the geochemical anomaly identification and the reconstruction of the geochemical background conforming to the metallogenic distribution using deep learning algorithms with different network structures. Given this, based on the 1∶200 000 stream sediment data of the copper-zinc-silver metallogenic area in southwestern Fujian Province, this study extracted the combined structural characteristics, spatial distribution characteristics, and mixed characteristics of multiple elements in the samples using three unsupervised deep learning models, i.e., AE, MCAE, and FCAE. Then, these characteristics were used to reconstruct the geochemical background and simulate the metallogenic distribution. The results show that the anomaly areas delineated by the FCAE model were the most consistent with the known copper ore occurrences, followed by the MCAE and AE models. The FCAE, MCAE, and AE models had an area under the curve (AUC) score of 0.80, 0.78, and 0.61, respectively. Moreover, the FCAE and AE models were not sensitive to the change in the convolution window size. These results indicate that when deep learning algorithms are constructed for geochemical anomaly identification, the algorithms based on the extraction of spatial distribution characteristics or mixed characteristics perform well, and those based on the extraction of combined structural characteristics or mixed characteristics have a strong anti-interference ability for the noise caused by the change or inconsistency of the spatial observation scale. This study provides some effective selection bases for constructing geochemical anomaly identification models based on deep learning algorithms.

Based on a brief description of the basic principle of the Acoustic Doppler Current Profiler (ADCP) and exemplified by some typical environmental monitoring engineering cases, this paper gives a brief account of the achievements made by this technique in such engineering fields of Hong Kong as marine environmental quality monitoring and marine engineering environmental evaluation. The practical engineering application shows that the adoption of ADCP technique could yield satisfactory environmental monitoring result. The importance and effectiveness of applying this technique to environmental quality monitoring is also explained.

The airborne geophysical exploration flying vessel which performs operation in middle and high mountain areas needs plateau adaptability.Through a comparative study of the characteristics of AS350B3 helicopter in such aspects as its taking off condition,maximum flying altitude,maximum endurance and plateau flexibility,the authors put forward the type-choosing principle and flying method of the airborne geophysical exploration flying vessel for low altitude and large scale survey.The practical surveying flying in a certain surveying area of Gansu Province has proved the feasibility of the principle and method put forward by the authors.Analysis shows that AS350B3 helicopter can meet the requirement of airborne geophysical exploration in such areas.

Due to historical reasons, the present coordinate systems of the geological, geophysical and geochemical exploration results are basically WGS84, BJ54 or XA80 systems; nevertheless, according to the NASG requirements on the overall use of CGCS2000 coordinates, in the future the coordinates for all kinds of results should be CGCS2000 coordinates, which causes inconvenient situation in using the results and in comprehensive research work. As a professional geographic information system software, ArcGIS has a wide range of applications in various walks. In this paper, the authors briefly introduced the ArcGIS built-in coordinate system, studied and deduced the calculation formula of the MOLODENSKY coordinate conversion method in ArcGIS, put forward the method to get the conversion and precision evaluation of transformation parameters between different ellipsoids, and cited practical examples for verification. On such a basis, the specific ideas and points for attention were analyzed for each coordinate system in the conversion of ArcGIS software to CGCS2000.

In the light of the pulse width of the radar wave, this paper deals with the difference and the relationship between the vertical resolution and the transverse resolution of the ground-penetrating radar, indicates the influence of the noise upon the resolution and, with practical examples, points out that the digital handling of the signal can greatly improve the resolution of the radar.

This paper analyzed the twin-T notch filter circuit, deduced the expressions of transfer function, center frequency, bandwidth and Q value. Through calculation, analysis and simulation, the optimal resistance and capacitance were selected for the characteristics of wide field electromagnetic signal and the suppression requirements of frequency interference. Experiments show that the optimal design of twin-T notch filter's minimum depth of suppression is -31.9 dB when the bandwidth is only 3.62, so the application of the optimal design of twin-T notch filter can not only keep the desired signal, but also maximally filter out frequency and its harmonic interference noise in the wide field electromagnetometer.

Fluorescence spectrometry is commonly used to determine polycyclic aromatic hydrocarbon and evaluate the migration of oil and gas as well as the properties of base oil. Lying in western China , Xinjiang is almost covered with snow in winter. According to the geographical climatic environment in combination with the low detection limit and high sensitivity of fluorescence spectrometry, the authors analyzed the snow and the soil below it along a profile in a known oilfield in Xinjiang by means of fluorescence spectrometry. The results of two-dimensional fluorescence spectra, constant-wavelength synchronous fluorescence spectra and three-dimensional fluorescence spectra are compared with each other and discussed in detail. The comparison results shows that snow can quite effectively adsorb the polycyclic aromatic hydrocarbon and have an abnormal indication for the oil and gas reservoir. These findings can provide some reference for the exploration of oil and gas reservoirs in unknown geographical climatic environment areas in the future.

Investigation and evaluation of the natural radiation level of Qingdao City were conducted by Qingdao Institute of Marine Geology from 2003 to 2005. The radioactive level of Qingdao City remains within the safe range of the natural background level, although the average dosage rate of the terrestrial γ-radiation is slightly higher than that of the National and Shandong Province Standard. The level of the terrestrial γ-radiation seems on the whole controlled by the local rocks. The terrestrial γ-radiation results from ²³²Th, ²³⁵U and ⁴⁰K, while ⁴⁰K or/and ²³²Th contribute more to the terrestrial γ-radiation than ²³⁸U, which is different from things of the other areas. In addition, the amounts of radionuclide contained in such materials as masonry, cement and concrete used for many construction projects like roads and architecture affect the level of terrestrial γ-radiation of the construction projects.

Based on full collection, arrangement and integrated study of information from 11 globe geoscience transects (called GGT for short) and tens of other geophysical profiles (seismic profiles, geothermal flux profiles and magnetotelluric sounding profiles) in the Chinese continent as well as shear wave three-dimensional velocity structural data that cover the Chinese continent and neighboring regions, the present paper has described crustal structure, lithospheric structure and rheospheric structure in the Chinese continent and neighboring regiona, and made a brief discussion on the prognosis of ore resources in the Chinese continent. The lithospheric structure of China was developed on the basis of rheosphere of three different sorts of natures and hence shows obvious inheritance. The lithospheric structure is to certain extent in accord with the geotectonic unit, suggesting that the crustal structure is influenced and restricted by the lithosphere. The crust and the upper mantle both exhibit low-velocity nature, and the vertical low-vvelocity zones of seismic waves seem to be the good environment for the formation of endogenic polymetallic ore belts.

Traditional sectional view algorithm lacks accurate processing capability for such phenomena as pinch off, absence, and lenses of strata. The accuracy of the algorithm can hardly meet production requirements. To solve these problems, this paper proposes an auto-matching algorithm for building geological sectional view by stratigraphic distribution pattern. First, the project drilling data structure is built; then, based on the distribution of strata, the patterns of strata are defined and the section line growth policies and rules of each model are deduced. From left to right, from top to bottom, the sequence stratum pattern matching method is used; according to the problem as to which section line the stratum point belongs to is determined; finally, the section line sets of points are connected into the line, thus finishing map annotation and map decoration. The algorithm overcomes the problem of poor continuity existent in the traditional drilling adjacent connection method caused by the lack of consistency disadvantage. Stratum pattern auto-matching method achieves automatic section line growth and can wipe out stratum pinch off, stratum absence, stratum lens phenomenon accurately. Experiments show that the geological profile constructed algorithm can accurately and efficiently reflect the stratigraphic structure of the study area, and hence it is widely used in engineering production.

This paper introduces a novel procedure for computing source waveforms, in which the direct derivation is not necessary, and the explicit expressions for these polynomials are also not required. The computation is performed recurrently via the product of a Hermite polynomial and the Gaussian. Numerical tests reveal that the computed wavelets can model source pulse more precisely.

Geological database has been widely used. In the whole geological database, geochemical database occupies an important position. Geochemical database can be classified into 6 types, namely, solid ore geochemical database, oil and gas geochemical database, isotope geochemical database, agro-ecological environmental geochemical database, geochemical analytical database and standard reference materials database. The present conditions, applications and development trends of geochemical database have been analyzed and discussed in this paper.

The high-resolution position data in the centimeter grade are extracted from the binary output records of the hand-held GPS position indicator, and the multiple average measurement and post-operation position difference correction method are used so as to decrease the planar locating error of the portable and cheap hand-held GPS position indicator from several meters to 1 m or so. Thus the precision of the sub-meter grade can be attained.

The present paper makes a brief description of the progress of several main electric methods which havebeen developed quite rspidly since 1980's.They include induced polarization method,frequency spectrum IPmethod,trandient electromagnetic method, controlled-source audio-frequency magnetotelluric method and GPR.

In this paper, recent advances in the research and development of quantum magnetometers have been described together with some suggestions on further research work.

This paper advances a new data processing technique-subregion median contrast filtrering method.It uses subregion to simulate spatial variation of the background, calculates critical values of anomalies with EDA technique, and measures the undulation of field values with the contrast as the datum. This technique fairly satisfactorily solves the problem of recognizing weak anomalies, and the preliminary application proves it to be effective.

Usually, city road consists of the surface layer and the subbase layer, and each layer contains several layers of different media with different relative dielectric constants. So using one relative dielectric constant to analyze the GPR data of all depths in city road detection is not accurate. This paper deduced the calculation formula of the equivalent dielectric constant of multi-layer underground media. Then the authors took two-layer media model and three-layer media model as examples to calculate the equivalent dielectric constant and the relation between the depth and the travel time. At last, theoretical modeling data of two-layer media were used to check the formula, and the results prove that the calculation formula of equivalent dielectric constant of multi-layer underground media is much better for practical GPR data analysis when there are multi-layer underground media.

The artificial source electromagnetic method is an important technique for deep resource exploration. The key challenge is to improve the depth and precision of detection through innovative technology. The detection mode of electromagnetic methods is evolving from far-field to near-field, and the study of near-source electromagnetic methods has become an international research frontier in recent years. Building on the recent advancements in wide-field electromagnetic methods and multi-channel transient electromagnetic methods, the short-offset transient electromagnetic method (SOTEM) has been further developed and proposed. The distinguishing features of SOTEM are its stronger signals and wider bandwidth, which are advantageous for achieving the detection requirements of greater depth and higher precision. This special issue presents eight articles covering the methods, techniques, software, and applications of SOTEM, providing strong support for the growing need for high-resolution subsurface detection.

Porphyry copper deposit is the most important copper deposit type in China. With the deepening of mineral exploitation, exploration geochemistry in mineral exploration has become increasingly important. Based on related literature, this paper sums up the exploration geochemical research results of porphyry copper deposits, which include such aspects as geochemical characteristics, exploration methods, anomaly evaluation and prospecting indicators. Exemplified by the Fujiawu copper deposit, this paper reports the latest advances in the study of porphyry copper deposits.

Starting with algorithm designing, training image,and practical application,the authors analyzed multiple-point statistics research trends both in China and abroad.On such a basis,the core principles of the main four MPS algorithms,their applicable ranges and advantages as well as disadvantages were analyzed,so as to forecast the trend of reservoir modeling.Multiple-point geostatistics is an international forefront research tool in stochastic modeling;nevertheless,as the algorithm is not yet mature,it should be further improved.On the basis of previous researches,the existing problems of the multiple-point geostatistics that need to be modified and the direction of the processing of training images are proposed,such as suitable processing of training image,choice of similarity methods,choice of standardized data,smoothing,coupling among algorithms,and expansion of the simulation extent for fractured-vuggy carbonate reservoir.In order to improve the usage of multiple-point geostatistics for reservoir stochastic modeling,we should spare no efforts to increase the simulation area,improve simulation accuracy,expand the scope of simulation of reservoir types,save simulation time and improve simulation efficiency.

The theoretical bases of oil and gas geochemical prospecting techniques are still very weak, and hence the prospecting techniques resting on these bases cannot be mature. If we want to study, develop and consummate the theory and methods of oil and gas geochemical prospecting techniques, our attitude towards the theory, the methods, the present situation, the existing problem and the new problems encountered in the development of oil and gas geochemical prospecting techniques must be practical, realistic and scientific. And we must have a clear and definite train of thought and scratch where it itches. Only in this way can our goal be attained.

The calculation error in far-sector topographic correction of regional gravity data originates mainly from the errors of approximation of digital to natural terrain and the interpolation errors of random grid, and, to a lesser extend, from the errors in position. The reading error and the altitude error, however, can almost be neglected. Adiscussion on ail these errors is given in this paper with special reference to the area of Qinling Mountains.

This paper introduces a method for studying the effect based on high-order statistics of GPR data. The basic idea of this method is the utilization of high-order statistical parameters in signal recognition and detection for processing and reconstruction of different models for GPR records. The model test shows that there are different high-order statistical features in different models, and the high-order statistics show obvious effect on suppressing background noise and multiple reflection of GPR data.

Through investigation and sampling Carya cathayensis kernels and soil of plantations, the heavy metals, Se, organic matter and other indicators in soil were analyzed, and the pollution degrees of heavy metals in soil were evaluated with risk screening values as the criteria. The content of heavy metals, Se, Ge and other trace components in kernels was analyzed, and the relationship between soil and kernels was discussed. The results show that the average values of Cu, Pb, Zn, Ni, Cr, Cd, As, Hg and Se in the soil of Carya cathayensis plantations are higher than those of the average soil of China, especially Cd is 5.6 times that of the average soil of China. Local soil Cd and As in the study area have reached the pollution level while the ecological risk of other heavy metals is slight. Carya cathayensis kernels have low Cd, Hg, Pb, As and other heavy metals content, no excessive heavy metal elements, low ecological risk, and high zinc content, with the potential to develop zinc-rich health food. Carya cathayensis has a significant difference in the absorption capacity of different heavy metals. The absorption capacity of zinc and copper is much greater than that of Cd, Cr and Hg.

The North America gravity database as well as database from Canada, Mexico and the United States are being revised, and the revision includes the following two items: the use of the internationally accepted terrestrial ellipsoid for the height datum of gravity stations rather than the conventionally used geoid or sea level, and the modification of procedures for calculating gravity anomalies, including corrections for theoretical gravity, atmospheric effect, height effect, Bouguer effect, indirect effect, terrain and bathymetry effect, and isostatic compensation effect.

The underwater magnetotelluric method is a technique performed on the water surface with the utilization of distant reference. Combined with the authors' practical experience, the present paper has described the working method of underwater magnetotelluric sounding technique (MT method) used in such waters as lakes and swamps as well as the measures taken for obtaining high-quality sounding data, and summed up some experience and understanding acquired in the work. All this provides basis for carrying out MT work in large area of waters.

A soil gas radon survey was performed on a large scale to determine the distribution of radon in soil of Zhuhai City in Guangdong Province by means of a portable radon monitor of a semiconductor alpha spectroscopy. The survey sampled 469 sites covering an area of more than 100 km². The average of soil radon concentration in the soil depth of 0.6 m is 55.94 ± 58.54 kBq/m³ in Zhuhai urban area, whereas the concentration is 7.14±8.75, 37.64±25.92, and 151.25±196.23 kBq/m³ in the Quaternary sediments, the mixtures of sediments and weathered grain of granite, and the weathered granite in Doumen District, respectively. The high radon potential areas are located within biotitic granites and new industrial districts, as indicated by the strong correlation between the radioactivity level and geological lithology. The mean value of soil gas radon concentration in Zhuhai urban area (ZUA) is about ten times as high as that in Guangzhou, Quanzhou and Jinjing City. The results show that Zhuhai area has higher radon potential, and hence protective measures against radon should be taken into account.

The base terrace of the Qingjiang red bed basin in central Jiangxi was studied to detect stratigraphic structure and aquifer characteristics by such means as integrated application of composite profiling, induced polarization and resistivity sounding. The optimum well site and the reasonable well completion technology were chosen and, as a result, a well was drilled which could produce more than 5 000 T/d. Pumping tests show that both the quality and the quantity of the water meet the requirements. Hydrogeophysical exploration indicates that the integrated application of the electrical methods in search for water is very effective in the study area.

An analysis of the relationship between the elements in the earth's crust and the life elements and a study of the pathogenesis of some typical endemic diseases have revealed that unbalance of trace elements in geochemical environments is likely to result in human diseases. The factors affecting the balance of trace elements in human bodies are geochemical environments and nutrition components. The authors hold that the important measures that can guarantee the balance of trace elements in human bodies lie in the optimization and utilization of geochemical environments and the balance of bioavailable trace elements from the nutrition.

Airborne gravimetry surveying is a geophysical survey method with the aircraft as a carrier. It can rapidly and efficiently extract middle and high frequency earth’s gravity field information in large areas. The commercialization of aeronautical gravity measurement technology is due to the maturity of dynamic differential GNSS positioning technology, which greatly improves the accuracy of dynamic velocity measurement and acceleration calculation of the carrier. And the accuracy of carrier dynamic positioning using the differential GNSS positioning technology depends on the accuracy of the ground reference station coordinates. In the actual work, through the establishment of GNSS control network to calculate the ground GNSS base station coordinates on the synchronization observation of national GPS geodetic control network, it not only spends much time and needs much cost but also has many difficulties in establishing the ground GNSS base station in the rare swamp, plateau, desert, unmanned areas and distant mainland’s island reef areas. With the construction of CORS station in China, the precision and the net dimension have been continuously improved. By using the data of CORS station, the method for determining the coordinates of the ground GNSS base station is employed by GAMIT, which has become a new trend. With the actual data of a survey area as an example, the authors conducted check and analysis of the base station coordinate accuracy and the measured gravity anomaly of the two methods, and readers can understand the application effect of the CORS system in the ground GNSS base station calculation in airborne gravimetry. It shows that the CORS system can not only meet the accuracy requirements of airborne gravimetry, but also improve the work efficiency.

The factors affecting the accuracy of bathymetric survey was analyzed in this paper. The errors in bathymetric survey mainly include instrument error, velocity error, tidal observation error, ship speed error and vessel factors. Based on a comprehensive analysis of causes of the measurement errors, this paper puts forward measures to improve the measurement precision, gives examples and points out maters needing attention in application.

This paper has summed up the development and new application of ground-searching radar in recent years. Based on detailed analysis of the principle and system structure of ground-searching radar, the authors put forward the train of thought for improving system structure of ground-searching radar and, aimed at solving the great noise existing in ground-searching radar work and the inadaptability in transplantation of seismic data-processing technique, raise a new scheme for underground interface high-resolution imaging of ground-searching radar.