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.

This paper studied element distribution in aqueous phase, sulfate phase and carbonate phase in the vertical profiles of soil for the salt section along the Tuwu-Yandong metallogenic belt in Eastern Tiansan. The authors revealed the mode of the influence of alkaline geochemical barrier composed of alkaline salts on the distribution of elements in the soil. The existing forms and distribution of elements in the supergene zone is obviously influenced by the alkaline geochemical barrier. Ca, K, Na are in different positions of salt deposition, and the sections of the alkaline geochemical barrier have different types, so that the distribution of elements differs in the vertical profile of soil.

The work area is located in the north-central part of Laos which is covered by rainforest and close to the intersection between Truong Son North-West trend magma-tectonic belt and North-East trend Louangphabang magma-tectonic belt. The result of soil survey shows that Cu and Pb, Zn, Ag, Sn, Mo, Sb, Hg, As, Cd, Co, Bi together represent a major element association for ore deposits characterized generally by similar growth and decline trends. The metallogenic elements of Cu, Pb and Zn are mainly distributed in the contact zone between granite and carbonate, displaying obvious zoning with other coexisting or associated elements such as Mo, Sn, Bi, Ag and Cd. Cu anomalies are mainly in the inner side close to granite, whereas Pb and Zn anomalies are mostly in the outer side close to carbonate. The soil geochemical characteristics show that the ore deposits in the work area should belong to skarn type with large metallogenic potential.

There are three deep faults in the aeromagnetic map of the Western Tianshan Mountains. These deep faults have very significant magnetic anomalies. They are not only the divisions of different tectonic units but also the important ore-controlling structure zones. In this paper, the authors deal with magnetic characteristics of the deep faults and the relationship between the deep faults and the mineralization. Nileke deep fault is one of the most important faults in this area. There are four large-size known iron ore deposits around Nileke deep fault. According to the latest high precision aeromagnetic survey, four anomalies have been proved to be related to the iron ore deposit. These anomalies are also located near Nileke deep fault.

In combination with geological conditions, this paper deals briefly with the different characteristics and roles of magnetic method, very low frequency method, transient electromagnetic method and IP sounding method in the ore-prospecting work. Some successful case studies of the prospecting for concealed ore bodies in some gold ore districts of western Henan are presented in this paper, which show that the rapid scanning survey by using magnetic method and very low frequency method (or VLF-EM method) can delineate ore-prospecting target areas, and the symmetric quadrupole IP sounding method can be used to predict buried depth of the ore body. These methods are effective means for economic and rapid detection of shallow-deep concealed and semi-concealed blind ore bodies and hence deserve widespread application.

Here are large-scale Yanshanian volcanic rocks distributed in Fengning area. Based on a comprehensive analysis of aeromagnetic, geophysical and geochemical data, the authors have found that there exists a concealed eruption breccia pipe around Heshundian area. Accompanied by volcanic-intrusive activities, a series of annular fault structures were formed in the vicinity of or around the crater. These structures provided ore-forming channels and space for deep ore-bearing hydrothermal fluids in association with the superposition of the regional tectonic movement. Recent prospecting practice has found Ag, Pb and Zn polymetallic mineralizations in northern and eastern parts of the volcanic structure. These mineralizations are expected to form economic industrial ore bodies. Based on a comprehensive analysis of ore-forming geological conditions of this area, the authors hold that the exploration work is likely to achieve new breakthrough in southern and western parts of the volcanic structure.

On the basis of an integrated analysis of the data related to the regional gravity and aeromagnetic survey on the scales of 1∶200 000 and 1∶50 000 in southwestern Henan in combination with a detailed study of deep-buried structures and faults as well as characteristics of magmatic rocks in the study area, the authors delineated concealed or semi-concealed intrusive bodies and faults. Furthermore, researches on the relationship between the mineralization zone, intrusive rocks and the structures based on geological, geochemical and geophysical data revealed that the features of regional gravity and aeromagnetic fields are related to the mineralization zone, with the delineation of 9 prospective ore-forming areas. The results contribute important information to the prospecting for deep and concealed ore deposits in southwest Henan area.

According to the geological features of the working area, the authors employed the V8 multi-function electrical instrument to scan the entire study area by using the transient electromagnetic method. Through data processing and interpretation, the underground geological bodies were delineated, and electric characteristics of the metallic ore bodies in the study area were also revealed.

Geochemical exploration has been gradually transformed from qualification into quantification. Based on previous research results, the authors put forward two methods, i.e., areal productivity integration and 3D geological blocks, to calculate the resources of concealed ore bodies in old diggings, which are characterized by lack of exploration engineering and deep burial. With the prediction of Mo resources in the Chengmenshan ore deposit as an example and the geological body rich in Mo as the calculation object, and according to the Mo geochemical halo formation in different cross-sections in combination with the characteristics of 3D ore deposit, the authors estimated Mo resources at the shallow part (the first space 0~-500 m) and the depth (the second space -500 m~-1 000 m) of the mining area. The calculation results show that the resources estimated by these two methods at the shallow part are consistent with actual estimations, but the 3D geological blocks method is better in predicting the resources at the depth.

The Shiyaogou ore deposit is a large-size molybdenum deposit newly discovered in the East Qinling molybdenum belt. the Shiyaogou ore deposit has proven reserves of more than 100,000 tons Mo, averaging 0.068%. Based on a systematic study of the results obtained from the geophysical and geochemical exploration in the Shiyaogou ore deposit , the authors sum up in detail the three-dimensional distribution regularity of the ore deposit. The data of geophysical and geochemical exploration were used step by step. The discovery of the large-size Shiyaogou Mo deposit not only favorably affects the stable development of Au polymetallic ore-prospecting work but also provides rare and valuable experience in search for more molybdenum resources in the Mo mineralized zone of East Qinling area. Geophysical and geochemical exploration should be further carried out as a necessary means.

With the KNM gold ore deposit as an example, the authors carried out qualitative discrimination of nuclear geophysical anomaly by using discriminant analysis composed of canonical discriminant and stepwise discriminant analysis. Discriminant analysis was employed for gold prospecting, while SPSS software was used for data analysis. It is found that, with these two means, accurate characterization of barren anomalies reaches 83.3% and 66.7% respectively, while accurate characterization of ore-related anomalies reaches 89.7% and 91.4% respectively.

This paper discusses methods of estimating airborne gravity anomalies. Based on the Kalman smoothing techniques, the authors developed the software for estimating airborne gravity anomalies. Research shows that, if this software is used to estimate airborne gravity anomalies, the standard deviation of the discrepancy is within 1 mGal in comparison with the data processing results by the imported GT-1A system software.

A detailed study of ray tracing, tomographic inversion method and numerical tomographic inversion algorithm were performed and, on such a basis, the method of using first arrival of shot to directly establish the initial seismic model was put forward. In addition, the tomographic inversion of near-surface velocity model process flow with reference to the refraction and logging and the high-precision rapid ray tracing method by multi-retracing and SIRT tomographic inversion were also suggested. The double grid technology was employed to improve modeling simulation accuracy and tomographic inversion imaging quality and, what is more, the multiple quality control plans were fully considered to ensure the precision of the final inversion velocity model. The ray tracing, tomographic inversion, graphics display and some other programs were developed, 10 different theoretical surface geological conditions were designed, the theoretical model was tested, and seismic data from Shengli, Sichuan and some other areas were studied. The results of tomographic inversion calculation and actual data inversion prove the correctness of the theoretical research.

According to the differences between angle gather data and multiscale and multi-direction characteristics of Curvelet transform, this paper proposes the utilization of angle fluid factor to discriminate different fluids. Models and real seismic data are used to test the method. The result is reliable, and the location and range of the reservoir can be satisfactorily obtained. In combination with other attributes, the method can provide better information for fine description of the reservoir. Making reference to cross-equalization methods of time-lapse seismic data, the wavelet cross-equalization method is used to equalize angle gather data. Then, Curvelet domain fluid anomaly separation technique is used to separate background field information (rock frame information) from fluid information, and the anomaly of the interesting layer can be obtained.

Antimultiple processing is an important step in marine seismic data processing. The multiple waves in marine seismic data are generally rather strong and very difficult to suppress, so the suppression of multiple waves decides the quality of processing results. There are many ways to suppress multiple waves; nevertheless, different approaches are based on different theories and have different targets. A single method can not suppress all multiple waves and hence fails to achieve the desired results. The authors employed the combined multiple wave attenuation technology, which combines SRME, radon transform and lift denoising to suppress multiple waves in actual marine seismic data, and has achieved good results.

This paper investigated the theories and methods of prestack joint inversion by utilizing PP and PS converted wave data sets. Actual multi-component seismic data from the oilfield were also used to delineate the deep buried volcanic gas reservoir based on the studied methods. Well log data show that the gas reservoir prediction results are consistent well with the well data, suggesting that prestack PP-PS joint inversion can avoid the multiple solutions of lithologic parameters caused by only using PP compression wave, and can improve the accuracy of gas reservoir prediction.

This paper describes two reasons for the decline in the quality of seismic signal in vibroseis: one is the contact with vibrator plate caused by external environmental conditions, and the other is the vibrator caused by the fault itself. The authors put forward different methods to tackle the decline in the quality of seismic signal in vibroseis and their application prerequisites. In practice, these methods have achieved good results.

This paper discusses two measurement methods for the total measurement, i.e., pulse-counting and Time-to-Count, and describes the working principles of these two methods as well as their advantages and disadvantages. Personal dosimeters which make use of these two measurement methods were designed. The advantage of Time-to-Count is reflected through a comparison of the performances of the two instruments.

Geochemical data distribution, especially the frequency distribution of trace elements, are positively deflective, and the calculation of the threshold is based on abnormal lognormal distribution. When qualitative analysis is conducted, the distributionof most of the sample is acceptable. But when quantitative analyzing lower limit of anomalies,the calculation must be in combination with the actual distribution of samples. This paper introduces the g-h distribution function to fit the sample data and ascertain the threshold according to the parameters. In combination with the sub-region median contrast filtering raised by Shi Changyi, the authors processed geochemical data of Gejiu and its peripheral areas and adjusted the size of the filter window by self-adapting, extracting the geochemical anomalies and delineating the targets.

The mine transient electromagnetic multi-directional cross observational system was adopted in limited space of adits on the two sides of the work face, and as many data as possible were collected in roof or floor of the work face. Relevant processing procedures were performed for collected data, such as data preprocessing, data transfer, data extraction and level slicing. An integrated analysis was made for different horizontal slices, and hence the physical parameters of the anomaly in the detection limits such as electrical features, central position and development trend were determined, thus providing a reliable basis for hydrogeological prediction and ensuring safety of the mining face.

According to the sampling of atmospheric dust fall in southern Songnen Plain, the features of dust flux and indicators are discussed in this paper with the countryside, town, and city as the unit. The content levels of 20 kinds of indicators in the atmospheric dust samples were studied. The results show that, compared with the soil background values, Hg and Cd in the atmospheric dust are significantly concentrated. With Al element as a reference, the calculation results show that Cd and S elements are significantly affected by human activities, with a large enrichment factor. The sources of the indicators were analyzed using the principal component analysis method. The results of the principal component analysis shows that the main element sources result form human activities, the superimposition of surface dust and human activities, and regional raised dust.

Modeling absorption and attenuation in time-space domain requiring a lot of computer memory with low computational efficiency, it is hard to simulate attenuation in time-space domain. We can use an empirical physical or mathematical formulation to simulate absorption and attenuation in frequency-space domain through introducing complex velocity and Q values. We can easily describe attenuation with high efficiency in frequency-space domain using nested dissection and Kjartansson's model. Numerical experiments demonstrate that absorption and attenuation affects all the frequency components of the wavefield and affects a greater impact on the higher frequency components, so it decreases the seismic record's resolution. It is very easy to simulate absorption and attenuation effects in frequency-space domain, providing a good foundation for visco-acoustic wave full waveform inversion on real data.

In this paper, the authors made Ricker wavelet-based adaptive matching pursuit decomposition of seismic signals and discussed the method of time-frequency representation by matching wavelets. Since the time-frequency information of matching wavelet's Wigner-Ville distribution is limited, this paper proposes a time-frequency representation based on adjustable window Short Time Fourier Transform. Furthermore, by using the complex spectrum of matching wavelets, this paper introduces a new time-frequency representation, which not only has the same resolution and energy concentration properties as Wigner-Ville method, but also retains the most basic time-frequency characteristics of the original signal without cross term and window truncation effects. Compared with time-frequency characteristics of Short Time Fourier transform and S-transform, the matching pursuit time-frequency representation and instantaneous spectral parameters have higher resolution. Real data application also shows that the matching pursuit time-frequency analysis is very suitable for seismic signal with non-stationary characteristics.

The transient electromagnetic sounding method is often processed with the step wave model by using square pulse wave activate source. This operation will result in obvious deviation in theory. The authors suggested using single pulse (function) active source electromagnetic sounding method for processing data and explaining the square pulse active source. Practice shows that this means is feasible.

Based on finite-element numerical modeling, the authors studied the feasibility of applying the resistivity method to monitoring underground geological variations. A time-lapse subsurface monitoring method based on geoelectrical observations is proposed in this paper. The numerical modeling result using 2D resistivity forward and inversion program shows that the relative variation of resistivity can serve as a good indicator for resistivity changes both regionally and locally. High-precision and large quantities of data observations of earth resistivity constitute the foundation of time-lapse subsurface monitoring. With the well-performed 2D or 3D resistivity modeling and inversion, this technique makes geo-electrical survey a useful time-lapse monitoring subsurface method.

Wells are always drilled in areas with a relatively great probability of good reservoir quality. The data from these well sources are distributed asymmetrically in the interesting area. Usually, some data are spatially clustered. It is necessary to correct this preferential clustering before making statistics. This paper introduces the Thiessen polygon method to determine spatial affecting sphere of each well and provides a new idea to solve the problem of determining polygon for the polygonal declustering method. A case study in the Shinan oil field is presented. The research result shows that this method is feasible.

Based on analyzing three cases, i.e., water stone riprap exploration of bank protection embankment, underwater exploration of concrete grid and gravel layer, and river waters yard landslide detection, the authors tried to illustrate the effect of the geological radar exploration in the freshwater of shallow water. The impacts of conductivity, dielectric constant and frequency detection were studied by using the antenna to an environment that the object detection is in. GPR fills the gaps of engineering investigation in the shallow water, and research on GPR and test in the non-ater area are of reference value.

The Controlled Source Audio Frequency Magnetotelluric Method for hydrogeological exploitation of coalfields was employed in this paper. The method for measuring water-bearing large-throw faults can not only effectively control their spatial locations but also qualitatively determine their water content. The result is in good conformity with known hydrogeological information.