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Thermal diffusivity (D) and thermal conductivity (κ) of harzburgite and dunite from Luobusha ophiolite were simultaneously measured up to 3 ​GPa and 823 ​K using the transient plane-source method in a multi anvil apparatus. The results show that the values of D and κ of both samples systematically decrease with increasing temperature and increase with increasing pressure. By combination of the thermal physical data of rocks and minerals and geophysical constraints, we performed numerical simulation on the thermal evolution of Tibet vary over depth, distance and geologic ages. The present results provide new constraints on occurrence of partial melting and its geophysical significance beneath Tibetan crust.

Crustal structure and fluid or melt originating in the deep crust and mantle are critical in regional magmatic mineral systems. However, the crustal structure and the processes that entrain and focus fluids from a deep-source region to a metallogenic belt remain relatively undisclosed. We present a magnetotelluric (MT) study of the eastern Qimantagh Metallogenic Belt (QMB) in the northern Tibetan Plateau. Data from 33 MT stations in two sections and 7 dispersed stations are acquired using a surface electromagnetic prospecting (SEP) system in frequency band ranges from 320 Hz to 0.00034 Hz. Data are converted by Bostick conversion and two-dimensional (2D) nonlinear conjugate gradient inversion. Our MT results reveal the geoelectrical crustal structure of the QMB, which consists of a southern low-resistivity domain that reflects the Kumukuri rift, a high-resistivity middle domain that represents the southern QMB in the central Kunlun belt, and a northern low-resistivity domain that covers the northern QMB and southwestern Qaidam block. We present a comprehensive tectonic and geophysical model of QMB based on the MT interpretation and geological analysis. We infer the high-resistivity domain as a reflection of a rigid crust and detached lithospheric mantle, this belt separate the QMB into northern and southern QMB. Most of the mineral deposits are found in the northern low-resistivity domain of QMB. Our study and findings provide an understanding of the tectonic evolution of the northern Tibetan Plateau, the crustal structure that controls the temporal and spatial distribution of magmatic rocks, and the geological signature associated with mineral deposits.

The exploration of podiform chromites in the Indus Yarlong Zangbo suture zone of southern Tibet has proved difficult because most known deposits pinch out and then reappear in the same direction. Several ground-based geophysical approaches such as gravity, magnetic, and controlled-source audio-frequency magnetotelluric (CSAMT) methods have been applied to explore for these chromite deposits but have mostly failed to delineate prospective areas. We have evaluated a successful podiform chromite exploration case history that is based on AMT. More than 8000 AMT stations were used in this study within a [Formula: see text] area of the ophiolite belt. Line separations were 80 or 40 m, and the station separation was 20 m. We implemented Bostick conversion and nonlinear conjugate gradient inversions for data interpretation, whereas 2D resistivity sections and 3D resistivity imaging were used to elucidate the inner structure and distribution of rock faces within the Luobusa ophiolite. Results from rock physics and drilling further indicate that resistivity-anomaly domains from these AMT results are correlated with rock faces in terms of fresh harzburgite, altered harzburgite and dunite, and they can thus be connected to concealed deposits. Therefore, we have developed three resistivity-anomaly models for chromite exploration, and we delineated several prospective regions containing exploitable deposits within the Luobusa ophiolite. Seven of the nine verified boreholes discussed in this paper intersected with chromite deposits; one comprises the largest and highest grade chromite deposit in China to date. Our AMT results provide the impetus for future chromite exploration in Tibet and enable a refined understanding of the structure and distribution of rock faces within the Luobusa ophiolite.

Shale gas is a particularly important research target on Chinese energy resources, especially in the Upper Yangtze region. Complex topography and geologic conditions challenge seismic exploration of shale gas in this area, and ground-based electromagnetic (EM) methods are used to aid recognition of the best reservoirs. However, the electrical properties of organic shale (EPOS) and its correlation to shale-gas petrology remain poorly understood. We studied EPOS and their correlation to shale petrology by measuring and analyzing the petrochemical features and complex impedance of rock samples from the Silurian Longmaxi and Cambrian Niutitang Formations in the Upper Yangtze, southwest China. Our study indicates that the organic shale in the Upper Yangtze features low resistivity and high polarizability in terms of a high negative phase, but no obvious low resistivity is observed among shaly sandstone and shales with lower and higher total organic carbon. Pyrite and quartz contents in the organic shale dominantly contribute to the EPOS with different mechanisms. Our result indicates that the EPOS bear relations to the petrology parameters of organic shale, which is essential for shale-gas evaluation and exploration. The correlation between EPOS and the shale-gas petrology promoted a new way for shale-gas exploration with complex geology, topography, and surface conditions in China, especially in the Upper Yangtze region, by using the ground-based EM method to evaluate the parameters of shale gas and to aid to delimit the productive reservoirs (“sweet spots”).

Karst cavity mapping is attracting great interest from engineering geologists because of its relation to the dangerous geohazards faced during engineering construction. Ground-based geophysical methods still face challenges in karst mapping, and concealed karst cavities potentially pose threats to tunnel construction in southwest China. Given the significant contrast in electrical resistivity between karst cavities and their host rocks, geoelectrical methods are widely used for mapping these cavities. We have developed a successful case history of mapping karst cavities on a planned railway route using controlled-source audio magnetotellurics (CSAMT). Scalar CSAMT, with frequencies ranging from 0.5 to 8192 Hz, was used for field data acquisition. A full-frequency domain apparent resistivity correction method was used for near-field corrections. Electromagnetic array profiling (EMAP) filtering was used for topographic and static shift corrections, and the Bostick conversion was used for data interpretation. Our study indicated that the results of the Bostick conversion with EMAP filtering were more acceptable than the results of rapid relaxation inversion and nonlinear conjugate gradient inversion in this case. The G Tunnel is a key tunnel along the Gui-Guang high-speed railway in southwest China. Initial geophysical and engineering geologic results suggest that the bedrock of the survey section of the G Tunnel route is sandstone. A CSAMT survey with three inline sections and three crossline sections over the tunnel route was conducted in two phases to verify the rock conditions of the tunnel route. A concealed karst cavity with a low-resistivity anomaly was found on the tunnel route and was verified by the borehole. Data from the CSAMT survey significantly refined our understanding of the subsurface engineering geologic conditions along the tunnel route.

This paper mainly discussed the experimental relationships between electrical properties and geological parameters such as brittle mineral content, total organic carbon (TOC) content and microscopic pore structure, with examples from Longmaxi organic shale in Sichuan province of China. With results derived from X-ray diffraction, organic geochemical measurements, nitrogen adsorption method and tests of rock electrical parameters, we came to the conclusions as follows: (1) Shale samples dominated by organic pores have the lowest resistivity, medium resistivity was found in samples mainly containing intraparticle pores and intergranular pores, and intercrystal pore dominated samples have the highest resistivity. (2) Brittle mineral content has positive correlation with rock's resistivity, as well as porosity and connectivity of intergranular pores. Low brittle mineral content suppresses electric double layers where ions exchange with clay minerals, ultimately resulting in increasing rock resistivity and decreasing rock polarizability. (3) High TOC content (>3%) is the most critical factor contributing to low organic shale resistivity, as increasing TOC content improves pore structure and reduces resistivity. The isomorphic substitution of the organic matter also serves to enhance shale conductivity and polarization. (4) Pyrite content has negative correlation with resistivity, while positive correlation with polarizability. Our study thus provides a series of basic parameters for shale gas exploration and exploitation, and discusses the geological features of significance for shale gas development in the Longmaxi Formation of this area. This is achieved by the determination of rock electrical parameters, which can be used to judge organic carbon and brittle mineral content to delineate shale areas as ‘brittle shale sweet spots’. In addition, in the process of monitoring hydrofracturing, the electrical characteristics of the low resistivity anomaly correspond to the possible existence of a fracture or fracture zone, which could provide more reliable geological structure information for the later exploitation of shale gas.

With the advent of the information age, big data, “Internet +", “intelligence +", “cloud computing” and other technological methods emerge in endlessly, the basic financial accounting work will gradually be replaced by intelligent robots, and this is a great opportunity to promote the development and transformation of management accounting. Management accounting, as a product of the combination of management and accounting, requires a large amount of information and data in order to play a specific role. In the context of the information era, management accounting can rely on the assistance of scientific and technological means to integrate and analyze enterprise information, and further promote enterprise decision-making, control, investment, etc. To serve the overall development situation, management accounting is promising. This article reviews the development of management accounting since the founding of the People’s Republic of China and summarizes the problems existing in the development process. On this basis, it provides guiding opinions and suggestions for further improving China’s management accounting.

We have carried out a field trial of a time-lapse continuous electromagnetic profile (CEMP) method for monitoring gas reservoir development. Several data acquisition methods were tested to establish a field-worthy practical procedure that maintained the consistency of time-lapse CEMP acquisition and ensured the reliability of collected data. An effective denoising and static correction algorithm has also been developed to sufficiently suppress noise and disturbance for data processing purposes. The resistivity variation with time was recovered using a time-lapse inversion method. Three continuous acquisition tests on a gas reservoir in western China produced results that clearly indicated the relationship between resistivity change and the change in gas and water ratio as well as pressure decreases. The field trial was a successful experiment in monitoring gas reservoir development with high-precision time-lapse CEMP surveys. The established data acquisition procedure, data processing algorithm, and the inversion-based interpretation have general applicability, and these may open new avenues for time-lapse monitoring in oil and gas production.

It is generally accepted that a major phase of the Earth's upper mantle is represented by ultramafic rocks, including olivine pyroxenites, dunites, and peridotites. Studies on the electrical conductivity of ultramafic rocks continue to attract a great deal of interest, and much progress in the study of the electrical conductivity of rocks and minerals at high temperatures and pressures has been achieved recently. However, publications that consider the electromagnetism of ultramafic rocks at room temperatures and pressures are few and far between. In this paper, we present a study of the complex impedance properties of ultramafic samples from the Luobusa ophiolite, and their relationship to petrography. Samples were regularized and were not processed (e.g., fluid extraction, including soaking) before they were measured, and an impedance/gain-phase analyzer was used for complex impedance measurements across a frequency range, 0.005~1000 Hz. Density, susceptibility, major minerals, and trace element contents for most of samples were measured for comprehensive analysis, but just density features and weight content of serpentine are discussed in this paper. Results show that chromite exhibits complex resistivity, far lower than harzburgite, but larger than dunite. Chromite also has more complex phases than dunite at frequencies lower than 0.02 Hz, while at the same time exhibiting less phases at frequencies ranging from 0.02 to 1000 Hz. In terms of resistivity, serpentine content, and sample density, resistivity increases alongside density, and serpentine content decreases. Given that serpentine content and density have a clear relationship with petrography and the degree of metamorphism of the Ophiolite complex, our study opens up new possibilities for understanding the inner structure and phases of ultramafic complexes, as well as their relationships to geological processes, using ground-based geo-electrical methods.

High-frequency electromagnetic sounding is an electromagnetic exploration method using the natural high-frequency electromagnetic field as a field source. It has higher resolution and greater depth penetration than the direct current method and is especially fit for geothermal energy exploration and low-and mid-level groundwater detection. We introduce a successful application of high-frequency electromagnetic sounding for evaluating geothermal water resources. The high frequency electromagnetic system (MT-U5A with a frequency range from 10 KHz to 1 Hz) is first applied to sample field data from China. A remote reference station is used to assure sampled data quality. We then perform 2D inversion image processing with the electrical method data. The results basically indicate the spatial distribution of underground geothermal water and provide favorable clues to finding the sources of the subsurface geothermal water in this area.

A successful case history of applying the high-frequency passive source electromagnetic (EM) method and controlled-source audiomagnetotellurics (CSAMT) to investigate the Qiyueshan (Q) Tunnel route is presented in this paper. The high-frequency EM system (EH-4, with frequency range from [Formula: see text]) and the CSAMT system (V6-A Multipurpose Receiver, with frequency range from [Formula: see text]) were used for the data acquisition. The orthogonal components of the electromagnetic field were measured in the high frequency EM method, while scalar measurements of the electrical and magnetic field components were used in the CSAMT method. The relevant electrical properties of the earth were extracted from the electromagnetic profiles. High frequency EM has high resolution in the shallow earth but a smaller depth of exploration, while the CSAMT method has a powerful signal but a lower resolution in the shallow earth. The integration of the two methods might be effective for the survey of the deep tunnel route. Q Tunnel, located in central south China, has a length of [Formula: see text] and a depth of up to [Formula: see text]. Half of the tunnel goes through karst terrain, where the geologic structures are very complex, due to cavities, underground rivers and faults. The EM mapping results distinguish the electrical resistivity of different rock formations. Five low-resistivity areas and four high-resistivity areas were found and nine faults were verified by the EM method. These findings were very useful for the later engineering design.

A successful case history of exploring for concealed structure using the high-resolution EM method in the investigation of the West-East Gas Pipeline Project’s B Tunnel is presented in this paper. The high frequency electromagnetic image system named STRATAGEM EH4, operating at frequencies ranging from 90 KHz to lHz, was used for data acquisition. The orthogonal components of the electromagnetic field were measured during the field acquisition and the relevant electromagnetic attributes of the object body were extracted from the electromagnetic data. Hybrid sources, consisting of natural and full tensor-controlled sources, were utilized to produce high-quality electromagnetic field data. B Tunnel lies in the western part of Hubei province, at depths of less than 200 m. The geologic setting of B tunnel is very complex. Following an initial geologic investigation, an outcrop considered to be a bedrock interface by investigators, collapsed during tunneling operations. A second investigation applied high-resolution EM and seismic refraction methods to reveal a more complex geologic structure along the tunnel route. The predicted rock classes and fault were encountered during the subsequent tunneling operations.

Total Organic Content (TOC) is one of the key and important parameters to effectively evaluate the shale gas formation production potential. According to geological deposition theory, the TOC is the basic key element that controls the form of pyrite in the marine sediment under deep water strong reducing deposition environment. There is a close relationship between the TOC and pyrite in such deep water reducing deposition environment. Through the laboratory measurement and analysis of the complex resistivity on marine shale formation core samples from South China, the high TOC shale reservoir core samples contain more pyrite, and they show clearly low resistivity and high polarization anomaly. In comparison with well log data, the laboratory measurements of TOC and pyrite are closely related to the results from the log data analysis. We concluded that high TOC marine shale formation has the characterization of low resistivity and high induced polarization (IP) anomaly. Based on the research results, the application of the induced polarization or complex resistivity method to measure the subsurface resistivity and polarization anomaly is a new approach to effectively evaluate the TOC content within the shale gas formation, and it has high potential value for future shale gas reservoir evaluation and characterization.

Southwestern Tibet plays a crucial role in the protection of the ecological environment and biodiversity of Southern Asia but lacks energy in terms of both power and fuel. The widely distributed geothermal resources in this region could be considered as potential alternative sources of power and heat. However, most of the known geothermal fields in Southwestern Tibet are poorly prospected and currently almost no geothermal energy is exploited. Here we present a case study mapping the Mapamyum (QP) geothermal field of Southwestern Tibet using audio magnetotellurics (AMT) and magnetotellurics (MT) methods. AMT in the frequency range 11.5–11,500 Hz was used to map the upper part of this geothermal reservoir to a depth of 1000 m, and MT in the frequency range 0.001–320 Hz was used to map the heat source, thermal fluid path, and lower part of the geothermal reservoir to a depth greater than 1000 m. Data from 1300 MT and 680 AMT stations were acquired around the geothermal field. Bostick conversion with electromagnetic array profiling (EMAP) filtering and nonlinear conjugate gradient inversion (NLCGI) was used for data inversion. The AMT and MT results presented here elucidate the geoelectric structure of the QP geothermal field, and provide a background for understanding the reservoir, the thermal fluid path, and the heat source of the geothermal system. We identified a low resistivity anomaly characterized by resistivity in the range of 1–8 Ω∙m at a depth greater than 7 km. This feature was interpreted as a potential reflection of the partially melted magma in the upper crust, which might correlate to mantle upwelling along the Karakorum fault. It is likely that the magma is the heat source of the QP geothermal system, and potentially provides new geophysical evidence to understand the occurrence of the partially melted magmas in the upper crust in Southwestern Tibet.

GEM Beijing 2011: International Workshop on Gravity, Electrical & Magnetic Methods and Their Applications Beijing, China. October 10-13, 2011. Karst cavity mapping using CSAMT: A case history of tunnel investigation in China Lanfang He, Xiumian Hu, Nanjing University; Ligui Xu, BGP; Xuben Wang, Chengdu University of Technology; Jian Li, Xuyou Lei, Donghua Wei, China Railway Eryuan Engineering Group

Pinus taeda suspension cultures grown in medium containing 2,4-dichlorophenoxyacetic acid showed only primary cell wall formation and essentially no lignification, as determined by histochemical, ultrastructural, chemical, and NMR spectroscopic analyses. However, these cultures maintained a functional phenylpropanoid pathway as demonstrated by formation of the lignans (-)-matairesinol and (-)-pinoresinol. Administration of [1-13C]Phe to these cultures, followed by solid-state carbon-13 NMR spectral analysis of their cell walls, demonstrated that the phenylalanine incorporated into the cell wall matrix was primarily as protein, rather than lignin. Successive transfer of the 2,4-dichlorophenoxyacetic acid-grown cultures to alpha-naphthaleneacetic acid-containing medium induced cell wall thickening concomitant with lignification. The presence of lignin was confirmed by histochemical, ultrastructural, chemical, biochemical, and NMR spectroscopic analyses. Specific labeling of the lignin polymer in situ with [1-13C]-, [2-13C]-, and [3-13C]Phe and analysis of the cell wall preparations by solid-state carbon-13 NMR spectroscopy permitted the first direct determination of the in situ bonding patterns in a gymnosperm lignin. Several dominant interunit linkages were observed, including beta-O-aryl, furanofuran, phenylcoumarin, and phenolic-linked monolignols, consistent with those predicted but hitherto not proven. Finally, milled wood lignin derivatives prepared from these 13C-specifically enriched lignin tissues gave a relatively high fidelity copy of the native lignin.

Summary Induced polarization (IP) is widely used in oil and gas exploration in the former Soviet Union, Russia, and China. Good results from hydrocarbon exploration were achieved in China recently by applying high-power spectral induced polarization (SIP) with exploration depth exceeding the buried depth of reservoirs. Precision synchronization between the transmitter and receiver is required for the amplitude spectrum and phase spectrum of SIP measurement in the current technology. The synchronization based on the GPS disciplined oven controlled oscillator (OCXO) is the usual method applied in the transmitter and receiver which are used for SIP exploration. The method increases weight and cost of the receiver because the GPS-disciplined OCXO uses the major part of the power consumption of the receiver. Furthermore, this method can not satisfy the measurement requirements of SIP in ocean-bottom conditions because of the lack of GPS signal. We put forward a measurement method of relative phase spectrum (RPS) to resolve the above problem. The IP information of a target is acquired by the amplitude spectrum and RPS of the complex resistivity. The method can decrease power consumption of the receiver by 50% because the RPS measurement does not require synchronization circuit between the receiver and transmitter. The RPS curve shape is similar to that of phase spectrum based on comparing typical parameters of the Cole-Cole model. The RPS owns the same IP information as the phase spectrum. In fact, the RPS formula proposed by here is equal to the phase spectrum formula which is linearly corrected to EM coupling. This was proven through a field experiment. The 3D SIP acquisition can be realized at low cost in the surface, the well, and the ocean-bottom if the phase spectrum measurement is replaced by the RPS measurement. It may expand the application of SIP in oil and gas exploration.

Summary: The western ZZ area, which lies in the northwest Huabei plain, was the most well-known area in Huabei for its abounding groundwater. During the past several years, the water table has been dropping year by year due to overuse of the surface water upriver and overexploitation of the groundwater. As a result, most wells in this area have dried up and some of the residential areas are at risk of not having drinking and irrigation water. Some geophysical prospecting has been carried out in this area and several boreholes, which were funded by the local government, have been drilled based on the geophysical results. But most wells have not found a good aquifer. In order to map the good aquifers and solve the water supply problem, a third geophysical ground exploration with joint evaluation of gravity and geo-electric methods was conducted. During the exploration, the former drilling results and geological information has been carefully studied by the survey group. Based on these, the target aquifer stratum was locked in calcareous rocks in this area. Five boreholes have been designed based on the geophysical results and three of them have been drilled and met good aquifers. The result indicates that good aquifers in the western ZZ area feature high density and resistance. This is different from most aquifers outside this area.

Heterogeneity of sugarcane lignin with respect to the composition of structural units in different morphological regions was studied by microautoradiography and some degradative analyses. Structure of the lignin differs among fiber, vessel and parenchyma. The lignin in the secondary wall of fiber is composed of syringyl (S)-, guaiacyl (G)- and p-hydroxyphenyl (H)-propane units with accompanying phenolic acid residues, and the proportion of these monolignols is S > G > H. The lignin in vessels of protoxylem contains more G and H units than S units, and that in vessels of metaxylem is similar to that in fibers. Phenolic acid constituent in sugarcane cell wall includes sinapic acid in addition to p-coumaric and ferulic acids. Ferulic acid deposits at the very early stage of lignification, and p-coumaric and sinapic acids increasingly deposit with the progress of lignification. Therefore, the ratio of p-coumaric acid or sinapic acid to ferulic acid increases with lignification. Parenchyma wall involv...

Summary A successful case history of mapping the concealed structure using high-resolution EM in the investigation of B Tunnel route is presented in this paper. The high frequency electromagnetic system named STRATAGEM EH4, with the frequency ranging from 90 KHz to 1Hz, is used for the data acquisition. The orthogonal components of the electromagnetic field are measured, and the relevant electromagnetic attributes are extracted on the basis of the characteristics of the electromagnetic profiles. Hybrid sources, including the natural source and the full tensor controlled-source, are utilized to collect high quality field data. B Tunnel lies in the western part of Hubei province, the south of central China. The tunnel is only buried at the depth of less than 200 meters, but the geologic structure is very complex because of the regional geological action. During the first time of the B Tunnel route investigation, the investigators were deceived by the outcrop of the rock fall, considering that it is from the bed rocks and the roof of the tunnel fell when tunneling was in operation. High-resolution EM and seismic refraction were used in the second time investigation. The “real” bed rock and the geologic structure were mapped this time and a hidden fault was also detected. The tunneling result fits closely with what we have predicted.

A successful case history of reservoir mapping of the geothermal water using a high frequency EM method is presented in this paper. The high frequency electromagnetic system (MT-U5A with frequency range from 10KHz to 1Hz) is used for the data acquisition, which is its first time using in China, remote reference was used for high quality field data. J County has a known hot spring and several wells were drilled for geothermal water used by sanatoriums. The water temperature ranges from 30 Centigrade to 93 Centigrade. But the geothermal water distribute only in a little area. High frequency EM method was used to map the reservoir of the geothermal water and to explore the source of it. We found the geothermal water is saltwater here and another very useful event, that is, the apparent resistivity beyond here is quite different to the other area. Based on this, we carried out 467 high frequency EM sites here. 2-D inversion is used for data processing. Distribution area of geothermal water of different depth has been mapped by this method. Finally, we gave a acceptable interpretation of the geothermal water source. Introduction J County lies on the northern of the famous Lao Mountain, Qingdao City. It is very famous for its hot spring in Hot Spring Country. For many years, the native government was working to develop the hot spring and several wells were drilled for geothermal water. But since then, no one knows where is the best site to drill and where is the source of the geothermal water. In order to exploit the geothermal water, high frequency EM method was used for the reservoir mapping. In 1930’s, the first well in J County was drilled by Japan. This well, which has a depth of 50-60m, is a artesian well and mainly used for bathe. After that, in 1957 and 1971, six borehole were drilled by the First Hydrology Branch of Sandong Geology and Mineral Bureau, five of them have been exploited for sanatoriums, the largest depth of them is 394m. In 1993, BGP Holiday Tour Place drilled a geothermal water well here, the water’s ground temperature is 76 Centigrade. Besides, some other geological survey had been carried out in J County since 1986 to 2000, but they have no certain conclusion about the magnitude of stock and the source of geothermal water. There are two important conclusions in the former exploration and the previous test in geothermal field. One is the buried depth of the geothermal water less than 400m. The other is the temperatures and salinity of the pore water are very high here. These often contribute to decrease the bulk resistivity within a rock mass. Above two facts made high frequency EM method can be a useful tool for the geothermal investigation here. The high frequency EM method survey was conducted by staff of the Fifth Division of BGP, China National Petroleum Corporation. Funding was provided by WenQaun Country, J County. The survey was performed between March,20-June,15, 2002. At the same time, some other techniques, such as Gravity, Magnetic method, Electric sounding were carried out for the geothermal exploration, those were not considered in this paper. The interpretation results were supported by the results of the hydrology survey. Regional Geology J County is located in south-west corner of Mouping-Jimo fracture zone, which lies in the Jiaolai seg of Nudong symon fault. This region is dominated by south-west to north-east trending fault. The secondary structure is south-east to north-west trending fault. The major formation here is Cretaceous system, which is deposit of river and lake faces, mainly consists of sandstone, gravelstone and mudstone. Qinshan Group is a deposit of middle-basicty to acidity volcanic rock, Laiyang group is a group of violet dominated siltstone, packsand and gravelstone. In the hill country, downfaulted basin and the major hydrographic net valley, there are Quaternary system formations, it is the protective covering of the underlying thermal reservoir. The major neotectonic movement here is the territorial up and down movement and the activity of some faults. The lastest neotectonic movement, especially the reactivity of the faults, is the major release point of the geothermal heat. The thermal locality is mainly located in the interchannel terrace, its east and west fringes have been cut out by the river. The surface layer is greyblack donk and sludgy tenacious clay. About one meter of the uppermost layer there have plenty of precontemporary siphonaceous worm excrement, it color has been changed by the sulfidization. The microstratification of the soil strata has been unreadable because of hydrothermal alternation. The distribution range of this kind of soil is similar to which of the thermal locality. According to the result of drill hole, the depth of Quaternary system formations is 12m, it is deep than its outside layers. A possible causality is selfmade barrier layer of hydrothermal water. This is the cap layer of the thermal reservoir. adame llite orthophyre quartzitic orthophyre Intrusion quartz itic orthophyre subdante llerite felsophyre andesitic porphyrite basaltic andesitic porphyrite Subvolcanic rocks sandy clay,sand and gravel silty clay,silt and grit Quaternary basaltic andesite,andesite and trachyandensite ash tuff,tuffaceous sandstone and liparite arkose,aleurolite and mudstone interbeding tuff basaltic andesite and shale interbeding gravel Cretaceous Line 1 Line 2 Figure 1. : Geological map of J County, the blue line is the layout of the High Frequency EM method sites. Field Survey We carried out 467 High Frequency EM method sites here. The survey line is shown in figure 1(the blue line). The field work layout is shown in figure 2. Three sets of MTU-5A(Phoenix Geophysics, Canada) real-time data acquisition system with induction coils were used for data acquisition, which is its first time using in China. Each system used two pairs of nonpolarizable C-C electrodes with a separation of 25 to 50m. Two sets of system were used for base data acquisition, one set is used for remote reference data acquisition. The remote reference is fixed at 9km away from the work area, because there are many power utilization sites in the area and the topography is smooth. In order to ensure each AMT site have its remote reference, three sets of system recorded simultaneously through GPS. The MTU-5A acquires data at sample rates 24 kHz (level 2), 24 kHz (level 3), and 150 Hz. Level 4 is acquired continuously, levels 2 and 3 are acquired at an interval, which is a multiple of 1 minute. The level 3 data is acquired for 1 second (2,400 scans) starting on the UTC second. It is acquired for up to 2 seconds in the minutes when level 3 acquisition is scheduled. The level 2 data is acquired for 0.1 second (2400 scans) starting on the UTC second. It is acquired for up to 4 seconds in the minutes when level 2 acquisition is scheduled. The hole in the AMT spectrum above 1 kHz falls in level 2 so that we allowed for plenty of data to be acquired at this level. Figure 2. : Layout the data acquisition system Data Analysis The electric and magnetic field time series were transformed into the frequency domain by The TSTOFT program, which calculates estimates of the magnetotelluric signal amplitude and phase (Fourier coefficients or 'DFTS') as a function of time and frequency. It corrects for system parameters and responses so that the estimates are as nearly as possible independent of the measurement system. The program defines time windows and center frequencies in a way, which is independent of the sampling rate or data acquisition start time, so that data from two different acquisitions is easily combined in subsequent processing. The 2*2 magnetotelluric impedance tensor Z relating the horizontal electric (Ex,Ey) to the horizontal magnetic (Hx,Hy) fields was determined using the robust remote reference method provide by the Phoenix Geophysics. Most sites have high quality data because of the using the remote reference and approved capability of the MTU-5A, in addition, no powerful noise in the area. A full 2-d inversion has been done for all the survey line data set. There is a remarkable event in the result of data analysis, that is, the apparent resistivity in the known geothermal water area is quite low than which in other area. The result is presented in Figure 3(a), which is concordant with the result of electric sounding (Figure 3(b)), the known marking of freshwater area and saltwater area mainly from the former geology survey and drill. This is a very useful event for the data interpretation and the evaluation of the geothermal water because we have known form the hydrogeological survey that the geothermal water is saltwater in J County.

Summary Geothermal energy is playing a larger role as an alternative energy source for both electricity generation and for space heating. Magnetotelluric (MT) and gravity surveys were conducted throughout Hungary in basins which were felt to be prospective for geothermal exploration. Integrated interpretations of this data have identified new drilling opportunities. The success of these surveys has resulted in additional 2D MT and gravity data acquisition and the onset of a drilling program to evaluate the identified geothermal potential.

Chromites mapping using geophysical methods proved difficulty during the past several decades, because most Chromites are feature as podiform deposits which always pinch out and reappear in the same survey line. Several ground-based geophysical methods including: Microgravity, Magnetic and Controlled Source Audio MagnetoTelluric (CSAMT) have been used for chromites mapping. However, the result did not satisfy the need of the mining geologists. A successful case history of chromites mapping using induced polarization method based on spread spectrum technology in Luobusa Ophiolite, Southern Tibet, is presented in this paper. Wireless Sensor Network (WSN) based electromagnetic system (SinoCGI) is used for the data acquisition, which is its first time using in China. Luobusa chromites mine is one of the chromites deposits with maximum mineral production in China. But drilling and ground-based geophysical exploration did not meet the good deposit for sustainable yield in the past several years. Experiment measurement in the lab indicates that the chromites samples and its host rocks sample characterize by different rock apparent resistivity and chargeability. Based on this, we conduct induced polarization method based on spread spectrum technology to map the potential favorite deposit. We carried out around 500 IP scanning stations and three 2-D IP sounding profiles in the working area with acreage of 0.5 square kilometer. The favorite chromites deposits which features as conduct and low polarizability has been mapped. Four boreholes have been drilled to verify the ore delineation by IP method, three of them met chromites, the other one met chromites mineralization. The result gives a new recognition on geophysical methods to chromites mining geologists in China. Introduction Chromite exploration is challenging (Mohanty et al., 2011). It is more difficult to explore podiform chromites, because this kind of ore body produces only very weak geophysical response. Luobusa chromites deposit is a typical podiform chromites lie in southern Tibet of China. Traditional geophysical methods, such as gravity, magnetic method and CSAMT, failed in exploring chromites in Luobusa, because of small podiform ore body and complex geological structure. In order to map the concealed ores, a distributed high precision 2D/3D IP instrument based on wireless sensor network (WSN), spread spectrum technology, and relative IP phase was developed. This new IP instrument can acquire high quality IP data with more than 150 channels simultaneously. We tested the new IP instrument in Luobusa, and got a satisfied result. Background and geological setting About 50 years ago, a herdsman in Luobusa, which is located in southern Tibet, found some chromites and told government agency. This revealed the biggest chromites deposit in China. About 500 boreholes were drilled, and the deposit is larger than 5,000,000 tons. However, it was very difficult SAGEEP 2013 Denver, Colorado USA http://www.eegs.org to find new ore body by drilling in recent years. Many geophysical methods were used in this area, but drillings suggested by geophysical methods met no ore body. Luobusha chromites deposit (Figure 1) is located in Luobusha town, Qusong county, Shannan district, Tibet. It is in the southern of Gangdisi Mountains and Nien-ch'ing-t'ang-ku-la Mountains, and is between the downstream and midstream of Yarlung Zangbo River with longitude as 92.15-92.24 degree, latitude as 29.18-29.23 degree. Luobusa is located in collision area between Gangdisi block and Himalaya block(Figure 2). The collision generated a long and deep fault. Ultra-mafic magma went up from the fault and brought chromites deposit in ophiolite. Figure 1: Location of Luobusha Chromites Deposit. Red rectangular shows the location of working area. Figure 2: Geological map of Luobusa and neighbor area (after WENJI BAI et al. 2000) SAGEEP 2013 Denver, Colorado USA http://www.eegs.org