Taking the lithostratigraphy complicated Lower Cambrian in the Upper Yangtze region as an example, guided by the theory of high resolution sequence stratigraphy, based on the outcrop, rock core, thin section and drill data, we identified 6 standards to divide sequence stratigraphy and 5 sedimentary cycles of combination style. The interface of shale sequence stratigraphy is difficult to identify, and the recognition of different grades of depositional cycle is the key factor. Based on the above, combined with the study of tectonics, lithofacies and organic carbon content, we established isochronous sequence stratigraphic framework and sedimentary model of rich organic shales, and carried out fine mapping of organic shale distribution based on the sequence units. The organic-rich shales are developed mainly in the early different grade of transgressive-regressive periods. The distribution of organic-rich shales in the different areas is varied. The organic-rich shales distribute mainly in Ziyang-Changning area in the Sichuan basin. There are four sets of organic-rich shales controlled by the poly-tectonic basement rift. A large set of organic-rich shales are developed in the western Hubei- eastern Chongqing, north- southeastern Guizhou and Yichang areas controlled by Early Cambrian upward flow of ocean currents. The distribution characteristics of organic-rich shales should be taken into consideration for shale gas exploration and exploitation.

In the forming process of tight sandstone oil and gas reservoirs, the spatial-temporal coupling relationship between high-quality source rocks and high-quality reservoirs is a crucial factor controlling the reservoir types and abundance. In order to better understand its controlling function, we applied the geochemical data, constant-rate mercury injection experiment, conventional mercury injection experiment, and fluid inclusions and other analytical data in the study area, and compared the tight oil reservoir in the southern Songliao basin with the tight gas reservoir in the northern Songliao basin. The distribution of a hydrocarbon generation and expulsion center of high quality source rocks is basically consistent with the overpressure zone, and its boundary limits the scope of tight oil-gas accumulation area. Besides, under the constraint of pore-throat structure, the lowest permeability of high-quality reservoirs is defined as 0.1×10^-3 μm² in the fourth member of the Lower Cretaceous Quantou Formation(K₁q₄)in the southern Songliao basin,while 0.05×10^-3 μm² in the Lower Cretaceous Shahezi Formation(K₁Sh)in the northern Songliao basin. Furthermore, one of the preconditions for forming tight oil-gas reservoirs is that the tighten period of reservoir should be earlier than that of the main hydrocarbon expulsion of source rock, which is the basis of the reservoir-forming mechanism. Spatially, the ‘reservoir sweet spots’ are developed always in the intersection of high-quality source rocks and high-quality reservoirs,where powerful pressure and high permeability and other geologic features are available.

According to the hydrocarbon generation and expulsion mechanism, the authors analyzed the relationship between TOC content and rock pyrolysis parameter S1, determined the low limit value of effective source rock TOC content of the lower member of the Xinhe Formation shale in Sartai sag, Yabrai basin. The low limit value of TOC content in the Xinhe Formation shale of Yanchang subsag and Xiaohu subsag are 1.0% and 0.7% respectively, while the source rocks in the Xinhe Formation of Suotuo subsag are unsatisfied with the hydrocarbon expulsion condition. Using the Δlog R method, the authors calculated the TOC content of the Xinhe Formation shale, then recognized the effective source rocks in wells and got the distribution characteristics of effective source rocks referring to the sedimentary facies and statistic thickness of effective source rocks in wells. The effective source rocks of the lower member of the Xinhe Formation are mainly distributed within Xiaohu subsag with the maximum gross thickness adjacent to 600 m, basically less than 100 m in Yanchang subsag, and there are no effective source rocks in Suotuo subsag. The higher the thermal maturity is, the lower the low limit value of effective source rock TOC content.

The paper focuses on the petrology and pore configuration of lacustrine source rock rich in organic matter, on the basis of the analysis of whole rock and clay mineral X-ray diffraction, organic petrology, maturity, porosity, argon ion polishing+SEM, and MP, through a case study of the First Member of Shahejie Formation from Well Luo 63 and Yi 21 cored interval in Bonan sag, Zhanhua depression. The results show that the source rock rich in organic matter is mainly composed of carbonate minerals, clay minerals and quartz, with a little feldspar, pyrite and gypsum, and the clay minerals are consisted of mixed layer of illite/smectite, and illite. From the top to the bottom of the cored interval, the contents of carbonate minerals increase, the clay minerals and quartz decrease, and the lithologic character changes from the calcareous mudstone to the argillaceous limestone. The source rocks are layered, or laminar and block like. The average porosity of the source rocks from the Well Yi 21 and Luo 63 is 2.09% and 4.43% respectively, and the porosity of the source rock with laminar structure is relatively high. The pore types of the source rock rich in organic matter are dominated by mineral matrix pores (inter-particleand intra-particle) and fracture pores with no organic-matter pores. The pore radius is from several nanometers to several micrometers, dominated by macro-pore with its pore diameter larger than 50 nanometers.

Nickel resources are rich and composed of magmatic type and weathering crust type for prediction in the Mid-Southern Africa. Four metallogenic epochs of nickel deposits and mineralized occurrences have been divided based on the data of 243 nickel deposits and their mineralization, which are Neoarchaean, Paleoproterozoic, Mesoproterozoic, and Neoproterozoic. Six metallogenic belts include Kaapvaal Paleoproterozoic Cr-Ni-Cu (PGE) metallogenic belt in South Africa, Great dyke Neoarchaean Ni-Cr(PGE) metallogenic belt in Zimbabwe, Francistown-Selebi-Phikwe Neoarchaean Ni-Cu-Au metallogenic belt in Namibia, Zambezi Ziemba-Lusaka Neoproterozoic Au-Ni-Cu metallogenic belt in Zambia, Wubendi-U Sagar Jin Mesoproterozoic Ni-Cu metallogenic belt in Tanzania,and Kibara Neoproterozoic Ni-Cu-Co metallogenic belt in Tanzania. We discussed the typical characteristics and metallogenic models of the nickel deposits which related with the breakup of continental margin Ni-Cu(PEG) deposits, large igneous provinces related Ni-Cu deposits,and weathering crustal Ni-Cu(PEG) deposits. The comprehensive research shows that there are great Ni mineral resources potential and good prospects in Bushveld ore district, Great Dyke of Zimbabwe ore district, Francistown-Selebi-Phikwe ore district of Botswana, and Musongati-Kabanga ore district of Tanzania-Burundi.

Numerous skarn Cu polymetallic deposits are discovered in the southern Bangonghu-Nujiang suture zone (BNSZ), which are related to the Bangonghu-Nujiang Middle Tethys Ocean southward subduction, collision, and post-collision. There are a lot of researches on a single deposit, but not on the contrast between two deposits. The authors systematically summarized the characteristics of S and Pb isotope of these deposits in combination with the previous researches on the Re isotope, the geochemical characteristics of metallogenic rock body, rock-forming and ore-forming age, and regional tectonic evolution, and took the contrasts between deposits into the study on the ore-forming materials of these deposits formed under different tectonic backgrounds. The results show that the δ³⁴S values of Shesuo deposit present a notable bimodel distribution,which can be explained by the mixing of stratum and mantle. In summary, the ³⁴S values were gradually enriched from the oceanic crust subduction stage (Shesuo), through the plate collision stage (Galale and Gaerqiong), to the post-collisional stage (Bangeria). The composition of Pb isotope indicates that the Shesuo deposit is enriched in radiogenic lead than the other deposits, and the ore forming material of Shesuo and Bangeria deposits were mainly sourced from the Nyainqentanglha group crystalline basement,while Galale and Gaerqiong deposits were from a mixture of crust-mantle materials, and the basement has a small contribution to the Gaerqiong deposit. In addition, the ore forming material of porphyry-skarn deposits has the characteristics of the mixture of crust-mantle materials, while the material of a skarn deposit mainly came from the upper crust.

The Zaozigou gold deposit is located at the west part of the Western Qinling Mountain range. It is one of the recently discovered large-scale gold deposits. The ore bodies are hosted in the Triassic Gulangti sedimentary rocks, and have a close relationship with the medium-acid dykes. The ore bodies and Indo-Sinian granitic veins are tightly controlled by faults; where the metal sulfides are stibnite, pyrite and arsenopyrite et al. Microscope observations showed that there are two-phase isolated primary inclusions in the gold-bearing quartz veins. Homogenization temperature falls in 129.8-324.3℃ with 203.2℃ as the average. The salinity w(NaCl) is 1.22%-10.73% with 6.04% as the average, indicating that the average density of ore-forming solution was 0.90 g/cm³, and the average depth was 2.00 km. The analyses of the fluid inclusion composition showed that the composition of gaseous phase is a NaCl-H₂O-CO₂ system, and the main fluid phase composition is a Na⁺-SO₄^2--Cl^- system. The Laser Raman spectroscopy revealed that the main composition in single inclusion are H₂O,CO₂ and SO₂, only a few with CH₄ and CO, suggesting that the ore-forming fluid in the Zaozigou deposit is a fluid of magmatic water mixed with ground water formed under low temperature, low salinity, and low density. The studies indicate that the mineralization has intimate relationship with two different proper fluid boiling and fluid mixing. The composition of the sulfur isotope is relatively stable, and the value of δ³⁴S_V-CDT changes from -10.30‰ to -8.10‰ with the average value of -9.33‰, suggesting that the sulfur was mainly derived from the deep seated magma and a little from sedimentary strata. The lead isotopic ratios of ore samples are ²⁰⁶Pb/²⁰⁴Pb 18.166-19.027, ²⁰⁷Pb/²⁰⁴Pb 15.608-15.741, ²⁰⁸Pb/²⁰⁴Pb 38.249-39.275, indicating the crust and mantle mixing lead. The characteristics of the deposit, the nature and resource of ore-forming fluids and material suggest that the Zaozigou gold deposit is a kind of epithermal deposit related with magmatism.

The Yangbishan iron-tungsten deposit is located in Shuangyashan area of Heilongjiang Province, tectonically in the central of Jiamusi massif, the eastern Central Asian Orogenic Belt. The major ore-hosting strata in this area are the metamorphic rock series of Dapandao Formation in Xingdong Group. The layered iron orebodies are mainly hosted in the lowest rock section of Dapandao Formation. The lenticular and vein scheelite orebodies occur in the footwall of iron orebodies, and are controlled by the contact zone between the gneiss granite and the marble of Dapandao Formation. The ore-bearing rocks of tungsten mineralization in the Yangbishan deposit include garnet skarn and diopside skarn. The metallic minerals in the tungsten ore are mainly of scheelite and pyrrhotite, with a small amount of magnetite, pyrite, chalcopyrite, sphalerite, cassiterite, arsenopyrite and molybdenite. The δ¹⁸O_quartz value of scheelite-quartz veins in the Yangbishan deposit is 10.9 ‰-14.8 ‰, the δ¹⁸O_water value is 3.6 ‰-7.5 ‰, and the δD value is -120.9 ‰—-66.2 ‰, which show that the ore forming fluid of the scheelite mineralization is dominated by magmatic water. The δ³⁴S value of metal sulfides in the skarn changes from 16.1 ‰ to 18.1 ‰, ²⁰⁶Pb/²⁰⁴Pb value from 17.879 to 18.863, ²⁰⁷Pb/²⁰⁴Pb value from 15.537 to 15.603, and ²⁰⁸Pb/²⁰⁴Pb value from 38.202 to 38.544. The data presented in this paper indicate that S and Pb in the metal sulfides mainly came from the ore-hosting strata and re-melted granitic magma. The geological characteristics of the tungsten mineralization in the Yangbishan deposit are similar to those of the skarn-type tungsten deposits. It can be concluded that the scheelite mineralization in the Yangbishan iron-tungsten deposit belongs to skarn-type deposits.

In this paper, we present the LA-ICP-MS/SIMS U-Pb ages and Hf isotope compositions of detrital zircons from the metasedimentary rocks and intrusive rocks within the Jinyinku Formation in the northern Jiamusi massif to constrain the depositional ages and provenance of the strata. All the zircons separated from our three samples are euhedral-subhedral in shape,and display striped absorption and/or oscillatory growth zoning patterns in CL images, implying their magmatic origin. The dating results indicate that the 72 analytical spots of zircons from a sericite schist yield ages between 1 955 Ma and 457 Ma that can be subdivided into five age populations with peaks at 814, 757, 568, 491, and 463 Ma. Their ε_Hf (t) values and two-stage model ages (T_DM2) range from -13.9 to -0.1 and from 2 411 to 1 715 Ma, respectively. The zircons from aplite and diabase that intruded in the Jinyinku Formation yield weighted mean ages of 263 Ma and 267 Ma, respectively. Additionally, the former has the ε_Hf (t) values of 0.9-2.0 and T_DM2 ages of 1 110-1 047 Ma;whereas the latter has the ε_Hf (t) values of -7.7-6.4 and T_DM1 ages of 1 206-662 Ma. In consideration with the occurrence of the granitoids with the ages of~430 Ma within the Jiamusi massif, zircon age populations, and Hf isotopic compositions, we conclude that the Jinyinku Formation formed between 463 Ma and 430 Ma (i.e., Late Ordovician to Early Silurian) in a passive continental margin setting,and sourced mainly from Neoproterozoic and Early Paleozoic terrane in the Jiamusi massif and adjacent regions.

The Buheta Cu (Au) mineralization district is located to the west of the north margin of Nalati tectonic belt, Zhaosu County in Xinjiang Province. Monzogranite and quartz diorite are developed in this deposit,and the Cu-Au mineralization is found in the margin of the plutons and the contact zone between the plutons and wall rocks. The LA-ICP-MS zircon U-Pb dating results of monzogranite and quartz diorite are (434.5±4.6) Ma and (445.7±5.1) Ma, consistent with Late Ordovician to Early Silurian. According to the geochemical data, they belong to shoshonitic granites of peraluminous S-type with high A/CNK value of 1.35-1.42 and 1.47-1.71 respectively. The granites exhibit weak negative Eu anomalies(δEu=0.67-0.80), enrichment in LREE and large-ion lithophile elements (such as Ba、Th and U),and depletion of high strength elements(such as Nb and Ta). It suggests that the granites were generated from the partial melting of metagreywacke. Combined with the regional tectonic evolution, we conclude that the emplacement of granites in Buheta mineralization district was related to the post collision stage of the Middle Tianshan plate and the Yili plate through a partial melting of middle and lower crustal sedimentary rocks.

The most rock types are Phanerozoic granites and volcanic rocks in the Great Xing'an Range, with small amount of basic and intermediate intrusive rocks which have been reported in Tahe, Tayuan, Fuxili, Wula Mountain and Biliutai. The differences of the formation ages and petrogenesis between those rocks provide the major basis and clues in the study on the evolution of crust and mantle in the Great Xing'an Range. We observed two irregular basic masses in the granitic complexes during the basic geologic surveys in the middle of Xiaokuile River, the Honghuaerji region, the north of east slope of the Great Xing'an Range. We obtained five points by systematical researches in petrography, chronology, elements,and Hf isotopes geochemistry. The two basic rocks are composed of fine-grained bojite and gabbro diorite. We collated the single grain zircon LA-ICP-MS U-Pb dating, and concluded that the age of diagenesis is 310-293 Ma. Rocks are the transitional series of metaluminous potassic-sodium and tholeiitic-calcalkalic. The main residual minerals of the initial magma that originated by low-degree (less than 5%) partial melting of the EM derived from the metasomatism of melt-fluid are pyroxene, garnet and perovskite. The evolution of magma was mainly of fractional crystallization followed by accumulation. The basic rocks were formed in the initial environment which was under the late collision between the Songnen massif and the Xing'an plot or the initial oceanic island-late oceanic arc.

The Mid-late Neoproterozoic strata in the Three Gorges area may record a series drastic changes on the earth system. Although the Liantuo Formation may experience the breakup of the Rodinia and the start age of the Nanhuan glaciation, its age and regional stratigraphic correlation are controversial. In this study, we obtained two SHRIMP U-Pb age of (810±7) Ma and (763±10) Ma from a tuff bed in the bottom of the Liantuo Formation. The older one may represent the resedimentation of the Huangling granites. Together with the reported ages, we suggest that the Liantuo Formation in the Three Gorges area was deposited during 780-714 Ma. The regional stratigraphic correlation suggests that the Liantuo Formation is related to Chengjing/Kaijianqiao Formation and the Banxi, Xiajiang and Danzhou Group. Whereas, due to the lack of the early stage deposition (820-790 Ma), the Liantuo Formation can be related only to the mid-upper part of the Xiajiang Group and Danzhou Group.

A total of 7 327 topsoil and 400 rock samples were collected in Beibu Gulf of Guangxi, and the concentration of the arsenic (As) and other elements or soil properties, such as K₂O, Na₂O, CaO, MgO, SiO₂, Al₂O₃, TFe₂O₃, Mn, Ti, soil organic matter (SOC) and pH, were analyzed to discuss the relationship between the As and parent rock, weathering process, main elements, and soil properties. Moreover, we attempted to delineate the primary and secondary relationships between these factors. The results of this study show that the concentration of As is 7.96×10^-6, lower than the background value of China soil. Weathering play a role in As accumulation more important than parent rocks. The results of Pearson and principal analyses indicate that Al-bearing, Fe-bearing minerals and SOC play a primary role in As accumulation, the influence of pH and Ca-bearing mineral is weak, and the role of K-bearing, Na-bearing and Mg-bearing minerals in As accumulation is negligible.

In the design of landslide prevention, the determination of thrust is a precondition for reasonable design of control engineering. The progressive deformation failure modes of three types of landslides were analyzed, and the progressive evolution process of the different types of landslides were described based on the weakening of sliding zone parameters in this study. The different part of sliding zone were portrayed spatially for going through three states of the pre-peak stress state, critical stress state and residual stress state according to the corresponding mechanical strength in the three stages of the pre-peak stress stage, the softening stage and the residual stress stage. The distinguish criterion of sliding block of critical state was proposed based on the unbalanced thrust method. The calculation model and calculation formula of thrust of progressive failure of landslides were established, and the parameter value method of sliding zone was proposed. Moreover, the thrust variation in the process of progressive failure was analyzed from the points of view of different types of landslides. The results show that when the different types of landslides were progressively damaged to the fifth states, the thrust of retrogressive landslide, load-caused landslide and complex landslide was 4 100, 4 980 and 3 150 kN/m respectively, and the thrust of load-caused landslide is the largest, indicating that there is a significant difference in landslide thrust in different modes. This method can not only reflects the progressive failure process of different types of landslides, but also solves the problem of the thrust calculation of landslide with strain softening properties, and further can provide a reasonable thrust estimation for the design of landslide prevention.

As a kind of loose structured deposits, the stability of landslide dams reduces with the upstream water level rising. Under the worst situation, a sudden dam-breaking would happen. Taking the Tangjianshan barrier dam as the research object, based on the similarity principle, the indoor flume model experiments were conducted to simulate the whole failure process in different conditions, including different impoundment, upstream water level,and particles composition. The monitoring results indicate that:The failure process can be mainly divided into seepage, overtopping, scour, and breach; The smaller the proportion of the composition particles accounts for, the lower the allowed seepage gradient of the dam is; Under the same grading of composed material and the same upstream water level, the sectional breach size is positively correlated with the impounding water. The experimental results reveal the overtopping failure law of landslide dams,and provide some theoretical reference for a breach prevention.

To explore the influence of a utility tunnel's dynamic boundary conditions on its seismic dynamic response, the authors targeted at the typical soil layer in Xiamen, China, and analyzed the site response under the effects of Rayleigh waves and shear waves through building a dynamic finite element (FE) numerical model, adopting the hardening soil model with small strain stiffness (HSS) as the constitutive model of soil, and constructing the three artificial boundary conditions, namely fixed boundary, viscous boundary, and free field. After evaluating the effectiveness of the three boundary conditions in terms of deformation characteristics and pseudo-spectral acceleration (PSA), the authors proposed an optimized dynamic boundary combination conditions in the seismic dynamic analysis of utility tunnels. The research results showed that under the effects of seismic waves (bottom horizontal acceleration time history) and Rayleigh waves, a viscous boundary condition only touched upon the absorption of external traveling waves while leaving out of the problem of seismic input and the elastic resilience of semi-infinite media outside the boundary, thus imposed restrictions on the soil mass's horizontal displacement within the model, and which resulted in a smaller horizontal displacement; under a free-field boundary condition, not the foregoing restrictions but the strong oscillations occurred; under the optimized dynamic boundary combination conditions of the excitation-applied side adopted fixed boundary, the excitation-free side viscous boundary, and the rest sides free-field boundary, there was less dynamic response cross interference under the effects of Rayleigh waves and bottom acceleration time history, so that the signals could be treated by linear superposition. In the meantime, the viscous boundary could absorb the dynamic response induced by seismic waves to a certain extent, and the free-field boundary could limit the deformation of the dynamic response induced by Rayleigh waves to some degree. The research findings are expected to provide a reference for an elaborate numerical simulation of the seismic response of underground utility tunnels and their seismic design.

Datong hydrological station is the first key interface to enter the Yangtze estuary, thereby, the relationship between hydrology and sediment directly affects not only the spatial and temporal distribution of suspended sediment in the Yangtze estuary,but also the evolution of Yangtze delta. Further research on the driving factors of the relationship between water and sediment at Datong Station will be helpful to better understand the pattern of sediment transport in the Yangtze River basin, and to provide a scientific basis for an in-depth study on the evolution of the basin landscape and its response to human activities. Based on the mathematical statistics method, we qualitatively and quantitatively studied the effects of climate change and human activities on water and sediment characteristics at Datong Station from the precipitation and runoff change, water and soil engineering and so on. The results indicate that the climate change affects the change of water and sediment transport to a certain extent, and more reflects in the effect of long-term changes in sediment transport. However, the influence of large water conservancy and other human activities on sediment transport reflects mainly in the trend and time points of abrupt change. Human activities are the direct and main cause for water and sediment changes at Datong Station.

A batch of experiments were conducted to investigate the feasibility and efficiency of in situ biostimulation for indigenous microbial community to remove Cr (Ⅵ) contamination in groundwater ranged from 20.0 to 110.0 mg/L. The results indicated that after 77 days of reaction, the Cr(Ⅵ) concentration decreased from an initial value of 20.0, 30.0, 50.0, 80.0, 110.0 mg/L to 0.0, 5.8, 19.0, 43.6 and 65.8 mg/L respectively,with the removal efficiency of 100.0%, 80.7%, 61.9%, 45.5%, 40.2% correspondingly. The sediment analysis demonstrated that the reduced Cr was combined stably with Fe-Mn oxides and organic matter in natural environment. In addition, with the reaction progress, the reaction system was gradually changed to acid condition, and pH was 5.80-6.70. The dissimilatory iron reduction occurred after Cr (Ⅵ) was completely consumed, with an increasing of aqueous Fe (Ⅱ) concentration, and its maximum concentration of Fe (Ⅱ) reached to 117.0 mg/L. Overall, the Cr (Ⅵ) that concentrated up to 110.0 mg/L can still be reduced by microorganisms in the natural fine sands through emulsified vegetable oil amendment, and the products are stable under natural conditions with little impact on a subsurface environment.

In order to understand the spatial variability of nitrate nitrogen in soil and provide a basis for control and remediation of nitrate contaminated soil, taking one typical agricultural irrigation area in Northeast China as an example, we analyzed the spatial variability characteristics and influencing factors of nitrate nitrogen in soil by geo-statistical methods. The results show that the spatial variation of soil nitrate nitrogen is significant, and the coefficient of variation is above 82.88%. There is strict autocorrelation of soil nitrate in the north-south direction of the first layer soil,the structural component of spatial variation is high. The spatial variation of nitrate in the second and third layers of soil is in a similar way as a fractal Brown movement, and the nitrate content of the fourth layer of soil is changed randomly in all directions. The total content of soil nitrate nitrogen decreases from the west to the east, and the content of soil nitrate were both high in the lower reaches of Hunhe River and near the Xihe River. The effects of different factors on the spatial variation of nitrate nitrogen are different. The content of nitrate in soil is consistent with the spatial distribution of organic matter content. The soil nitrate nitrogen in paddy field decreases linearly with depth,while the content of nitrate nitrogen in other types of soil has a rebounce after a downward decline, which is associated with the soil environmental characteristics with surface loam and sandy soil rich in nitrate.

In an integral equation (IE) method, the storage of Green's coefficient matrix and solution of linear equation system are always challenging for its development and application. Quasi-linear (QL) approximation method assumes that a linear relationship exists between the background and abnormal field. It can deal with nonlinear problems effectively. For a multiple-transmitter airborne EM (AEM) problem, however, the calculation is substantially slowed down. In this paper we present an algorithm based on quasi-linear approximation (MGQL) of multiple grids, through utilizing the Toeplitz property of the coefficient matrix to store it and the fast fourier transform to achieve the matrix-vector multiplication so as to reduce the computational complexity. This method combines the advantages of IE and QL, and can be a fast and accurate tool for a numerical modeling for the multiple-transmitter airborne EM. Numerical experiments show that the MGQL method is efficient for AEM modeling. The memory and time requirement for MGQL method is much less than that of the existing IE methods. Especially for large grids, the computation of this method can be accelerated by over 10 times than before. It is expected that its extraordinary computational efficiency will fundamentally improve 3D AEM inversions.

To speed up 3D magnetotelluric (MT) modelling, we introduce a novel algebraic multigrid-aggregation-based algebraic multigrid method (AGMG) into three dimensional forward modeling of magnetotelluric. We used the finite-volume algorithm based on the Yee's grids to discretize quasi-static Maxwell's equations with Dirichlet boundary conditions,and used the AGMG method to solve the final large sparse linear equation system in electric field. Through the coarsening of AGMG and the aggregating based on N-passes of a pairwise matching algorithm applied to the matrix graph,we proposed three different AGMG algorithms:1) the classic V-cycle AGMG algorithm;2) the AGMG preconditioned conjugate gradient algorithm (AGMG-CG); 3) the AGMG pretreated generalized conjugate residual method (AGMG-GCR). We performed 3D MT modelling for typical geo-electric models with different iteration,and analyzed the features of the AGMG techniques through comparing with ModEM algorithm. The results show that the AGMG methods are accurate and robust, the AGMG preconditioner improves the convergence of the classic V-cycle AGMG and Krylov subspace methods greatly. The AGMG-GCR method is the most effective one presented in this paper,which speeds up the modeling by ten times more than the ModEM codes for large-scale grids (144×152×104). The AGMG-GCR is especially suitable for large-scale 3D MT modeling because of its high precision, fast convergence, and robust iteration.

Geometry design plays an important part in seismic exploration. Optimum geometry can not only improve the quality of datum but also reduce the cost of acquisition. Through the forward modeling, with the increase of offset we found the phenomenon that the events would cross or even merge, and the stratigraphic sequence would become confused. According to the characteristics of a single vertical cable and multiple vertical cables, we designed the corresponding geometries, and then evaluated and optimized the designed geometries. The conclusions are drawn as follows:First, to increase shot point density is better than to increase shot area to improve bin fold; when a shot line interval is equal to a shot point interval, the distribution uniformity of a bin fold in each bin is the best. Second, when the target layer is inclined, the illumination area shows the shape of trapezoid, and part of the area can't be illuminated. The illumination loss can be compensated through increasing the number of shot line along the structural trend, and increasing the length of shot line along the downdip direction at the same time. Third, when the target layer is anticline or syncline, to increase the scope of illumination by increasing the radius of the maximum ring is small, although the marine vertical cable is moved every where. The best way is to deploy multiple marine vertical cable in a ring. Fourth, when a shot area is equal to a receiver area, to improve bin fold of the center area by increasing both of them doesn't work. However, it works thoroughly when the shot area is bigger than the receiver area.

Because of the Tanlu fault, many tectonic movements occurred in the eastern sag of Liaohe depression, all of which were accompanied by volcanic activities with different intensity. So volcanic rocks are widely developed. The volcanic rocks are dominated by basalt and trachyte, which are divided into 5 lithofacies and 14 sub-facies. Furthermore, based on the analysis of conventional logging curve and electrical image logging, 10 lithofacies/sub-facies are recognized such as explosive facies (pyroclastic flow, surge sub-facies), effusive lava flow facies (hyaloclastite, tabular flow, compound flow sub-facies), extrusive dome facies (inner zone, intermediate zone, and outer zone sub-facies), volcaniclastic facies (resedimented volcaniclastics, epiclast-bearing volcanogenic deposits sub-facies). The pyroclastic flow sub-facies ischaracterized by welding, and pyroclastic surge sub-facies is characterized by various beddings; the hyaloclastite sub-facies has high CNL, the tabular flow sub-facies is with smoothed logging curves of DEN, CNL and AC, and the compound flow sub-facies is with finger-shape logging curves; from inner zone to outer zone, the resistivity decreases; the ranges of GR values of the sub-facies of resedimented volcaniclastics and epiclast-bearing volcanogenic deposits sub-facies are different, and the resedimented volcaniclastic deposits is with horizontal beddings. The volcanic facies control the type of primary reservoir space, and affect the secondary transformation, the physical properties, the storage, and the effectiveness of the reservoir. The reservoir of hyaloclastite sub-facies with pore development has good physical properties; however, because the internal vertical structure is inconsistent and strong heterogeneous, the oil content of the reservoir is poor. The lithology and structure of the pyroclastic flow sub-facies is consistent vertically, the reservoir physical properties are relatively uniformly distributed, which is a favorable facies belt for further exploration and development.

In the exploration and development of oil field, it is always a difficult problem to accurately and efficiently identify fractures in reservoirs. The conventional well log is easy to identify the fracture but the accuracy is low. The imaging log has high resolution and high accuracy but complicated for artificial identification. In order to conquer the shortcomings of conventional and electrical imaging well log fracture identification, this paper presents an efficient and accurate method for reservoir fracture identification. The authors selected fracture samples based on the response of fractures in electric imaging log to establish conventional log comprehensive factor Y₁ and imaging log factor Y₂ for fracture recognition, then combined Y₁ and Y₂ to build reservoir fracture identification factor Y₃. Y₃ is used to identify fractures, which is more accurate than conventional log with the sampling interval 0.002 54 m which is much less than the conventional log interval 0.125 m. Compared with the electric imaging log, it can not only save time and labor but also increase the efficiency of the automatic fracture pick up. The method was applied to the identification of volcanic reservoir fractures in Wangfu area, which quickly and accurately identified the reservoir fractures, and its accuracy is about 80%. This can be a reference for the identification of other types of reservoir fractures.

In order to study the micropore structure of petroleum reservoir and develop 3D micro percolation model, CT(computed tomography)scanning and image processing of typical low- permeability reservoirs were carried out in the H152 area of the middle section of Shahejie Formation in Dongying depression, and a micro digital core model was established. Then, through the analysis and calculation of the model, the reservoir pore throat network model attributions of different scales of pores and throats were displayed intuitively and clearly in three-dimensional space. Based on the analysis and calculation of dynamic and static parameters such as pore structure, porosity, permeability and pressure drop, a micro percolation model of reservoir samples was established. According to the comparison of algorithm and analysis of the parameters, it is concluded that:Compared with the traditional median filter, the non-local-means filter algorithm that based on the comparison of similarity and the accuracy of the model is improved; The CT-based digital core can provide a reliable digital model for geological research; Based on the assumption of isobaric surface, the numerical simulation of percolation was carried out, and the characteristics of fluid transport were analyzed. The numerical simulation of percolation provides a new way to reveal the transport law of low permeability reservoir.

Aiming at the difficulties of geological mapping at shallow cover areas Northeast China, such as fewer outcrops, lower efficiency, lower precision and accuracy, we developed a geophysical and geochemical information integration technology for geological body identification. It is suitable for the shallow cover area in Northeast China, where it is huge with the features of strong physical weathering and small soil displacement. In this method, the entire study area is divided into a number of statistical units, the regional aeromagnetic information in each unit is transformed into characteristic parameters, such as mode, interquartile range, frequency, skewness, kurtosis, and the regional geochemical information in each unit is transformed into the characteristic parameters, such as acidity, alkalinity, calcium content, aluminum content, content of calcium and magnesium, content of aluminum and silicon, content of magnesium and iron, and individual trace elements. Then, all the units are classified step by step based on their characteristic parameters to finally identify geological bodies. Taking somewhere in a typical shallow overburden area in Northeast China as an example, we applied this method. By comparing the results with the known geological information, the recognition results of geologic units are in good agreement with the known information. This method can provide richer geological information and new clues for regional geological research.

The research tries to solve the problem of lithological classification in the area where it's hard to implement a geological survey, in the meanwhile, by using a thermal method to find tectonic features which are hidden under the visible light. Some minerals, like quartz and feldspar, do not exhibit absorption features in the VNIR and SWIR regions, but display fundamental molecular absorption features in the TIR wavelength region.These characteristic spectra always reserve on the rock surface's measured spectra. On the basis of the emissivity spectra of the rock samples which are measured by FTIR in the region of thermal infrared spectroscopy, the lithology could be classified by band ratio method of ASTER TIR image. The measured emissive spectra of blueschist rock samples' in Akesu carry a large amount of information. The Restrahlen Features (RF) positions of muscovite quartz schist are similar to that of the monzonitic quartz schist. Their resampled spectra curve shows that the rock emissivity increases from ASTER Band 12 to Band 13, but only muscovite quartz schist has a higher emissivity value in Band 13 and Band 14 than Band 10 and Band 12, which could be distinguished from other samples. The Muscovite Index (I_m=((B14·B13)/(B10·B12)) is established to indicate the distribution of muscovite's content in the study area. The chlorite epidote schist's spectra are in the high value position, which is the same as that of the rock diabase, but it still has a significant RF position in wavelength 10.5μm corresponding to the ASTER Band 13. So we built up the Basite Index (I_b=(B12·B14)/(B13·B13) to indicate the basic rocks in Akesu geological body. According to these two expressions, we obtained band ratios on ASTER TIR emissivity products, and got the results of Akesu thermal infrared I_m and I_b image in a colored lookup table.
I_b and I_m images have a good reflection of the lithology distribution, which indicates a rich content of muscovite in the southeast Akesu and a rich basic rock in the northeast Akesu. The stratum in the northwest could be devided into several layers corresponding to the samples we collected in the field work. The diabases are clearly visible in I_b image. On the basis of these images, we drew a new Geological sketch map and found a rootless hook fold in Akesu blueschist. The previous research did not exhibit it on their map. The rootless hook fold indicates that the south part of Akesu blueschist bore a greater pressure than the north part. It illustrates a tectonic model of oceanic plate southward subduction to Tarim craton which has been put forward by Nakajima in 1990, and the thesis of Wentao Huang has a same conclusion as ours.
The authors consider that thermal infrared remote sensing has a wide application prospection for mineral identification and lithological classification.