Combineing closely the practical exploration and guided by multidisciplinary geological theory and technology, a comprehensive geological model has been set up to explain and restore paleogeomorphology unit attributes of the Ordovician weathering crust of eastern Ordos basin. Meanwhile, according to drilling and logging geologic data, authors also combine basin tectonic evolution with results of “impression method” organic integration and results of “residual thick method”, discuss the methods and thinking of Ordovician weathering crust paleogeomorphology restoration, and its ancient landscape development characteristics through in-depth analysis of the stratigraphic combination under and above Ordovician unconformity erosion surface, and explore a new method of palaeogeomorphologic reconstruction-“synthetic method”. The research results show that the stratigraphic combination, under and above Ordovician unconformity erosion surface in the eastern of Ordos basin, can be divide into four basic types including “up thin down thin”, “up thick down thick”, “up thick down thin”, “up thin down thick” , and eight sub models which were “up relative thickening down relative thinning”, “up relative thinning down relative thinning”, “up relative thinning down relative thickening”, “up relative thickening down relative thickening”, etc. The corresponding paleogeomorphology explanation includes three two-level paleogeomorphology units as karst highland, karst slope, karst basin,and eleven three-level paleogeomorphology units including monadnock, tableland, residual tableland, level terrace, cheuch, shallow depression,deep depression etc. The Karst highlands occurs restrictively in the southwestern research area.The Karst slope occupies most of the study area where the  main paleogeomorphology units were slope tableland and slope level terrace. The Karst basin is located in the eastern study area and the main paleogeomorphology units include basin shallow depression.

Submarine gas hydrates are closely related to active tectonics. Recently submarine active tectonics in the northern South China Sea attract much attention because of exploration of submarine gashydrate in the past decades. We descript the features of faults, earthquakes, and volcanic activity and other active tectonics relating to gashydrate. There are three sets of active faults including NE-, NEE-EW-, NW-striking faults in the northern South China Sea, of which NWtrending faults cut the other two groups. Most of these active faults are inherited from preexisting basement faults. NE- and ENE-trending faults are crustal or lithospheric faults. The earthquake distribution is focused on a NE-trending striped region of the northern South China Sea. However, the NW-trending earthquakes are controlled by the Red River strike-slipping fault. Gas chimneys are related to active structures that play an important role of the formation of the gashydrates, as same as the channel which provides the gas to vertically migrate up to the place under appropriate temperature and pressure for gas-hydrate formation. The distribution of volcanic rocks clockwise rotates from east to west. Based on seismic profile, the volcanic rocks are controlled by tensional fault. The distribution of gashydrates in the eastern part is affected by the NW-trending active faults, however, the west is inextricably linked with the submarine landslide.

In order to find out distribution zones of high-quality reservoirs in Penglai area, based normal thin sections, casting thin sections, scanning electron microscope analysis data and core data, the reservoirs have been worked on lithological characteristics, reservoir property and pore structure, diagenesis, diagenetic minerals, diagenetic environment, diagenetic stage and diagenetic evolution sequence in Member 2 of Xujiahe Formation. The results show that the reservoirs have experienced diagenesis such as compaction, cementation, corrosion, and fracture, it is now in the stage A of middle diagenetic stage. Three types of diagenetic facies are divided based on diagenesis, diagenetic minerals and their effect on the reservoir quality, these facies include high compactionauthentic minerals cementation facies, high compactioncorrosion of unstable components facies, and tectonic fracture facies. According to various well logging response characteristics, five normal logging curves and imaging logging data which are sensitive to the diagenetic facies are chosen to characterize diagenetic facies, which include compensated neutron logging(CNL), density logging(DEN), acoustic slowness(AC), natural gamma ray(GR), resistivity log(R_t) and EMI, different types of diagenetic facies has various response characteristics on various logging curve and their combination, and the vertical and plane distribution of diagenetic facies can be figured out with well logging data. The favorable diagenetic facies are used to optimize favorable regions of oil and gas bearing zones. The high quality reservoir distributed in the middle part of the slope on the plane surface.

Based on field surveying on the outcrop and comprehensive laboratory study, combining with the fundamental principles and methods of sequence stratigraphy, the authors analyze the sedimentary characteristics of the Wumishan Formation occuring in the western Yanshan Mountains, which are mainly composed of tidal flat carbonate rocks and rich in stromatolite. The Qiangou section, the most complete section in study area, can be divided into 26 third-order sequences which can be combined into six second-order sequences (S.1-S.6). Every third-order sequence includes three parts, which are transgressive system tract, early highstand system tract, and late highstand system tract. By correlation of sequences in the study area, the sequence stratigraphic frameworks have been established. According to the distribution of sedimentary facies belts, the paleographic environment has been preliminarily reconstructed. During the deposition period of the Wumishan Formation, the paleographic environment of the First and Second Member was slow transgression. Up to the deposition period of the Third and Fourth Member, the paleo epicontinental sea reached maximum. After then, in the deposition period of Fifth and Sixth Member, the paleo sea regressed to the center of subsidence.

Physical characteristics of sandstone in Luozigou basin were studied qualitatively and quantitatively with thin sections, mercury intrusion, SEM, X-ray diffractions and some other methods. Results show that the main lithological types of Dalazi Formation are lithic arkose and arkose with low compositional maturity and low textural maturity. The physical  characteristics of sandstone were characterized by high porosity ( 16.2% to 26.4%) and very low permeability(0.13×10^-3μm² to

1.68×10^-3μm²), and the porosity type was mainly secondary pores which accounst for 88% of the whole porosity. Result of organic element analysis，chromatography，maceral microscopy and rock pyrolysis showed that large amounts of organic acids generated during the thermal evolution of mudstone and shale in Luozigou basin and dissolute feldspar in sandstone, which lead to high secondary porosity. While, at the same time, associated products of the dissolution blocked the throat to some extent. These two processes make the sandstones show high porosity and low permeability.

Authigenic carbonate minerals are important proxies for the methane seepage and its periodical variation. In order to identify carbonate mineral easily and quickly, the authors discuss whether the end-members (which are aragonite, high-Mg calcite, biogenic calcite and detrital individually) model presented by previous researchers is applicable, and then calculate the authigenic carbonates contents according to the Sr/Ca and Mg/Ca ratios of the bulk sediment of two cores individually in Shenhu area in the northern South China Sea. The results show that there are authigenic carbonate minerals in different depths, which are also proved by the results of XRD and the appearance of authigenic high-Mg calcite and aragonite crystals in the sediments. The appearance of the authigenic carbonate minerals show that the methane seepages has been existing in ancient time and nowadays. The vertical variances based on the sedimentary geochemical proxies implicate that the methane seepages had multi-stages variations. So the end-members model presented by previous researchers can be used in the northern South China Sea. The end-members model is a good method to gain the high-resolution authigenic carbonate minerals profiles, consequently to identify methane seepages recorded in marine sediments, and potential to trace methane seepages and to explore gas hydrate in extent area.

The Hulin basin is a Meso-Cenozoic, down-warped, faulted basin located in the eastern part of Heilongjiang Province, which superimposed on the Jiamusi uplift. The structural evolution can be divided into 3 stages, and the structural characteristics and deformation mechanism for each stage are significantly different. 1)A series of separate NE trending half-graben fault depressions developed at the NW-SE-directed extensional stage in the Early Cretaceous. 2)Some of the early depression-controlling normal faults reversed and formed inversion structures during NW-SE compressional stage in Late Cretaceous, the Hulin basin switched into a depression basin with multi-depocenters under the NW-SE-directed compression depression. 3)The tectonic framework changed significantly at the NNW-SSE-directed compression stage in the Paleogene-Quaternary, not only some of the early depression-controlling normal faults reversed, resulting in large-scale inversion structures, but also the NEE trending large-scale thrust faults (Dunhua-Mishan fault zone) and fault-propagation-related folds between the Qihulinhe depression and the central uplift formed, which together controlled the formation and sedimentation of the basin, and the Hulin basin transformed into a NNE trending, down-warped compressional basin which are composed of the central uplift, the south and the north depressions. The Northeast China has been always in an active continental margin tectonic setting since the Cretaceous. The formation mechanism of Hulin basin, which is included in the eastern basin groups of the Northeast China, is related to the subduction of Izawa Naqi plate, the Pacific plate to the Eurasian plate. The Dunhua-Mishan fault zone are NE trending sinistral strike-slip faults, and the NE segment near the the Hulin basin transform into the NEE trending thrust fault, the thrusting of the NE segment of the Dunhua-Mishan fault zone may be related to the NEE trending transformed compression of the NE trending sinistral strike-slip of the fault. The Dunhua-Mishan fault zone developed at the Hulin period of Eocene-Oligocene, and showed continuously activities from the Hulin period to Quaternary.

The Sichuan (Chuan)-Guizhou (Qian)-Hunan (Xiang) tectonic belt (CQXTB) can be divided into four different sub-belts. The Xuefengshan tectonic belt (XTB), one of the four sub-belts, is the most particular and hotly debated on its genetic mechanism, because it’s just located in the gravity gradient belt of South China block, and the thickness of lithosphere changes greatly along the both sides of the XTB. The structural styles of CQCTB are analyzed. The geological basement of XTB shows a flower style and constitutes a thick-skinned structure together with Chuan-Qian fold belt, as a whole. The XTB is characterized by compressive-twisting features and its basement uplifts to the maximum height in the Yuanma basin. The lithosphere thickness of South China is also transformed with time. Referring to the deep seismic reflection profile, the authors draw the deep and shallow structure profile maps of the QXTB. Based on the different coupling styles between middle-upper crust and lower crust, the authors discussed the deformation process of the lower crust. The lower crust’s downward bidirectional subduction under the XTB forms a root without subduction into the mantle. Meanwhile, the lithosphere is bended due to the thickening of crust. After then, the lower crust and upper mantle probably depressed due to Rayleigh-Taylor instability of dense subcrustal lithosphere, where the lower crust and upper mantle sank into the asthenosphere mantle. Finally, under the extensional tectonic background, the asthenosphere rose, which resulted in the delamination of lithosphere at the east of XTB during the Late Mesozoic Era.

The Hongqiling copper-nickel sulfide deposit mainly consists of No.1, No.2 and No.7 ore-bearing intrusions. The Re-Os isochron age of No.2 intrusion ((215.0±24.0) Ma) is consistent with zircon SHRIMP U-Pb age of the intrusion, (212.2±2.6 ) Ma, but the Re-Os isochron age of No.1 intrusion((237.0±16.0) Ma) is greater than zircon SHRIMP U-Pb age of the No.1 intrusion, (216.0±5.0) Ma. All these data indicate that Re-Os isochron ages of disseminated ores are not completely reliable. The Re-Os isochron age is greater than zircon SHRIMP U-Pb age, which is usually interpreted as crustal contamination inducing heterogeneity of Os isotopic. However, the research shows that No.1 and No.2 intrusions are mixed with some of the Earth’s crust substance, and the mixing volume of No.2 intrusion is slightly higher than that of the No.1 intrusion, which indicate that hybridization of crust materials is not the cause of heterogeneity in initial ¹⁸⁷Os/¹⁸⁸Os ratios, the major reason should be a further research. The initial ¹⁸⁷Os/¹⁸⁸Os ratios of No.1 and No.2 intrusions are 0.215±0.043 and 0.302±0.089, and γ_Os values range from 67.5 to 155.8 and 113.9 to 206.9, respectively, which indicate that the oreforming intrusions interfuse some crustal materials with possibly 20%-30% crustal Os contamination in Hongqiling area, and crustal materials might be the key factor to promote liquation ore formation.

The liquid immiscibility and hydrothermal fluid exsolution from magma are the important separation mechanisms of ore-forming fluid from granite magma. At present, the understanding of the two mechanisms is mainly from researches of melt and fluid inclusions, or none-in-situ experiments. The newest hydrothermal diamond anvil-cell (HDAC) is used to observe the two processes in situ. In exsolution experiments with the initial sample of silicate and pure H₂O or LiCl dissolved aqueous fluid, the H₂O-rich fluid separated from H₂O-saturated silicate melt when H₂O is saturated in silicate melt. In the experiment of liquid immiscibility with the initial samples of NaAlSi₃O₈-LiAlSiO₄-SiO₂-LiCl-H₂O, the silicate melt balls can be separated into a H₂O-rich melt and H₂O-poor melt during cooling from homogeneous silicate melt. The sharp fall of pressure can induce the liquid immiscibility. These experimental results show that the hydrothermal fluid exsolution occurred in H₂O-saturated silicate melt is the second boiling of magma, and plays a great role in the mineralization of granite type deposit. The H₂O-rich melt separated from granite magma by liquid immiscibility can crystallize big and oriented crystals, suggesting that liquid immiscibility of granite magma is an important formation mechanism for granite pegmatite. The differences between the above two type experiments suggest that the element Lithium is an important factor for liquid immiscibility in granite magma. In the further research, we should combine the HDAC with microbeam analysis in order to analyze the enrichment process of metal element at high temperature and pressure.

Located in the Central Fujian Rift, the Meixian Pb-Zn deposit is a large volcanogenic massive sulfide Pb-Zn (-Ag) deposit. Based on a detailed field study, the authors identify Yanshanian porphyry granite (148.9±1.4 Ma, 152.0±2.1 Ma) in the Meixian deposit by LA-ICP-MS zircon U-Pb dating. Geochemical analyses show the porphyry granites have high SiO₂ and potassium abundances, moderate Al₂O₃, alkaline contents, and weak peraluminous. Chondrite-normalized REE distribution pattern display right skewed shapes showing fractionation between LREE and HREE with flat HREE pattern. These granites are enriched in large ion lithophile elements (LILEs) and high field strength elements(HFSEs) without obvious depletion in Nb-Ta, indicating that they were high-potassium calc-alkaline I-type granite formed in post-collision environment. Their parental magma were experienced strongly fractional crystallization of amphibole, biotite, plagioclase and some other accessory minerals. These porphyry granites are spatially associated with lead-zinc bodies, their magma are enriched in volatile component, large ion lithophile elements and have underwent high degree differentiation by fractional crystallization, indicating the Later Jurassic magmatism in the study area is very favorable for the skarn mineralization and extensively superimposed and reformed the earlier stage massive sulfur lead-zinc ore bodies.

SHRIMP U[CD*2]Pb zircon ages are reported for rhyolites in the bimodal volcanic rocks from the Phlaythong area at the Southern of Laos. The zircons with well-defined oscillatory zoning from rhyolite sample yielded mean ²⁰⁶Pb/²³⁸U age of (229.0±2.0) Ma, which represents the eruption age of the volcanic rocks during Middle to Upper Triassic (T_2-3). Geochemically, the basalt shows an average SiO₂ content of 50.70%, enrichment of TiO₂，MgO，CaO，TFeO，LILE(Sr，Rb，Ba，Th) and LREE, and depletion of alkali, P₂O₅ and HFSE. Rhyolites are generally characterized by rich SiO₂(76.33%), alkali(w（K₂O）＞w（Na₂O）), and poor TiO₂, MgO, CaO and TFeO, they have relatively high Th, U and Zr and rather low Ta, Nb, Ba, Sr and Ti, and display obvious negative anomaly of Ba, Sr and Ti, obvious enrichment of LREE, noticeable negative Eu anomalies (δEu=0.31-0.82). According to this research, the basalt was originated from depleted asthenosphere mantle (DM) material upwelling and contaminating a little part of crustal materials, and rhyolite resulted from melting crustal materials heated by basaltic magma and felsic magma. The bimodal volcanic rocks are the products of partial extension in an intracontinental rift.

Zircon LA-ICP-MS U-Pb dating and geochemical analyses were carried out for the beryl-bearing pegmatite of Tengchong-Lianghe area, western Yunnan. Dating results revealed that the beryl-bearing pegmatite were formed at (48.1±0.8) Ma (MSWD=4.0). Zircon morphology and trace element feature indicate that the zircons suffered from hydrothermal alteration. The beryl-bearing pegmatite shows similar characteristics with respect to major elements, trace elements and rare elements with muscovite granite which formed during 55-52 Ma. They are sub-alkaline series, peraluminous granite with strongly Eu depletion, relatively enriched HREE with （La/Yb）_N=1.61-1.92 and showing typical M-type of REE tetrad effect. The genesis of beryl-bearing pegmatite is related to the evolution of muscovite granitoids and the crystallization temperature of beryl-bearing pegmatite is 581 ℃. It indicates the overthickened crust tectonic setting caused by India-Asia continental collision.

Plagioclases with special zonal structure were seen occasionally in diorite intrusion in Pingshun, southern Taihang Mountains. The plagioclases is characterized by high Ca-riched basic plagioclases (An>63) in the core and Na-riched in the rim, and a corrosion zone formed between the core and the rim that composed epidote and sericite. In addition there are distinctive compositional differences between core and rim of the plagioclase xenocrysts. Based on the evidences from the components and textures of the plagioclause, the following scenario about the magma evolution is tentatively suggested. Mantle magma originating from the EMI underplated to lower crust and crystallized Ca-riched basic plagioclases under high temperature. Crustal source magma originated by melting of lower crust with the help of heat-carrying mantle magma. Mantle magma and crustal magma ascended quickly along Taihang deep fault, intruded into shallow crust, and mixed. Meanwhile, early-formed basic plagioclases dissoluted because of sudden reduced pressure and formed corrosion zone with irregular shape. The crust-mantle magma crystallized Na-riched plagioclases on the basis of Ca-riched basic plagioclases and formed plagioclases with special zonal structure, providing the most direct evidence to magma mixing in the study area.

There are a series of landslides developing along Pingding-Huama fault zone. The properties of these landslides are evident. The origin of these lanslides is similar. In fault zone landslide generally consists of one or more secondary landslides. The sliding mass has two layers or three layers, which are composed of deposited loess, strong weathering zone of fault and fault broken zone. The landslides slip along fault strike generally and re-slip time after time historically. According to deformation measurement data in recent years, the landslide is a stage of constant speed creeping deformation at present. The processing of their deformation presents to be creeping to tensile fracture (plastic flow tensile fracture) and then to junior landslide slipping. The landslide formation is in coupling of endogenic and exogenic geological processes that are fault action, earthquake, rainfall and human engineering activity. The long time activity of Pingding-Huama fault provides precondition for these landslides formation. The rocksoil mass characteristics are material basis of landslides activity for ages, while rainfall, earthquake and slope toe excavation are mainly factors that trigger these landslides to lose their stability. Therefore, it is necessary to further study the mechanism of fault zone landslides in coupling of endogenic and exogenic geological processes so as to provide a scientific basis for the prevention and early warning of landslide disaster.

Pit soil rebounding during excavation will cause piles rebound and produce lateral friction in pit.Three-dimensional finite element analysis method was conducted to study the behavior of single pile and pile group under excavation. Results show that the rebounding displacement of single pile can be divided into two parts, namely, one is caused by the rebounding of soil around the pile and the other is caused by the rebounding of the bearing layer. The rebounding displacement and the degree of lateral friction of central pile were reduced by the shielding effects of outer piles. The relative reduction in rebounding displacement in 5×5 pile group increased with the increase of relative bearing stiffness ratio, and this kind of variation depended on the pile location in the group. Based on three cases studied, the larger the number of piles in a group, the greater the shielding effects presented. The number of piles had greater influence on shielding effect than pile spacing.

In order to provide reliable basis for foundation bearing capacity of Changchun hard plastic old clay and to discuss appropriate measures for determining the characteristic value of subsoil bearing capacity, laboratory soil test and in-situ testing methods including loading test and cone penetration test(CPT) are carried out,  and the characteristics value of subsoil bearing capacity (306-425 kPa), the value of CPT(1.9-3.3 MPa), natural void ratio (0.63-0.72) and liquidity index (0.02-0.25) are collected. Based on the test data, there can be found a linear correlation between characteristic value of subsoil bearing capacity and the value of CPT, between characteristic value of subsoil bearing capacity and natural void ratio and between characteristic value of subsoil bearing capacity and liquidity index. Therefore, an empirical formula is presented, which the characteristic value of subsoil bearing capacity can be calculated according to the value of CPT. And then a calculation table about the characteristic value of subsoil bearing capacity of Changchun old clay is summed up according to the laboratory soil test indexes.

Two aspects are always neglected in the existing research about start-up criterion of translational gliding landslide：one is the normal component force of hydrostatic pressure at posterior border of slope，which acts on slip surface，the other is the action range of confined water. Therefore the calculation results of start-up criterion of translational gliding landslide are inaccurate. Overall force analysis are exerted on translational gliding landslide，meanwhile the conception of action range of confined water is introduced，then the modified start-up criterion is deduced. The modified start-up criterion is applied to analyze the results of physical simulation. It shows that the result of the modified criterion is about 6.0% to 15.5% larger than the traditional criterion and much  close to the observed value. The modified criterion is proved to be accurate. Mechanism analysis is applied in the differences of critical hydraulic between the test results and the calculation results obtained from the modified start-up criterion of translational gliding landslide. When the sliding surface inclination of the model slope is less than or equal to 8 degree，the test results are greater than the calculation results obtained from the modified start-up criterion because of the hysteresis of seepage and the inhomogeneity of permeability layer. When the sliding surface inclination is greater than 8 degree，the test results are less than the calculation results due to decrease of the model stability with increase in test time.

The authors analyzed the spatial distribution of phosphorus in sediments to control the the eutrophication. Thirteen samples in surface sediment and surface water were collected, sequential extraction methods was used to acquire NH₄Cl-P, BD-P, NaOH-P, HCl-P, and Res-P, and the spatial distribution characteristics of these different forms of phosphorus and their impact on soluble phosphate were analyzed. The results indicated that the contents of different P fractions in the sediments varied greatly. The total P (TP) contents ranged from 808.5 to 1 698.7 mg·kg^-1. Phosphorus contents in NH₄Cl-P, BD-P, NaOH-P, HCl-P and Res-P ranged from 8.1 to 31.1, 41.9 to 84.9, 151.6 to 348.2, 312.2 to 819.9 and 226.8 to 1 003.0 mg·kg^-1, which represented 0.65%-1.85%, 3.19%-6.57%, 10.8%-24.34%, 20.26%-52.18% and 24.41%-58.33% of the total P, respectively. The total dissolved P of pore water has high correlation with the NH₄Cl-P, BD-P, NaOH-P in sediments, with 0.892, 0.848, 0.749 correlation coefficient. The results showed NH₄Cl-P, BD-P, NaOH-P as the main source of P release control.

Temperature time-series records were used to determine groundwater-surface water (GW-SW) exchange. If it is assumed that the temperature on the top boundary is oscillated in a sinusoidal pattern, the analytic model to calculate the seepage velocity by temperature damping can be obtained. Two typical analytic solutions are Hatch solution and Keery solution. The study shows that the Hatch solution is more accurate due to taking thermal diffusion into account. So it’s recommended that Hatch solution should be adopted to calculate seepage velocity. A typical permeable medium is taken as a case, and limitations and applicability of the model were discussed. It is shown that only when the study area can be simplified as a homogeneous medium and vertical seepage is dominant, the analytic model can be used. For the common interval of test points (around 1.0 m), it’s more effective to compute seepage velocity from -1.0×10^-5 m/s to 8.0×10^-5 m/s by using amplitude damping method and from 0.0 m/s to 1.6×10^-4 m/s by using phase lagging method, respectively. For the analytic model, the two test points must have amplitude damping and phase lagging. So the seepage velocity in the domain should be estimated firstly, and the reasonable interval of test points be designed then. It is shown from a case study that this method is available for evaluating the temporal variation of GW-SW exchange.

The complexity degree of the terrain and irregular degree of the border need to be fully considered in stability analysis of tailings dam. Thereby we established the true 3D seepage field of the tailings. Real seepage basin of the tailings was built by using SVOffice software without generalizing terrain and boundary conditions, and the three-dimensional transient seepage fields of the last stage filling was simulated under the normal water level (427.77 m)and flood peak(434.50 m). The results show, under two different conditions, the maximum drainage amount are both 6 100 m³/d. At the same time, the infiltration surface escapes on both sides of stacking dam, and the escape range is larger on the side far away from the drainage well, which is mainly affected by the seepage basin. Initial level of the tailing has a great impact on the seepage field of damming and the infiltration surface is the highest at the beginning of damming under flood peak. According to the simulation results, five blind drainage ditches are designed, which ensures that the infiltration surface will not escape on any position of stacking dam.

The 0-1 test is a new binary test to decide the regular or chaotic motions，which is applied directly to time series data and does not require phase space reconstruction. It is proved to be an effective test after test for chaos of Chebyshev map. The 0-1 test was carried out on monthly precipitation time series from 1958 to 2011 of 640 meteorological stations of China, and the density-based spatial clustering algorithm considering both spatial proximity and attribute similarity (DBSC) was used to perform spatial clustering. It is showed that monthly precipitation time series of all stations are chaotic, further more, the spatial distribution of K shows significant characteristic with spatial variability. In the large-scale, the country can be divided into four sub-regions, that are northwest with the highest K value, southern with the second highest, north and northeast with median and Qingzang district with the lowest. In the small-scale, 29 spatial clusters are found considering both spatial location and chaos degrees. The chaotic spatial clustering results not only coincide with the large-scale distributions of climate types, but also reflect the local variation of precipitation systems, which provides a new approach and methodology to study the temporal and spatial variation of precipitation systems.

In order to study the variations and correlations of moisture, salt, pH and urease activity in soil layers of 0-50 cm of paddy under freeze-thaw action, the soil samples were collected from paddy of Da’an City which is in the area of saline-alkaline soil in western Jilin Province. A freeze-thaw cycle of the indoor simulating experiment was freezing for 12 hours and thawing for 12 hours to simulate the transport of water and salt and the dynamic changes of soil enzyme activities under the repeated freezing and thawing condition in day and night. Then soil moisture content, salt content, pH and urease activity were tested by mass method, residue drying method, potentiometry and indophenol blue colorimetry respectively to analyze the variation law and the correlations under different freeze-thaw conditions. The results show that the depth of soil layer is one of the main influencing factors of moisture content, salt content, pH and soil urease. The moisture and salt in soil layers of 20-50 cm transfer continuously to the surface layer and moisture content shows significant correlation with salt content, which suggests that salt transfer is determined by moisture transfer to some extent. Except for the layer of 10-20 cm, soil urease activities in all layers decrease at different degrees. In frozen-thaw process, moisture content, salt content and pH all show significant correlations with soil urease activity. And soil urease activity is affected by many factors such as the number of freeze-thaw cycles, temperature, salt content, pH, organic matter and other related factors. Therefore, freeze-thaw action plays a crucial role in causing or aggravating the salinization of paddy topsoil. Freeze-thaw action results in the decrease of urease activity, which will further affect the soil fertility.

Nitrogen loss load of non-point source in small watershed was calculated and analysis and control research of water pollution sources in  Danjiangkou were carried out. Based on the monitoring of watershed section and runoff plots, the average annual nitrogen loss modulus and nonpoint source pollution nitrogen load of different land use types were calculated using mean concentration method in Yingwugou watershed. The results showed that the total nitrogen content was the major exceeded pollutant in runoff and nitrate nitrogen content was always greater than the ammonia content. When the slope of sloping cropland was greater than 25°, severe nitrogen loss and poor water quality happened. The rural production and living pollutant emissions had a great impact on water quality. Nitrate nitrogen concentration and total nitrogen concentration both increased greatly from watershed section 1 to mouth station. The average annual total nitrogen loss modulus of farmland, grassland and forestland were 0.36, 0.22 and 0.09 t／(a·km²), respectively. The average non-point source pollutant concentration of ammonia nitrogen, nitrate nitrogen and total nitrogen in watershed export were 0.17, 4.71 and 7.55 mg/L, respectively. The average point source pollutant concentration of ammonia nitrogen, nitrate nitrogen and total nitrogen in watershed export were 0.20, 2.12 and 4.08 mg / L, respectively. The average total nitrogen runoff loss modulus in Yingwugou watershed was 0.89 t／(a·km²). The total nitrogen is the major pollutant affecting water quality. The nitrogen loss of sloping farmland and rural garbage must be controlled effectively.

Based on the knowledge of the TEM theory, the secondary field direction generated by the heterogeneities in the position of the receive loop is different when the local heterogeneities exist below large fixed transmit loop, which may result in attenuation curve deviating from the response curve of the homogeneous body. In order to analyze the impact of heterogeneities to the attenuation curve, we adopts large fixed loop equipment whose area is 150 m×150 m and emission current is trapezoidal wave with the amplitude of 10 A and turn-off time  of  176 μs. We use the electromagnetic signal attenuation rule of multi-turn and close-wound coil, namely anomaly loop to simulate the response curve of  shallow heterogeneities whose time constant is respectively 1 ms, 3 ms or 5 ms.When the anomaly loop is located below the transmit loop or its frame edge, with the different relative position between the transmit loop, anomaly loop and receive loop, that will change the mutual inductance of them and cause the response of the anomaly loop negatively and lead to the integrated response attenuation curve of the receive loop appearing zero-crossing condition. So we need to attract attention of the negative response in the subsequent processing when the heterogeneities exist below the large fixed loop.

Occam’s inversion is reliable and  able to incorporate varying levels of the priori information. The Choice of Lagrange multiplier is computationally expensive and some direct selection methods are then suggested in this paper.  We modified the selected method of Lagrange multiplier in 2D magnetotelluric Occam’s inversion. In the search progress, the misfit between  the forward model response and  observed data are added and compared with  the  target level. This can eliminate superfluous forward calculation in the last iteration of the phase of bringinge misfit down and the phase of smoothing out the unnecessary structure. This modification  can accelerate inversion and more accordant with   the Occam’s idea.Through inversions of several synthetic and field data,it is improved that forward caculation number can be reduced to 20%-50%.

First-arrival times at high transmitter-receive angles are often very difficult and inaccurate to pick up by   conventional methods  because of low signal/noise in the data.  We introduce a new traveltime picking scheme based on cross-correlation. First, we normalize each trace by signal maximum and  sort the data into common-ray-angle gathers. Then, we align traces in each common-ray-angle gather by cross correlating with the other trace of  the highest signal-to-noise ratio, determine mean trace for each angle gather. Finally, we pick first-arrival time on each mean trace, cross-correlate each trace in data set with appropriate reference waveform for that angle, and determine first-arrival time. In the test of synthetic data and field data, the approach improves the results. Compared  with velocity tomography derived from common time picking technology, the new velocity tomography is more accurate, more clearly, and more helpful to distinguish the target under the ground.

In seismic wave modeling, a high-order time marching scheme is required in order to increase the accuracy of the algorithm. However, ordinary unsplit perfectly matched layer(PML) absorbing boundaries are constrained to low-order time schemes. The auxiliary differential equation PML (ADE-PML) is a kind of unsplit PMLs that can be applied to arbitrary-order time schemes, and also can implement complex-frequency-shifted (CFS) coordinate tensor to enhance the performance of PML at high-angle incidence.We introduce the ADE-PML in the numerical modeling in fourth-order Runge-order time scheme for acoustic wave equations, and validate the efficiency. The numerical experiments demonstrate that CFS ADE-PML preforms better than non-CFS ADE-PML at high-angle incidence. Besides, there are minor distinctions among the absorbing efficiency of different update schemes for auxiliary variable, and the solution calculated by explicit scheme better agree with the analytical one. The long-time computation of energy decay shows that ADE-PML is stable up to 2 × 10⁵ steps.

Seismic wave modeling in frequency-space domain is the foundation of full waveform inversion in frequency and Laplace-Fourier domain. An accurate seismic wave modeling with surface topography is the kernel of full waveform inversion which can direct process data recorded on relief surface. Based on acoustic wave equation with PML absorption boundary condition, the free surface condition on relief surface is included into the optimized 9-points finite difference algorithm in frequency space domain. Then the variable grid method which refines the grid near the surface and remains the rest unchangeable is introduced to increase the computational efficiency and decrease the memory cost. The theoretical analysis and numerical test show that: 1) the diffraction caused by grid discretization of the relief surface can be suppressed by refining the grid; 2) through the variable grid method, computational efficiency can be improved for several times and the memory cost can also be decreased for several times easily; 3) the energy of artificial reflection caused by the boundary of fine and coarse grid is less than 2% of the energy of the original  wavefield which is acceptable for the seismic wavefield modeling and inversion.

Geophone array receiving can greatly improve the signaltonoise ratio of data in some complex terrain and interference wave development areas. This kind of array uses more than one geophone to receive seismic wave at the same time as the input of a seismic trace. It suppresses interference wave mainly using the difference of the propagation direction between the effective wave and interference wave. We promote combinatorial theory from the plane to the undulating surface based on the theory and method of geophone array. We discusses the response of geophone array in the undulating surface and compared the response of effective wave and interference wave after the geophone array filter. Through the analysis，the suppression degree of interference wave is increased gradually with the increase of tilt when interference wave spreads along the up dip direction in undulating surface area. And the suppression degree of interference wave is increased gradually when interference wave spreads along the down dip direction. At the end of the article, the geophone interval of geophone array was optimized with inversion method. In the case of that geophone array direction characteristics are known, we can get the geophone interval that is matched. More numerical calculations shows that the response of effective wave is significantly higher than that of interference wave in geophone array filtered seismic data.

At present, Archie’s formula with variable cementation exponent（m） and saturation exponent（n） is still applied in quantitative evaluation of saturation of low resistivity oil reservoirs as one of the main methods. However, the influencing factors of m and n in low resistivity oil reservoirs are varied with area due to the different causes of low resistivity oil reservoirs. Therefore, the study on influencing factors and variation laws of m and n in Archie’s formula in low resistivity oil reservoirs in different areas is necessary. Samples of low resistivity oil reservoirs are cored in Putaohua Formation of southern Golong area according to division standard of low resistivity oil reservoirs, and also have definite variation of lithology, physical property, electric property. Then, petrophysical experiment of one sample is designed. A plot of m and n with parameters of petrophysics, pore structure, excess clay conductivity is made from petrophysical experiment data. The analysis shows that the values of m and n in low resistivity oil reservoirs is less than those of m and n in conventional oil reservoirs, and m and n in low resistivity oil reservoirs increase as porosity and permeability composite index, median radius, mean radius, radius mean increase. The m of low resistivity oil reservoirs decreases as shale volume fraction, cation exchange capacity, the ratio of micropore volume and movable fluid volume increase, and increases as T₂ geometric mean value increases, while the n of low resistivity oil reservoirs increases as porosity, the ratio of porosity and shale volume fraction increase. The m has a good correlation with T₂ geometric mean value, the ratio of micropore volume and movable fluid volume in low resistivity oil reservoirs, while the n has an excellent correlation with porosity and permeability composite index, mean radius, maximum radius, radius mean. The result reveals that pore structure has a larger effect on m and n of low resistivity oil reservoirs, and also shale volume fraction has a larger effect on m of low resistivity oil reservoirs, and T₂ geometric mean value or the ratio of micropore volume and movable fluid volume can be used to determine the mof low resistivity oil reservoirs, and porosity and permeability composite index, average radius, maximum radius, radius mean can be used to determine the n of low resistivity oil reservoirs.