Geoscience

Cenozoic Tectonics of the Yellow Sea and Its Oil-Gas Exploration

Wan Tian-Feng HAO Tian-Yao-

2009, 23(3): 385-393.

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To study the tectonics of the Yellow Sea is the common concern project. Although the oil-gas exploration has undergone more than 30 years in South Yellow Sea, the exploration progress of that is not successful. There are two nearly NS trending shortening and compression epochs (135-52 Ma and 23-0.78 Ma) and two nearly E-W trending shortening and compression stages (52-23 Ma and 0.78 Ma-) at the Yellow Sea and its adjacent areas during Cenozoic. Four tectonic epochs during Cenozoic have important influences on forming, migrating and preserving oil-gas reservoirs. An embryonic form of the basinrange framework occured in Cretaceous and Paleocene (135-52 Ma), and Eocene-Oligocene (52-23 Ma) is the main forming epoch for oilgas source. During Miocen-Early Pleistocene (23-0.78 Ma), tectonism caused favorable passage for oil-gas migration along NNE trending faults. Since Middle Pleistocene (0.78 Ma-) the NNE trending faults are closed and make a good condition for reservation of oil-gas, controlled by E-W trending shortening. The authors suggest to pay more attentions to the oil-gas exploration at the intersections between NNE trending existing faults and Eocene-Oligocene systems, and also pay attentions to the upper parts in South Yellow Sea area.

Types of Structural Transfer Zone in Compressional Area and Its Significance of Petroleum Geology

NING Fei TANG Liang-Jie ZHU Chuan-Ling HE Chun-Bo ZHANG Yu WANG Peng-Hao CHEN Qu

2009, 23(3): 394-400.

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Structural transfer zone is a significant geologic structure which regulates the displacement of major thrust faults in thrust belt. According to the geometric relationship of adjacent major faults in cross section with a case study in central uplift, Tarim basin, the structural transfer zone in compressional area can be classified into convergent, divergent and synthetic assemble patterns. Convergent assemble pattern develops popup structural style in transfer zone; transfer zone of divergent assemble pattern develops triangle zone; synthetic assemble pattern transfers its displacement by imbricate fault. The possible styles of thrust fault linkage in transfer zone were discussed. The main factors that control the formation of the structural transfer zones were analyzed which are related to the substrate characters, detachment surface, difference in sedimentary facies and lithology, and stress patterns and so on. Structural transfer zone, which is relatively a complicatedly deformed area, not only becomes an important play for hydrocarbon accumulation owing to its control of euxinic sediments distribution, but also provides pathways for hydrocarbons migration because of closely spaced faults. Moreover, all kinds of structural traps related to fault and anticline potentially developed in structural transfer zone.
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Analysis of the Hechi-Yishan Fold-thrust Zone in North of Guizhong Depression

HOU Yu-Guang，WANG Xin-Wen，WU Li-Qun，FAN Hao

2009, 23(3): 401-408.

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Obvious differences in thrust directions, structural styles, and deformation levels are observed at different structural segments of the Hechi-Yishan foldthrust zone as indicated by the results of geological cross-sections structural explanations and the calculated amounts of structural deformation. In Hechi and Yishan sections, with a middle tectonic deformation intensity, thrust-nappe structure and imbricate structure thrusting from north to south develop respectively. In Liucheng section, the largest structural deformation quantity, and imbricate structures thrusting from south to north are discovered. In Yingshan structural segment, a gentle deformation and normal strike-slip flower-shaped structures with thrusting from north to south are observed. Lateral and vertical transform zones in the Hechi-Yishan fold-thrust belt are assumed to have regulative effects on these differences. On the basis of deformation characteristics in different segments and the tectonic setting, deformation mechanism of the fold-thrust zone was discussed.
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Constraints of Paleozoic Normal Faults on Structural Characteristics in South Guizhou

CUI Min TANG Liang-Jie GUO Tong-Lou TIAN Hai-Qin

2009, 23(3): 409-413.

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The east-west Paleozoic normal faults are well developed in South Guizhou, as well as the Mesozoic and Cenozoic of the north-south thrust faults and folds. According to the planar distribution of the strata, fold and fault, field observation and interpretation of seismic profiles, the constraints of Paleozoic normal faults on structural characteristics are studied, combined with the thrust of Xuefeng Uplift. The results show that the Paleozoic eastwest normal faults took effect as the transfer zone during the process of Mesozoic and Cenozoic deformation. The structural characteristics of seismic section are interpreted by the geometry model of transfer zone established in this region. The fault displacement increases around the fault plane in the hanging wall of the transfer zone （normal fault）. Conversely, the fault displacement decreases along the distance from fault plane in the footwall of transfer zone （normal fault） or vanish.

The Structural Styles in Dongpu Sag，Henan

CHENG Xiu-Shen

2009, 23(3): 414-422.

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Complex half-graben structures developed in the Paleogene hanging wall along Lanliao fault in Dongpu sag. Dongpu sag, which forms plenty of north-northeast basement faults, has a structural architecture with east-west zonation and south-north subsection. There are two regional transfer zones, which extend from east to west along Baimiao-Nanhejia and Maogang-Liutun respectively, and partition the Tertiary extensional fault-sag into south, middle and north districts. Each district has different features in structural styles, depositional configuration and hydrocarbon accumulation. During the complicated tectonic history, not only the clastic rocks, but also the salt rocks have taken part into deformation in Dongpu sag; the tectonic stress-field is mainly extensional at earlier stage and is superposed by wrench stress later. Therefore, four structural styles, such as extensional faulted structures, transform structures, extensional fold structures and salt structures, accompanied with strike-slip structures have developed in such a tectonic setting, which comprised the main structural types of Dongpu sag characterized by rift basin.

The Stress Numerical Simulation of Laojunmiao Structural Belt of South Margin, Jiuquan Basin

HU Ye CENG Zuo-Xun BO Liang-Yun SUN Ting-Bin YIN Chong-Jun

2009, 23(3): 423-429.

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Laojunmiao structural belt is located in Cenozoic foreland thrust belt of south margin, Jiuquan basin,which is superposed over the south uplift and Shida depression of Early Cretaceous faulted basin. The author adopts the structural stress numerical simulation analysis in this article, and makes the stress analysis separately based on the Cenozoic planar fault system and NE geological profile of Laojunmiao structural belt. Through contrast with the oil distribution area, we can draw the conclusion as the following: X-displacement field shows that fault displacement in the west of structural belt is characteristic of left-lateral slip component; The middle of the structural belt mainly consists of thrust faults; In the east, the fault displacement has the component of right-lateral strike slip; for the Y-displacement, it is characteristic of leftlateral slip. Low stress areas which are surrounded by high stress in the Laojunmiao structural belt are the most advantageous oil accumulation regions. We should take these stress traps as an emphasis in the process of oil exploration, such as low stress traps in Miaoxi anticline, the middle clamping piece, the bottom part of Laojunmiao thrust belt and the wing of Laojunmiao anticline.

Features of Neotectonic Movement in the Source Area of the Minjiang River

WU Xiao-Ping，HU Jian-Zhong

2009, 23(3): 430-439.

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In order to further understand the Late Cenozoic tectonic activities of the Minjiang River fault, this paper studies the rivervalley landform, Cenozoic basins and planation surface in the source area of the Minjiang River so as to explain its neotectonic movement features The results show that the valley landform is characterized by the alternating wide and narrow valleyes The source area developed three planation surfaces, which reflect strong neotectonic movement and significant landform differences Since the Neogene,the regional evolution has mainly experienced the faulted depression in the early stage(53 Ma),the thrust system accompanied by sinistral strikeslip movement in the middle stage (18 Ma), and the axially tilting uplift in the late stage(013 Ma)The landform was obviously influenced by the neotectonic movement, which formed the Quaternary fault basin, planation surface and river terraces. Neotectonic movement in this region is characterized by the SN zonation and the EW asymmetric tilting movement. This research provides morphological evidences for further study on tectonic activities in the eastern margin of the Tibetan Plateau

Late Quaternary Activity of the NEE-Striking Fault Belt in Northern Shanxi Fault-depression Zone

LU Hai-Feng，LI Yu-Sen，MA Bao-Qi， WANG Cheng-Hu

2009, 23(3): 440-446.

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North foot fault of Wutai Mountains,south margin fault of Lingqiu basin and Paifang fault array each other by run-in NEE orientation in Shanxi faultdepression zone. We study the Neotectonic behaviors, motion patterns and the active difference of segments of the fault according to geomorphologic principle, method of the geologic structure and satellite photograph explanation. The results preliminarily show: (1)The three faults are all Late Quaternary fault with rightstriking smoothing;(2) From the core to outside of the Shanxi basin,the activities of the north foot fault of Wutai mountains,the south margin fault of Lingqiu basin and Paifang fault were weakenning in the same era;(3)The activities of the three faults show characteristics of segmentation, the activity of the middle segment is the strongest since Late Pleistocene,activities in the east segment are stronger than those of the west segment. These results imply the complexity and association of the activity of different structures under the same area tectonic background. 

Forming and Simulation of Three-Dimensional Morphology of Stylolites in Tieshan, Hubei Province, South China

FAN Hang-Yu，XIAO Zhi-Yong， ZENG Zuo-Xun

2009, 23(3): 447-455.

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Stylolite, which is identified in the limestone, is widely used to determine stress direction, calculate the finite strain and estimate the original thickness of strata. In addition, stylolites are also the storage spaces and transportation channels of oil, natural gas and underground water. Stylolites commonly developed in Tieshan formation are suitable for the simulation. Using the Shadow Moiré method and GIS technique, this study analyzed several samples collected from Tieshan area for their three-dimensional digital morphology, which proved quantitative scale, slope, roughness, distribution of troughs, two-dimensional sections view, and amount of pressure solution of stylolites. Further we promoted the morphology of the stylolites. This paper concluded that stylolites in Tieshan area were produced by compaction and pressure solution in limestone. The forming of the stylolites depends on both factors, i.e., the nature of rock mechanics and the solution-release mechanism created by the local stress concentration.

Study of Fluid Inclusions of Beidagou Gold Deposit in Heihe City, Heilongjiang Province

LV Jun，MO Xuan-xue，ZHAO Zhi-Dan，HAN Zhen-zhe

2009, 23(3): 456-464.

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Beidagou gold deposit is a newly-discovered small-size gold deposit, located in the Yanshanian Da-hinggan Mountain metallogenic belt.The petrographic study, microthermometry and component analysis of fluid inclusions in quartz veins show that (1) Four types of fluid inclusions were found in the mineralized quartz veins, i.e., liquid inclusions, two-phase liquid-vapor inclusions, vapor rich inclusions, and vapor inclusions; (2) Homogenization temperatures of fluid inclusions in quartz ranged from 160 ℃to 380 ℃, the ore-forming fluid belonged to NaCl-H₂O system, salinity ranged from 0.2% to 2.0% (NaCl_eq^), density ranged from 0.550 g/cm³ o 0.912 g/cm³,and pressure ranged from 6×105 Pa to 210×10⁵ Pa, corresponding to the depth ranging from 0.06 km to 2.10 km; (3) pH values of ore-forming fluid ranged from 6. to 6.7, and (CH₄+CO+H₂）/n(CO₂)values in mole fraction ranged from 0.027 to 0.271, indicating a weak acidity and reducing environment. All these characteristics indicate that Beidagou gold deposit is a mesothermal-epithermal gold deposit related to the Yanshanian volcanism

Characteristics of the Ore-forming Fluids in Alteration Zones of the Pulang Porphyry Cupper Deposit in Yunnan Province and Its Metallogenic Significance

GUO Xin DU Yang-Song LONG Zhen-Shan LI Shun-Ting LI Jing

2009, 23(3): 465-471.

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The Pulang porphyry copper deposit occurs in the southern segment of the Indosinian YidunZhongdian islandarc belt and is a largesized copper deposit discovered in China in recent years. This deposit has a typical alteration zonation of porphyry copper deposit, varying from potash and silicic alteration in the inner through phyllic alteration in the middle to propylitic alteration in the outer. This paper presents new petrographic observations, homogeneous temperature measurements and laser Raman microprobe analyses of fluid inclusions in quartz grains from the three alteration zones of the deposit. It is shown that the average homogeneous temperature of oreforming fluid decreases from 274.4 ℃ through 236.4 ℃ to 203.0 ℃ with outward variation of alteration zone and indicates an evident temperature decreasing trend, which may be resulted from partial participation of meteoric water in mineralization. The laser Raman microprobe analyzing data are consistent with existence of oreforming fluid with high sulfur and chlorine during mineralization in the deposit, and support occurrence of intensive mineralization caused by this high temperature oreforming fluid with high sulfur and chlorine in the potash and silicic and phyllic alteration zones.

Wall Rock Alteration and Its Relations to Gold Mineralization of the Liba Gold Deposit, Gansu Province

ZHANG Han-Cheng，XIAO Rong-Ge，WANG Jing-Bin ，LIU Jin-Hui，QIN Xin-Long，BAI

2009, 23(3): 472-480.

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Western Qinling orogenic belt is one of the hot spots for orogenic and Carlin-type gold deposits exploration in China, where a super large gold deposit called Liba has been found. After choosing the No.6 ore belt of Liba gold deposit as a case for systemically studying alteration mineral association, host rock alteration zoning and gold mineralization features, the authors sum up the alteration zoning mode of this type of gold deposit. Typical concentric zonal structure can be distinguished clearly, which shows that three alteration zones from inner to outer are pyritization silicificationsericitization zone, sericitization zone and chloritization zone.The altered mineral assemblages in each zone are pyrite+sericite+quartz±arsenopyrite±muscovite±tourmalinite±calcite, sericite+chlorite+quartz+pyrite±biotite and chlorite+biotite±sericite±pyrite respectively, and corresponding to the three alteration zones which are Au enrichment zone, Au mineralization zone and no Au mineralization zoneMigration of elements in alteration rock shows that alterations of wall rock and its zoning are resulted by hydrothermal fluid and rock reaction; Au mineralization occurs accompanied with mineral alteration, and mineralization of Au has a close relation to pyrite mineralization and disseminated silicatization.

Sedimentary Environment Research for the Yushan Bauxite Ore Deposit in Western Henan Province, China

LI Zhong-Ming，ZHAO Jian-Min，WANG Qing-Fei，MA Rui-Shen，JIAO Zan-Chao，LIU Hua-Fei,

2009, 23(3): 481-489.

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The Yushan bauxite ore deposit in the western Henan Province is a large concealed deposit discovered by Henan Institute of Geological Survey in 2005, which belongs to layer-G bauxite of North China Platform. The deposit-bearing strata of the Upper Carboniferous can be divided into two facies and further to four microfacies according to the systemic analysis of drilling data, i.e. lithologic association, sedimentary structure and chemistry feature of the allite series. The allite series of Yushan bauxite is formed in sedimentary environment of the shallow marine such as the coastal, the tidal flat or the lagoon, and the bauxite is mainly developed with the microfacies of oolitic (or classic) deposit that is formed in the upper part of restricted subtidal zone. Importantly, the allite series of the Yushan bauxite is the product resulting from a complex process of three cycles from the rapid transgression to the slow regression that form three bauxite sequences from the bottom to the upper part correspondingly, and the bauxite sequence with the large-scale distribution is formed in the last large-scale transgression-regression cycle. Therefore, this study is a good complement for the theory of bauxite formation in Carboniferous Benxi Formation in the North China Platform.

Typomorphism Characteristic Research of Barite in the Black-Rock-Series-Type Ni-Mo Deposits in the Lower Cambrian in Hunan-Guizhou Area

JIANG Yong-Hong

2009, 23(3): 490-496.

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Applying the electron microprobe and sulfur isotope analysis methods, the paper makes research into the typomorphism features of the barite of the two samples in the black-rock-series Ni-Mo deposits in Hunan and Guizhou area.The barite chemical component features of Zhongnancun in Zunyi, Guizhou and Ganziping in Zhangjiajie, Hunan are as the following: contents of Cr2O3, NiO, and SiO2 are relatively high, 0.39%, 0.96%, and 0.65%, respectively; and the content of Al₂O₃is relatively low, below 0.15%.The Sr/Ba values vary from 0.011 to 0.034.The δ³⁴S values measured from the samples of Ganziping of Zhangjiajie in Hunan vary from 54.3‰ to 57.4‰.The study of typomorphism features of the barite, such as its composition and isotope, reflects the hydrothermal genesis of the barite.

Petrogenesis of the Late Ordovician Helin Intrusive Complex in the Southeastern Xiaoxinganling Mountains

HAN Zhen-Zhe，ZHAO Han-Dong，LV Jun，LI Juan-Juan， LI Wen-Long，WANG Pan-Xi

2009, 23(3): 497-507.

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The Late Ordovician Helin intrusive complex in the southeast of Xiaoxinganling Mountains consists of a series of different rocks，including amphibole gabbro，(quartz)diorite，tonalite and monzonitic granite. Intrusive, inclusive and gradual transitional contact relationship has been recognized among different rock types. Some microgranular dioritic enclaves have been discovered in(quartz）diorite, tonalite and monzonitic granite. The enclaves have mainly ovoidlike shape, possibly caused by plastic flow, typically magma structure, acicular apatite as well as K-feldspar and quartz phenocrysts of host rocks, indicating an origin of magma mingling enclaves(MME). The intrusive complex is characterized by enrichment of large ion lithophile elements LILE(Ba，Sr，Rb)and HFS (U，Th，Zr，Ce)relative to primitive mantle, suggesting derivation of crust. However relatively high ε_Nd（t）values（-2.38 to -3.77）reflects a mantlederived source. In summary, petrographic petrochemical and geochemical characteristics of the Helin complex suggest mixed crustmantle origin. It can be attributed to underplating of mafic magma in an active continent marginal arc setting.

Application of High-precision Geomagnetic Method in Volcanic Rocks Prediction of Gulong-Changjiaweizi Fault-depression in North Songliao Basin

TANG Jin-Sheng LI Cheng-Li YANG Hai-Bo CUI Rui-Hua

2009, 23(3): 508-514.

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The processing and interpretation techniques of high precision magnetic method are applied in deep-layer volcanic rocks prediction of GulongChangjiaweizi faulting-depression in Songliao Basin and the application results are discussed. The magnetic anomalies are produced by the superposition of basement lithology and volcanic rocks, therefore it is very difficult to predict the deep-layer volcanic rocks by applying the conventional high-precision geomagnetic method. The slide-trending and wavelet multi-scale analysis can be a powerful tool for separating the magnetic anomalies of the volcanic rocks, and the analytical signals and vertical derivatives of magnetic anomalies can indicate and identify the lithology of volcanic rocks. This technique can also be applied in the prediction of deep-layer volcanic rocks in other areas.

Division and Correlation of Volcanic Eruptible Gyration and Period of Kalagang Formation in Niudong Area,Xinjiang

LUO Quan-Sheng，NIE Chao-Qiang，WEN Chuan-Jiang，LIU Quan-Zhou，JING Wen-Bo

2009, 23(3): 515-522.

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Based on the systemic coring data and analysis test data, combined with well logging and seismic data, and according to the characteristics of lava lithology, electrical property,petrochemistry and so on, along with the seismic reverberation of different lithology and lithofacies, volcanic strata of Kalagang Formation in Niu dong area in Malang sag of Santanghu basin can be divided into different units，such as layer, cyclothem, period, and sub-gyration. Regarding volcanic eruptible period as the basal unit of lava stratigraphic division and correlation, the lava stratigraphic division and correlation in this area has been done. The study indicates that fracture eruption is the main eruptible mode in Kalagang Formation. Volcanic distribution reveals that the thickness and number of the volcanic layer decrease distinctly from southwest to northeast. Kalagang Formation has the thickness of more than 1,000 meters and can be divided into eight sub-volcanic eruptible periods and four sub-gyrations.

Stratigraphic Hydrocarbon Reservoir's Accumulation Elements and Trap Models in 3^rd Member of Shahejie Formation in Xinglonggong Area,Baxian Depression, Hebei

LI Qing-Li LIANG Hong-Bin XU Xin-He CAO Lan-Zhu LI Rui-Jun- LI Shun-Li ZHENG Hua-Chao

2009, 23(3): 523-530.

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The petroleum exploration prospective of deep strata in rift depression is always concerned by lots of geologists. Xinglonggong area, closely adjacent to Baxian depression which is the petroleum generation depression, has many advantageous hydrocarbon accumulation conditions. In this area, some industrial petroleum traps were searched in Dongying Formation and 1^st Member of Shahejie Formation. The petroleum exploration degree of this area was much lower than those of other places in3^rd Member of Shahejie Formation, which was the deep strata in the Baxian depression, although a few exploration wells confirmed that there were some favorable elements to hydrocarbon's accumulation, especially, to the stratigraphic reservoirs. According to hydrocarbon accumulation theory of petroleum geology, the favorable conditions of stratigraphic hydrocarbon accumulation and trap models discussed in this paper are as follows: Firstly, the hydrocarbon sources are sufficient because the traps of the 3^rd Member of Shahejie Formation are close to source rocks which are shales from the 4^th, 3^rd , and 1^st members of Shahejie Formation; Secondly, the reservoir conditions are very good owing to the sandbodies of large scale delta front and some turbidity deposition; Thirdly, oil accumulation of stratigraphic reservoir benefits from the slope breaks and synsedimentary structures; Finally, the gypsum, gypsum shales, shaly gypsum, halites and shales can act as caprocks. According to the structure area dividing, three areamodels of stratigraphic petroleum trap are summarized: abrupt slope, gentle slope and depression models. In abrupt slope area, structurestratigraphytrap and small scale delta front sandbodies developed. In gentle slope area, hydrocarbon is prone to accumulate in large scale delta front, overlapping strata and some sandbodies adjacent to unconformityHowever, in the depression area, pinched out sandbodies are typical, i.e., below the break areas of abrupt slope, fan delta front reservoirs and turbidity sandbodies are favorable petroleum traps, and under those areas of gentle slope, delta front reservoirs, turbidity sandbodies and sheet sand bars are the places for hydrocarbon accumulation in the low system tract. According to the studies of petroleum accumulation elements and trap models, those areas below the break point of Wenan gentle slope in the east part of Xinglonggong area are considered to be the most profitable place for hydrocarbon exploration.

Contrast Study on the EPR Characteristics of Coals of Different Metamorphism Types

LI Xiao-Meng CAO Dai-Yong

2009, 23(3): 531-534.

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Through electron paramagnetic resonance(EPR) analysis of high-rank coal samples from the Carboniferous coal located in the northern foreland basin of Dabie orogenic belt in the eastern China, the evolution characteristics of aromatic structures of coals of different metamorphism types and the effecting factors are studied. The result indicated that the evolution of the free radical density, the line width and the Lande factor demonstrates the good uniformity, and there is a regular tendency with the increasing of reflectance of vitrinite. The tectonic stress promotes and strengthens the aromatic ring polymerization and the aromatic layer superposition, and causes the tendency of leading evolution of coals.
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Comprehensive Assessment of Rock Burst of Yufengsi Deep-buried Tunnel in Three-river Orogenic Belt， Northwest Yunnan

ZHANG Yong-Shuang，LIU Jing-Ru，WANG Ke，WU Shu-Ren，GUO Chang-Bao，XIONG Tan-Yu

2009, 23(3): 535-544.

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The mechanism and prediction of tunnel rock burst have been two main research issues in engineering geology and rock mechanics for many years, and become the choke points for underground engineering development. Taking an example from Yufengsi deep-buried tunnel of Yunnan-Tibet Railway which passes through the south part of Yulong Mountain of Three-river Orogenic Belt, factors related to tunnel rock burst are systemically analyzed on the basis of field investigation. According to the results of rock mechanics test, field stress analysis and numerical simulation, multiple criterions have been adopted to predict and comprehensively assess the risk of tunnel rock burst, which has important instruction to the deep tunnel design and the prevention of disasters associated to tunnel rock burst.

Research on Geo-engineering Conditions of the Lijiang-Shangri-La Railway Section of the Yunnan-Tibet Railway Based on the GIS Method

GUO Chang-Bao ZHANG Yong-Shuang JIANG Liang-Wen SHI Ju-Song WANG Ke SUN Yuan-Di

2009, 23(3): 545-552.

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According to the geo-engineering problems in the alternative lines of the Lijiang-Shangri-La railway section of the Yunnan-Tibet railway, the paper comprehensively analyzed the factors of the regional geological setting and topography, the rock group of engineering geology, the slope structure, geo-hazards developing status, the earth’s crust stability, the human engineering activities, the precipitation and the distance to the valley, and established the analytic hierarchy process (AHP) and mathematical models according to the expert scoring. The paper established the computational formula of engineering geological condition index and calculated the impact factor weights, and made the engineering geological condition zoning based on the ArcGIS 9.2 platform. The calculation results show that the engineering geological conditions are mainly poor and medium in the study area. Based on the results of the engineering geological zoning and real data analysis, the paper made optimization of the southern segment of Lijiang-Shangri-La railway line. The research methods and conclusions in the paper are of good guiding and reference to the construction and planning of the project in the study area.

Analysis of Rock Stress Field Variation in Two Circular Caverns during the Excavation Process

WANG Shuai WANG Cheng-Hu Shen-Nai-Ji

2009, 23(3): 553-558.

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The stability of caverns is the focus of study on water conservancy and hydropower industry, railways, highways, defense, energy development and reserve, and other fields. Based on a hydroelectric power station hole project in Xinjiang,this paper uses numerical simulation of 3D-Sigma software to establish five cavern models which contain two circular chambers, and simulates the rock stress field change in actual excavation process. Through setting up stress monitoring points such as top arch, bottom arch, left and right arches, the paper analyzes the stress field change in pre-chamber excavation process,the impact of post-excavation of the cavern to pre-stress field and the changing range of stress field with the hole distance increasing, and obtains the feature of stress intensiveness in the actual excavation process. The research results have some reference value for the stability control of the deep caverns.
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Consolidation and Compressibility of Unsaturated Silt Clay and Test Study on Volume Change

WU Li-Jun，JIANG Guan-Lu，LI An-Hong，LIANG Dong

2009, 23(3): 559-563.

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For studying consolidation mechanism of unsaturated soil which was correlative with matric suction, and extending the applicability of consolidation theory,consolidation mechanism of unsaturated soil under different saturations was discussed by analyzing the water soil characteristic curve based on the latest experiment results. The results indicated that the ultimate settlement is only related to the module of compression. The consolidation velocity of unsaturated soil is reducing with the initial degree of saturation, and the time of saturated soil achieved complete consolidation is longer than unsaturated soil. The instantaneous settlement of unsaturated soil under high degree is less than that under low degree in virtue of the compression of mixture in soil. Because of saturation and matric suction in consolidation, the consolidation settlement under high degree is more than that under low degree.

Synthetic Analyses of Remote Sensing and Geochemical Surveying Data in the Ore Exploration in Areletuobie, Xinjiang

LIU Lei FENG Cheng-Gui YANG Feng-Zhu ZHUANG Da-Fang QIU Dong-Sheng

2009, 23(3): 564-568.

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The study area is located in Areletuobie, Xinjiang. The redundant vegetation and cloud may seriously interfere with the discrimination of the minerals with diagnostic features. Crosta technique taken to the image of the study area didn’t acquire good results. As a result, masking technique was undertaken to eliminate the influence of the vegetation and cloud. Crosta technique was taken to the new images to identify the diagnostic features of the hydroxylminerals, carbonateminerals and the iron oxides. The relevant images, for instance, hydroxyl layer from TM1, 4, 5 and 7, were classified by four thresholds, i.e.<μ+1.64 σ-μ+2σ、μ+2σ-μ+3σ and >μ+3σ3. Being treated as remote sensing anomalies the last three groups were endued with special colors and overlapped with the false composite images that were combined with geochemical surveying data through data fusion. The ore exploration targets were delineated by synthetic analyses of multiinformation. Through field work the existences of several altered outcrops were confirmed and a copper deposit was discovered. The validity of the method has been approved.

A New Transformation Method of Exploratory Profiles from 2D to 3D Coordination Systems

LI Guang-Jiang CHEN Ai-Min DENG Min LI Jiao-Jiao

2009, 23(3): 569-574.

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As the important achievements in the mine designing and producing processes, the exploratory profiles are very significant for modeling the threedimensional mine. The transformation of the profiles from 2D to 3D coordination systems, and the evaluation and emendation of transformed errors are important. For reasons of complicated work of traditional transformation, this paper promotes a new method to transform the coordination of the profiles. Based on the standard deviation of section area of the geological entities, an evaluation of the transformed error is put forward. Then, the method to assess the error is investigated, and a transforming-domain based algorithm to transform the coordination of the profiles is proposed, the algorithm and its complication are depicted in detail. Finally, a practical example which uses the profiles of a metal mine in Hunan Province shows that the method proposed in this paper is feasible, and the transforming result is better than that based on the single benchmark.

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