Welcome to visit Geoscience!

Table of Content

    20 February 2005, Volume 19 Issue 2
    Previous Issue    Next Issue
    Engineering Geology and Environmental Geology
    Progress and Applications for Digital Landslide
    WANG Zhi-hua
    2005, 19(2):  157-164. 
    Asbtract ( 7580 )   PDF (903KB) ( 1374 )  
    Related Articles | Metrics

    The essence of digital landslide technique is to capture basic landside information through remote sensing (RS) and spatial positioning combined with other survey methods; and by using GIS technique to manage and store the digital information; and then based on the landslide-geo-principium to make spatial analysis and establish digital three-dimensional, geo-referenced and multi-elements thematic landslide model serving the landslide survey, monitoring, assessment and disaster prediction and so on. This paper introduces the application for digital landslide technique through 4 examples: ① three dimensional landslide models for Jinlong Mountain；②satellite monitoring Yigong Landslide；③study for landslides in key towns of the Three Gorges；④Qianjiangpin Landslide.

    Surface Fractures and Their Hazard Effects on Engineering Construction along the Golmud-Lhasa Railway across the Tibetan Plateau
    WU Zhen-han, HU Dao-gong, WU Zhong-hai, YE Pei-sheng, LIU Qi-sheng
    2005, 19(2):  165-175. 
    Asbtract ( 4996 )   PDF (2616KB) ( 1406 )  
    Related Articles | Metrics

    After field geological survey on the scale of 1∶2,000 and comparative measurement in different seasons, four types of surface fractures, seismic fractures, fault fracturs, permafrost fractures and ice fractures, were discovered along the Golmud-Lhasa railway across the Tibetan Plateau after engineering geological mapping on the scale of 1∶2,000. Seismic fracture zones are consisted of and accompanied by seismic fractures, seismic scarps, pressure ridges, sag-ponds and pull-apart basins.Typical examples include the Xidatan palaeo-seismic fracture zone, seismic fracture zone of the Kunlun Ms 8.1 earthquake occurred in November 14,2001, the south Hohxil palaeo-seismic fracture zone, seismic fracture zone of the Bengcuo Ms 8.0 earthquake occurred in 1951 and seismic fracture zones along normal fault in east of the Nyainqentanglha Mts.caused by Jiuzila Ms 7.5 earthquake occurred in 1952 and Yangbajain Ms 8.0 earthquake occurred in 1411.Fault fracture zones often form in active fault zones and appear as long extension with stable trending, they are jointly controlled by active faulting, underground water concentration and freezing expansion.Permafrost fracture and ice fracture are both the result of freezing expansion without evident relation to tectonic deformation and regional structures. Seismic fracture, fault fracture and permafrost fracture all gave negative effects on engineering construction and formed geological hazards at many localities along the Golmud-Lhasa highway and railway. Ice fractures formed in freezing rivers and lakes and on the top of pingos have not shown any hazard effect on engineering constructions up to the present.

    Numeric Simulation on Destructive Effect of Golmud-Lhasa Railway Resulting in Stick-Slip Movement of the Eastern Kunlun Fault
    HU Dao-gong，OUYANG Yong-long，YE Pei-sheng，WANG Lian-jie，WU Zhong-hai，WU Zhen-han
    2005, 19(2):  176-180. 
    Asbtract ( 6547 )   PDF (1011KB) ( 1324 )  
    Related Articles | Metrics

    The Eastern Kunlun Fault (EKF) is one of the most active seismogenic faults in the northern Qinghai-Tibet Plateau. Earthquake activities in the future or abrupt strike-slip movement of the EKF will bring serious hazards to Qinghai-Lhasa railway. On the basis of kinematics character of the EKF, this paper stimulates two deformation effects (the epicenter is located near the railway or far away it) when the earthquakes with 8 m and 3 m level left-lateral displacement, occur respectively. The result shows that the southern bedrock and Quaternary of the EKF have 8 m left-lateral strike-slip displacement when epicenter is located near the railway. However, the level displacement of Quaternary near the railway is smaller, rail and groundsill show successive left-lateral crooked deformation. It has just 4-5 m successive left-lateral crooked deformation; Two sides of the railway cause the N-E direction tensile opening and N-W direction earthquake apophysis. Deformation effect is similar when the epicenter is located far away the railway, but the extent of displacement became smaller, and the rail and groundsill have the 1-2 m successive left-lateral crooked deformation. Therefore, the great earthquake induced by EKF in the future will result in great deformation and destruction of Qinghai-Lhasa railway whether the epicenter is located near the railway or not.

    The Late Quaternary Normal Faulting of Fenghuo Shan Thrust-Folds Belt in Central Qinghai-Tibet Plateau
    WU Zhong-hai，WU Zhen-han，HAN Jin-liang，ZHANG Yong-shuang，HU Dao-gong，JIANG Wan
    2005, 19(2):  181-188. 
    Asbtract ( 6920 )   PDF (690KB) ( 1039 )  
    Related Articles | Metrics

    In the central Qinghai-Tibet Plateau, there is a NE trending and S-shaped graben called Erdaogou basin .The graben, about 25 km long and about 2 km wide, cuts the east-west trending Fenghuo Shan thrust-folds belt which had been formed during Tertiary or from Late Cretaceous to Palaeogene. The basin floor is covered by Late Quaternary deposits.The graben is apparently asymmetric with the main boundary fault along its northern margin. Many phenomena indicate the active normal faulting with the component of left lateral strike-slip along the fault zones striking NE60°-90° and dipping 50°-80° to the south Along the footwall of fault, there is a prominent triangular facet, which is 200-300 m above the surface of piedmont plain.At the base of triangular facets, faulting is pressed by south-east facing fault scarps cutting fluvial fans and travertine platform. The well-preserved fault scarps offset vertically the fluvial fans about 1,5 m and 4,5±1 m formed during Holocene, and Late Pleistocene respectively and maybe offset left lateral the fluvial fans 8.10 m formed during Late Pleistocene,Age results of U-series and thermo luminescence (TL) indicate that offsets of the Holocene and Late Pleistocene fluvial fans represent the fault throws since 5-6 ka B.P. and 34-16 ka B.P. respectively,These suggest that the average vertical slip rate is 0.28±0.06 mm/a and the left lateral strike slip rate is 0.5-0.8 mm/a along the faults at north side of Erdaogou graben. This corresponds to a “spreading” rate of 0.1-0.2 mm/a across Erdaogou graben. The relief across the normal fault indicate that the minimum cumulative displacement on fault maybe is about 500 m. Based on the minimum cumulative throws and average slip rate of fault, the initiation age of the normal faulting may be no younger than 2.3 Ma.The new data from Erdaogou graben are similar to those from Shuang Hu graben and Wen Quan graben in central Qiangtang block and demonstrate that the rate of Late Quaternary extension in central part of the Qinghai-Tibet Plateau is roughly an order of magnitude lower than in southern Tibet.The lower slip rate of normal faults is also coincide with less prominent morphologic expressions of grabens or rifts in central Tibet, less continuous and shorter than those in southern Tibet. Based on the slip magnitude of fault in central Tibet, the cumulative extensional rate perhaps did not exceed about 3 mm/a across the Qiangtang block during Late Quaternary.

    Characteristics and Origin of the Akaraz Shan Complex in the Western Kunlun Mountains
    CHEN Hong-wei, LUO Zhao-hua, MO Xuan-xue, ZHAN Hua-ming
    2005, 19(2):  189-197. 
    Asbtract ( 1433 )   PDF (750KB) ( 1237 )  
    Related Articles | Metrics

    Akaraz Shan complex is located in the south zone of the Western Kunlun Mountains, cropping out a 2 km long section along the Xinjiang-Tibet road, which including some rock types such as monzodiorite, quartzmonzodiorite, granodiorite, monzogranite, syenogranite and alkaline feldspar granite. By studying the geological, geochemical and isotopic geochemical characteristics of the complex, the disequilibrium mineral assemblages, appearance of the quartz and feldspar xenocrysts in the mafic microgranular enclaves, similarity of the trace element distribution patterns of the rock samples, and contribution of the mantle and lower crust to the complex's Sr, Nd and Pb isotopic systems were found. It was concluded that the complex originated from crust-and mantle-derived magma mixing, and the mantle-derived magma underplating was the efficient amse of the magma mixing.Therefore, the mantle-derived magma underplating was probably an important mechanism that resulted in the magmatic activities of the Late Indosinian in the Western Kunlun area.

    Petrological and Geochemical Characteristics of Granodioritic Cryptoexplosion Breccia and Zircon SHRIMP Dating in the Baoshan Area, Hunan Province  
    WU Guang-ying,MA Tie-qiu,BAI Dao-yuan,LI Jin-dong,CHE Qin-jian,WANG Xian-hui
    2005, 19(2):  198-204. 
    Asbtract ( 5957 )   PDF (517KB) ( 1291 )  
    Related Articles | Metrics

    The study on the cryptoexplosion breccia in petrology and geochemistry indicates that the breccia and matrix are high potassium calc-alkaline metaluminous granodiorite, which formed through crust-mantle interaction.Zircon SHRIMP dating shows that breccia of granodriorite yields 207Pb/206Pb age of 164.1±1.9 Ma, and matrix of granodiorite yields 162.2±1.6 Ma. Both breccia and matrix almost formed at the same time. Petrological and geochemical characteristics of granodioritic cryptoexplosion breccia are the same as ore-bearing granodiorite porphyry. The contents of metallogenic elements, such as W, Mo, Cu, Pb, Zn, etc., are very high in the breccia and matrix. And there are some polymetallic mineralizations in the boundary between granodioritic cryptoexplosion breccia and country rocks. It infers that granodioritic cryptoexplosion breccia may be the ore-bearing parent rock as well.So this has a very important significance to exploring more polymetallic ore deposits in the research area.

    Comparative Research of Lithogeochemistry for Jiulongzhang and Xiangshan Volcano-Intrusive Complexes
    ZHANG Wan-liang，LIU De-chang，LI Zi-ying
    2005, 19(2):  205-210. 
    Asbtract ( 3011 )   PDF (204KB) ( 1223 )  
    Related Articles | Metrics

    Jiulongzhang and Xiangshan volcano-intrusive complexes are the Mesozoic rhyodacitic volcano-intrusive complexes associated with uranium ores in southern China. Xiangshan volcano-intrusive complex is the wall rock of the biggest volcanic-rock uranium ore deposit in China, and the main body is rhyolitic porphyroclastic lava, accompanied by hypabyssal or ultra-hypabyssal intrusive rocks such as dacite-porphyry and granite-porphyry. Jiulongzhang volcano-intrusive complexes are dominantly rhyolitic welded tuff, accompanied by dacite.porphyry and quartz monzonite-porphyry, and so on, and the uranium resources are being assessed.The comparative studies of lithogeochemistry for the volcano-intrusive complexes both from Jiulongzhang and from Xiangshan reveal that the chemical compositions of the volcano intrusive complexes in the two areas are very close , and the trace element spidergrams and REE patterns basically coincide with each other.It is also shown that the two volcano-intrusive complexes have the same source features and the active continental margin tectonic settings. At the same time, it is found that, from early volcanic magma activities to later intrusive magma activities, the content of SiO2 and the Rb/Sr ratio decreased, on the contrary, the content of MgO and the ratios of K/Rb, Ba/Rb and LREE/HREE increased. It is shown that the hypabyssal or ultra-hypabyssal intrusives are not the products of the volcanic magmatic differentiation.

    Study on Rheology Characteristics of the Lianyunshan Complex in Northeastern Hunan Province
    LI Jin-dong,PENG He-qiu,JIA Bao-hua,CHEN Jun,GUO Le-qun,HE Jiang-nan,TANG Xiao-s
    2005, 19(2):  211-216. 
    Asbtract ( 1476 )   PDF (347KB) ( 1075 )  
    Related Articles | Metrics

    The Lianyunshan complex, cropping in the JiulingMufushan range in the northeastern Hunan Province, belongs to the paleo-Proterozoic crystalline basement rocks. By means of field structure analysis, petrofabrics and fractal dimension analysis of quartz, the authors have carefully studied the deformation feature and mechanism of the Lianyunshan complex in the northeastern Hunan Province. The results are : （1）the Lianyunshan complex has undergone two stages of the earlier ductile shear and the later ductile reconstruction. Plastic flow deformations of quartz grains are mainly rhombohedral slip; （2）strain rate gradually reduces from the earlier structural schist (gneiss) of middle strain rate（10-8.8s-1）to the later ductile reconstruction striped migmatite of low strain rate（10-12s-1）;（3）plastic flow deformation mechanism of the rocks not only reflects amphibolite facies formed in the midupper crust environment, but also suggests that the deeper crustal material in the Xuefeng land have not yet been uplifted.

    Paleotectonic Settings of the Metamorphic Tectonostratigraphy in the Eastern Beihuaiyang Belt
    WANG Guo-sheng，MA Wen-pu，XU Yi
    2005, 19(2):  217-223. 
    Asbtract ( 1421 )   PDF (213KB) ( 1006 )  
    Related Articles | Metrics

    There are different opinions on regarding to the paleotectonic settings of the previous so-called Foziling Lithogroup in the eastern Beihuaiyang belt, north foothills of the Dabie Mountains. This difference is derived from the mixing of tectonostratigraphic units with different tectonic settings and geologic history under the name of Foziling Lithogroup and the study of paleotectonic settings based on the Foziling Lithogroup as a whole. Recent work in structural and tectonic deformation, petrography and geochemistry on the so-called Foziling Lithogroup indicates that it is composed of two distinct tectonostratigraphic units separated by a nearly horizontal ductile shear detachment system. The newly defined tectonostratigraphic units above and below the detachment zone are named as Zhufoan Lithogroup and Luzhenguan Melange respectively. Sedimentary characteristics together with the petrographic and geochemical analysis results revealed from the newly defined units in this study imply that the Luzhenguan Melange was formed in a passive continental margin, the Zhufoan Lithogroup, however, was formed in the southern active continental margin of the North China Plate. These research results indicate that the collision between the North China and Yangtze plates in the Palaeozoic is supposed to be located in the north of Zhufoan Lithogroup, and the Yangtze Plate served as a subducted plate beneath the North China Plate.

    Study on the Fluid Inclusions from Xiejiagou Gold Deposit in Shandong and Its Geological Significance
    WEI Yan-guang,WANG Jian-guo,DENG Jun,ZHANG Zhi-qi,LIN Ji-zhao,YAN Shun-ling
    2005, 19(2):  224-230. 
    Asbtract ( 10997 )   PDF (228KB) ( 2140 )  
    Related Articles | Metrics

    Xiejiagou gold deposit is a newly found alteration deposit which occurred in Linglong granite at the Jiaodong area, Shandong. By analyzing the temperature, pressure and the component of the fluid inclusions in three mineralization stages, it is included that this gold deposit is an epithermal deposit and the gold-bearing fluid is salt-water solution. In the first mineralization stage, the homogenous temperature of fluid inclusions ranged from 320 ℃ to 350 ℃, with salinity from 2.7% to 6.6% NaCl equivalent and density from 0.498 g/cm3 to 0.886 g/cm3; in the second mineralization stage, the homogenous temperature of fluid inclusions ranged from 270 ℃ to 330 ℃, with salinity from 3.6% to 8.4% NaCl equivalent and density from 0.571 g/cm3 to 0.959 g/cm3; in the last mineralization, the homogenous temperature of fluid inclusions ranged from 250 ℃ to 290 ℃, with salinity from 5.8% to 10.6% NaCl equivalent and density from 0.724 g/cm3 to 1.158 g/cm3.So the evolution of goldbearing fluid was a process that temperature decreased and salinity and density increased. CO2 and H2O are the main components of the fluid, with CO, CH4, H2S, SO2 and N2 involved. There are some positive relationships between the content of CO2 in the fluid and the grade of gold in the ores. The assemblage of different fluid inclusions and the evolution of fluid show that immiscibility is the key element for mineralization.

    Study of Pyrite Typomorphic Characteristics of Wulong Quartz-Vein-Type Gold Deposit in Dandong, Liaoning Province, China
    ZHOU Xue-wu, LI Sheng-rong, LU Li, LI Jun-jian, WANG Ji-zhong
    2005, 19(2):  231-238. 
    Asbtract ( 4741 )   PDF (241KB) ( 1031 )  
    Related Articles | Metrics

    Wulong quartz-vein-type gold deposit is located in Dandong City, Liaoning Province, China.It is a magmatic-hydrothermal deposit enclosed in mylonite or ultramylonite.The deposit is controlled by Jixingou Fault (F2) and No.100 Fault (F3).In this paper the authors studied minutely the occurrences, shapes, compositions and their typomorphic ratios  (Fe/(S+As)，Co/Ni，S/Se）, sulfur isotopes, thermoelectric coefficients of the pyrites in Wulong quartz-vein-type gold deposit, analyzed the pyrite typomorphic coefficient characteristics, sumed up the pyrite genesis and prospecting typmorphic characteristics, took out the major genesis and prospecting information of the pyrite, prognosticated firstly mineralization perspective of the depth in the ore area and the quartz vein in outer target area by using the triangle illustration of the pyrite composition characteristic，which not only provided reliable mineralogy basis for the genesis of Wulong gold deposit, but also given efficient evaluation for prospecting assessment of the depth in the ore area and the quartz vein in outer target area.The authors consider that Wulong gold deposit is mesogene and hypergene magmatic-hydrothemal deposit. It is very good for prospecting assessment of the depth in Wulong ore area and No.220 vein, No.38 vein, No.2 vein in outer target area.

    Progress in Research on the Quaternary Geology in the Source Area of the Yellow River
    CHENG Jie,JIANG Mei-zhu,ZAN Li-hong,LIU Xue-qing,XU Xiao-jing,LU Pin
    2005, 19(2):  239-246. 
    Asbtract ( 1545 )   PDF (299KB) ( 1137 )  
    Related Articles | Metrics

    The Quaternary sequence of the source area of the Yellow River is set up on the basis of research on the natural exposures and cores, and it consists of the Lower Pleistocene, Middle Pleistocene, Upper Pleistocene and Holocene. The Lower Pleistocene is alluvial and lacustrine sediments; the Middle Pleistocene is composed of lacustrine, glacial and fluvioglacial sediments; the Upper Pleistocene consists of lacustrine, glacial, fluvioglacial, pluvial and alluvial sediments; and the Holocene is made of alluvial, pluvial and lacustrine sediments.Three glacial periods in the source area since the Middle Pleistocene are recognized, which are the last glacial period, the reciprocal second glacial period (late Middle Pleistocene) and the reciprocal third glacial period (early Middle Pleistocene). During the reciprocal third glacial period an ice sheet in the source area may be formed.The last glacial period is divided into two stadial stages with an interstadial stage. Evolution of lakes of the source area during the Quaternary went through three stages.The first stage is the Early Pleistocene, in which numbers and areas of lakes largely decreased compared to those of the Pliocene and lakes developed only along the south foreland of the Buqing Shan.The second stage, lake-expending stage, is the Middle Pleistocene.Lake cover at that time was ten times in area more than that of the Early Pleistocene. The last stage is the Late Pleistocene and the Holocene and is recognized two lake-expanding periods with two lake-shrinking periods.The Yellow River in the source area occurred from the last Late Pleistocene to the earliest Holocene, and meanwhile the Yellow River captured the current of the upper reaches of the Yangtze River.

    Research on Provenance and Paleocurrents in the Meso-Cenozoic Hefei Basin
    JIANG Zai-xing, XING Huan-qing, LI Ren-wei, LUO Dong-xiang
    2005, 19(2):  247-252. 
    Asbtract ( 1510 )   PDF (212KB) ( 1190 )  
    Related Articles | Metrics

    Based on the latest geophysical and geological data, this study has dealt with the provenance and paleocurrents in the Mesozoic and the Cenozoic in the Hefei Basin with seismic stratigraphy and sedimentology, four provenance and paleocurrent systems have been recognized .The variation of the  provenance and paleocurrents  indicates the regular characteristics of the Hefei Basin .The main properties of provenance and paleocurrents changed with time from Dabiedominated provenance and paleocurrent system in Jurassic to both Dabie-dominated  provenance and paleocurrents and Zhangbaling-dominated provenance and paleocurrents in the Cretaceous. The Bengbu provenance and paleocurrent system became the main provenance and paleocurrents in the Cenozoic.This study comes to the conclusion that Zhangbaling system is the predominant, Huoqiu and Bengbu systems are the secondary.

    Depositional Palaeogeography of Cretaceous of Kuqa Depression in Northern Tarim Basin
    XIAO Jian-xin, LIN Chang-song, LIU Jing-yan
    2005, 19(2):  253-260. 
    Asbtract ( 3449 )   PDF (481KB) ( 1437 )  
    Related Articles | Metrics

    The distribution patterns of environments and facies in different stages of Cretaceous (Lower Cretaceous) in Kuqa depression are discussed from point of view of depositional palaeogeography in this paper. The division of sequence stratigraphy , the system tracts and sedimentary facies distributions are linked up with the structural environments inside and around the depression. The structural evolution of foreland basin of Kuqa depression in Cretaceous has its phases, which control the characteristics of depositional palaeogeography development in the depression in different stages. The depositional palaeogeographies of Yageliemu stage and early Shushanhe stage have a clear zonation from north to south and show characteristics of accepting the sediments from both the north and south of source areas,having the coarse detritus in the northern abrupt slope of the depression.The most part of Tabei Uplift had subsided under water at the stages of later Shushanhe and Baxigai, and was overlapped by the highstand system tract at Bashenjiqike stage.The major reservoir horizons of the large scale of gas field Kela 2 are located in the facies zone of the braided-delta at the  Bashenjiqike stage, which have a stable and wide distribution called as the “sandy body apron of braided-delta”

    Pre-Mesozoic Basement Characteristics in the Eastern Depression of the North Yellow Sea Basin
    XIAO Guo-lin，SUN Chang-hong，ZHENG Jun-mao
    2005, 19(2):  261-266. 
    Asbtract ( 1526 )   PDF (882KB) ( 1180 )  
    Related Articles | Metrics

    The North Yellow Sea Basin is the only one offshore petroliferous basin of China that is very lowly explored and where we have not made breakthroughs in oil and gas. However, Korea has discovered commercial hydrocarbon in the east of the basin.Three boreholes of Korea in the eastern depression give evidences that lower Paleozoic strata (Pz1) act as the pre-Mesozoic basement of the main body of the eastern depression and differ greatly in geophysical properties from the overlying Mesozoic-Cenozoic strata dominated by sandstone and mudstone. These geophysical data can be reliably used to infer and determine the characteristics of the Mesozoic-Cenozoic basin basement. Based upon the interpretations of gravitational, magnetic and multichannel seismic data, there is an evidence that the maximum buried depth of the pre-Mesozoic basement is about 5.5 km in the North Yellow Sea Basin. If taking the previous buried depth of 1 km as the boundary of the basement, the eastern depression has an area of about 1,700 km2.Pre-Mesozoic basement of the depression mainly consists of carbonate rock of Lower Paleozoic, in the northeast corner of the depression may exist Late Paleozoic basement made up of clastic rock, and there may be Proterozoic basement of epimetamorphic rock in the south of the depression.

    Geological and Geochemical Characteristics of the Silicified Rocks in Jiangzi Basin and Their Implications for Mineralization
    FU Wei,ZHOU Yong-zhang,YANG Zhi-jun,NIE Feng-jun,LI Wen ,
    2005, 19(2):  267-273. 
    Asbtract ( 5204 )   PDF (229KB) ( 1022 )  
    Related Articles | Metrics

    The Lower Cretaceous in southern Tibet mainly consists of the submarine fan system, which is widely developed in Jiangzi Basin. Near the Shalagang antimony deposit, which is the biggest in southern Tibet, a segment of the submarine fan was silicified.According to the mineralogy and geochemistry features, the silicified mudstones and limestones were identified Besides the quartz, the albite was found in the silicified mudstones, but the silicified limestones contain only calcite without albite.The geochemical data show that the silicified mudstones contain relatively high content in Al2O3 and Na2O，and reveal high value of ΣREE and distinctly δ(Eu) anomaly.These features indicate that the elements of the silicified mudstones are mainly derived from the source rocks. For the silicified limestones, the contents of the trace elements are related to the silicification, and four groups are identified to reveal the mobility of the trace elements.The values of ΣREE and LREE/ HREE are increasing with the growing of the silicification intensity.With these geological and geochemical features, it can be inferred that the fluids, which led to the silicification processes, are characterized by mid-low temperature, rich in SiO2 and alkali material and metal elements.It is suggested that these SiO2-rich fluids have close associations with the genesis of the antimony mineralization in this area.

    Hydrocarbon Migration Conditions of the Buried Hill in the West Slope of West Sag in Liaohe Depression
    SHAN Jun-feng, CHEN Zhen-yan, ZHANG Zhuo, YUAN Xuan-jun
    2005, 19(2):  274-278. 
    Asbtract ( 1544 )   PDF (195KB) ( 913 )  
    Related Articles | Metrics

    Based on the analysis of accumulation conditions of buried-hill reservoirs in the west slope of west sag in Liaohe depression, this thesis emphasizes on the hydrocarbon migration conditions of buried-hill reservoir. The oil in buried-hill reservoir of the west slope has four types of migration paths.Different migration paths have different characteristics.There are many ways for oil to buried hill, but the most effective way is to migrate oil directly from above or lateral contacted source rocks, resulting in the formation of big buried-hill reservoirs.Oil accumulation by unconformity or fault also can form buried-hill reservoirs rich in oil and gas.These research results can make buried-hill exploration more effective in the west slope, or even in whole Liaohe depression.

    Origin of the Heavy Oils from the Bamianhe Oilfield, Dongying Depression
    LI Chun-mei,LI Su-mei,LI Xue,PANG Xiong-qi,WANG Ming-pei
    2005, 19(2):  279-286. 
    Asbtract ( 1478 )   PDF (478KB) ( 914 )  
    Related Articles | Metrics

    Obvious variations of oil properties were observed from the oils of the Bamianhe region, Bohai Bay Basin, eastern China Heavy oils are mainly distributed in high position tectonically whereas normal oils are in low position with relatively short distance from the depo-center of source rock. Detailedly geochemical investigations of 31 oil samples show that the heavy oils of Bamianhe oilfield are characterized by low concentration of saturated hydrocarbons with low ratios of saturated/aromatic hydrocarbons, and low content of hydrocarbon fractionation with low molecular weight i.e. alkyl alkanes, naphthalene and phenanthrene, suggesting light to middle degree of secondary alteration.Oils from adjacent Chaoqiao oilfield are featured by occurrence of 25norhopane series besides the similar characteristics of biodegradation in the Bamianhe oilfield. It is suggested that secondary alteration is crucial for the formation of the heavy oils in the Bamianhe area. Additionally, the immature oils in the Shaziling oilfield with similar source rocks to the Bamianhe display chacteristics of normal oils rather than that of the heavy oils, which infers that early hydrocarbon degradation does not result in indigenous heavy oils, which further proves secondary alteration is the main factor responsible for the heavy oils in the Bamianhe oilfield.Oil pools with shallow burial depth are liable to be destroyed under relatively bad reserve conditions.

    Evolution Characteristics of Extensional Faulted Depression Basin——An Example from Beier Depression in Hailaer Basin
    SHEN Hua，LI Chun-bai，CHEN Fa-jing，YIN Wei，ZHANG Yu
    2005, 19(2):  287-294. 
    Asbtract ( 1495 )   PDF (734KB) ( 1227 )  
    Related Articles | Metrics

    The Beier depression in the Hailaer basin is an extensional faulted depression of the Early Cretaceous epoch.Based on seismic data and well logs, the evolution of Beier depression is discussed in this paper.It is concluded that alternation of extension and shortening is occurred through the evolution of this depression.Development of three sedimentary cycles，superimposition of extensional and inversion structures, and formation of oil reservoirs were controlled by three activities of tension and compression in the Early Cretaceous epoch.In general, the processes of extension and shortening control the structural styles and sedimentary cycles, and also are responsible for the distribution of source-reservoir-cap rock assemblages, and the migration, accumulation and preservation of oil and gas.

    Analysis of Well-to-Seismic Calibration Parameters and Thin Reservoir Calibration: A Case Study of HD4 Oilfield in the Tarim Basin
    WANG Xiao-ping，WANG Xun-lian，LING Yun，ZHANG Hong-mei ，WU Lin
    2005, 19(2):  295-302. 
    Asbtract ( 1686 )   PDF (1151KB) ( 963 )  
    Related Articles | Metrics

    Donghe sandstone, the main reservoir of HD4 oilfield in the Tarim Basin, is the thin reservoir whose thickness is less than 1/4 seismic wavelength; therefore the top and bottom of the reservoir cannot be identified through seismic data. In order to calibrate properly the thin reservoir of HD4 oilfield with acoustic velocity, based on the theory of well-to-seismic calibration, the influence of the dominant frequency, kind and phase of the wavelet, and acoustic velocity on the synthetic traces was analyzed, moreover, the differences between interval velocity from stacking velocity and acoustic velocity were discussed. A new method using reference layer and adjusting acoustic velocity for calibrating thin reservoir was proposed. A reference layer is the thick stratum with stable sedimentary environment, and it corresponds to a high-amplitude and continuous reflector to be easily traceable in the seismic section. The results of well-to-seismic calibration are effective by selecting Permian igneous rock and Carboniferous double-peak limestone as the reference layers, adjusting appropriately acoustic velocity and choosing the most suitable wavelet.

    Application of the Induced Polarization Method on the Measurement of the Water-Contained Area in the Junggar Basin
    LU Li-ping，WU Gang，WANG Jun
    2005, 19(2):  303-308. 
    Asbtract ( 1535 )   PDF (198KB) ( 916 )  
    Related Articles | Metrics

    The method of induced polarization (IP) is used to analyze the location of the water-contained area in the Junggar Basin. By analyzing the single-point curves of the apparent resistivity and the apparent polarization, the initial information of the geology about the water-contained situation and the geological strata were recognized as well as the aquifer and the depth of the top layer in the study area. Based on the above, the 2D direct current electric inversion software is used to deduce the apparent resistivity to be close to the real resistivity of the stratum. In the analytical process, it can be found that there are some water resources in Basin Five Well, and in the area traversed by the lines of P200201, P200202 and P200207, the water content is higher.The upper Dushanzi Group of the Pliocene Formation（N2d2）is the ample aquifer, and the lower Dushanzi Group of the Pliocene Formation（N2d1）is the scanty aquifer.The characteristics of the aquifer in Basin Five Well are that the water exists in high-resistance layer while does not in low-resistance layer. It is revealed that the sandstone sediment is loosen in this area and the degree of mineralization in groundwater is low, and the groundwater quality is typically good according to the degree of mineralization.

    Comparison between ETM+and ASTER Data for Extraction of Alteration Information: A Case Study of Fenghuangshan Orefield, Tongling, Anhui Province
    MAO Xiao-chang, LIU Wen-can，DU Jian-guo, XU Wei
    2005, 19(2):  309-314. 
    Asbtract ( 3319 )   PDF (696KB) ( 1210 )  
    Related Articles | Metrics

    With the advent of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), a 14-band multispectral sensor operating onboard the Earth Observation System (EOS). Terra satellite, the availability of spectral features in the shortwave infrared (SWIR) portion of the electromagnetic spectrum has been greatly increased.This allows us to reveal the detailed spectral characterization of surface targets, particularly of minerals with diagnostic spectral features in this wavelength range, such as clay minerals.In this study, Landsat ETM+ and ASTER remote sensing data were used to map the alteration of rocks and minerals in Fenghuangshan Orefield based on the spectral feature analysis. Principal component analysis (PCA) was done using four ETM+bands as input bands to extract clay-alteration information, based on the relationship between the wavelengths of the ETM+ bands and absorption features of the clay minerals. PCA was also applied to the subsets of four and six ASTER bands to discriminate two kinds of clay minerals in the study area: kaolinite+sericite and chlorite, using the Crosta technique proposed by Loughlin.The subsets were selected according to the bands with characteristic spectral features of key alteration mineral end-members in the VNIR and SWIR of the spectrum. The information of clay mineral distribution was extracted by each data set. Comparison between ETM+ and ASTER data for extraction of alteration information in this study shows that ASTER data has better capability for recognition of alteration minerals.

Author Center
Office Online
Journal Online
京ICP备08011785号-7
Copyright © Geoscience, All Rights Reserved.
Tel: 010-82322463　E-mail: xddz@cugb.edu.cn
Powered by Beijing Magtech Co., Ltd.