2017 Vol. 23, No. 2

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MODEL BUILDING OF SURFICIAL DEPOSITS IN PLANE AREA——A CASE STUDY OF 1:50000 MAPPINGOF SHENGCITANG TOWN
ZHAO Zeng-yu, WANG Wei, LI Xiang-qian, CHENG Yu, GUO Gang, ZHANG Xiang-yun, JIAO Fei-xiang
2017, 23(2): 182-188.
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In the 1:50000 mapping pilot projects, taking the surficial geological mapping of Shengcitang Town as an example, the building of the 3D model of this area is studied.15 NW trending geological routes are arranged according to the remote sensing image. The characteristics of superficial deposits within the depth of 3~4 m areare revealed by Eijkelkamp groove drilling. The work flow with DSI as the key technology of 3D superficial depositsmodel building is introduced. The groove drill core description is quantified as spatial attributes of grain size. Then, geological marker horizons are established based on the drill core. The 3D grid model with grain size attributes is constructed by interpolating the grain size of all cores, and the changes of vertical lithofacies is studied by taking an example of the 3D profile AA' with northwest strike.In order to study the changes of vertical lithofacies, taking the river facies layer after removing agricultural soil as an example, combining with the geomorphological characteristics, surficial lithologic and lithofacies boundaries in study area are outlined.The research suggests that 3D surficial deposits model holds significant value to regional geological survey, geological map drawing, lithology and lithofacies boundaries outlining and Holocene quaternary geology research. This model also can be used in environmental geological research like shallow groundwater antipollution, soil pollution problems, etal.
APPLICATION AND PRACTICE OF THE NEOTECTONIC GEOLOGICAL MAPPING METHODS——A CASE STUDY OF 1:50000 MAPPING PILOT IN HULESITAI, INNER MONGOLIA, CHINA
JIA Li-yun, YE Pei-sheng, ZHANG Xu-jiao, HE Ze-xin, YANG Xing-chen, ZHOU Qing-shuo, YE Meng-ni, LIU Xiao-tong, LI Cheng-lu, WU Ze-qun, ZHOU Wei, HE Xiang-li
2017, 23(2): 189-205.
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Neotectonic investigation is the foundation of the study of crustal movement, evaluation for geological hazards, environmental geology and crustal stability. With great theoretical and practical significance, neotectonic investigation is one of the key content of regional geological mapping.The area of the 1:50000 mapping pilot of the Hulesitai, Inner Mongolia, is located at the north boundary of the Hetao fault-subsiding belt. Frequent tectonic activity, complex stratum, variable landforms and extensive development of piedmont faults are all ideal neotectonic materials for studyand investigation in this area. In this article, the investigated objects for 1:50000 geological mappingis described, the survey technology methods combination of "space-ground-deep"is summarized (remotesensing, integrated geophysical,geochemical and detailed field geological survey, ancient earthquake trench with laser scanning, drilling and chronology methods), and its adaptability in the tectonic active area on the basis of predecessors' area method theory is studied. With reference to the "general provisions of 1:50000 regional geological survey," and "1:50000 regional geological survey technical requirements (provisional)" and other relevant technical requirements, the results of geological survey are expressed on the geological map with the digital mapping technology. This methods combination of survey technology is not only an effective exploration of neotectonic investigation mapping method, but also an important reference for the new round of large-scale investigation mapping for other tectonic area.
APPLICATION AND EXPLORATION OF GEOPHYSICAL METHODS IN GEOLOGICAL MAPPING IN STRONGLY WEATHERED AREA
CHEN Song, CHEN Chang-jing, WU Jun, LIU Lian, BU Jian-jun
2017, 23(2): 206-213.
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Due to the unique geological feature of Southern China area, such as thick overburden layerfew outcrops, thick-growing vegetation and difficult access, it is difficult to effectively identify the geological characteristics of weathered layers and its underlying strata, rocks, structures and minerals by means of traditional geological mapping methods. Through comprehensive geophysical methods including shallow earthquake, high density resistivity and EH4 electromagnetic imaging, the geological characteristics like weathering layer thickness, bedrock lithology and occurrence, and buried fault are tested. By analyzing the data obtained from this 3 methods and the results of field investigation, the validity and applicability of this 3 geophysical methods are studied, and a series of geophysical methods for geological mapping in strongly weathered area are preliminarily summarized.
THE APPLICATION OF GROUND PENETRATING RADAR TECHNOLOGY IN GEOLOGICAL MAPPING OF SHALLOW COVERED ACTIVE TECTONICS REGION:A CASE STUDY OF 1:50000 MAPPING OF NEOTECTONIC ZONE AND ACTIVE TECTONIC ZONE IN QING TONGXIA AREA, NINGXIA
YIN Yan-guang, SHI Wei, GONG Wang-bin, QIN Xiang, ZHAO Yi
2017, 23(2): 214-223.
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Ground Penetrating Radar (GPR) detectionisa widely-used detection method in geological survey owing to its advantages of high-resolution, accurate positioning, high speed, flexibility, convience, profile visualization, real-time image display and so on. GPR detection technology is applied to detect Quaternary system and blind faults in the mapping of 1:50000 shallow covered active tectonics zone of Qingtongxia, Ningxia. Detection results show that 40MHz GPR can effectively detect the quaternary system structure within 30 m below the surface, and 3 sets of Quaternary strata can be clearly defined. Drilling results confirm that Holocene Lingwu formation (Ql) from bottom to top is comprised of mudstone, gravel layer, and sand or mud with gravel. The radar image reveals that the south of the Liumugao fault of main fault has structural features of upward divergence and downward convergence with flower structure, which is consistent with the results of trench investigation.It shows that GPR can accurately demarcate the plane position and vertical detail structure of blind faults. This work indicates that GPR technology is feasible, effective and convenient for blind fault investigation and sequence division of the upper part of the Quaternary in shallow covered active tectonic zone.
THE EXPERIMENTAL RESEARCH OF SEISMIC WAVE VELOCITY OF SANDSTONES IN HAMI, XINJIANG AND THE ENLIGHTMENT TO THE WORK OF PROPERTY ON SPECIAL GEOLOGICAL MAPPING
WANG Huai-min, WANG Hong-cai, YIN Chang-ji, LI A-wei, ZHAO Wei-hua, DU Wei
2017, 23(2): 224-231.
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The seismic wave velocity of sandstones in Hami in the process of special geological mapping isstudied in this article. The effects of density, porosity and pressure on seismic wave velocity under different pressure(0~200 MPa)are analyzed by applying ZBL-U520 nonmetal ultrasonic detector and AutoLab 2000 computer-controlled servo hydraulic triaxial test system. The results show that wave velocity and density are positively correlated, but there is a negative correlation between wave velocity and porosity. The degree of linear relationship between density or porosity and P-wave is higher than that of S-wave. Both P-and S-wave velocities of sandstones in Hami area increase notably with the increasing pressure which denotes a strong logarithmic relationship.Besides, the adaptability of test methods of ZBL-U520 nonmetal ultrasonic detector and AutoLab 2000 computer-controlled servo hydraulic triaxial test system are analyzed.In conclusion, in respect of geological mapping it is suggested that not only should we collect samples to test the seismic wave velocity of rocks at normal temperatures and pressure, but also we should analyze the seismic wave characteristics under different formation pressure to comprehensively understand the seismic properties in special geological mapping.
40Ar/39Ar GEOCHRONOLOGY OF SUPERGENE JAROSITE FROM LIUHUANGSHAN COPPER POLYMETALLIC DEPOSITS IN Tu-Ha BASIN AND THE ENLIGHMENT TO WEATHERING, LANDSCAPE EVOLUTION AND PALEOCLIMATE
YANG Jing, ZHENG De-wen, CHEN Wen, WU Ying, XU Ying-xia, YANG Li
2017, 23(2): 232-242.
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Supergene jarosite is widely distributed in oxidation zone of sulphide deposits in arid-semiarid area. Precise 40Ar/39Ar age constraints of supergene jarosite can not only define the timing of sulfide secondary enrichment, but also provide key information on the geochronology to the regional geomorphic evolution and paleoclimatic evolution. In this article, 40Ar/39Ar laser incremental heating analysis of jarosite from the Liuhuangshan copper polymetallic deposit in Tu-Ha Basin is conducted, and the age of Eocene weathering mineral is defined for the first time. Combined with the published chronology data, it indicates that the profile of oxidation zone of ore deposit from the higher elevation sites recorded the more complete and lasting regional weathering events. The presence of ancient weathering ages in current outcrops in Tu-Ha Basin suggests that denudation was not homogeneous, and the landscape evolution followed a scarp retreat model. The ages in this present study and published ages demonstrate that chemical weathering and supergene enrichment under an arid-semiarid climate are mainly concentrated in the following period:27.7~23.3、16.4~14.7、11~7.8 Ma. After the 11~7.8 Ma, a progressive change from arid-semiarid climate towards hyperarid climatic, and predominantly hyperarid climate may had persisted at least since 4.1~3.3 Ma.
THE RECOGNITION OF THRUST NAPPE STRUCTURE AND ITS TECTONIC SIGNIFICANCE IN BEISHAN AREA, WUSHI COUNTY, SOUTHWESTERN TIANSHAN
ZHA Xian-feng, CHEN Rui-ming, GU Ping-yang, HU Chao-bin, ZHUANG Yu-jun
2017, 23(2): 243-252.
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Reasonably defining the tectonic attributes of Sorthwestern Tianshan not only has important scientific significance and practical value to the accurate division of Tianshan tectonic units, but also plays an importantrule in revealing the tectonic evolution during Paleozoic in Central Asian orogenic belt. Based on geological mapping and field structure analysis in Beishan area, Wushi County, Southwestern Tianshan, 5-phase deformation is recognized, including 2-phase thrust structures. The geometry and kinematics studies of the main thrust nappe structure prove that the thrust nappe structure yield with N-S direction. The structural deformation style of the thrust nappe can be established, and it presents root zone to front zone of nappe from north to south. According to the material composition and deformation features of thrust nappe structure, we think that Beishan area should be classified into the thrust nappe structure in north margin of Trim Plate in Paleozoic. It may provide deformational information for understanding the regional tectonic units division as well as the tectonic evolution in Southwestern Tianshan since Neopaleozoic.
THE PETROGENESIS AND TECTONIC SIGNIFICANCES OF SILURIAN WEST-LUOTOUJUAN ROCKS FROM BEISHAN NIUJUANZI AREA IN GANSU PROVINCE, NW CHINA
YU Ji-yuan, JI Bo, GUO Lin
2017, 23(2): 253-263.
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West-Luotuojuan Adakitesin Beishan Niujuanzi Area belongs to Peraluminous calcium alkaline magma series with a high content of SiO2(>57.94%), Al2O3(>16.66%), a low content of MgO( < 4.32%), a relatively high Na2O/K2O ratio, displaying Na-rich feature. In respect of trace elements, it has a high content of Sr (589×10-6~1170×10-6), a low content of Y (4.60×10-6~13.90×10-6) and Yb (0.43×10-6~1.32×10-6).The differentiation of light and heavy rare earth is obvious ((La/Dy)N=4.60~13.87, (La/Yb)N=7.17~20.58), and there is not obvious anomaly of Eu (Eu/Eu*=0.85~1.32). Rich in light rare earth and large ionlithophile elements, and the loss of high field-strength elements Nb, Ta, Ti and heavy rare earth HREE, are similar with the typical Adakite rocks which formed by subducted oceanic crust melting.It is believed that West-Luotuojuan Adakite is a partial melting product which warm oceanic crust in Silurian (U-Pb age of 428.9 Ma) period moving to Gongpo spring-east Qiyi mountain early Paleozoic active continental margin in the process of subduction. The study of the rock mass provides evidence for the view that Beishan orogenic belt closed in the late early Paleozoic and split anew in the early late Paleozoic.
THE LANDFORM FORMATION PROCESS OF ALPINE-GORGE IN BEISHAN, WUSHI COUNTY, SOUTHWESTERN TIANSHAN
CHEN Rui-ming, ZHA Xian-feng, GU Ping-yang, ZHUANG Yu-jun
2017, 23(2): 264-271.
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The geomorphological evolutionisbasically influenced by the tectonic and its regular pattern. Based on the observation of Quaternary deposit and erosional landform of Gunguntielieke river valley in Beishan, Wushi County, Southwest Tianshan, combing with the published stratigraphic chronology, the evolution of erosive geomorphic in Middle Pleistocene and Holocene are reproduced. In Middle Pleistocene, the geomorphological cutting depth is more than 1870 m, which is much deeper than 50 m in Holocene and it is believed that the alpine-gorge in this area was formed in Middle Pleistocene. Generally developed Middle Pleistocene fold thrust structure in Southwest Tianshan, resulting in the rapid and substantial mountainuplift, is the main cause of the alpine-gorge geomorphology in Beishan. The fold thrust structures extended to the basin, which led to the decrease of amplitude of the uplift of the mountain to the basin. It reveals the spatial regularity of the geomorphological evolution in Beishan. There is a close relationship between the process of Quaternary tectonic uplift and geomorphological evolution in Southwest Tianshanmountainaccording to this stuty.
RESEARCH PROGRESS ON THE FORMATION MECHANISM AND QUANTITATIVE CHARACTERIZATION OF MULTIPHASE FRACTURE NETWORKS OF TIGHT SANDSTONE
SUN Zhi-yong, CHEN Kai-yuan, FENG Jian-wei, SUI Shu-ling
2017, 23(2): 272-279.
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Tight sandstone oil gas is an important unconventional resource.As the primary seepage channel, fracture networks commonly have the charactistics including complex distribution regularity as well as multiphase development and filling process, which directly influence fracture prediction accuracy.At present, there is no systematic method for solving the quantitative prediction of structural fissures, which is still in the exploration stage. Therefore, it is necessary to explore more about fraction networks identification, filling process and formation-superposition evolution mechanism. and set up a reasonable fracture characterization model for quantitative prediction of fracture networks parameter distribution range. On the basis of plenty of literature research, it is believed that the research of tight reservoir fracture is mainly in three key directions.Field observation and core observation were carried out to analyze the development characteristics of fracture networks.combing with tectonic evolution history and fluid-inclusion analysis, fractures development times were defined. Then, hydrothermal filling simulation experiments and rock mechanics experiments were conducted to reveal the mechanism of fractures filling and dynamic process of fractures from initiationto extension and superposition. Finally, experimental statistical methods were used to establish the anisotropic failure criterion in view of different filling rules and create quantitative characterization of fracture parameters based on the principle of conservation of energy and the theory of strain energy density factor. At last, a theoretical system of multiphase fractures development and their parameters characterization were formed and completed, which provides an important scientific basis for the exploration and exploit of tight sandstone gas field.
FRACTURE DEVELOPMENT PREDICTION BASED ON AZIMUTHAL ANISOTROPY ANALYSIS OF PRE-STACK SEISMIC-TAKE XUJIAHE FORMATION OF PUGUANG GAS FIELD FOR EXAMPLE
XIONG Jin-hong, CHEN Cen, CAO Zhan-yuan, TAN Xian-feng, KUANG Hao
2017, 23(2): 280-287.
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In the beginning of this paper, the forward model is established and stimulation is carried out on the fractures from different angles according to the unique lithology characteristics of Xujiahe formation in North Puguang. In view of the different point of azimuthal to simulate the fracture, the rule is summed up that along the direction of the fraction the amplitude of the fraction reduces as the offset increases.Then, the pre-stack seismic data is processed.The velocity analysis and the pre-stack time migration stack are processed to meet the requirement of fracture prediction.Finally, based on the analysis of the variations the amplitude with azimuth and the analysis of the variations the frequency with azimuth, through invesion, the data cubes of strike direction and the density of reservoir fractures are obtained. Guided by the fracture prediction, Pulu1-2H Well was deployed, and a good anticipated effect was achieved.
SIMULATION ANALYSIS OF THE INFLUENCE OF THE RESERVOIR WATER LEVEL FLUCTUATION RATE ON THE STABILITY OF SHUANGJIAPING ACCUMULATION LANDSLIDE IN YA'AN
LI Peng-yue, BA Ren-ji, NI Hua-yong, WANG Dong-hui
2017, 23(2): 288-295.
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The stability of reservoir bank slope after impounding has been a hotspot for research, the periodic fluctuation of the reservoir water level can change the seepage field of the slope and then affect its stress field which can induces the deformation of the rock-soil mass. The effect of the reservoir water level fluctuation is especially significant for the stability of the landslide.In this paper, Shuangjiaping landslide at the Pubugou Hydropower Station Reservoir Area is chosen as the research object.On the basis of investigation and analysis, according to the theory of unsaturated soil mechanics, taking the soil-water characteristic curve and permeability into consideration, the stability and seepage value of Shuangjiapingaccumulation landslide under steady-transient conditions were calculated under the action of reservoir. Using the Seep module of GeoStudio software to simulate the landslide groundwater fluctuation under the action of reservoir, the changes of the internal seepage field in accumulation landslide under different reservoir fluctuation conditions were calculated and the results are coupled to the stability calculationin the slopemodule.The study results show that, as the water level rising, the landslide stability rise at first then get lower, and the higher the rate of elevation, the greater the extent of the decrease of the landslide stability. In water level decline phase, the stability of the landslide shows the trend first reduce gradually recover, and the higher the water level decline rate, the lower the extent of the decrease of the landslide stability.The study results have an important significance for the geological disaster monitoring and early warning, disaster prevention and mitigation, regulation of the storage capacity of reservoirs.
RISK ASSESSMENT OF SEISMIC LOESS LANDSLIDE BASED ON NEWMARK MODEL IN BEISHAN, TIANSHUI CITY
CHENG Xiao-jie, YANG Wei-min, XIANG Ling-zhi, ZHANG Shu-xuan, LI Huan-bin
2017, 23(2): 296-305.
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Based on the method of field investigation and indoor analysis of Beishan in Tianshui City, Gansu Procince, the analysis of the hazard analysis of the seismic loess landslide is carried out in this article based on the Newmark accumulated displacement method. Through analyzing the disaster-forming environment, combining with the investigation data of the existing landslides and unstable slopes, in fully consideration of the angle relationship between the azimuth angle of the source and the slope angle of the area, the calculation and comparison of the slope prone angle under the dominant slope angle and the inferior slope angle are carried out.Then the accumulation of slope displacementis calculateby using the regression equation when the PGA is 0.3g. Finally, the probability of instability of slope under earthquake load is calculated. On this basis, the risk assessment of the Seismic loess landslide of Beishan area was carried out. The analysis results show that introducing the relationship between the slope angle and the azimuth of seismic source in the risk assessment of the Loess Landslide in the Newmark model is helpful to improve the accuracy of the risk assessment of the small area (large scale).
ANALYSIS OF DETRITAL COMPOSITION, HEAVY MINERAL COMBINATION CHARATERISTICS AND SAND PROVENANCE OF NEOGENE SANDSTONES, MAZHATAGE MOUNTAIN IN THE CENTRE OF TARIM BASIN
LI Qin, LIU Jian
2017, 23(2): 306-314.
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Developed in the hinterland of the tarim basin, Neogene sedimentary stratain the centre of Tarim basin are well-outcropped and hold the information about the uplift and denudation of provenance orogenic belt.Using the methods of paleocurrent, sandstone detrital component and heavy mineral assemblages characteristics, combing with regional tectonic evolution of the study area, the sedimentary response relationship between the paleogeomorphology pattern and the uplifting and denudation of the sediment source area is discussed in Mazhatage Mountain. Results show that the overall pattern of the ancient landform in the study area is high in the west and low in the east, the sediment source of the study area before the early Pliocene mainly comes from the West Kunlun orogenic belt and Pamirsorogenic belt, while since the beginning of Pliocene epoch the sediment source mainly comes from Pamirs orogenic belt, and in the early Pliocenethere was an obvious structural uplift movement in the source area, and a rapid rise and denudation tectonic event occurred during the pleistocene period
ORE-CONTROLLING STRUCTURAL CHARACTERISTICS OF DAPING GOLD DEPOSIT IN YUNNAN AND PROSPECTING ORIENTATION RESEARCH
ZHANG Yao-yao, ZHANG Da, WU Gan-guo, DI Yong-jun, LIU Jun, BU Xing-chen, LI Xing-jian
2017, 23(2): 315-326.
Abstract (602) HTML (209) PDF (4665KB)(32)
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Ailaoshan gold metallogenic belt is one of the most important gold metallogenic belts of Himalaya epoch in China, and Daping gold deposit is the most representative gold deposit in this metallogenic belt. On basis of the introduction of the geological features of Daping gold deposit, taking the relevant theories and methods of ore-controlling structure analysis, mineral exploration and metallogenic prediction as the main means, comprehensive investigation and research work are carried out around the geological structure pattern of the Daping gold deposit, the type and nature of ore-controlling structure of the main gold belt, the geometrical shape and extension of the main ore bodies, and the spatial distribution characteristics of the gold bodies. It is believed that the main conductance structure of the deposit is Xiao xinjie fault, and the secondary fault system, formed under the influence of the left walking slide on Xiao xinjie fault, is the main reservoir structure. On this basis, the tectonic ore-controlling model and prospecting model are established, and the direction and space of the deep and peripheral ore-prospecting of the main ore belts are stated, which can provide scientific basis for the deep prospecting verification.
SIZE EFFECT EXPERIMENT OF UNIAXIAL COMPRESSIVE STRENGTH OF THREE TYPICAL ROCKS
WANG Lian-shan, SUN Dong-sheng, ZHENG Xiu-hua, ZHAO Wei-hua, LI A-wei, LI Quan
2017, 23(2): 327-333.
Abstract (758) HTML (163) PDF (2375KB)(43)
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Size effect is a popular and difficult issue in the field of rock mechanics. In this paper, the uniaxial compressive strength of marble, diorite and tuffsamples with the maximum sample size 400 mm×400 mm×800 mm were tested using the self-developed large-scale rigid testing machine. Two cases of size effect of rock uniaxial compression strength were conducted:one is with the same aspect ratio and the other is different aspect ratio with the same length and width. The results show that, with the increase of samples dimensions, the uniaxial compression strength decrease in logarithmic function form and gradually approach to a certain value in the case that with the same aspect ratio; In the case that with different aspect ratios, the length and width of the samples are 200 mm×200 mm, and the heights are 200 mm, 400 mm, 600 mm and 800 mm respectively. The uniaxial compression strength decreased first and then increased as the increase of aspect ratio of samples. And the corresponding failure modes of samples are complex splitting, splitting and shear failure respectively as the increase of aspect ratio. The results of uniaxial compression strength of different dimensions presented in this paper provide the basic data for the size effect research of rock samples. At the same time, the results have some reference value for the correction of size effect in the practical engineering.