2013 Vol. 19, No. 4

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DEVELOPMENT CHARACTERISTICS OF THE GEO-HARZARDS IN BAOJI CITY, SHAANXI PROVINCE
SHI Ling, WANG Tao, XIN Peng
2013, 19(4): 351-363.
Abstract (395) HTML (124) PDF (2593KB)(35)
Abstract:
This article makes use of detailed geo-hazard investigation data in 12 districts and counties of Baoji City in recent 7 years, based on collecting and sorting out main types and spatial distribution characteristics of geologic disasters in Baoji area, and analyses the general development characteristics, different development characteristics of various geologic disasters types in Baoji area and their impacts. It is preliminarily revealed that development types of geologic disasters in Baoji city mainly include:landslide, collapse, debris flow and unstable slope. These geo-hazards generally indicate clustering, unexpected, periodic and in chainlike. Development characteristics among all types of disasters, landslides and collapses happen most frequently and cause serious damage. Debris flows account for relatively rare part. Unstable slopes often occur together with collapses and mainly prone to collapse disaster. In each year, the heavy rainfall during rainy season will induce small scale landslides and collapses, especially the loess landslide and collapse in front of and behind of houses in urban residential area. Eluvia layer landslides and collapses due to slop cutting of mountain roads which occur frequently need to be paid special attention to monitoring, prevention and reduction of geologic disasters in Baoji city.
MAIN TYPES AND DEVELOPMENT LAW OF GEO-HAZARDS IN THE MIANNING PART OF YAAN-XICHANG EXPRESSWAY
ZHANG Rui-duan, GUO Chang-bao, SUN Jin-zhong, ZHANG Yong-shuang, FU Xiao-xiao, WANG Xi-hai
2013, 19(4): 364-376.
Abstract (232) HTML (212) PDF (4206KB)(20)
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On the foundation of data collecting and field geological survey, main geo-hazard types and development law in the Mianning part of Yaan-Xichang expressway have been summarized to prevent disasters caused by collapses, landslides, debris flows. Studies showed that the main geo-hazard types in the study area were landslide and debris flow, with taking debris flow as the main content. They were characterized by wide distribution, high density and great harmfulness. In space and time, they were group-occurring and concentrative inducing. Geological structure, neotectonic movement and formation lityology were inherent effect factors of frequent occurring of such geo-hazards as collapses, landslides and debris flows in the Mianning part of Yaan-Xichang expressway. Rainfall, earthquake and human engineering activities were most important inducing factors of the geo-hazards.
RESEARCH PROGRESS ON MECHANISM AND QUANTATIVE PREDICTION OF STRUCTURAL FRACTURES IN TIGHT-SAND RESERVOIRS
XU Hui-yong, FENG Jian-wei, GE Yu-rong
2013, 19(4): 377-384.
Abstract (216) HTML (138) PDF (1122KB)(23)
Abstract:
As fractured tight-sand reservoirs was thought to be an important type for exploration and production of unconventional oil and gas resources at present, understanding mechanism of structural fracture networks in reservoirs accordingly is thought to be the research focus. From sides of structural geology and rock mechanics to make comprehensive analysis, such as comparisons of rock damage mechanics experiments, constitutive relation of composite formation and its failure criteria, and quantitative method for predicting fracture distribution, it is shown that generation, location, orientation of fractures and quantification are the keys to predict fracture networks. Then it is shown that there exist three main directions for fracture research, including fracture mechanism study using structural geology, damage mechanics and laboratory experiments, composite rock failure criterion based on energy conservation law considering multiple factors, and fracture parameters of three-dimensional quantitative characterization using finite element numerical method based on fine structure model.
K-Ar DATING OF FAULT GOUGE FROM THE MAIN FAULT OF WULONGGOU GOLD DEPOSIT IN DULAN, QINGHAI PROVINCE
LU Lu, ZHANG Yan-lin, WU Zhen-han, HU Dao-gong
2013, 19(4): 385-391, 446.
Abstract (282) HTML (97) PDF (2870KB)(9)
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In this paper, K-Ar dating of three fault gouge samples from the main fault belt in Wulonggou gold ore in Dulan, Qinghai Province were made to determine the activity time of the brittle fault. Then the relationship between the main fault and mineralization was discussed. The age of self-generated illite within the fault gouge samples is 185.54±3.06 to 165.11±3.28 Ma, which represents the formation epoch of the main fault being the late of Early Jurassic to Middle Jurassic. Combining with the field geological condition, it is suggested that main fault damaged and modified mineralization in the late of Early Jurassic to Middle Jurassic.
ESR DATING OF THE PALAEOGENE IN MULI BASIN IN THE MIDDLE OF QILIAN MOUNTAINS AND ITS GEOLOGICAL SIGNIFICANCE
QI Bang-shen, HU Dao-gong, WANG Jin-shou, ZHAO Xi-tao, ZHANG Xu-jiao, ZHANG Yao-ling, YANG Xiao-xiao, GAO Xue-mi
2013, 19(4): 392-402.
Abstract (205) HTML (112) PDF (2334KB)(12)
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The technique of ESR was applied to determine the Cenozoic red beds, Muli Basin, therefore, we can get the age of sedimentary and tectonic deformation. The results indicated there were huge thick Cenozoic Red Beds and tectonic deformation geochronological data, well recording the uplift of Qilian Mountains. Based on the ESR dating, the Tertiary sediments include the Eocene to Oligocene Huoshaogou Formation (40.2~35.3 Ma), which consists mainly of lacustrine facies and the Oligocene Baiyanghe Formation (32.6~24.3 Ma), which consists lacustrine and fluvial facies. From late Eocene to early Oligocene, an obvious angular unconformity exists between the upper and lower strata and it can be inferred that Qilian Mountains area has been a tectonic deformation and uplift, which has corresponding connection with the early Cenozoic uplift of Qilian Mountains.
GEOCHEMICAL CHARACTERISTICS OF BEIYI AND NANLIU OREBODIES IN THE SHILU IRON DEPOSIT IN HAINAN PROVINCE
YANG Xu-gang, HU Bao-qun, GAO Hai-dong, XU De-ru, LI Man-gen, GUO Tao
2013, 19(4): 403-412.
Abstract (249) HTML (132) PDF (2858KB)(11)
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Beiyi orebody and Nanliu orebody are the two main orebodies of Shilu iron deposit in Hainan Province, with high research value, ore-bearing wall rocks being the diopside-tremolite rocks and iron ores being mainly composed of hematite and tiny magnetite. By studying geochemical characteristics of wall rocks and ores of two orebodies and comparing their material composition differences, we hope that it could provide some useful information for prospecting in depth and periphery of deposit. Two orebodies have pronounced differences. The distribution patterns of main elements and trace elements of Beiyi's and Nanliu's high-grade Fe ore samples of two orebodies are pronounced; except that CaO and Co of Beiyi orebody's diopside-tremolite rocks are less than Nanliu orebody's, the remaining oxides and trace elements are more than Nanliu samples'. Beiyi orebody's diopside-tremolite rocks and high-grade Fe ores have weak Eu negative anomaly, and Nanliu orebody's iopside-tremolite rocks and high-grade Fe ores have Eu positive anomaly, and all samples have the characteristic of weak Ce negative anomaly and LREE depleted and HREE enriched relatively. It reflected that metallogenic environments or late hydrothermal fluid affected of two ore bodies are different.
PETROGENESIS AND TECTONIC SIGNIFICANCE OF GRANITE IN THE HAOYAOERHUDONG GOLD DEPOSIT IN INNER MONGOLIA
LIU Jian-chao, WANG De-quan, ZHANG Hai-dong, MEN Wen-hui, ZHENG Li-hong, ZHAO Zong-qin, Li Qiang, GAO Hai-long
2013, 19(4): 413-422.
Abstract (294) HTML (199) PDF (3573KB)(8)
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The Haoyaoerhudong gold deposit is a mesothermal-epithermal deposit with ultra-large reserves and low grade. Hercynian granite was developed in the gold deposit. Granitite, granite aplite, granite pegmatite and granite-porphyry could be found in the Haoyaoerhudong gold deposit. The content of SiO2 is from 65.36 to 73.07, and Na2O/K2O is 0.43 to 1.01, with average value of 0.75. The granite dikes belong to high potassium calcium alkaline. The biotite granitization belongs to shoshonitic series. The variation tendency of other elements with following the content of SiO2 is obviously linear, and then it expresses the characters of Ⅰ-type granite. The content of ∑REE ranges from 64.86×10-6 to 164.80×10-6, which means low content of REE. The ratio of (La/Yb)N ranges from 6.59 to 16.98, revealing apparent fractionation between LREE and HREE. The distribution curve of REE is right deviation. The δEu average value of biotite granitization is 0.30. The δEu average value of granite dikes is 0.65, indicating high and medium negative anomaly of Eu elememt. The biotite granitization showed low Sr and low Y characteristics. The granite dikes showed high Sr and low Y characteristics. According to the geochemical characteristics, the granitoids belong to collision-post collision environment Ⅰ-type granite.
STUDY ON TECHNOLOGY OF SLOPE/LANDSLIDE STABILITY ANALYSIS AND EARLY WARNING UNDER HEAVY RAINFALL
ZHU Zhi-ming, ZHOU Kai-rui, TAN Chun-hong, BIAN Jing-sheng, WEI Yuan, ZOU Zu-yin
2013, 19(4): 423-430.
Abstract (214) HTML (145) PDF (2705KB)(22)
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Erman mountain landslide of Han Yuan County as the example, according to the exploration of landslide site conditions and indoor test of soil parameters; Choosing a built-in VBA for development tool to develop the side (slip) slope stability analysis plug-in based on ArcGIS, which makes the study regional risk zoning assessment diagram. Results show that the special topographical condition, geological structure after the earthquake, continuous heavy rains filled water load, slope unsaturated seepage flow, increasing the pore water pressure and rapidly reducing the soil matrix suction, leads to the shear strength decreased of the slope slip plane in the soil and finally landslides. Risk zoning evaluation chart of research area based on ArcGIS and the actual situation of slide have goodness of fit. Research result provides a new way for further analyzing the effect on side slope (slip) and warning under heavy rainfall condition.
TRANSFER COEFFICIENT METHOD AND ITS IMPROVEMENT FOR THE CUTTING SLOPE
WANG Zong-lin, LIANG Tian-yi, LIANG Bing
2013, 19(4): 431-439.
Abstract (194) HTML (186) PDF (1929KB)(32)
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The traditional calculation method of slope stability coefficient assumes that the direction of the interaction force between slide blocks is same with that of the sliding surface of last block. However, when the sliding surface is relatively steep or gradual, or when the ground water is involved, the same direction cannot be guaranteed, which leads to the calculation deviation. Thereupon an improved calculation method of the transfer coefficient is put forward in which the effect of still water and flowing water is taken into consideration. Finally it comes to a conclusion that the result from the calculation method of the transfer coefficient is accurate and reliable to a certain extent since the assumed slope stability coefficient obtained from this calculation method is more precise in contract with that from other calculation methods.
RESEARCH ON THE APPLICATION OF TURNAROUND FRACTURING TECHNOLOGY IN INJECTION-PRODUCTION CORRESPONDING WELLS
LI Min
2013, 19(4): 440-446.
Abstract (139) HTML (74) PDF (2093KB)(22)
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In order to solve the difficulty of the low permeability reservoir's low production of old wells and poor flood effectiveness in Shuguang mine area of Liaohe Oilfield, an injection-production corresponding wells of turnaround fracturing technology research is carried out. Through turnaround Mechanism, fracturing project of injection-production corresponding wells research, diverting agent selection and field conduct, it gets good effect on increasing production and injection. During this application research, turnaround fracturing technology is used for injection and production wells and widening the range of the turnaround fracturing, makes further proving turnaround fracturing has important significance to tap production and energization, and to improve the recovery of the low permeability reservoir.

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