2001 Vol. 7, No. 2

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THE THEORY AND METHOD OF EVALUATION OF REGIONAL CRUSTAL STABILITY BASED ON CONCEPT OF “SAFE ISLAND”
HU Hai-tao
2001, 7(2): 97-103.
Abstract (262) PDF (193KB)(14)
Abstract:
The concept about "safe island" created by late Professor Li Siguang (J.S.Lee) is described in this paper from that there are a few weak destroyed districts in high intensity area of a strong earthquake. Author pointed out so-called "safe island" means the area which belongs to relative stability massif from the point of view tectonic activity. The regional crustal stability grading and its main evaluation indexes are given in the paper.
ANALYSIS ON SISMIC RISK OF THE CONVEYANCE WATER TUNNEL ENGINEERING IN SHENZHEN
AN Cheng-xuan, SUN Ye, YANG Mei-ling
2001, 7(2): 104-110.
Abstract (151) PDF (238KB)(8)
Abstract:
With reference to the existing determination and evaluation about seismic intensity in Shenzhen region,according to the analysis of seismogeology and the calculation of exceeding probability,and in consideration of importance of the conveyance water tunnel engineering,the nearly east-west line between ZD3 and ZD3 of the tunnel is taken as the zonation boundary of seismic intensity,north of which belongs to an intensity of Ⅵ and south an intensity of Ⅶ.
THE GEOLOGICAL AND GEOCHEMICLA CHARACTERISTICS OF THE JIFENG KOMATIIITESIN THE DA HINGGAN LING MOUNTAINS
HU Dao-gong, ZHENG Qing-dao, FU Jun-yu, LIU Xu-guang
2001, 7(2): 111-115.
Abstract (210) PDF (244KB)(8)
Abstract:
Field geological survey and geochemistry indicate that the metamorphic ultrabasic rock in Jifeng area of the north Da Hinggan Ling Mountains is komatiite with spinifex texture. The komatiite series consists of the ultramafic komatiite, basaltic komatiite, tholeiite and gabbro. The komatiite displays a geochemical trend from ultramafic to mafic,and the tholeiite shows a geochemical trend from rich Mg to rich Fe. The felsic igneous rock overlying the komatiite series displays a calc alkaline trend. The komatiite REE patterns show smooth or slightly rich in LREE, similar to that from South Africa. The eight samples composed of komatiite, tholeiite and gabbro yield a reasonable isochron age of 1727Ma±74.7Ma with INd=0.510725±0.0000798, εNd (t)=6.94±1.56. It is suggested that the Jifeng komatiites were derived from the depleted rheosphere mantle during the early Mesoproterozoic. This crustal accretion event might be related to the splitting of the Songnen Massif from the southorn continental margin of the Siberia Massif.
GEOCHEMICAL STUDY ON TECTONIC SETTING FOR NEOPROTEROZOIC GRANITOIDS, NORTHERN MARGIN OF SONGNEN MASSIF, CHINA
ZHENG Qing-dao
2001, 7(2): 116-122.
Abstract (157) PDF (232KB)(7)
Abstract:
The characteristics of granitoids petrology and geochemistry in the north margin of Songnen Massif indicates that the Neoproterozoic granitic bodies have typical rock association and ortho-succession magmatic evolution series belonging to convergent plate boundary. The Keluo pluton is I-type granite and formed in a tectonic setting of the continental arc. The Shuanghe pluton is S-type granite and formed in the zone of the intercontinental collision. The Jiutoushan and the Liutun units formed in post-orogenic and epeirogenic uplift periods, respectivly. The tectonic magmatism suggests that the plate tectonics had operated in the north margin of Songnen Massif in the Neoproterozoic.
ON ANISOTROPY OF SURFACE TOPOGRAPHY OF ROCK JOINT
ZHOU Hong-wei, XIE He-ping, Kwasniewski M A, YANG Zon-yee
2001, 7(2): 123-129.
Abstract (160) PDF (251KB)(12)
Abstract:
Based on date of surface topography of rock joint measured by laser profilometer, by transferring the height distribution into the slope distribution and taking spectral analysis of slope distribution, the anisotropic behavior of surface topography of rock joint is discussed in this paper. The general statistical parameters can supply the average measurement of certain behavior of individual profiles, but can not catch the behavior of anisotropy. However, the power spectral density can characterize both the shape of a profile at the large scale and the fluctuation at the small scale, therefore it is superior to the general statistical parameters. In this paper, a parameter called index for the accumulated power spectral density is defined to characterize quantitatively the anisotropy of surface topography of rock joint.
AN EXPERIMENTAL STUDY ON THE BRITTLE-PLASTIC TRANSITION IN GABBRO
SANG Zu-nan, ZHOU Yong-sheng, HE Chang-rong, JIN Zhen-min
2001, 7(2): 130-138.
Abstract (140) PDF (392KB)(7)
Abstract:
In this paper,an experimental study of brittle-ductile transition in Panzhihua fine grained gabbro was performed under a Griggs-type apparatus with NaCl as the confining pressure medium. Experiments were conducted in conditions of:450MPa~800MPa confining pressure,600℃~1150℃ temperature,and 1×10-4~3.125×10-6/s strain rate.The results of experiments show that the deformation of the gabbro is brittle fractures at temperature 600℃,semibrittle flow at 700℃~850℃,and plastic flow at temperature higher than 900℃.The temperature of brittle plastic transition is 700℃~900℃ at the confining pressure 450MPa~800MPa.The major factors that influence the brittle-plastic transition in the gabbro are temperature and strain rate,and the influence of confining pressure is secondary.
STUDY ON EFFECT OF PORE PRESSURE ON STRAIN LOCALIZATION OF ROCK AND DIGITAL SIMULATION
WANG Xue-bin, PAN Yi-shan, DING Xiu-li, SHENG Qian
2001, 7(2): 139-143.
Abstract (144) PDF (186KB)(8)
Abstract:
Firstly,a series of advance on effect of pore pressure on strain localization of solid has been introduced in this paper Secondly,the effect of pore pressure on strain localization(shear bands) of the rock has been modeled based upon fast Lagrangian analysis.The results modeled show that the pore pressure has an great influence on the strain localization;The increase of pore pressure prevents shear bands from developing fully and causes tension failure of rock sample.
THE STUDY OF RELEASING AND QUANTITATIVE CALCULATION OF CO2 UNDER THE CONTACT METAMORPHOSE EFFECT
SUN Zhan-qang, LIU De-liang, ZHENG De-san, YANG Xao-yong, WANG Bai-chang, CHEN Yong-jian, ZHANG Giao-dong, TAN Ying, LE Zhen-sheng
2001, 7(2): 144-150.
Abstract (153) PDF (253KB)(10)
Abstract:
To discuss that metamorphic carbonate rocks release the amount and ability of CO2 and CO2 releasing conditions,CO2 flux, which metamorphic carbonate rocks release in contact metamorphism, is analyzed and calculated quantitatively on the basis of metamorphic reaction and time integrated fluid flux. The results suggest that the value of CO2 flux is 0.729×104~2.446×104 mol/cm2,CO2 is provided mainly by contact metamorphic reations. The generation and release of CO2 are positive correlation with the degree of metamorphism, and XCO2 in fluids continuously increases form the zone of dolomite to the zone of calcite, but in the zone of essonite, fluid flux is the largest and XCO2 sharply decreases for the influence of magmatic water.
THE STUDY OF METHOD ABOUT SOME MINUTE METALLIC SULPHIDE SEPARATION AND EXTRACTION
FENG Yan-wei
2001, 7(2): 151-154.
Abstract (100) PDF (111KB)(7)
Abstract:
This paper mainly discusses a problem that how is separated and extracted some minutemetallic sulphide from ores of the Ginya "Carlin-type" gold deposit, Guangxi Province. Author has improved technique and manipulation skill. The experiment has been a success. The result of experiment has offered trustworthy data for this gold deposit genesis.
JIYANG BRUSH STRUCTURAL SYSTEM AND ITS RELATIONSHIP WITH OIL AND GAS
XU Shou-yu, LIU Ze-rong
2001, 7(2): 155-160.
Abstract (159) PDF (172KB)(6)
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After discussing the characteristics of Jiyang Brush Structural System and the distribution of oil and gas in this area,the paper analyses the relationship between the Brush Structural System and hydrocarbon from the viewpoint of the formation and evolution of the Jiyang Brush Structural System.The paper points out that Jiyang Brush Structural System resulted from several rotations of the West Shandong Uplift that were caused by large scale strike slip of Tan-Lu Fracture.And the activity of teh Jiyang Brush Structural System controlled the distribution,migration and accumulation of hydrocarbon within it.Oil and gas are enriched at the diverging area of the brush structural system and are poor at the converging area.
THE ACCUMULATIVE CONDITIONS OF THE MIDDLE ORDOVICIAN OIL AND GAS IN LUNNAN AREA, TARIM BASIN
KUANG Hong-wei, PENG De-tang, LI Nan
2001, 7(2): 161-166,103.
Abstract (130) PDF (243KB)(6)
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The article discusses the accumulative conditions of the Middle Ordovician oil and gas in Lunnan area, Tarim basin,by studying the strata and the sedimentary facies and in combination with synthetical interpretation of seismic data. It points out that the conditions of oil source reservoirs and cap rocks are suitable for the carbonate rock traps, the formation times of traps coincides with those of source rocks which drained hydrocarbons, and the growth of reservoir is controlled by sedimentary facies. It is possible for this conditions to form lithological oil trap.
CHEMICAL COMPOSITION AND CHARACTERIZATION OF CHEMICAL WEATHERING OF LATE TERTIARY RED CLAY IN XIFENG,GANSU PROVINCE
CHEN Yang, CHEN Jun, LIU Lian-wen
2001, 7(2): 167-175.
Abstract (212) PDF (294KB)(6)
Abstract:
Geochemical studies have been conducted on the red clay samples from Xifeng,Gansu Province,China.Results show that these samples are enriched in carbonate and depleted in other elements such as Si,Al,and Fe.To eliminate the effect of the carbonate fraction,five samples were leached by 1mol/L acetic acid.It can be found that the acid-insoluble fractions of the samples have similar compositions,indicating same sources.The distribution patterns of rare earth elements and trace elements indicate the similarity of eolian origin between the red clay and Quaternary loess and paleosols.Further investigations show that the red clay experinece the incipient stage of chemical weathering characterized by removal of Na and Ca.Several geochemical parameters such as CIA values,Na/K and Rb/Sr ratios in the acid insoluble fractions reveal that the red clay has undergone more intense chemical weathering than loess and paleosols,suggesting that the paleoclimate on the Loess Plateau has evolved from warm and moist conditions during Late Tertiary to dry and cold conditions during Quaternary.
THE RESPONSE OF THE DEVELOPMENT OF FEN RIVER TO NEOTECTONIC MOVEMENT AND PALEOCLIMATE CHANGES SINCE LAST NON-GLACIATION STAGE
HU Xiao-meng, YANG Jing-chun
2001, 7(2): 176-180.
Abstract (190) PDF (158KB)(8)
Abstract:
There have existed three accumulation terraces (T3,T2 and T1) and an erosional one in Linfen Basin since last non glaciation stage (MIS5).By the means of loess paleosol series and TL,we make out that these terraces occurred in 130kaBP,130kaBP~52kaBP,52kaBP and 9kaBP respectively.Normally,neotectonic movement and paleoclimate changes are two important factors influencing the development of the alluvial landform.Analyzing the characteristics of the sedimental structures of some sections in these terraces,we draw some conclusions:①It was the neotectonic uplift occurring in 130kaBP that resulted in the formation of T3.②Because the weather became wet and warm during L1 SS and S0,and down erosion of Fen River strenghtened,the changes of paleoclimate during late Pleiocene contributed to the development of T2 and T1.③The occurrence of the erosional terrace shows there probably had some big landslides taking place in 130kaBP~52kaBP in Sanmeng Gorge,which blocked the Yellow River for a long time.