Table of Content

04 March 1987, Volume 9 Issue 1

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Brief Report

BASEMENT WEAKNESS ZONES ON NORTH CHINA PLATFORM AND ITS RELATIONSHIP WITH SEISMIC ACTIVITY

Zhang Jia-Sheng, Lao Qiu-Yuan

1987, 9(1):  1-15. 

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Based on the analysis of the formation and evolution of the crystalline basement for the North China platform, the characteristics of huge ductile shear zone are studied. The zone in point were formed during the early Proterozoic time and can be subdivided into three systems trending northeast, with a width va-ring from saveral hundred meters to more than twenty kilometres, strenching for some thousand kilome-tres. Along these zone reworked gneiss and mylonite have been commonly developed. The relationship between the successive activition of major basement weakness zones that occurred later on and seismic activities is discussed here along with the general trend of recent adjustment of dis-placements and regular seismic activities.

NATIONAL EARTHQUAKE-GROUNDWATER NETWORKS OF OBSERVATION HAS BEEN ESTABLISHED

1987, 9(1):  15-15. 

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SCIENTIFIC AND COMMENDING CONFERENCE FOR 20-YEAR SEISMIC WORKS IN BEIJING

Yao Yan-Zhi

1987, 9(1):  16-16. 

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A PRELIMINARY STUDY ON LOW VELOCITY LAYER IN THE CRUST IN NORTH CHINA

Sun Wu-Cheng, Li Song-Lin, Luo Li-Lei, Yue Hua-Fong

1987, 9(1):  17-26. 

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According to the features of deep seismic sounding records and the velocity structures in the crust, the Q-value structures as well as other geophysical data in North China, This paper gives an illustration on the existance of low velocity layer; research has been made on the formation of the low velocity layer along with some geological phenomenon related to the low velocity layer such as tectonic movement, earthquake hypercenter distribution and geothermal anomaly.

PROCESSING AND INTERPRETATION OF REMOTE SENSING INFORMATION FOR THE MIDDLE OF TANCHENG-LUJIANG FAULT ZONE

Gao Xin-Xin, Zhang Bu-Chuen, Shen Mei-Qin

1987, 9(1):  27-34. 

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The following problems are presented in this paper. The remote sensing geological methods are used to process and interpret remote sensing information for the middle of Tancheng-Lujiang fault zone, the distribution of main faults in the region, especially the faults in cryptic fields and some transcurrent faults which are approximately perpendicular to the main faults.The results which are essentially in conformity with the field works, are achieved by processing the satellite tapes using the method of enhanced high-pass fittering. Some useful data are derived from also essential phenomena analysis of active faults and measurement of apparatuses.We have established the preliminary interpreting marks of active faults in the region after interpreting the layer and tectonics and examining them in field works.The surface distribution of the faults in the region, including the situation of the transcurtent faults and the characteristics of the active faults, are clearly shown in Fig.2, which illustrates also the characteristics of the active faults from north to south.

RESEARCH ON THE FAULT ACTIVITY FOR DETERMINATION OF THE POTENTIAL HYPOCENTRAL AREA FOR THE LIAODONG PENINSULA

Zhang Yu-Ming, Quo Wen-Xiu, Wang Liang-Mou

1987, 9(1):  35-41. 

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Based on the data of the fault activity, this paper mainly deals with evaluation of seismic risk and determination of potential earthquake sources in the region of low-moderate earthquakes such as the Liaodong Peninsula, where any trace of paleoearthquake has never been found.Results from our investigations are as follows; 1)the M≥5 earthquakes in the study region had a close relation to the faults that were activ in late Pleistocene; 2) the active faults in the region can be classified into three types on the basis of their characterized motions by predominat stick-slip, creep and contemporaneous stick-slip with creep and the M=6 earthquakes the region had a close relation to the stickslip segments of the faults; and 3) the probable maximal magnitude of earthquakes along some faults were estimated from the length of the faults that were active in late Pleistocene and the maximal displacements along a few faults.

DEVELOPMENT OF ECONOMIC CONSTRUCTION AND CONSULTING ENGINEERING SEISMOLOGICAL SERVICE

Ding Meng-Lin

1987, 9(1):  42-44. 

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ESTIMATE OF DIFFERENTIAL FLOW STRESS AND STRAIN RATE FOR HONGHE FAULT ZONE

An Lin-Ji, He Yong-Nian

1987, 9(1):  45-59. 

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Microstructures of quartz in Honghe mylonite zone are studied and recent result of microstructural paleopiezometry is used in this paper to estimate the differential flow stress and strain rate for the southern Honghe fault zone. The calculations show that the differential flow stress during the development of mylonites of the southern Honghe fault zone varied gradually from 45MPa in the south to 120MPa in the north. Because the formation depth of mylonite zone became shallow from south to north, this variation indicates the decrease of flow stress with depth. The strain rate was roughly of the order of 10^-12/sec.

THE THIRD NATIONAL SYMPOSIUM ON ISOTOPIG GEOCHEMISTRY HELD IN YICHANG

1987, 9(1):  60-60. 

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FIRST SYMPOSIUM ON YOUNG GEOCHRONOLOGY HELD IN BEIJING

1987, 9(1):  60-60. 

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THE MECHANICAL PROPERTIES OF FAULT GOUGE OF HONGHE FAULT ZONE AT HIGH TEMPERATURE AND PRESSURE

Li Jian-Guo, Wang Sheng-Zu, Zhang Bo-To, Shi Liang-Qi, Shi Qui-Mei

1987, 9(1):  61-71. 

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The mechanical properties of fault gouge of Honghe fault zone were studied at temperatures up to 600℃, confining pressures up to 700 MPa and strain rate of 4.4×10^-5/s, At room temperature and high pressure the stress-strain curves of gouge were characterized by linear and non-linear stages of deformation, at high temperature and pressure the non-linear deformation was presented in the curves. The failure strength of gouge increased with increasing confining pressure at the same temperature, and de creased with increasing temperature at the same confining pressure. As the content of calcite in gouge was more than 20 %, the failure strength at high temperature decreased with increasing confining pressure, this anomalous change in mechanical behavior of gouge may be related to the plastic deformation and solid-gas transition induced by calcite and to the decreasing effective pressure caused by increasing pore fluid pressure. The a-coustic emission activity occurred in the gouge specimen during deformation, but no stress drop was observed in the stress-strain curve. After the differential stress reached the failure strength, the gouge specimen underwent a gradual failure process. The initial and effective elastic modules were determined from the stress-strain curves of gouges, the former were smaller than the latter. The gouge was lithified at T≥400℃ and σ₃≥300 MPa confining pressure, according to the lithifying conditions of temperature and pressure, the existing depth of clayey gouge does not exceed 10-15 km, Because the failure of gouges took a gradual character, it is favorable for the active fault with gouge to slide stably.

THE EXPERIMENTAL STADY OF ELECTRICAL PROPERTIES OF CARBONATE UNDER HIGH TEMPERATURES AND PRESSURES

Guo Cai-Hua, Gao ping, Song Rei-Qing, Zhang You-Nan

1987, 9(1):  72-76. 

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The electrical conductivity of Beijing dolomite and limestone has been studied by means of a high pressure apparatus of solid medium piston cylinder type. It is found that on each lgγ=f(1/T) curve there was a discontinuity interval followed by a straight line segment with a steep slope,and the electrical resistivity was very low (several Ω-m) at higher temperatures.Post-run X-ray powder diffraction revealed that graphite was deposited on the surfaces of samples. It was the newly deposited graphite layer that resulted in high conductivity of the sample.The physicochemical environments of the decarbonation and the onset temperature of graphite deposition were investigated and it is reasonable that a graphitic high conductivity layer might be formed in certain geolgical period, provided that there exists carbonate along with proper geological conditions in the crust.

APPROACH TO THE MATHEMATICAL EXPRESSIONS OF THE FUNCTIONS OF SHEAR STRAIN γ(x) AND DISTORTION DISTANCE s(x) ACROSS DUCTILE SHEAR ZONES

Xu Jun-Yuan

1987, 9(1):  77-84. 

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Based on the mathematical features of many shear strain curves across ductile shear zones, the expressions of the functions of shear strain γ(x) and distortion distance s(x) were given. They have not been theorically verified, but a lot of facts, some of which are presented in this paper, would prove them true. In this sense they are exponential formulae, which may play an important role in studies of deformation on ductile shear zones.

ANALYSIS AND APPLICATION OF DATA ON THE WATER LEVEL FLUCTUATIONS IN TA-YUAN WELL IN BEIJING

Du Pin-Ren

1987, 9(1):  85-90. 

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The barometric efficiency was calculated with three kinds of methods and the spectral analysis and harmonic analysis were made of hydrograph and microbarograph records from the Ta-Yuan well. The porosity n, matrix bulk modulus E_m, and specific storage S_s of the aquifer were estimated.

QIONGHAI REMOTE SENSING GROUND TILT NETWORK HAS BEEN ESTABLISHED AND TESTED

Zhang Cun-De

1987, 9(1):  90-90. 

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RADIOCARBON DATES(4)

Jieo Wen-Qiang, Peng Gui, Li Hong-Chun

1987, 9(1):  91-98. 

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SYMPOSIUM ON GEOLOGY OF CONTINENTAL MARGINS HELD IN NANJING

1987, 9(1):  98-98. 

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