1997 Vol. 3, No. 1

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THE EPSILON-TYPE STRUCTURAL SYSTEM OF SOUTH CHINA
Zhao Jianwei, Wang Zhishun, Zhu Dagang
1997, 3(1): 1-9.
Abstract (209) PDF (370KB)(10)
Abstract:
The frontal arc of the epsilon-type structural system of South China is distributed on the continental margin of South China and Northern Vietnam,the apex of which reaching as far southwards as the northern side of the Xisha Islands latitudinal structural system.The west reflex arc appears at the Nianqingtanggula-Boshula mountains and its southern side,whereas the east reflex arc is located in the southern Yellow Sea.There are Mesozoic-Cenozoic magmatites and dynamometamorphic rocks along the arcuate belt.The backbone is mainly represented by the N-S-extending fold belt starting from Sichuan,Guizhou,Yunnan,to Guangxi province.The structural system began to develop during the Indo-sinian orogeny,took full shape in the Yanshanian movement,and had a strong activity in the Himalayan epoch.Its determination is conducive to the knowledge of tectonic framework of South China,and its relation to the distribution of mineral resources.It also provides the fresh evidence for the way in which East Asia continent moved.In face,it is the tie between the Tethys tectonic domain and the Pacific tectonic domain.
TECTONO-MINEROGENIC CYCLES AND MINEROGENETIC EVOLUTION THROUGH GEOLOGICAL HISTORY IN THE QINLING OROGENIC BELT
Wang Pingan, Chen Yuchuan
1997, 3(1): 10-20.
Abstract (193) PDF (402KB)(22)
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It has been disputed for a long time whether tectonic and minerogenic cycles did ever exist through geological history.On the basis of the theory and method of the minerogenic series of ore deposits,the authors advanced and discussed a concept of "tetono-minerogenic cycle".Cyclicity of tectono-minerogenic activities in the Qinling orogenic belt is systematically discussed in this paper,and six tectono-minerogenic cycles are drawn:(1) from the Latest Archean to the initial Proterozoic;(2) the Early Proterozoic;(3) Middle Proterozoic and the Late Proterozoic;(4) the Early Paleozoic;(5) the Late Paleozoic and (6) Mesozoic to Cenozoic.Minerogenic evolution is duscussed by a summarization of the characteristics of each of the six minerogenic cycles.The mineralization in the Qinling orogenic belt was either long and continuous or intermittent and cyclic.Many of the ore deposits are formed in two major peak mineralization periods,one is from the Middle Proterozoic to the Early Paleozoic,characterized by mantle-derived magmatic intrusions and marine volcanism;the other is from the Mesozoic to the Cenozoic,during which the intermediate and acid magmatic intrusions and continental volcanism are mainly derived from the crust or with a mantle-crust source.The 24 minerogenic series of ore deposits in this orogenic belt are considered to have formed in three major types of tectono-minerogenic processes,ie splitting,convergence,and a relatively stable stage.The mineralization associated with volcanism and splitting would have experienced a vibration between the north and south Qinling orogenic belt through out the geological history.
ON THE FORMATION AND SPLITTING OF GONDWANALAND
Qian Weihong
1997, 3(1): 21-29.
Abstract (358) PDF (361KB)(18)
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The formation and splitting of Gondwana land is still open to discussion.First,in this paper the Earth is considered to have involved the astronomical evolution and geological evolution.During the period of the astronomical evolution the Gondwana land formed at the south pole and high latitude areas.At the early stage of geological evolution the horizontal motion of magma might have driven the original crust to split and its northern edge might have drifted to where the outer-core liquid converged i.e.along the small circle from the Mediterranean Sea,southern edge of Qinghai-Tibet Plateau,Fiji,to the Caribbean Sea.On reaching low Latitudes,the splitted continents began to drift in the east-west direction and thus formed the mid-ocean ridges.
TECTONIC EVOLUTION AND THE GOLD DISTRIBUTION IN EASTERN HEBEI
Zhao Yinzhen, Jiang Xirong
1997, 3(1): 30-37.
Abstract (212) PDF (369KB)(13)
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After a study of the structural features and their genetic relations in Eastern Hebei,the authors establish the structural systems of the region.A discussion of the tectonic evolution and their relation with mineralization is made on the basis of the determination of the age of the tectonic movements.It was found that the distrbution of the gold depesits is controlled by sysmetallogenic structural system,a system which was active during mineralization.
At the same time,the authors carried out a model experiment of the synmetallogenic stress field of some typical gold areas for the prediction of the blind ore bodies,and achieved good success,yielding 22.72t of pure gold.
TRANSFORMATION FROM DUCTILE SHEAR ZONES TO SHEAR FRACTURE AND RELATED LITHO METALLOGENESIS
Wang Yiqiang, Sun Fengyue, Lü Guxian
1997, 3(1): 38-44.
Abstract (120) PDF (308KB)(11)
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It has been known from rock deformation experiments that,under moderate load,creep may finally develop into fractures in rocks.In laboratory experiment of rocks with 3 different axial stresses shear fractures have been found within the very tiny ductile shear zones.It is realized that myloinites are not necessarily favourable to the accommodation of later faults.However,it is very common for both fracture and ductile behaviour to oceur together.Because of the significant difference in strain rates of drag folding and faulting,the most possible mechanism is that to dragging may precede faulting.Therefore,ductile shear zones can lead to shear fracture at the same structural level where ductile deformation develops.The high temperature and abrupt pressure drop ensuing in the process may result in partial melting,material migration and unloading of hydrothermal fluids to trigger litho-metallogenesis.The authors consider that this mechanism can afford to explain such problems as the dynamical process for rock and mineral formation and the formation of duplex structure.
A PRELIMINARY STUDY ON RHEOLOGICAL BEHAVIOR OF ROCKS IN XISHAN,BEIJING BY USE OF BOUDINAGE
Zeng Zuoxun, Fu Yongtao, Li Yanxia
1997, 3(1): 45-49.
Abstract (180) PDF (217KB)(8)
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Both mechanical analysis and simulating experiment of boudinage indicates its non-Newtonian fluid behaviour.This paper attempts a quantitative evaluation of the rheolegical parameters of rocks from a study of the boudinage structures in Xishan,Beijing.The authors obtain a stress exponent between 3.06 to 7.69,for the calcite-quartzvein embedded in cipolino and a viscosity ratio for the two varying from 8.74 to 20.27;a stress exponent of 2 57 to 4.75 for the quartz vein in slate and a viscosity ratio of them ranging from 94.8 to 175 8;and a stress exponent between 2.25 and 3.93,for the siliceous bands interbedded in dolomite and a viscosity ratio between them varying from 2.38 to 4.26.
STUDY ON THE MAGNETIC STRATIGRAPHY OF THE QIANGTANG FORMATION AND THE NEOTECTONISM
Qian Fang, Zhang Jingqing
1997, 3(1): 50-56.
Abstract (196) PDF (295KB)(11)
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The Qiangtang Formation,at the pass of the Kunluns,596m in thichness,having a magnetic stratigraphy age of about 2.90-0.65Ma B.P.,is overlain unconformably by the morianes of the Wangkun Glacial stage about 0.65-0.60Ma B.P.and underlain by the out wash gravel of the Jingxian Glacial Stage about 3.00Ma B.P.in age.The Hipparion sp newly discovered in the Qiangtang Formation was determined to be of 2.08Ma age.Since the habitat of the Hipparion sp is about at a height of 1000-2000m above sea level,at a latitude of about 32.56°,it is estimated that the East Kunlun Mountains region might have undergone an uplifting at a rate of about 2.3-3.1mm/a and a Northward horizontal movement of about 143 mm/a since Quaternary.Meanwhile,the Xidatan sinistral slip fault in the East Kunlun Mountains has a slip rate of 10mm/a.
MICROMORPHOLOGY OF EXPERIMENTAL ROCK CRACKS
Zhu Dagang
1997, 3(1): 57-62.
Abstract (157) PDF (235KB)(7)
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Short duration compression,extension and bending experiments of limestone and sandstone cylinders were made in the laboratory.The tensile microcracks produced by extension are closely spaced,leaving zigzag trails at an angle of less than 90 degrees to the extension uniaxial compression produced dominantly relatively long and straight ones,while bending gave rise to two sets of smooth fractures intersecting at an angle of more than 90 degrees towards bending.
THE FLINN DIAGRAM OF ANISOMETRIC GRAINS
Xu Xingwang, Ma Tianlin, Sun Liqian, Shang Ling
1997, 3(1): 63-70.
Abstract (155) PDF (306KB)(10)
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The Flinn diagram of an isometric grains are divided by lines a=1, b=1,and a=b,and curves a2b=1 and ab2=1 into ten subregions,corresponding to ten different combinations of ex,ey,ez,and strain types.The lines and curves represent the special combination of ex,ey,ez, and strain types.There are altogether eighteen strain types of deformed rocks.We have four equations to express a and b that represent respectively the four quarters divided by the lines a=1/K1 and b=1/K2,the equations of a and b depend on the bulk deformation behaviour of rocks.An application of the new diagram to determine the strain of deformed rocks as well as their types is here given.
AN APPROACH TO NUMERICAL SIMULATION OF 3-D TECTONIC STRESS FIELD OF THE OIL-GAS-BEARING BASIN
Tan Chengxuan, Wang Lianjie, Sun Baoshan, Hu Daogong, Xu Shouli
1997, 3(1): 71-80.
Abstract (213) PDF (398KB)(21)
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In this paper,a numerical simulation of the present 3-D tectonic stress field of the Zhangqiang Depression is made using Super SAP finite element program,the technology and methodology here developed can be applied to other petroliferous basins.A knowledge of the existing stress state of an oil basin may prove useful to a quantitative study of the history of the expulsion and accumulation of hydrocarbons,avoidance of damage to wellcasings,and to reasonable recovering of oil as well.
FRACTAL CHARACTERISTICS OF FAULT SYSTEMS AND ITS RELATION TO OIL-GAS TRAPS IN KERKANG OIL FIELD OF LIAOHE BASIN
Zhou Xingui, Sun Baoshan, Liu Jinghong
1997, 3(1): 81-87.
Abstract (393) PDF (297KB)(10)
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Geometric characteristics of the fault system as indicated by the three seismic reflection layers T1,T1,T1 are studied by using fractal theory in Kerkang oil filed of Zhangqiang depression.As a result,the authors find that these fault systems are statistically self-similar within the scale range studied (r=0.5cm to 8cm).But different fault systems have different fractal dimension values D that reflect the complexity of their geometry.The size,number and spacing of faults within the same scale range may affect the magnitude of D obtained by box-counting method.There is a good correlation between D and the percentage of the individual fault system in different subregions divided.A comparision of the results of different subregions of different reservoir types shows that D value in the east subregion is higher than that in the west subregion for T1,and that the D value in west subregion is slightly higher than that in the east subregion for T1.It is shown that the higher the D value,the larger the oil-gas abundance (oil-bearing area or output of oil,gas and water) in the subregions.Such a relation between D values of fault systems and oil-gas distribution will provide a clue for researching the accumulation of oil and gas and their prediction in petroliferous basins.
A STUDY ON THE RELATIONSHIP BETWEEN ROCK STRESS AND OUTBURSTS OF COAL AND GAS
Wang Xihai
1997, 3(1): 88-94.
Abstract (222) PDF (266KB)(9)
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The relationship between rock stress determined by AE method and the coal and gas bursts in the Xieer coal mine is given in this paper.It shows that the bursts occur in high stress areas,and none in normal or low stress areas.
1997, 3(1): 95-96,49.
Abstract (107) PDF (120KB)(7)
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