1999 Vol. 5, No. 3

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TECTONIC DEFORMATION AND THERMAL STRESS FIELD IN QINGHAI-TIBET PLATEAU
WANG Lian-jie, CUI Jun-wen, WANG Wei
1999, 5(3): 1-7.
Abstract (142) PDF (129KB)(13)
Abstract:
The tectonic deformation in Qinghai-Tibet plateau displays strong compression, shortening and thrust in South-North direction since Cenozoic.During the compression and shortening, extensional structure is developed in Qinghai-Tibet plateau.For the purpose of understanding formation extensional structure in compression environment, thermal stress field and displacement field by temperature rising is calculated in crust.The feature of thermal stress field is described.A rising in temperature in lithosphere may cause very substantial tensile stress in shallow and compression stress in deep crust.Considering stress field caused by combined effect of northward push from Indian plate, gravity and thermal stress, tectonic deformation features in Qinghai-Tibet plateau can be understood better.
CRUSTAL EXTENSION-SHORTENING OF QINGHAI-TIBET PLATEAU AND MECHANINCAL PROPERTIES IMPLICATIONS
CUI Zuo-zhou
1999, 5(3): 8-12.
Abstract (246) PDF (103KB)(7)
Abstract:
The amount of extension and shortening of the crust of the Qinghai-Tibet plateau is roughly calculated from its thickness using the method of balanced section.The results show that it has shortened about 1400km in the N-S direction and extended 25~30km in the vertical direction.Such a tremendous shortening and extension may indicate that the crust of Qinghai-Tibet plateau behaves as a elasto-viscous rather than rigid body.
DISCUSSION ON CENOZOIC TECTONICS AND DYNAMICS OF ORDOS BLOCK
DENG Qi-dong, CHENG Shao-ping, MIN Wei, YANG Gui-zhi, RENG Dian-wei
1999, 5(3): 13-21.
Abstract (266) PDF (125KB)(32)
Abstract:
The Ordos block is peripherally surrounded by fault zones and faulted basin zones of Cenozoic age.Its southwestern boundary is a compressional tectonic belt trending NW, along which left-lateral strike-slip fault zones with thrust components, such as the HaiyuanLiupanshan fault zone, and corresponding faulted basins have developed, with both the maximum left-lateral strike-slip rate and the maximum horizontal shortening rate of 10mm/a. Both the Yinchun-Jilantai faulted basin zone of its western boundary and the Shanxi faulted basin zone of its eastern boundary are NNE-trending right-lateral shear zones with extension components, while both the Weihe faulted basin zone of its southern boundary and the Hetao faulted basin zone of its northern boundary are nearly EW-trending left-lateral shear zones with extensional components.All these shear zones have Holocene horizontal and vertical slip rates of 5mm/a and 0.3~3mm/a, respectively.With regard to the history of their development these faulted basin zones have a different timing of initiation.The Weihe and Yinchuan faulted basin zones have at first initiated in Eocene, the Hetao faulted basin zones in Oligocene, and the Shanxi faulted basin zones in Pliocene.During the Cenozoic, the Ordos block has been a situation of slow uplift, with an amount of uplift of 160m since 1.4Ma B.P. For the Ordos internor, the Moho discontinuity is 40~42km in depth, with a gentle variance, and the high conductive layer of the upper mantle is 123~131km in depth, while for the peripheral faulted basin zones of the block, the Moho discontinuity has relatively uplifted about 1.5~6km, and the high conductive layer of the upper mantle is only 70~100km in depth.Deformation analysis from geodetic surveying indicates that the Ordos block and its southwestern boundary area now are still uplifting, with uplift rates of 1~2.8mm/a and 4.4mm/a, respectively, and that the peripheral faulted basin zones are relatively subsiding, with an amount of -4~-5mm/a.Within the internor of the Ordos block, there are a few earthquakes of magnitude 4~5, and no earthquakes magnitude equal to and more than 6. All the earthquakes whose magnitudes are equal to and more than 6 in this area have occurred along peripheral active fault zones and in faulted basin zones.The results of the solutions of mechanism at the sources and the measurments of ground stress and the fault-slip vector indicate that the principle compressional stress in the Ordos area is oriented in NE-NEE, consisting with the regional stress field showed by the kinematic characterics of the peripharal active fault zones of the Ordos block.Such a stress regime may probably come from the Qingzang Block movement which is towards the northeast.On the other hand, the upwelling of deep materials beneath the faulted basins could play an important role in the neotectonic movement of the Ordos block.So the combination of the regional stress field with the upwelling of deep materials controls the dynamics of the Cenozoic Ordos block movements.
THE FEATURE AND FORMATION MECHANISM OF ARCIFORM THRUST-NAPPE STRUCTURE ZONE OF THE SOUTHERN NINGXIA
LI Tian-bin
1999, 5(3): 22-27.
Abstract (128) PDF (102KB)(9)
Abstract:
The southern Ningxia's arciform structure zone, extending 150~300km, consists of four great arcuate thrust-nappe structural belts with a convex toward the northeast.Every belt is composed of many thrust sheets and back margin fault basin.They formed typical basin-range structures.Since Yanshanian movement because of movenent and convection of upper mantle substance took place intracrust substance lateral movement, detachment along the layer surface of incompetent, forming thrust-nappe on the front margin while extensional gliding and tensional fault depression on the back margin, accompanied with that the crust was thicker or thinner, at the end the basin-range structure were formed.
THERMAL HISTORY AND TECTONO-GEOMORPHIC EVOLUTION OF PANSHAN PLUTON AT SOUTHERN MARGIN OF THE YANSHAN OROGENIC BELT
WU Zhen-han, CUI Sheng-qin, ZHU Da-gang, FENG Xiang-yang
1999, 5(3): 28-32.
Abstract (236) PDF (122KB)(9)
Abstract:
The thermal history and uplifting of the Pangshan pluton at the southern margin of the Yanshan orogenic belt were studied in detail by thermochronological dating.It was revealed that the Panshan pluton was intruded at a depth of about 10km before 226.48Ma. This was followed by a rapid cooling at a rate of 10.22℃/Ma during 226.48~204.95 Ma subsequently, it was uplifted 2.5km in the period of 204.95~118Ma at a rate of 0.028mm/a, 1.33km in the period of 118~80Ma at a rate 0.035mm/a, approximately 7km during 80~35 Ma at a rate of 0.08 mm/a, and about 0.5km since 35Ma at a rate of 0.014mm/a.The ring structures system surrounding the pluton formed a little earlier than 226.48Ma, and the boundary normal fault between it and the North China Basin was formed and became active mainly during 80~35Ma.
THE EVOLUTION OF MESO-CENOZOIC FAULT AND TIMES OF THE COMPRESSION AND EXTENSION STRUCTURE IN THE EAST YANSHAN AREA AND XIALIAOHE BASIN
MA Yin-sheng
1999, 5(3): 33-39.
Abstract (304) PDF (342KB)(8)
Abstract:
The analysis of structural evolution in the East Yanshan Area and Xialiaohe Basin since Meso-Cenozoic shows that this area has experienced five times of compression deformation (the end of Middle Triassic, Early Jurassic, Late Jurassic, Cretaceous and Paleogene) which resulted in withering or disappearing of the early basins and basin reversion and form ed compression structures, and three extensional periods in which Middle and Late Jurassic fault basin, Cretaceous fault basin, and Cenozoic rift basin were formed respectively. The compression and extension occurred alternatively, compression structure and extensional structures developed alternatively in the structural evolution.
PLIOCENE-QUATERNARY FAULTING PATTERN AND LEFT-SLIP PROPAGATION TECTONICS IN NORTH CHINA
ZHANG Yue-qiao, P. Vergely, J. L. Mercier
1999, 5(3): 40-46.
Abstract (231) PDF (139KB)(22)
Abstract:
North China includes two extensional domains:the grabens surrounding the Ordos block in the west, and Huabei-Bohai plain basins in the east.Pliocene-Quaternary faulting in grabens around the Ordos block displays predominantly normaldip slip displacements with a right-lateral or left-lateral slip component, indicating a NW-trending extension.Pliocene-Quaternary faulting in the Huabei-Bohai Plain basins has occurred along NNE-trending faults with oblique slip including right-lateral strile slip and normal components.The major EW-trending Qinling fault svstem bounds both extensional domains on the south and displays left-lateral slip decreasing in magnitude from west to east.The NNE-striking Tanlu fault zone bounds the extensional domains on the east and displays rightlateral strike slip movement, consistent with EW-trending compression and N-S-trending extension.A kinematic model linking North China deformation with left-lateral slip on the major Haiyuan fault on the NE margin of Qinhai-Tibetan plateau and on the Kunlun fault gives a new insight into eastward propagating extrusion tectonics in China.ln this model, displacement on the Haiyuan fault is accommodated by the counterclockwise rotation of the Ordos block and folding along its SW margin.Motion on the Kunlun fault continues along the Qinling fault system into eastern China where it is accommodated by reactivation of NNE-trending pre-existing faults.
A EXPLANATION FOR CRUSTAL FORMATION AND CONTINENTAL SHIFT
QIAN Wei-hong
1999, 5(3): 47-52.
Abstract (289) PDF (63KB)(6)
Abstract:
The formation of the earth crust and its evolution is a key issue for geodynamics or continental dynamics.The formation of original continental plates and their split and shift are illustrated in this paper using a dynamical scenario.
ON LAYER-SLIP,DIP-SLIP AND STRIKE-SLIP FAULT SYSTEMS
SUN Yan, LI Ben-liang, LIU Hai-ling, WNAG Xing-yuan
1999, 5(3): 53-57.
Abstract (278) PDF (92KB)(18)
Abstract:
The thin-skinned layer-block structures confined by the reverse dip-slip fault in a leading edge, normal dip-slip fault in a back edge and strike-slip faults (lateral sinistral and/or dextral fault)widely developed in the middle-lower Yangtze River area, may result from layering of rock materials and energy, and structures as well as layer sliding.
The mechanism for the dip-slip and strike-slip in the layer-block structure in the shallow crust is similar to that in terrane and plate tectonics at depth, and to the origin of the slip-apart and tear-apart fractures in fracture mechanics and the knifeedge and helical dislocations in solid physics.
METALLOGENIC REGULAR OF GOLD DEPOSIT IN XIAOBAN,FUJIAN,AND ITS VICINITY AND THEIR FURTHER EXPLORATION
WU Gan-guo, CHEN Bai-lin, HUANG Ren-sheng, WU Jian-she, ZHANG Da
1999, 5(3): 58-64.
Abstract (176) PDF (180KB)(17)
Abstract:
With more than 20 gold deposits (or gold ore spots)and favorite oreforming conditions, Xiaoban and its vicinity are a concentric area of gold deposit in middle part of Fujian.The main metallogenic and ore-controlling factors for the gold deposit in the area are a favorite assemblage of metallogenic and ore-controlling structures, the metamorphic rocks of Proterozoic Mayuan Group and the itermidiateacid magmatic activity in the early Yanshanian;and all these are also the important prospecting criteria.The main kind of gold deposit is magmatic hydrotermal type, and the altered fractured rock type predominated in gold mineralization.The targets of further gold ore exploration in the area are as follows:Xiaoban, Longmenchang, Yangmei, Xuzhou, Lingtouping and Gekeng. Particularly more attention may be paid to the minor scale gold deposits or gold ore spots situated in volcanic depression and to altered fractured rock type gold deposits like Xiaoban-Shuangqishan in the Mayuan Group metamorphic rocks beneath the volcanic cover rock.
A PRELIMINARY STUDY ON THE ORE-CONTROLLED STRUCTURE IN THE XITAN GOLD MINE,XINJIANG
ZHANG Xue-ren, WANG Ping-an
1999, 5(3): 65-70.
Abstract (173) PDF (118KB)(13)
Abstract:
The Xitan gold deposit is of a quartz vein-type with little sulfides.Their locations of appearance and spatial distribution are related to the repeated activities of the Qlugemingtashi ductile shear zone and the major Kushui fault and the resulting lower order structutes.It was considered to be controlled by a brush structure.Several geophysical prospecting profiles laid out on this basis have revealed some gold anomalies Therefore the brush structure can serve as one of the bases for gold prediction in this region.
ENVIRONMENTAL EFFECT OF ENGINEERING ACTIVITIES OF YELLOW RIVER WATER CONSERVANCY IN ANCIENT CHINA
LI E-rong
1999, 5(3): 71-75.
Abstract (228) PDF (51KB)(6)
Abstract:
Historically in China, the engineering activities of the Yellow River water conservancy were mostly focused on the water harnessing, while the silt harnessing was neglected.As a result, the Yellow River became gradually a world-famous above-ground suspended river and a "watershed" in the middle part of the Huang-Huai-Hai (Yellow R.-Huaihe R.-Haihe River)Plain.This has, on the one hand, changed the primary geological environment of the largest plain of China and, on the other hand, created the new geological environment of the Bohai Sea, Yellow River delta and coastal plain with an area over 10 000 km2 in the recent 800 odd years.
Based on the historical facts, it is suggested in this paper that the traditional concept on the Yellow River water conservancy should be changed and the silt in the Yellow River should be paid attention to.The silt is regarded as a precious wealth and should be, in an aimed and planned way rather than a laissez-faire attitude, led to an appropriate area to fill the sea and create the land.As the soil loss in loess plateau is an irresistible natural process and the amount of silt is practically infinite, the sea-filling and land-creation by utilizing the transported silt by Yellow River (though in a relatively long period of time)is incomparably more advantageous than by mountain excavation and sea-filling.
The paper suggests that the ideal area for the land accretion with the Yellow River silt is the Yellow Sea coast at northern Jiangsu rather than the Bohai Sea, because the latter is small in area and is our inland sea.The Bohai Sea could be quickly filled up with the silt of Yellow River, but the changing of Bohai Sea into land is quite harmful to North and Northeast China with respect to climate, hydrology etc.Key words:Yellow River;water harnessing;silt harnessing; sea-filling and land accretion
GEOLOGICAL HAZARD MONITORING AND MONITORING SYSTEM
LIAO Chun-ting
1999, 5(3): 76-83.
Abstract (270) PDF (232KB)(13)
Abstract:
Geological hazard monitoring and monitoring system are outlined in this paper. Geological hazard monitoring system should have functions of digitalization, automation and network.The characteristic information prior to geological hazards is transformed digitized information by transducer to transmit and store it.The experimental study of displacement transducer and an application of deformation monitoring system to Lianziya danger rock in the Three Gorges on the Yangtze River are given in this paper also.
NEOTECTONIC MOVEMENT AND THE TEMPORAL-SPATIAL DISTRIBUTION OF GEOLOGICAL DISASTERS IN CHINA CONTINENT
ZHANG Chun-shan, ZHANG Ye-cheng, HU Jing-jiang, GAO Ging-zhao
1999, 5(3): 84-88,21.
Abstract (193) PDF (94KB)(13)
Abstract:
China is among the countries that have most serious geological disasters.The geological disasters wide-spread in China are of varied types and frequent occurrence, not only harming lives and properties of the people, but also deteriorating the natural resources and environment.The resulting losses have a wide profound influence on the social economy. Due to widely varied conditions of climate, landform, geological structure and social condition, there is considerable difference in their types, strength and destructiveness in different areas.Broadly we have two large hazard-striking regions, the east region and west region, which are divided into a number of subregions.Their occurrences are mostly found to be irregular cyclic and accumulative.In the future, the prevention and control of geological disasters will be a very arduous task over certain period of time.
SATELLITE IMAGE INTERPRETATION OF CONTINENTAL GLACIER LANDFORM IN INNER MONGOLIA
LI Bang-liang, LI Zhi-zhong, HAN Tong-lin
1999, 5(3): 89-95.
Abstract (203) PDF (81KB)(11)
Abstract:
After the discovery of a planty of glaciated pots in Chifeng City, Inner Mongolia, in Great Hinggan Mountains and its both side area geomorphological types formed by glacial erosion and moraine are studied based on the deciphering of remote-sensing image.It is found that most of glacial pots, distributed on giant glacial boulder, sheepback rock or rock drumlin, resulted from that in Huanggangliang Mountai, Qilaotu Mountain, Damatushan Mountain southern end of the sheet was obstructed, rotated and dispersed when Mongolia giant glacial sheet of movement toward the south overpassed the Great Hinggan Mountains.
1999, 5(3): 96-96.
Abstract (105) PDF (24KB)(10)
Abstract:

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