1998 Vol. 4, No. 1

Display Method:
ON COMPOUNDING TECTONICS
Qiu Yuanxi
1998, 4(1): 1-12.
Abstract (122) PDF (485KB)(6)
Abstract:
Tectonic compounding common in the earth crust and lithosphere is the records of repeated tectonic movements.There is a great variety of tectonic compounding the basic types of which include the compounding of various structural features, and that between structural features and geological formations as well as that of various geological formations.The compounding structures may be either autochthonous or allochthonous;they may also comprise structural features caused by the same manner of tectonic movements or by different manner of tectonic movements;and finally,there may be compounding of structures of all sizes ranging from microscopic ones up to tectonic belts or even tectonic domains.
The author emphasizes the concepts of compounding tectonic domains and regional tectonic systems.These concepts have been used to explain the mechanism of the formation of regional tectonic systems in China and adjacent areas.
MINERAL FISSION-TRACK DATES AND RESEARCH ON UPLIFTING VELOCITY OF QINGHAI-XIZANG PLATEAU
Jiang Wan, Mo Xuanxue, Zhao Chonghe, Guo Tieying, Zhang Shuangquan
1998, 4(1): 13-18.
Abstract (173) PDF (233KB)(6)
Abstract:
From the results of fission-track dating of different minerals from the granodiorite of the middle Gangdise granitoids belt in Qinghai-Xizang Plateau,the authors suggest that the uplifting of southern Qinghai-Xizang Plateau is episodic,there having occurred a slow uplifting from the emplacement of the intrusive to about 30 Ma,which was followed by an acceleration in velocity from 30 to 7 Ma and a rapid uplifting since 7 Ma.
PALEOTECTONIC FEATURES OF SICHUAN-GUIZHOU N-S-TRENDING STRUCTURAL BELT
Huang Jijun
1998, 4(1): 19-24.
Abstract (145) PDF (437KB)(11)
Abstract:
The Sichuan-Guizhou N-S-trending Structural Belt whose basement shows a two layer structure composed of lower ‘competent’ strata and upper incompetent ‘soft’ strata consists of a series of simple or composite folds and accompanied faults in which were involved strata from Late Paleozoic to Jurassic.The structures in the cover rocks were mainly controlled by the underlying paleotectonic framework.Paleouplifts and paleodepressions in the belt bagan to occur in early Cambrian and developed gradually from the south to the north.
FABRIC AND DYNAMIC IMPLICATION OF THE DUCTILE DEFORMATION ZONE IN JIAOLUOTAGE AREA IN XINJIANG AUTONOMOUS REGION
Xu Xingwang, Ma Tianlin, Sun Liqian, Li Guishu
1998, 4(1): 25-32.
Abstract (205) PDF (387KB)(10)
Abstract:
The ductile deformation zone in Jiaoluotage area in Xinjiang Autonomous Region developed in E-W-trending Carboniferous volcanic and sedimentary formation between the Tuha Block and the Mid-Tianshan Block,and comprises a set of E-W-striking and upright penetrative foliation.The deformation features can be broadly divided into four orders in size.Fabric analysis of them indicates a symmetry of the deformation,implying an origin of symmetrical tectonic deformation.Development of many compressive structural features parallel to the major boundary shows that they may result from compression perpendicular to the deformation zone (plane).The ductile deformation zone in Jiaoluotage area is,therefore,a ductile compressed zone.
THE ORIGIN OF THE MAZHAN BASIN AND ITS RELATIONSHIP TO THE TAN -LU FAULT ZONE
Hong Jingpeng, Miyata Takao, Sun Yuanlin
1998, 4(1): 33-36.
Abstract (175) PDF (222KB)(7)
Abstract:
Detailed investigation on the lithofacies and the syn-sedimentary structures in the basin as well as the determination of the fission-track ages of zircons from two tuff layers and of the fossils collected in the basin indicates that the Mazhan Basin is a typical Late Cretaceous strike-slip basin related to the Tan-Lu Fault Zone,which suggest that the Tan-Lu Fault Zone,at least part of it,had undergone a notable sinistral strike-slip during Late Cretaceous.
THEORETICAL DISCUSSION ON 3-D HYDRAULIC FRACTURING IN SITU STRESS MEASUREMTNT
Chen Qunce, An Meijian, Li Fangquan
1998, 4(1): 37-44.
Abstract (243) PDF (300KB)(20)
Abstract:
In this paper,the mechanics analysis for the traditional 3-D hydraulic fracturing in-situ stress measurment method is done,and a new theoretical model proposed.The minimum principal stress criteria adopted in the new model,compared with the minimum tangential stress criteria of traditional method,illustrates the mechanism during hydraulic fracturing procedure more objectively.To illustrate the procedure of this method and its applicability,the genetic algorithms inversion technique is adopted to estimate assumed stress state.The results show that the method is applicable.
ORE-CONTROL FEATURES OF ARC STRUCTURES AT BOTH ENDS OF THE BAILONGJIANG ANTICLINORIUM OF THE WESTERN QINLING
Wang Ping'an, Xu Gang, Dong Faxian, Zheng Daxing, Wu Ganguo, Liu Xiaochun, Liu Jianmin, Li Zhongjian, Hu Chuanjiu, Zhao Yanqing, Li Yadong, Liu Hongyun, Yan Shenghao, Du Zitu
1998, 4(1): 45-50.
Abstract (119) PDF (220KB)(19)
Abstract:
The hydrothermal gold,uranium,arsenic and antimony deposits in the Bailongjiang anticlinorium of the western Qinling orogen are controlled by fault structures and closely related to magmatism and sub-volcanism in the Mesozoic.Two sets of en echelon arranged arc structures occur respectively at both ends of the Bailongjiang anticlinorium,controlling two highly mineralized areas (HMA) in the south-western Qinling.The Dashui-type gold deposits with gold-bearing jasperoid ores (an oxidation type),and the Lar'erma-type Au-U-Cu deposits with gold and uranium siliceous mudstone ores enriched in organic carbon (a reduction type) in the Maqu-Ruo'ergai Au-U(Cu) HMA in the west,are controlled by the Dashui arc structure and the Langmusi arc structure respectively.The Manaoke-type As-Au deposits,Xiaojinchang-type Fe-Cu-Au deposits,and the Xinguan-type hydrothermal gold deposits in the Zhouqu-Wenxian Au(Cu) HMA in the east,are controlled by the Wudu arc stucture and Wenxian arc structure respectively.As the major ore-control structures,the subsidiary fractures at the apices of the arcs have exerted some important effect on the formation of the two huge gold deposits,the Dashui super-large gold deposit and the Xinguan Lianhecun large gold deposit,as well as on the hypabyssal alkaline intermediate-acid magmatic and continental volcanic rocks which are genetically associated with the mineralization of the gold and uranium deposits.
EARLY YANSHANIAN TECTONIC STRESS FIELD AND ITS CONTROL OF GOLD MINERALIZATION OF THE KUANCHENG-QINGLONG-JINCHANGYU GOLD DEPOSIT-CONCENTRATED REGION OF THE EAST HEBEI PROVINCE
Wu Zhenhan, Zhang Jingxue
1998, 4(1): 51-57.
Abstract (174) PDF (375KB)(13)
Abstract:
Strong crustal movement and tectono-magmatic activity of early Yanshanian period occurred in the Kuancheng-Qinglong-Jinchangyu gold deposit-concentrated region of east Hebei Province,and resulted in the formation of major regional compressional-shear faults and magmatic zones and more than 20 gold deposits.The early Yanshanian regional tectonic stress field played an important role in the formation and evolution of these faults and gold metallogenesis.On the basis of field investigation and palaeostress measurement,the early Yanshanian regional geodynamic condition,displacement directions and differential stresses of several locations of this gold-concentrated region were determined.Then the corresponding regional tectonic stress field of the early Yanshanian period was calculated by using the finite-element numerical modelling methods,and the relationship between regional tectonic stress field and gold mineralization was analysed.The following conclusions regarding the early Yanshanian regional tectonic stress field were obtained:(1) the maximum principal compressional stress is oriented in NW-SE direction while the minimum principal compressional stress in N E-SW direction for most units;(2) the regional differential stresses range from 2.5 to 220 M Pa;(3) the direction,magnitude and gradient of regional tectonic stress evidently controlled the distribution of gold deposits and gold mineralization.
THE STUDY OF METAMORPHIC CORE COMPLEXES IN THE XUEFENGSHAN AREA
Hou Guangjiu, Suo Shutian, Wei Qirong, Zheng Guizhou
1998, 4(1): 58-62.
Abstract (307) PDF (240KB)(6)
Abstract:
After the study of the metamorphic core complex of the Xuefengshan,Hunan Province,the writers found that it is similar to the Cordilleran counterpart in structure,deformation mechanics,and detachment features,except for that its upper plate is composed of Neoproterozoic very low-grade metamorphic rock and Paleozoic strata and that the complex was formed between Late Devonian and Early Carboniferous.Its control of the Woxi vein gold deposit is discussed in the paper.
ON TECTONIC FEATURES OF THE MAJOR FRACTURAL ZONES AND THEIR CONTROL OF MINEROGENESIS IN THE GOLD AREA OF THE MID-XUEFENGSHAN MOUNTAIN, HUNAN PROVINCE
Zhu Dagang, Meng Xiangang, Wang Jianping, Tian Xiaojuan, Liu Xiangqin, Zhao Jianguang
1998, 4(1): 63-71.
Abstract (345) PDF (384KB)(11)
Abstract:
A study of the major fracture zones in the gold-forming area of the Mid-Xuefengshan Mountain has been made by an analysis of the macrostructural features,the microstructural deformation and the tectonogeochemistry.The basic features of these zones and their control of minerogenesis are discussed in this article.The authors point out that the north east-trending ductile-brittle shear zone is the major structure as passageway for ore fluid in the gold-forming area of the Mid-Xuefengshan Mountain and that the north-west-trending fault is an important host structure along which the presently explored gold ore bodies are distributed.
EXPERIMENTAL STUDY ON MIGRATION AND ACCUMULATION OF ORE-FORMING ELEMENTS UNDER HIGH TEMPERATURE AND PRESSURE
Chen Bailin, Dong Faxian, Li Zhongjian
1998, 4(1): 72-77.
Abstract (235) PDF (262KB)(6)
Abstract:
There are migration and accumulation of ore-forming elements in rocks deformed under high temperature and pressure.The results of the experiment shows that this differs for different elements in the same mineral and for same element in different minerals under the same condition.And it is found that the structures of the deformed rocks not only provide the passageway and space of deposition for the ore-forming fluid,but also play an important role in the activation and differentiation of the ore-forming elements at the initial mineralization.
THE GEOTHERMAL FIELD AROUND THE TANCHENG LUJIANG FAULT ZONE IN EAST CHINA
Bai Jiaqi, Wang Xiaofeng, Feng Xiangyang
1998, 4(1): 78-88.
Abstract (206) PDF (466KB)(11)
Abstract:
A heat flow plot from 117 measurements on both sides of the Tancheng-Lujiang Fault Zone shows a larger frequency of heat flows between 50 mW/m2 and 80mW/m2 in the central south segment of the fault with an average of 67.67mW/m2,notably higher than the average global value(63mW/m2),also somewhat higher than that of the China Continent (66mW/m2).There is a gradient zone from the west to the east side of the fault zone,rising from an average of 55.35mW/m2 on the west side to an average of 67.78mW/m2 on the east side.This suggests there may be remarkable difference in the crustal structure of both sides of the fault,as is agreeable to the existence of a low velocity,low resistance layer in the lower crust and a higher Moho on the east side of the fault revealed by geophysical survey.
ACOUSTIC EMISSION SIGNATURES OF VARIOUS ROCK TYPES FROM THE NORTH TARIM BASIN
Shao Zhaogang, Ding Yuanchen
1998, 4(1): 89-96.
Abstract (139) PDF (305KB)(8)
Abstract:
AE characteristics and classification of curves of total AE accounts versus applied stress for rock specimens from the North Tarim Basin during the whole process of loading are discussed in the paper.It is put forward that four methods can be used to determine the AE curve types of rocks.A statistical analysis of the results for rock samples collected from the wells and surfaces in the North Tarim Basin Oil Field shows the presence of "Ⅰ" and "Ⅲ" curve types of AE curves for sandstone and mudstone and "Ⅰ" type for dolomite,limestone and basalt in the area.