1996 Vol. 2, No. 1

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1996, 2(1): 1-5.
Abstract (107) PDF (432KB)(22)
Abstract:
RECENT PROGRESS OF THE STUDY ON NEOGENE-QUATERNARY BOUNDARY IMPACT EVENT
Wu Xihao, Xu Heling, Deng Jiwen, Jiang Fuchu, Yin Weide, Xiao Huaguo, Ma Peixue, Ma Shulan, Kong Ping, Sun Donghuai, Zhu Yizhi, Li Chunlai
1996, 2(1): 8-16.
Abstract (203) PDF (582KB)(18)
Abstract:
Up to now, five kinds of micrograins, including cosmic dust, microtektites, volcanic spherules, impact volcanic ash and organic spherules, especially the iridium anomalies in bulk rock and micrograins have been discovered in the strata around the Gauss/Matuyama bound-ary in Duanjiapo loess/red clay section located at the south margin of the North China Loess Plateau.From these records, tow impact events with a time interval of ca.0.1Ma have been determined, having an age of 2.53-2.48MaBP and 2.43-2.42MaBP respectively.The early one, as can be correlated not only to the climate stratigraphic red clay/loess transition, but al-so to the magnetostratigraphic Gauss/Matuyama transition, is undoubtedly the Neogene/Quaternary boundary impact event.It is also shown in this paper that a comprehensive mode of origin can be used for explanation of the coexistence of impact records with different prop-erties.
UPLIFTING AND SHORTENING OF TIBETAN PLATEAU AND VISCO-ELASTIC DEFORMATION ANALYSIS
Wu Hongling, Wang Wei, Wang Lianjie, Zhang Lirong, Cui Junwen
1996, 2(1): 17-24.
Abstract (170) PDF (562KB)(23)
Abstract:
Based on the strong deformation which has taken place in the Himalayas and the Tibetan plateau caued by the northward push of the Indian plate since Cenozoic, an estimate by simulation is made of the strain rate of each tectonic unit and the consequent amount of u-plifting and shortening of the Plateau since 40Ma B.P.using two-dimensional visco-elastic Finite Element Analytic Method.The Mechanical Paramaters of rocks of each terrane, espe-cially the order of magnitude of the effective viscous coefficient η are deduced by inversion method.Detail calculation shows that in addition to the dynamic mechanism and boundary condition, the physical property of rocks play an important sole in determining the tectonic stress field and strain rate.It is the varied mechanical properties of the different lithospheric layers that lead to the difference in the stress field, displacement field and in the strain rate and resulting comolication of geologic strctures.
ADVANCE OF APPLICATION OF GEOMECHANICS TO THE RESEARCH OF ORE-FIELD STRUCTURES
Liu Xun
1996, 2(1): 25-33.
Abstract (122) PDF (684KB)(25)
Abstract:
The achievements and advance of the application of geomechanics to the research of ore-field structure are introduced in this paper in the following aspects:(1)relationship be-tween the deformation and phase transformawtion of rocks and minerals and the concentra-tion and dispersion of elements under tectonic force;(2)rocks and ore deposits resulting from the process of tectonic force;(3)syn-mineralization structural systems and their control of rocksand minerals;(4)some regularities, concerning the control of rocks and ores by tectonic systems;(5)the tectono-geochemistry;(6)localization of ore minerals in a prevailing tectonic stress field and its modelling;(7)a tectonic model for orecontrol;(8)ore deposits prediction. The results obtained to date are stimulating, and more would be expected in the future.
A STUDY OF STRUCTURAL CONTROL OF ORES IN THE DULAN AREA,QINGHAI
Zhou Xianqiang, Song Yougui, Deng Jun, Chen Zhengle
1996, 2(1): 34-41.
Abstract (133) PDF (817KB)(32)
Abstract:
A study of the formation and evolution of the tectonic systems present in the area and their relation to mineralization shows that the E-W- and N-S-trending structures and the West China system are pre-mineralization tectonic systems, and that anterior peripheral fold-belt of the Qinghai-Tibetan eta-type structure and the Hexi system are the main ore-control-ling tectonic systems.In addition, a discussion is also made on the tectonic system control of sedimentary formation and magmatism, and on the control of ore by different orders of struc-tures of a tectonic system as well as by their compounding.
ANALYSIS OF THE TIME SEQUENCE OF COMPOUNDING OF STRUCTURAL DEFORMATION SYSTEMS AND THE RESULTING EFFECTS IN TONGLING AREA
Liu wencan, Li Dongxu, Gao Dezhen
1996, 2(1): 42-48.
Abstract (195) PDF (560KB)(20)
Abstract:
A study of the effect of compounding of structural deformation systems in the Tong Ling copper-gold area is made based on a division of the structural deformation systems involved and an analysis of their time-sequence.The history of structural deformation and changes of tectonic stress field are also brought to light.This must be useful for achieving a knowledge of ore-genesis and prediction of the hidden deposits in the area.
DUCTILE DEFORMATION IN THE MIDDLE CHONGAN-SHICHENG STRUCTURAL ZONE
Chen Bailin, Cai Benjun, Lin Qiantong, Chen Jianguo
1996, 2(1): 49-54.
Abstract (138) PDF (433KB)(25)
Abstract:
The middle part of the Chongan-Shicheng tectonic zone is characterized by duc-tile deformation in the early stage and brittle fracturing accompanied by low-temperature quartz veins in the late stage.The early ductile deformation is well represented by the be-haviours of the Youling-Yanai shear zone about 2-5 Km wide as indicated by typical my-lonite associations, lineation, S-C fabrics and S+Z type fabrics of quartz optical axis.Fi-nite strain measurements show a maximum shear strain of about 1.16-3.46.The total dis-placement is 1.9 Kin.The differential stess is about 60-90MPa.It was formed at medium temperature of 400-500℃ and a higher strain rate.
THE DEFORMATIONAL TEXTURE OF THE BANXIA ANTICLNE AND ITS BEARING ON ENGINEERING GEOLOGY OF MIDDLE QINGJIANG RIVER IN WESTERN HUBEI
Wu Shuren, Xu Ruichun, Mei Yingtang, Jian Wenxing, Liu Zhizhong
1996, 2(1): 55-61.
Abstract (138) PDF (866KB)(21)
Abstract:
After a brief description of the geological settings of the two dam sites located re-spectively in Shuibuya and Banxia in the middle reaches of the Qingjiang river of westen Hubei province'an analysis of the deformational textures of the Banxia anticline was made in terms of its characteristic geometry, intraformational fold, axial plane cleavage and sec-ondary fault.The texture was formed and developed in the major phase of Yanshanian move-ment.The major engineering geological conditions of these two dam sites sitting on opposite limbs of the anticline are controlled by its deformational texture.
ROCK STRESS MEASUREMENTS IN A PLANNED TUNNEL FOR DIVERSION OF WATER FROM THE YELLOW RIVER
Wang Lianjie, Ding Yuanchen, Liu Qisheng, Shao Zhaogang, Tan Chengxuan, Wang Wei, Chert Guizhong
1996, 2(1): 62-69.
Abstract (170) PDF (494KB)(22)
Abstract:
Both hydrofracturing method and acoustic emission method were employed for stress measurements at depth of 360m and 420m respectively in two drill holes at Taiyuan, Shanxi.The results obtained will be used in the tunnel design for the water diversion pro-ject.In this paper the two methods are first described.From the measurements, the design of the planned tunnel and the problem of rock burst are also discussed.It is shown that if the strike of the tunnel is taken to be parellel to the maximum horizontal stress and a right shape for the tunnel section is adopted, the probability of rock burst will be reduced.
A COMPARISON OF THE RESULTS OF STRESS MEASUREMENTS OBTAINED BY AE WITH THAT BY HYDROFRACTURING AT TAIYUAN,SHANXI
Ding Yuanchen, Shao Zhaogang
1996, 2(1): 70-76.
Abstract (190) PDF (445KB)(22)
Abstract:
Acoustic Emission stress determination method was applied at Taiyuan, Shanxi, for the water-diversion project and the results obtained are given in the paper.A comparison of the results with that by hydrofracturing shows a good agreement of the measurements. The maximum principal stress estimated by AE at a depth of 500m is 26.7MPa.
A STUDY OF THE TECTONIC STRESS FIELD DURING INDOSINIAN EPOCH IN YANSHAN AREA
Chen Zhengle, Yang Nong, Chen Xuanhua
1996, 2(1): 77-82.
Abstract (169) PDF (368KB)(22)
Abstract:
Based on the analysis of the regonial structures in Yanshan area northeast of Bei-jing, we have reconstructed the paleo-stress field during Indosinian Epoch, and achieved sat-isfactory results by mathematical modeling using finite elements analysis method of iteration.
THE CHARACTERISTICS OF VOLCANIC EVENT DEPOSITS AND THEIR TEMPORAL-SPATIAL DISTRIBUTION OF BENXI AND TAIYUAN FORMATIONS IN NORTH CHINA PLATFORM(NCP)
Zhong Rong, Sun Shanping, Fu Zeming
1996, 2(1): 83-91.
Abstract (252) PDF (1227KB)(28)
Abstract:
From a study of a good number of coal fields and coal mines of the North China Platform, 12 volcanic event layers which can be grouped into 6 stages have been discovered by the authors in Benxi and Taiyuan Formations.These volcanic event deposits are wide spread in the region and consist mainly of turfs, tuffites and tuffaceous sedimentary rocks. There is some regularity in their temporal-spatial distribution.The volcanic fragments were probably from different volcanic sources to the north and south of North China Platform and the magma of volcanic matter was, maybe, from the lower crust.
1996, 2(1): 92-94.
Abstract (86) PDF (276KB)(21)
Abstract:

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