2005 Vol. 11, No. 2

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INHERITING AND DEVELOPING LI SIGUANG'S THOUGHT ON EARTHQUAKE PREDICTION
ZHAO Wen-jin
2005, 11(2): 97-109.
Abstract (109) PDF (373KB)(9)
Abstract:
This paper reviews Li Siguang(J.S.Lee)'s thought on earthquake prediction and emphasizes the great significance of the view of following China's own road to carry out geostress observation and research and investigation of the active tectonic systems proposed by Li Siguang.According to the practice and experience in the work relating to earthquake prediction over the past 40 years,the paper further elucidates the idea that in the new situation we should make new supplements and developments of the thought and method.It is suggested that in the future,while we should continued to undertake earthquake prediction practice and sum up the experience,we should strengthen the study of the seismogenic mechanism.In addition,some concrete suggestions about how to carry out this research work is put forward.
TRIGGERING OF LOCAL EARTHQUAKES IN THE QAIDAM BASIN BY THE SUMATRA EARTHQUAKE
MA Yin-sheng, SI Da-nian, AN Mei-jian, WANG Xiao-feng, HUO Guang-hui, LI Guo-qi, YIN Cheng-ming, ZHANG Xi-juan, SHI Wei, DU Jian-jun
2005, 11(2): 110-116.
Abstract (129) PDF (452KB)(8)
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A magnitude 9.0 earthquake,which was the strongest earthquake in the past four decades,occurred just off the northwest coast of Sumatra,Indonesia,on December 26,2004.It caused serious damage and casualties.This large earthquake left as long as more than 1000 seconds of records at the Shizigou seismograph station in the western part of the Qaidam basin a distance of 4000 km from the epicenter.It has also triggered the local seismic activity in the western Qaidam basin.The frequency of the local earthquakes in the day after the occurrence of the large earthquake was 10 times as high as it had been.From the distribution of the local seismic activity triggered by the large earthquake,the causative faults triggering the local earthquakes in the western Qaidam basin are the Huatugou fault and Hongliuquan fault on the southern side of the Yingxiong Range.
CHARACTERISTICS OF RADON ANOMALIES IN WATER ON THE NORTHEASTERN MARGIN OF THE QINGHAI-TIBETAN PLATEAU AND THEIR RELATIONS TO EARTHQUAKES
LI Zuo-tang, HE Shao-lin, LIU Bin, YIN Zhi-gang, LI Qiu-hong, DANG Hong
2005, 11(2): 117-128.
Abstract (116) PDF (375KB)(8)
Abstract:
By combining the geomechanical point of view and active fault distribution with the earthquake precursor phenomena,the paper discusses the regional characteristics of the hydro-geochemical seismic precursor anomalies on the northeastern margin of the Qinghai-Tibetan plateau,e.g.the background level of the precursor anomaly and anomaly ratio.The tectonodynamic cause of the departure of precursor anomalies from the future epicenter is preliminarily discussed and the quantitative indications for the seismic risk estimates and seismogenic location forecasting are provided,which have certain practical value for the prediction of earthquakes of Ms ≥ 4.1 in the area.
APPLICATION OF SEISMIC PHASE ANALYSIS IN THE INTERPRETATION OF DEEP SEISMIC REFLECTION DATA
LIU Kui, ZHAO Wen-jin
2005, 11(2): 129-134.
Abstract (98) PDF (916KB)(9)
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By a meticulous study of INDEPTH deep seismic reflection profiles,the authors found that not only the strong reflection line-ups of the deep seismic reflection profiles may reflect the structure of the deep interior of the crust but also the seismic phases in the upper,middle and lower crust have somewhat different features.By applying the seismic phase analysis in the study of deep seismic reflection exploration,we may use the difference in seismic phase features to interpret the deep reflection seismic profiles sufficiently,and thus more abundant and reliable materials may be provided for the study of the crustal structure.
RESULTS OF ROCK STRESS MEASUREMENTS AND ENGINEERING APPLICATION OF A RAILWAY TUNNEL IN NORTHWESTERN YUNNAN
LI Jin-suo, PENG Hua, Cui Wei, MA Xiu-min, YANG Shao-xi, LIAO Jian-she
2005, 11(2): 135-144.
Abstract (167) PDF (452KB)(34)
Abstract:
Rock stress state in situ is determined by the hydrofracturing method for rock stress measurement in a railway tunnel in northwestern Yunnan.According to the distribution features of the rock stress,combined with the mechanical parameters of the tunnel wall rocks,the stress filed in the tunnel area is simulated by using the three-dimensional finite elements.According to the in-situ stress measurements and three-dimensional finite element calculation,the basic features and distribution of the rock stress in engineering area are given,and the possibility of occurrence of geological hazards such as rock bursts during excavation of the tunnel is analyzed.Furthermore,the scientific basis for the lining design of the tunnel,choice of the tunnel's cross-section and determination of the axial direction of the tunnel is provided.
GEOLOGICAL CHARACTERISTICS OF THE HONGYEJIA THRUST SHEAR ZONE NORTHWEST OF HEIHE IN THE HEILONGJIANG RIVER VALLEY AND ITS SIGNIFICANCE
FU Jun-yu, YU Rong-wen, SONG Ya-qin, ZHANG Jin-lian
2005, 11(2): 145-152.
Abstract (217) PDF (286KB)(8)
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The Hongyejia thrust shear zone northwest of Heihe in the Heilongjiang River valley extends in an E-W direction in the junction between the southern side of the Luomahu median uplift and the northern margin of the Paleozoic Handaqi fold belt.According to the degree of deformation the north,central and south strong deformation belts may be distinguished.Macroscopic observations indicate that the sense of shear movement is south-directed.Three samples of rocks of different ages in the strong strain belts give K-Ar ages of 155 to 158 Ma,suggesting that the age of the thrust shear is terminal Middle Jurassic.The discovery of this tectonic zone supports the view that the influence of the Paleo-Asiatic tectonic domain on the Northeast China microblock persisted till the Middle Jurassic.
CHARACTERISTICS OF TECTONIC DEFORMATION OF THE YUESHAN PLUTON ON THE SOUTHERN MARGIN AND ITS GEOLOGICAL SIGNIFICANCE
LIN Ci-luan, LIU Qiang, YANG Kun-guang, MA Chang-qian
2005, 11(2): 153-159.
Abstract (110) PDF (514KB)(7)
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Zircon U-Pb ages of the Yueshan pluton in eastern Hubei indicate that this pluton is a granite body resulting from anatexis of an old granite body and its intrusion in the middle Yanshanian(139 Ma).The depth of emplacement of this granite body obtained by the hornblende geobarometer is up to 24.5 km.Macroscopic structures,strain measurements and quartz c-axis fabric analysis suggest that the Yueshan pluton underwent NW-SE extension and vertical compression during its deep-level emplacement.Numerous similar rock bodies are distributed in the southern Dabie Mountains,thus suggesting that the NW-SE regional extensional regime controlled the tectonic development in the southern Dabie Mountains in the middle Yanshanian period.
A METHOD FOR RESTORATION OF THE ORIGINAL LAYER THICKNESS BY USING FRACTURE BOUDINS
XU Yun-feng, ZENG Zuo-xun, WU Wu-jun
2005, 11(2): 160-163.
Abstract (102) PDF (156KB)(8)
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Fracture boudins are the result of combined discontinuous deformation of competent layers and continuous deformation of ductile layers.Take for example the fracture boudins occurring at Maquegou,Tieshan,Hubei,a new method of calculating the finite strain of a rock layer and restoring the original thickness of the layer is presented.It is very easy to operate and yields conclusive and reliable results.
(U-Th)/He DATING TECHNIQUE AND THERMOCHRONOLOGY AND THEIR APPLICATIONS IN GEOLOGY
YANG Mei-ling, CHEN Xuan-hua
2005, 11(2): 164-171.
Abstract (157) PDF (314KB)(9)
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In the paper the(U-Th)/He dating technique and thermochronology are introduced and the theoretical basis and technical requirements are dealt with.In addition,the applications of the (U-Th)/He dating technique in studies of small-magnitude exhumation,paleogeomorphology and high-precision dating of young geologic bodies are presented and the application prospects are discussed.
SEDIMENTARY EVOLUTION OF THE NAM CO BASIN,TIBET,SINCE 116ka BP AND QINGHAI-TIBET PLATEAU UPLIFT
ZHU Da-gang, MENG Xian-gang, ZHAO Xi-tao, SHAO Zhao-gang, MA Zhi-bang, YANG Chao-bin, WU Zhong-hai, WANG Jian-ping
2005, 11(2): 172-180.
Abstract (137) PDF (322KB)(9)
Abstract:
U-series isochron dating of lacustrine and lakeshore deposits shows that six lake terraces below 48m above lake level and highstand lacustrine deposits from 48 to 139.2m above lake level have formed along the banks of the Nam Co since 116ka BP.Three sedimentary facies may be distinguished.Their evolution progressed through four stages:① 116 to 72 ka BP:a deep lake environment predominated in the basin,with a paleolake level 140 to 48 m above the level of the present Nam Co; ② 72 to 37 ka BP:the lake environment was of moderate depth,with a paleolake level 48 to 26 m above lake level; ③ 37 to 30 ka BP:a shallow lake environment occurred,with a paleolake level 26 to 19 m above lake level; and ④ 30 ka BP to present:the lake has become progressively shallow and the paleolake level was <19m above lake level.The response of Nam Co basin deposits to the Qinghai-Tibet plateau uplift reveals that the plateau has experienced the following stages since 116 ka BP:the stable stage and progressive rapid uplift stage(116 to 37 ka BP),the abrupt and strong uplift stage(37 to 30 ka BP),and the relatively stable stage(since 30 ka BP).The uplift of the Qinghai-Tibet Plateau is a multi-stage,variable-speed and nonuniform complex process.
THE AGE OF LATE CENOZOIC MOLASSE IN THE FRONT OF THE WESTERN KUNLUN,XINJIANG AND ITS SIGNIFICANCE
LI Xi-chen, WANG Yong, DING Xiao-zhong
2005, 11(2): 181-186.
Abstract (116) PDF (203KB)(6)
Abstract:
Late Cenozoic sediments in the Kokyar section in the front of the West Kunlun record the uplift process of the Qinghai-Tibet Plateau.Paleomagnetic study shows that the molasse in the front of the West Kunlun formed in the late Miocene to early-mid Pliocene,reflecting that a rapid uplift process took place in the West Kunlun-Qinghai-Tibet Plateau in the late Miocene.Analysis of the sporopollen record and regional geological data indicates that the thick-bedded conglomerate in the upper part of the Kokyar section should be early-middle Pliocene in age,while the deposition of the entire molasse should begin still earlier,i.e.in the late Miocene.The depositional record and climatic change suggest that a prominent tectonic uplift event occurred on the Qinghai-Tibet Plateau in the late Miocene.
MAIN MINEROGENETIC SERIES AND METALLOGENIC CHARACTERISTICS ON HAINAN ISLAND
LIAO Xiang-jun, WANG Ping-an, DING Shi-jiang, Huang Xiang-ding, DONG Fa-xian, LIU Xiao-chun, LEI Wei-zhi
2005, 11(2): 187-194.
Abstract (155) PDF (1164KB)(10)
Abstract:
Hainan Island contains abundant mineral resources and the metallogeny and mineralogenetic series on the island display many similarities to those in South China or the Nanling region but also have their own features.The best example is that the mineralization intensity of the Indosinian mineralogenetic series related to granitic magmatism is notably higher than that of the Yanshanian mineralogenetic series of the same type.In this paper,in light of the concept of the mineralogenetic series,the mineral deposits(occurrences) on Hainan Island are grouped into nine mineralogenetic series.The mineralization there occurred from the Neoproterozoic through Quaternary,and magmatism and weathering-sedimentation contributed most greatly to the formation of mineral deposits of commercial value.
Celebrating the 40th Anniversary of the Discovery of the Fossil “Yuanmou Man” in Yuanmou County
2005, 11(2): 195-196.
Abstract (158) PDF (99KB)(5)
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