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    20 September 1995, Volume 1 Issue 1
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    TECTONIC SIGNIFICANCE OF LARGE FAULT SYSTEMS TO THE STUDY OF PALEO-PLATES
    He Guoqi, Lu Shuning, Li Maosong
    1995, 1(1):  1-10. 
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    The area of central Asia is composed of three paleo-Plates: the Siberia, the Kazakhstan-Jungar and the Tarim. Each paleo-plate has its characteristic large fault system and each system, in turn, includes two sets of faults. The first set, which is of major importance runs parallel to the margin of the ancient continent, whereas the second set is always approximate per pendicular to the ancient continental margin. The internal features of every system exhibit much harmony during their evolution. These faults have evolved through two stages. The first stage, which is characterized by the formation of ophiolite or ophiotitic melange belts,corresponds to the disintegration of the continental crust. In contrast, the second stage coincides with the collision of paleo-plates. It is beyond doubt that the faults which were developed at the first stage have suffered intense reformation. It is concluded that the geometric relations between the large fault systems and the ancient continental margins are produced by an integration of continental disintegration and divergence, convergence and collision of moving plates. Significance of large fault systems also discussed in terms of the division of paleo-plates, the discrimination of their relative motion and the recovery of their primitive geometry.

    Article
    ON PLATE COLLISION KINEMATICS: TAKING THE JIANGNAN AND THE EASTERN TIANSHAN OROGENIC BELTS AS EXAMPLES
    Shi Yangshen1, Shu Liangshu1, Guo Lingzhi1, Sun Jiaqi2
    1995, 1(1):  11-21. 
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    The collisional tectonic kinematics is one of the important studying methods of plate tectonics and is used to ascertain the senses of movement, the polyphase deformation and the tectonic evolution. The present authors have been working for more than l0 years in the jiangnan Proterozoic orogenic belt and the Eastern Tianshan Paleozoic orogenic belt and have obtained a plenty of in formation of ductile shear deformation and firsthand kinematic evidence. The authors presented and summaried the following research results of collision tectonic kinematics. 1. There are 6 geological indicators of the plate collision-suture zone, i. e., ① the tectonic melange, ② the high pressure metamorphic zone and region metamorphic zone, ③ the collision type granite, ④ the large-scale ductile shear zone, ⑤ the polyphase deformation zone and ⑥ geophysically abnormal zone. 2. The 4 major aspects for the research on lower and middle-deep seated tectonic kinematics are: ① the mylonitic rocks including feldspar-quartz mylonites, mylonitized rocks and phyllonites, ② special folding style such as sheath fold and recumbent fold, ③ stretching lineation, foliation and cleavage, ④ kinematic ductile shearing sense indicators including strain indicators, rotation indicators,shear indicators,etc. . 3. The 5 types of ductile shear zone are divided based on origin mechanism;① subduction type, ② thrust type, ③ fault zone type, ④ strike slip type and ⑤ extension type. Finally, the authors reported in brief some new results and understanding about the collision kinematics in the Jiangnan orogenic belt and the Eastern Tlanshan orogenic belt, for example, regional sense of shear and polyphase deformation (thrust, strike-slip and extension) corresponding to the evolution history of regional tectonics .
    MORPHOLOGICAL CHARACTERISTICS OF THE EARTHQUAKE SURFACE RUPTURES ON AWAJI ISLAND , ASSOCIATED WITH THE 1995 SOUTHERN HYOGO PREFECTURE EARTHQUAKE
    Aiming Lin
    1995, 1(1):  22-33. 
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    The earthquake fault system on northern Awaji island accompanying the 1995 Southern Hyogo Prefecture Earthquake consists of three earthquake surface rupture zones, namely Nojima Earthquake Fault, Matsuho Earthquake Fault, an d Kusumoto Earthquake Fault. The Nojima Earthquake Fault,18 km in length, extends from Awaji-cho and the northern tip of Awaji island to Ichinomiya-cho and wag developed along the pre-existing Nojlma fault in the northern segment and as a new fault in the southern segment. The northern segment of the Nojima Earthquake Fault is composed of several subparallel shear faults showing a right-step enechelon form and a lot of extensional cracks showing a left-step enechelon form, whereas the southern segment consists of some discontinuous surface ruptures which are concentrated in a narrow zone a few tens of meters in width. This fault shows a general trend striking N 30°-60°E, 75°-85° dipping to SE. The deformational topography and striations on the the fault plane generated during earthquake faulting show that the Nojima Earthquake Fault is a right-lataral strike-slip fault with minor reverse movement. Displacements measured at a lot of outcrops are generally 1.0-2.0 m in horizontal direction and 0.5-1.0 m in vertical directions in the northern segment and a few cm to 20 cm in both horizontal and vertical direction in the southern segment. The largest displacements are 180 cm in horizontal direction,130 cm in vertical direction, and 215 cm in netslip measured at the Hirabayashi fault scarp. The Matsuho Earthquake Fault striking N 40°-60°W is also found along the coastal line trending NW -SE at Awaji-cho for about 1 km at the north end of Awaji island. The Matsuho Earthquake Fault extends along the pre-existing geological Kusumoto fault for about l km near the noutheastern coastal line, generally striking N 35°一60°E and 60°-70°dipping to NW. Based upon morphological and geomorpholocal characteristics,the Nojima Earthquake Fault can be divided into four fault segments which exhibit a right-step enechelon form. Geological and geomorphological evidence and aftershock epicenter distributions show clearly that the distributions an d geometry of these four segments are controlled by the pre-existing geological structures. It documented that deformation along the earthquake faults involves the pulling-apart and the pushing-up processes which have produced the extensional cracks, pull—apart basins, flexural folds and pressure ridges.
    THE ELASTlC PROPERTlES OF S-TYPE AND l-TYPE GRAMTOIDS lN GUANGDONG PROVlNCE AND THElR TECTONIC MEALING
    Jiang Jiahuang1, Yang Shufeng1, Chen Hanlin1, Zhu Guoqiang1, Wang Zhenguo2, Ji Zhonglin2, Zhang Boyou2, Guo Sujie2
    1995, 1(1):  34-40. 
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    The compressional-wave velocities (Vp) and shear-wave velocities (Vab and Vav )of early Paleozoic S-type and I-type granitoid samples collected from the central and west part of Guangdong province were measured accurately both at atmospheric pressure and room temperature and during heating (up to 1 05℃ )and pressuring (up to 5. 06 × 1 0 7 Pa). Through systematic calculation, we obtained the average values of wave velocities (Vp,Vab an d Vav ),the ratio of compressional-wave velocities and shear-wave velocities (Vp/Vab)and Poisson’s ratio under atmospheric pressure and room temperature and the curves of P-wave and S-wave veloities at various pressures and temperatures. The values of wave velocities(V p,Vab and Vav),Vp/Vab and Poisson’s ratio are different obviously between S-typ e and I-type Granitoids. The average values of wave velocities(Vp, Vab and Vav), Vp/Vab and Poisson’s ratio of S-type granitoids are 5005m/s,2897m/s,2591m/s and 0. 25 and smaller than those of I-type granitoids (5512m/s,2937m/s,2671m/s and 0. 30) especially in compressional-wave velocities. the difference is 507m/s and is 1 0 of wave velocity value of S-type granitoids. The values of Vp/Vab for S-type and I-type granitoids are larger than 1. 70 and located in the normal range of granitoids, but the values of I-type granitoids are larger than that of S-type granitoids. The values of wave velocities of S-type and I-type granitoids increase gradually with increasing pressure and decrease gradually with increasing temperature, but the range of S-type granitoids is larger than that of I-type granitoids obviously. The anisotropy of S-type granitoids is up to 1.10 and larger than that of I-type granitoids. From the elastic properties of S-type and I-type granitoids, we can conclude that the structure and porosity in S-type granitoids are better developed than those in I-type granitoids, and the granite body was intensely compressed in the direction of NNW-SSE during the process of formation.
    TH E ANALYSIS 0F DEFORMATION SUCCESSION IN W EST TIANSHAN , XINJIANG
    Cui Kerui
    1995, 1(1):  41-49. 
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    The tectonic evolution of west Tianshan includes three deformation cycles and six deformation generations, which bear close relationship with sedimentary, metamorphic and magmatic events. The first deformation generation (early palaeozoic or earlier) is characterized by tight fold compression schistosity and injection of magma. The second generation (Sflurian to Devonian) is indicated by ductile shearing and structural transposition and by melange zone and metamorphic zone of high pressure and low temperature. The third generation (Carbonf’erous to early Permain) results in nappe structure, superimposed fold, and metamorphism of lower greenschist facies. The fourth generation (1ate Permian to Triassie) is consistent with late orogenic extension and stress relaxation with resultant extensional faults, tensile breccia, intrusion of A –type granite and extrusion of basaltic magma. Orogenic belt obducting and strike-slip faults are characteristic of the fifth deformation generation (Jurassic to Eogene). The sixth generation (Neogene to Quaternary) are characterized by block faulting with obducting and strike-slip movements. Based on the study of the deformation succession, theoretical bases are provided for understanding the geologic history and for prospecting mineral deposits of the West Tianshan area.
    INTRACONTINENTAL SUBDUCTION OF THE YANGTZE CONTINENT AND CONTINENT REDUCING—INFERRED FROM MUSCOVITE (TWO MICA) GRANITES
    Deng Jinfu, Zhao Hailing, Mo Xuanxue, Liu Houxiang, Luo Zhaohua
    1995, 1(1):  50-57. 
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    This paper briefly demonstrates that the muscovite (two-mica)granite is a petrological record of intracontinental subduction. The Indosinian-Yanshan Lan (245-122M a) two-mica granites are widely distributed in the South China Continent and the Tianshui-Yajiang region, and the foreland fold-belts are developed on both side of the Yangtze Continent. Such a symmetric feature and their structural setting indicate the intracontinental subduction of Yangtze Continent beneath both the South China Continent and the Songpan-Ganzi fold belt. Based on both the total width of two-mica granite zones on both sides of the Yangtze Continertt (about 650km ),the minimum subducted width of Yangtze continent is estimated to be 650km. The present width of Yangtze continent is about 680km,therefore the Yangtze Continent and is reduced at least to about one half of its original width by the Mesozoic intracontinental subduction. Alternatively, the subducted area may be a m icro-continent situated between the Yangtze Continent and Jiangnan orogenic belt. This paper gives a criterion to recognize and distinguish the intracontinental subduction zone and the thrust tectonic zone. The tectonic boundary between the Yangtze Continent and Qinling orogenic belt is a thrust-strike slip tectonic zone rather than a intracontinental subduction zone. The Jiangnan orogenic belt and Longmenshan orogenic belt a believed to be the overriding continents, rather than to belong to the Yangtze Continent. The inner side of the Mesozoic Southeast orogenic zone is considered to belong to the Higher Himalaya-type in tracontinental subduction zone rather than to the Yarlu Zangbo-(Tsangpo-)type or the Hsu’s (1987) collision orogenic zona-type. The intracontinental subduction is believed to be the main mechanism for the formation of the South China Continent, which underwent both of the Neoproterozoic and the Caledonian intracontinental subduction events resembling the YarluZangbo-type or the Hsu’s (1987) collision orogenic zone type. Both the multiple intracontinental subduction and formation of muscovite granites with consequent concentration of the metallic elements of continental crust affinity may be a favouruble dynamic background for the formation of the large and superlarge W –Sn-Sb-N b-Ta-REE-U ore deposits in the South China Continent
    THE MESOZOIC TECTONIC SETTING OF NORTH CHINA PLATFORM AND ITS RELATION TO HYDROTHERMAL M ETALLOGENESIS
    Hu Shouxi1, Ye Ying2, Zhao Yiying1, Liu Hongying1
    1995, 1(1):  58-66. 
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    The initial Eurasian plate was formed during the Late Hercynian cycle. Its intense interaction with Paleo-Pacific plate (includmg Farallon,Kula and Izanagi plates) took place during the Indosinian event and was the kinetic source not only for the extensive metamorphism and ductile shearing, but also for A -type subduction and relevant granitoid formation in the North China Platform, espacially along its margin. After the formation of initial Eurasian Plate in the final phase of the Hercynlan cycle, North China Platform with its Early Precarnbrlan crystalline basement was situated in an intensely campressive tectonic setting caused by two dominant stress fields related respectively to Paleo-Pacfic subduction and further compression and to compression and A-type subduction between that platform and the Siberian plate to the north and the South China Plate to the south. Tectonic line created by the former stress field strikes in NE and NNE directions, along which there are important granitic and metallogenic belts in East China. Mineral deposits, ore fields and belts controlled by this tectonic line shows inistral strike-slip character following the pattern along which the components of the Paleo-Pacific, such as Farallon,Kuia and Izanagi, acted on East China continent. The latter stress fie1d is related to intraplate compression in S-N direction and has brought about granitic belts and relevant hydrothermal ore deposits arranged in E-W strike. “The remote tectonic effect” caused by the Paleo-Pacific acting on initial Eurasian Plate dies away from the subduction zone or coast line, so that the predominant NE-and NNE-trending tectonic pattern in the coastal area gives its way to the NWW-and EW-trending pattern westwards. This is demonstrated by the examples from Mesozoic Au, Mo and other hydrothermal mineral deposits and orefields in Jiaobei and Huaxiong Terranes at the cast and south margin of North China Platform.
    OXYGEN DIFFUSION IN MINERALS AND ITS BEARING ON RETROGRADE ISOTOPE EXCHANGE IN ROCKS
    Fu Bin1;2, Wang Xue-jun1, Zheng Yong-fei1;2,
    1995, 1(1):  67-79. 
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    Effects of oxygen self-diffusion in minerals on oxygen isotope composition have been studied theoretically. When igneous or metamorphic rocks slowly cool under closed system conditions, oxygen isotope redistribution can occur due to diffusion-controlled retrograde isotope theoretically calculated oxygen isotope fractionation factors, the oxygen isotope compositions of some case examples have been estimated for given cooling rates. During cooling of metamorphic and plutonic rocks, oxygen diffusion between minerals can be the principal mechanism to cause retrograde isotope exchange. There are two types of models to simulate the effects of oxygen diffusion: (1) Giletti model, a simple cooling rate model which predicts the effect of slow cooling in a closed-system on the oxygen isotope composition of single minerals; (2) Eiler model, a fast grain boundary model which predicts both the zonation profile of δ18O within mineral grains and the bulkδ18O value of each mineral in the rock. Both models have advantages and disadvantages with respect to reality. However, application of the models will help to interpret possible variations in oxygen isotope composition of minerals and to preclude effects of open-system exchange (e.g., water/rock interaction, magma degassing). Case examples are tested to show the applicability of the diffusion models to natural assemblages. These include the granulite-grade metamorphic rock from Einasleigh in Australia, the tonalite from San Jose in USA and the granite from Suzhou in East China. The theoretical prediction forδ18O agrees well with the experimentally measured values. For the Suzhou granite, the lowδ18O value is interpreted to indicate the interaction of its protolith with meteoric water at high temperatures. The water/rock interaction after granite emplacement can be excluded by the constraints from diffusion-controlled oxygen isotope exchange.
    INTERGROWTHS OF HEXAGONAL AND MONOCLINIC PYRRHOTITES AND THEIR GENESIS FROM MASSIVE SULPHIDE DEPOSITS OF NORWAY
    Gu Lianxing1, Yin Lin1, F. M. Vokei2
    1995, 1(1):  80-92. 
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    Microscopic investigations have provided further evidence that pyrrhotite in the massive sulphide ores of the Norwegian Caledonides was mainly formed during sedimentation and diagenesis and has undergone polyphase metamorphism, deformation, recrystaliization and annealing. A minor portion of the pyrrhotite was formed during diaphthoretic and metahydrothermal events. No pyrrhotite was found in the present study that appeared to have been derived from pyrite by progressive metamorphism. Observations using a magnetic colloid revealed that intimate intergrowths of the hexagonal and monocilnic varieties can be exhibited by either sedimentary-diagenetic, retrogressive or metahydrothermal pyrrhotite. The intergrowths are classified morphologically in to crystallographically controlled lamellar patterns and fissure- or grain boundary-controlled irregular ones. Those two Patterns were form ed either by exsoiution from the hexagonal solid solution or by replacement of the hexagonal variety by sulphur-rich fluids. Recent research indicates that volcanogenic massive sulphide deposits can form at temperature higher than 300°~350℃, and even above 450℃. Such temperatures may be attained particularly in the case of proximal deposits and are favourable for the crystallization of hexagonal pyrrhotite (hpo), which will be able to exsolve moncolinic pyrrhotite (mpo) during cooling if the bulk composition plots in the hpo+mpo region. Monoclinic pyrrhotite will he absent in the case of ores that were formed under sulphur-poor sea-floor conditions or at temperatures be low 254℃. Metamorphism at temperatures exceeding that of the mpo-hpo transition will erase earlier exsolved monoclnic pyrrhotite by homogenization during reocrystallization and annealing. Such a proof of homogenization will account for the fact that the monoclinic variety is normally absent in recrystallized and annealed pyrrhotite. Well-preserved moneclinic lamellae in retrogressive and metahydrotharmal pyrrhotites may indicate that these pyrrhotites have fiever been affected by post-crystallization and high-temperature events. Most of the volcanogenic massive sulphide deposits in old orogenic belts have, to various extents, been subjected to metamorphism, recrystallization and annealing. This could be considered as one of the most important reasons for the absence of monoclinic pyrrhotite in their ores.
    TECTONOGENETIC MINERALOGY OF STIBNITE FROM LANNIGOU GOLD DEPOSITS, GUIZHOU PROVINCE
    Chen Wu1, Zhang Fusheng2, Qian Handong1, Hu Yong1
    1995, 1(1):  93-96. 
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    Based on the examination of super microstructure and micromorphology in stibnite from Lannigou micro-disseminated gold deposits of Guizhou province, the wavy microfissure in stibnite crystal, which are filled by cinnabar, are observed and some deformation super microstructure, such as deformation twin, stacking fault, free dislocation, dislocation wall and subgrain are revealed. All these super microstructures provide genetic information on microscale for the tectonic processes developed between the stages of Sb and Hg mineralizations.
    THE DISCOVERY AND EXPLOITATION OF TH E “SINOIODINE—BEARING MINERAL WATER” FROM DEZHOU CITY , SH ANDONG PROVINCE
    Chao Qincheng, Zhao Guangtao, Sun Yuepeng
    1995, 1(1):  97-100. 
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    This the first work to verify the rare iodine-bearing natural drinking mineral water named “Sino iodine-bearings mineralwater”. The study shows that this mineralwater was formed in a Cepozoic fault-bounded basin with weakly basic and oxidizing hydrogeochemical condition. It is the product of the reaction between the groundwater end the continental clastic sediments. The high-quality water belongs to the iodine-bearing soda type mineralwater with slightly higher concentration of fluorine. In order to exploit the water reasonably, the electronic percolation technique is suggested to be used co reduce the fluorine during large-scale production.
    ANALYSIS OF PALEOHYDROGEOLOGY FOR THE MINERAL1ZATION IN ⅪANGSHAN URANIUM ORE-FIELD
    Zhou Wenbin, Li Xueli
    1995, 1(1):  101-108. 
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    Xiangshan uranium more-field is a famous hydrothermal uranium ore-field. It occurs in the fossil hydrothermal systems within Xiangshan Mesozoic volcanic basin and is the product of water-rock interactions in the hydrothermal systems. Therefore, the reconstruction of the paleohydrogeological setting is of great importance to genetical study of the mineralizations and to the prospecting for the deposits. Based on field geology, tectonic evolution history and paleo-climate condition, after the paleohydrogeological stages and zonation were defined in this paper, the recharge, discharge zones and movement of the paleo-groundwater were analyzed, and then the formation condition of the hydrothermal systems was discussed. TWO ore-forming hydrothermal systems in Xiangshan ore-field have been recognized by means of tectonopaleohydrogeological analysis. One is the north hydrothermal system which produced the sodium-metasomatic type Uranium deposits, and the other is the west hydrothermal system which yielded the fluorite-hydromica type uranium deposits. According to hydrogen and oxygen stable isotope studies, fluids of the hydrothermal systems as considered to have been derived mainly from meteoric water. Modeling of the paleogethermal field shows that the heat for Xiangshan hydrothermal system was derived mainly by ground water circulation to deep levels in a relatively higher geothermal gradient.
    DISCOVERY OF THE SPIRAL ULTRA-MICROFOSSILS IN PELAGIC MANGANESE NODULES AND THEIR SIGNIFICANCE
    Zhang Fusheng1,Bian Lizeng1, Lin Chengyi1,Zhou Lvfu1,Du Dean1, Chen Jianlin2,Shen Huati2,Han Xiqiu2
    1995, 1(1):  109-116. 
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    The spiral ultra—microfossils have been discovered in the pelagic knobbly manganese nodules from the East Pacific Ocean (Photo 1) with the help of transmission electron microscope JEM 200CX. It has been revealed that the chain-like and the spiral ultra-microbes are the real builders of the stromatolite (admirabilis), i.e. the coatings of manganese nodules (Photo 2). The colony of the spiral microbes are of disk-like or irregular morphology with a sunken center (Photo 3). The nutritive hypha and the reproductive hypha can be discriminated based on their morphology (Fig.1). The branching nutritive hypha grow from the center of colony to its periphery and the width of the hypha bundles is about 17-60nm. The spiral reproductive hypha about 2-4nm in diameter (Photo 4,5,Fig.2). The screws formed by the spiral reproductive hypha are 3-25nm wide and 35-200nm long. The spheroidal sporangium of 9-50nm in diameter can be seen among the mycelium (Photo 6). The spheroidal spores of 4-6nm diameter can be found in these case. The authors propose setting up a new species Spirisosphaerospora pacifica in the Actinomyes. The discovery of the ultra-microfossils has produced a direct evidence in support of biogenec formation of the manganese nodules. Some peculiar feature of the pelagic manganese nodules such as heterogeneity in mineral composition, poor crystallinity, special structure and texture, can be explained reasonably by the biogenic formation. The new ultra-microfossils as a large molecule will promote the research work on the origin and evolution of life.
    FEATURES AND DISTRIBUTION OF MIAOLINGIAN HIPPARION FAUNA (LATE MIOCENE, BAODEIAN) IN NORTH CHINA
    Zhang Yunxiang, Xue Xiangxu
    1995, 1(1):  117-121. 
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    The Miaolang substage, which corresponds to the age interval of 7-5 M a, was defined by Xue Xiangxu et a1. in 1995. The typical assemblage is Mianliang Hipparion fauna found in Fugu County, Shaanxi. According to preliminary identification, the chief species of the fauna are Adorocula eximia variabili, Hipparion sp. Chilotherini, Honanotherium sp. Chleuaslochoerus steblini, Eostylocerus blainvillei, Muntiacus cf. lacustris, Cervavilus novorossias, C. demissus, Procapreolus latifrons, etc.. The faunas in this Substage include thee found in Longjiagou, Gansu, at different localities of Xin’an, Henan, at some localities of the Baode area, in the Mahui Formation, Shanxi and in the Lantian Formation, Shanxi. The common features of the faunas are: (1) all faunas contain abundant fossil of Cervidae, such as Eosty locerus blainvillei, Muntiacus lacustris, Cervavitus novorossiae, C. demissus, Procapreolus latifrons, ets., (2) Acerorhinus is the dominant element of Rhinocerotidae and no fossils of rea1 Chilotheerium have been found, (3)most animals of these faunas, have low-crowned teeth, such as Honanotherium,Gazella gaudryi and Chleuastachoerus Steklini, (4) Hipparion,platyodus is the main species of hipparionine in this Substage. They were widely distributed in north China and most of these animals were typical forest dwellers.