bluuebunny/crossref_metadata_2025 huggingface dataset:
Puziwan Gold Deposit in Shanxi, China: A Special Linear Cryptoexplosive Breccia Type Gold Deposit
Authors: Fengzeng YAN
Published: September 2010

Abstract  The Puziwan gold deposit is a special linear cryptoexplosive breccia type deposit found in northeastern Shanxi, China, in recent years. The deposit is located in a secondary metallogenic belt of the most famous Au‐Ag polymetallic metallogenic belt along the north margin of the North China platform. The secondary metallogenic belt is a synmagmatic tension‐shear fault‐fracture belt of ENE linear trend. The Indosinian cryptoexplosive breccia body, quartz monzonitic porphyry (beschtauite breccia), quartz monzonite (243.7 Ma, K‐Ar), Yanshanian granite‐porphyry (105±6 Ma, Rb‐Sr) and orebodies mostly occur as dykes or veins and short lenses along the structural fracture belt. The orebodies are emplaced in the fractured cryptoexplosive breccia body in the tectonomagmatic belt and their attitude is consistent with that of the breccia body. The orebodies have two types: one is shallow‐seated thick and big ones, which are short‐lenticular in plan and wedge‐shaped in cross section, shallow buried, large in size and high‐grade; the other is lean orebodies, which occur as parallel veins at depths. The ores are mainly of Au‐Ag polymetallic sulphide‐rich breccia type. Pyrite (limonite) is the dominant metallic mineral, with subordinate chal‐copyrite, galena, sphalerite, tenantite, native gold, electrum, native silver and argentite. The gangue minerals consist mainly of quartz and plagioclase, with subordinate carbonate minerals, alunite chalcedony and kaolin. Kaolinization is the characteristic alteration type. Sulphide minerals contain abundant trace minerals such as Cu, Pb, Ag, Sb and Hg, while in the ores Ag, Cu, Pb, Zn, As and Sb are the best indicator element assemblage of Au. The δ34S(%o) values of the ores rane from −3.2%o to 5.3%o, with average −0.102%o. The δO H2O(%o) and δ(%o) values are in the ranges from −3.1%o to 7.73%o and from −64%o to −90%o respectively. The Pb isotopic compositions of the rocks and ores in this region indicate that Pb comes from three tectonic sources—upper mantle, lower crust and orogenic belt. The inclusion homogenization temperature are in the ranges of 110 to 220°C and 230 to 310°C, which suggests that the deposit formed under meso‐epithermal conditions. The ore‐forming pressures range from 6 to 32 MPa and the depths are 230 to 1200 m. In view of the above, the Puziwan gold deposit is genetically ascribed to a high‐sulphur (alunite‐kaolin) meso‐epithermal gold deposit related to subvolcanic rocks. This gold deposit formed during the Indosinian stage (245.9±0.3 Ma) and then was influenced by a thermal event in the Yanshanian stage (142.9±0.5 Ma).
A Study of the Accompanying Relationships between Uranium and Oil
Authors: Huaiyuan LI
Published: September 2010

Abstract  It is not occasional that uranium deposits and oil accumulation occur in the same depression in the Erlian basin, Inner Mongolia. Some evidences show certain relations between uranium and oil in origin. This paper discusses and analyses the evidence for the relations between uranium deposits and oil and gas accumulation in terms of spatial distribution, geology, hydrochemistry and geochemistry. The paper also deals with the mechanism of the formation of uranium deposits and points out that it is of significance to use uranium as an indicator to search for oil and vice versa.
Affinity between Palaeozoic Blocks of Xinjiang and Their Suturing Ages
Authors: Fuxiang GUO
Published: September 2010

Abstract: The Kazakhstanian plate was near the Tarim, Sino‐Korean and South China‐Southeast Asian plates in the Middle‐Late Cambrian and Late Ordovician, and approached the Siberian plate in the other periods of the Early Palaeozoic. The Ili and Toksun‐Yamansu terranes had been split from the Tarim plate before the Middle Devonian and then went close to Angaraland in the late Early Permian. The Beishan area on the northeastern margin of the Tarim plate came close to Angaraland first in the early Early Permian. The suturing age between the Tarim and Kazakhstanian‐Siberian plates is generally the same as that between the Turkey‐Central Iran‐Gangdise and South China‐Southeast Asian plates. The suturing event took place in the early Early Permian, while the corresponding tectogeny occurred between the Early and Late Permian.
Thermal Evolution of Plutons and Uplift Process of the Yanshan Orogenic Belt
Authors: Zhenhan WU , Shengqin CUI , Dagang ZHU , Xiangyang FENG , Yinsheng MA
Published: September 2010

Abstract: Thermochronological dating was used to study the thermal evolution of the Mesozoic plutons and uplift history of the Yanshan orogenic belt. The results show that the cooling history of the plutons is complicated, corresponding to the inhomogeneous uplift process of the Yanshan orogenic belt. The Panshan granite cooled fast during 226.48–204.95 Ma at a rate of 10.22°C/Ma after its emplacement at a depth of about 10 km, and its fast uplift occurred in about 96–35 Ma at an average rate of 0.115 mm/a. The Wulingshan pluton cooled fast during 132–127.23 Ma at a rate of 94.34°C/Ma, and its rapid uplift occurred in 86–45 Ma at an average rate of 0.186 mm/a. The Yunmengshan granite cooled fast during 143–120.99 Ma at a rate of 19.51°C/Ma, and its rapid uplift occurred in 106–103.95 Ma and 20–0.0 Ma at a rate of 1.06 mm/a and 0.15 mm/a respectively. The Sihetang granite‐gneiss uplifted rapidly since 13 Ma at an average rate of 0.256 mm/a. The Badaling granite uplifted rapidly since 6 Ma at an average rate of 0.556 mm/a. The Cenozoic uplift of the Yanshan Mountains can be well correlated to the rifting process of the surrounding basins.
Qinling Faunal Region—The Third Ordovician Faunal Region: International Correlation
Authors: Fang PEI
Published: September 2010

The Ordovician conodont faunal provinces were previously divided into the Midcontinent and Atlantic Faunal Regions situated respectively in low and high latitudes, where warm‐ and cold‐water type conodont faunas flourished respectively. According to the international correlation this paper proposes the third Ordovician conodont faunal region—Qinling Faunal Region, in which cold‐water conodont faunas were well developed in the Early to middle Middle Ordovician and warm‐water conodont faunas were well developed in the late Middle and Late Ordovician, indicating that the Qinling Region was situated in high latitudes earlier and in low latitudes later. The origin was only due to plate movement. In the Qinling Region the time interval of the change of the conodont fauna from the cold‐ to warm‐water type was 4 Ma (from 474 to 470 Ma), during which the fauna geographically spanned 40° of latitudes, with a movement velocity of nearly 1.12 m/a, indicating that the high‐latitude plates were divorced and reduced in the late Middle Ordovician, while the low‐latitude plates were converged and accreted. According to the features of the conodont faunas, the Qinling Faunal Region can be divided into the North Tarim, Wudang, Scandic and Pingliang provinces.
Trachytic Rock and Associated Fenitization in the Bayan Obo Ore Deposit, Inner Mongolia, China: Evidence for Magmatic‐Hydrothermal Mineralization Related to a Carbonatitic Complex
Authors: Zhongxin YUAN , Ge BAI , Zongqing ZHANG
Published: September 2010

Trachytic rock and its altered rock—fenite—in the Bayan Obo ore district, Inner Mongolia, China, were referred to as slate or feldspar rock before, and identified by the authors for the first time (in 1992). In the paper the mineral assemblages, structures and textures and petrochemical compositions of the rocks, as well as the electron microprobe analysis of feldspars in the rocks are described. The Sm‐Nd isochron age of the trachytic rock is 1096 ± 56 Ma, with INd=0.51100±4 (2 s̀) and ɛNd(t)= −4.4 ± 0.7. Alterations of the trachytic rock, including microclinization, riebeckitization, aegirinization and biotitization, and accompanied rare element and REE mineralizations are discussed. Based on the occurrence of the trachytic rock and associated fenitization it is deduced that the Bayan Obo Fe‐Nb‐REE ore deposit is genetically related to magmatic‐hydrothermal activity of an alkali carbonatite complex.
Micro‐area Chemical Composition and Preserved P‐T Evolution Trace of Phengite in Albite Gneiss from the Donghai Ultrahigh‐Pressure Metamorphic Area, East China
Authors: Fulai LIU , Zeming ZHANG , Zhiqin XU , Jingsui YANG , Huifen XU
Published: September 2010

Study of micro‐area chemical compositions indicates that phengite in albite gneiss from hole ZK2304 of the Donghai region has evident compositional zoning. SiO2 and tetrahedrally coordinated Si contents decrease, and Al2O3, AlIVand AlVIcontents increase gradually from core to rim. However, K2O, MgO and FeO contents basically remain unchanged from core to rim. According to P‐T estimates obtained from geothermometers and barometers, combined with previous experimental data, the core belt (micro‐area I) of phengite was formed at T=637–672°C and P=1.55–1.73 GPa, and the transitional belt (micro‐area II) of the phengite were formed at T=594–654°C and P=1.35–1.45 GPa. Towards the rim belt (micro‐area III), the temperature decreased slightly, but the pressure decreased rapidly with T=542–630°C and P=1.12–1.19 GPa. The P‐T evolution path recorded by the compositional zoning of phengite is characterized by significant near‐isothermal decompression, revealing that the gneiss has undergone high‐pressure‐ultrahigh‐pressure metamorphism. The compositional zoning of the phengite in the albite gneiss may have formed in the geodynamic process of rapid exhumation in the Sulu ultrahigh‐pressure metamorphic belt.
Geological Features of the Eastern Sector of the Bangong Co‐Nujiang River Suture Zone: Tethyan Evolution
Authors: Jianping WANG
Published: September 2010

According to an analysis of the geological features in the eastern sector of the Bangong Co‐Nujiang River suture zone, the Tethyan evolution can be divided into three stages. (1) The Embryo‐Tethyan stage (Pz1): An immature volcanic arc developed in Taniantaweng (Tanen Taunggyi) Range, indicating the existence of an Embryo‐Tethyan ocean. (2) The Palaeo‐Tethyan stage (C‐T2: During the Carboniferous the northern side of the Taniantaweng Range was the main domain of the Palaeo‐Tethyan ocean, in which developed flysch sediments intercalated with bimodal volcanic rocks and oceanic tholeiite, and Pemian‐Early Triassic are granites were superimposed on the Taniantaweng magmatic are; on the southern side the Dêngqên‐Nujiang zone started secondary extension during the Carboniferous, in which the Nujiang ophiolite developed, and the Palaeo‐Tethyan ocean closed before the Middle Triassic. (3) The Neo‐Tethyan stage (T3‐E): During the Late Triassic the Dêngqên zone developed into a relatively matural ocean basin, in which the Dêngqên ophiolite was formed. By the end of the Triassic intraocean subduction occurred, and the ocean domain was reduced gradually, and collided and closed by the end of the Early Jurassic, forming the Yazong mélange; then the Tethyan ocean was completely closed.
Evidence of the Pan‐Lake Stage in the Period of 40–28 ka B.P. on the Qinghai‐Tibet Plateau
Authors: Mianping ZHENG , Yifeng MENG , Lejun Wei
Published: September 2010

The Qinghai‐Tibet plateau is one of major saline lake regions in China, where saline lakes are widespread and constitute an important object of researches on the palaeoclimatic change in the region. On the basis of comprehensive investigations of the evolution of the lake's surface and sediments on the plateau, the authors have further demonstrated the existence of a pan‐lake stage (river and lake flooding stage) on the Qinghai‐Tibet plateau during the period of about 40+‐28 ka B.P. and analyzed the palaeoclimatic characteristics of the pan‐lake period and relationships between the ancient monsoons and the uplift of the plateau since the beginning of the Quaternary.
Tree‐Ring Carbon Isotopic Constraints on Carbon‐Water Exchanges between Atmosphere and Biosphere in Drought Regions in Northwestern China
Authors: Shilu WANG , Guojiang WAN
Published: September 2010

The comparison between the carbon isotope and the index of ring width of a pine disc from the Tuomuer Peak region in Xinjiang shows that the effects of climate changes on the tree‐ring growth and carbon isotopic fractionation varies with time. The reason is probably relative to the characters of climate changes and adaptability of the tree‐ring growth to climate changes. The relationships between the atmospheric CO2 level and the revised δ13Cair by the tree‐ring carbon isotope indicate that the carbon cycle is not in a steady state, but under a stage‐change condition in this area. It also can be concluded that the ratio of CO2 from the terrestrial eco‐system has increased, and the flux of CO2 exchange between the atmosphere and the biosphere was gradually increasing over the past century. In addition, the results also confirm the validity and superiority of the carbon isotope to the research of the water‐use efficiency.
Engineering Geological Study of the Active Tectonic Region for Hydropower Development on the Jinsha River, Upstream of the Yangtze River
Authors: Sijing WANG , Guohe LI , Qiang ZHANG , Chaoli LAN
Published: September 2010

The Jinsha River runs across the Hengduanshan north‐south tectonic zone where neotectonism was relatively strong, accompanied by various geologic hazards. In this case, it seems necessary to make a quantitative assessment and grading of the engineering geological environment for the planning and development of hydropower projects on the Jinsha River.

The studies of crustal structures and activities of neotectonic fault blocks provide a three‐dimensional geomechanics model for us to make an assessment of the engineering geological environment. Based on the survey data and results from geologic hazard risk analysis, a hierarchical analysis model on the quality of the engineering geological environment is established with respect to the crustal stability, ground stability, and rock and soil mass stability. Nine factors relevant to the geological environment are selected and five levels are used for the quality grades: very bad, bad, mediocre, good, very good. The result indicates that active deep faults have an influence on the engineering geological environment of the Jinshajiang region.

Finally, the authors present a preliminary evaluation on the constructional suitability of each planned site in the middle and lower reaches of the Jinsha River.
Experiment of Coal Leaching and Study of the Separation of Trace Elements
Authors: Guijian LIU
Published: September 2010

Leaching is an important way of separation of trace elements from coal. Based on leaching experiments, the content of trace elements separated out from coal is related to their existing state and content in coal, the duration of leaching process, temperature of leaching liquor and its acidity and basicity. The higher the temperature of leaching liquor and the longer the leaching time, the higher the contents of separated trace elements will be. In the course of leaching, the pH values of leaching liquors change and different trace elements are affected differently by the pH values.
Application of Seismic Anisotropy Caused by Fissures in Coal Seams to the Detection of Coal‐bed Methane Reservoirs
Authors: Mei LIU , Jingwei GOU , Guangming YU , Jiandong LIN
Published: September 2010

Coal‐bed methane is accumulated in micro‐fissures and cracks in coal seams. The coal seam is the source terrace and reservoir bed of the coal‐bed methane (Qian et al., 1996). Anisotropy of coal seams is caused by the existence of fissures. Based on the theory of S wave splitting: an S wave will be divided into two S waves with nearly orthogonal polarization directions when passing through anisotropic media, i.e. the fast S wave with its direction of propagation parallel to that of the fissure and slow S wave with the direction of propagation perpendicular to that of the fissure.

This paper gives the results of laboratory research and field test on the S wave splitting caused by coal‐seam fissures. The results show that it is feasible to detect fissures in coal seams by applying the converted S wave and finally gives the development zone and development direction of these fissures.
Alkaline Intrusives at the East Foot of the Taihang‐Da Hinggan Mountains: Chronology, Sr, Nd and Pb Isotopic Characteristics and Their Implications
Authors: Guohan YAN , Baoliang XU , Baolei MU , Guanyu WANG , Zhaoshan CHANG , Tingli CHEN , Yongchao ZHAO , Xiaofang WANG , Renhu ZHANG , Guangsheng QIAO , Zhuyin CHU
Published: September 2010

Based on the Rb‐Sr isochron dating results, this paper suggests that the alkaline intrusive belt at the east foot of the Taihang‐Da Hinggan Mountains were formed between 135 and 122 Ma. And the alkaline intrusives in the north and south sections of this belt have entirely different Sr, Nd and Pb isotopic characteristics, i.e., all the rocks in the south section have positive ɛSr(t) and negative ɛNd(t) values and all those in the north have the opposite values. On the ɛSr(t) versus ɛNd(t) correlation diagram, the samples from the south are concentrated along the enriched mantle evolution trend lines and nearby, while those from the north fall along the depleted mantle trend lines and nearby. On the Pb isotope composition diagram, most of the samples from the south section fall on the mantle Pb evolution line and nearby, while those from the north lie between the Pb evolution lines of the mantle and the orogenic belt. The above‐stated isotopic characteristics not only indicate that the source rocks of the alkaline intrusives in the south section have a close connection to materials from the enriched mantle reservoir, while those in the north are related to materials from the depleted one, but also reveal that the upper mantle below the North China platform is enriched and that below the Inner Mongolia geosyncline is depleted.
U‐Pb Zircon Dating of the Yeniutan Granitic Intrusion in the Western Sector of the North Qilian Mountains
Authors: Jingwen MAO , Zuoheng ZHANG , Ping JIAN , Zhiliang WANG , Jianmin YANG , Zhaochong ZHANG
Published: September 2010

Zircons from granodiorite and biotite granite in the Yeniutan granitic intrusion in the western North Qilian Mountains yielded a weighted mean 206Pb/238U apparent age of 460±3 Ma, suggesting that the intrusion originated during the late stage of plate subduction. Its related Ta'ergou and Xiaoliugou deposits are two of the few large tungsten deposits formed in the plate subduction environment in the world. The U‐Pb dating of the zircons from the biotite granite gave a discordant lower intercept age of 183±4 Ma, which implies that the Yanshanian event was probably superimposed on the North Qilian region.
Biostratigraphy of Triassic Marine Reptiles in Southwest Guizhou and Its Adjacent Area
Authors: Liting WANG , Jinling LI , Xinjin WANG , Chun LI , Tianzhuang WU , Jun LIU
Published: September 2010

Abstract  This paper briefly reviews the Triassic marine reptile fossils in Guizhou Province, especially the fossils that have been recently found in the Guanling area. Based on three sections at Guanling and Xingyi, Guizhou Province and Luoping, Yunnan Province, four horizons with vertebrate fossils are recognized in the Middle and Upper Triassic of this area; They are from bottom to top: Member I and Member II of the Guanling Formation, and the Zhuganpo Member and the Wayao Member of the Falang Formation.
Tectonic Evolution of the Junggar Foreland Basin in the Late Carboniferous‐Permian
Authors: Shuping CHEN , Yiwei ZHANG , Liangjie TANG , Guoping BAI
Published: September 2010

Abstract  A comprehensive study has been carried out to subdivide and correlate the Upper Carboniferous and Permian sedimentary successions in the Junggar basin based on outcrops and drilling and geophysical data. The study results, combined with geological analyses of the basin's periphery and the basement, as well as studies of the sedimentary rocks within the basin, the unconformities, tectonic geometry, kinematics and geodynamics, lead to the conclusion that the Junggar basin was characterized by the development of foreland basin systems during the Late Carboniferous and Permian. During that period, three foreland basin systems were developed: (1) the northwest foreland basin system, which trended nearly north‐south from Mahu to the Chepaizi Palaeo‐mountain during its early stage of development and thus it was also referred to as the west foreland basin system; (2) the Karamaili foreland basin system in the east and (3) the Northern Tianshan foreland basin system in the south. These systems are different in size, development stage and time of formation. The first two are developed earlier than the third, but they are smaller in size. All the structures in the Junggar basin have resulted from the integration and superposition of structural elements in the above three systems. In general, the development of the Junggar basin can be divided into four stages. Stage I was marked by the creation and evolution of the marginal western foreland and the peripheral Karamaili foreland basin systems during the Late Carboniferous‐early Early Permian (C3P1ja). Stage II was characterized by the development of complicated foreland basin systems during the middle‐late Early Permian (P1jb‐P1f) when the three foreland basin systems took their shapes. Stage III was the integration stage of peripheral foreland basin systems during the Middle Permian (P2) in which steady and slow tectonic subsidence prevailed. Stage IV coincided with the shrinking of foreland basin development during the Late Permian (P3).
The Lanshantou Kyanite‐bearing Eclogite with Coesite Inclusions in the Sulu Ultrahigh‐Pressure Metamorphic Belt and Its PTt Path
Authors: Shouxi HU , Jinggui SUN , Hongfei LING , Ying YE , Changquan Fang , Yiying ZHAO
Published: September 2010

Abstract  Coesite inclusions are found in kyanite from the Lanshantou eclogite in the Sulu ultrahigh‐pressure (UHP) metamorphic belt. This discovery extends the stable region of kyanite to over 2.4 GPa. As an important UHP metamorphic belt in China, the Sulu eclogite belt is the product of A‐subduction induced by strong compression of the Yellow Sea terrane to the Jiaodong‐northereastern Jiangsu terrane during the interaction of the Eurasian plate and Palaeo‐Pacific plate in the Indosinian. It stretches about 350 km and contains over 1000 eclogite bodies. Most eclogites in this belt belong to Groups B and C in the classification of Coleman et al., and commonly contain kyanite, while the Lanshantou eclogite belongs to Group A and contains coesite. The MgO, CaO and FeO contents in garnet and pyroxene show regular variation from the core to the rim, which reveals the PTt paths of progressive metamorphism during the Early Mesozoic (240‐200 Ma) and retrogressive metamorphism during the Late Mesozoic and Cenozoic exhumation.
Garnet‐bearing Granulite Facies Rock Xenoliths from Late Mesozoic Volcaniclastic Breccia, Xinyang, Henan Province
Authors: Jianping ZHENG , Min SUN , Fengxiang LU , Chunyang WANG , Zengqiu ZHONG , Xiling Zhu
Published: September 2010

Abstract  This paper presents the primary results of petrologic, mineralogical and petrochemical studies of garnet‐bearing granulite facies rock xenoliths from Xinyang, Henan Province. These xenoliths, which are found in a pipe of late Mesozoic volcaniclastic breccia, are of high density (3.13–3.30 g/cm3) and high seismic velocity (Vp = 7.04–7.31 km/s), being products of underplating of basaltic magmas and had experienced granulite facies metamorphism. The underplating and metamorphism took place before the eruption of the host rock. Petrographical studies and equilibrium T‐P calculations show that these xenoliths were captured at a 49 km depth and experienced at least a 16 km uplift before they were captured. The dynamics of the uplift could be related to the continent‐continent collision between the North China plate and the Yangtze plate during the Triassic.
Rock Series and Genetic Types of Granitoids in the Western Kunlun Orogenic Belt, China
Authors: Yaohui JIANG , Xunruo ZHOU , Xingjian RUI , Kunyi GUO , Jurui HE , Wanzhi YANG
Published: September 2010

A systematic geological and geochemical study was conducted for the granitoids of different periods in the western Kunlun orogenic belt. The study indicates that the granitoids belong to tholeiitic, calc‐alkaline, high‐K calc‐alkaline, alkaline and shoshonitic series, and that there are 5 genetic types, i.e., I‐, S‐, M‐, A‐ and SH‐type, of which SH‐type is first put forward in this paper, which corresponds to shoshonitic granitoids.
The Altun Fault: Its Geometry, Nature and Mode of Growth
Authors: Junwen CUI , Li LI , Jingsui YANG , Yongjun YUE , Pengwu LI , Jianxin ZHANG , Wen CHEN
Published: September 2010

The Altun (or Altyn Tagh) fault displays a geometry of overlapping of linear and arcuate segments and shows strong inhomogeneity in time and space. It is a gigantic fault system with complex mechanical behaviours including thrusting, sinistral strike slip and normal slip. The strike slip and normal slip mainly occurred in the Cretaceous—Cenozoic and Plio‐Quaternary respectively, whereas the thrusting was a deformation event that has played a dominant role since the late Palaeozoic (for a duration of about 305 Ma). The formation of the Altun fault was related to strong inhomogeneous deformation of the massifs on its two sides (in the hinterland of the Altun Mountains contractional deformation predominated and in the Qilian massif thrust propagation was dominant). The fault experienced a dynamic process of successive break‐up and connection of its segments and gradual propagation, which was synchronous with the development of an overstep thrust sequence in the Qilian massif and the uplift of the Qinghai‐Tibet plateau. With southward propagation of the thrust sequence and continued uplift of the plateau, the NE tip of the Altun fault moved in a NE direction, while the SW tip grew in a SW direction.
Thrusting and Exhumation Processes of a Bounding Mountain Belt: Constraints from Sediment Provenance Analysis of the Hefei Basin
Authors: Shaofeng LIU , Wencan LIU , Shaowu DAI , Siji HUANG , Wuyun LU
Published: September 2010

Lithic (or gravel) composition analyses of the Jurassic Sanjianpu Formation and Fenghuangtai Formation in the Hefei basin show that the sediment provenance consists mainly of four kinds of rock units: the basement metamorphic complex, granitic rocks, medium‐ and low‐grade metamorphic rocks, and sandy and muddy sedimentary rocks, which are distributed along the bounding thrust belt. The whole stratigraphic section can be divided into 2 lithic sequences and 7 subsequences. The regular distribution and changes of lithic fragments and gravels in lithic (or gravel) sequences reflect that the bounding thrust belt of basin has undergone 2 thrusting cycles and 7 thrusting events. Lithic (or gravel) composition analyses of the basin fully reveal that the northern Dabie basement metamorphic complex was exhumed on the earth's surface in the Middle and Late Jurassic, and extensive intermediate and acid intrusive rocks were developed in the southern North Huaiyang or northern Dabie Mountains during the basin's syndepositional stage.
Post‐Collisional Ductile Extensional Tectonic Framework in the UHP and HP Metamorphic Belts in the Dabie‐Sulu Region, China
Authors: Shutian SUO , Zengqiu ZHONG , Zhendong YOU , Zeming ZHANG
Published: September 2010

The present‐day observable tectonic framework of the ultrahigh‐pressure (UHP) and high‐pressure (HP) metamorphic belts in the Dabie‐Sulu region was dominantly formed by an extensional process, mostly between 200 and 170 Ma, following the Triassic collision between the Sino‐Korean and Yangtze cratons. The framework that controls the present spatial distribution of UHP and HP metamorphic rocks in particular displays the typical features of a Cordilleran‐type metamorphic core complex, in which at least four regional‐scale, shallow‐dipping detachment zones are recognized. Each of these detachment zones corresponds to a pressure gap of 0.5 to 2.0 GPa. The detachment zones separate the rocks exposed in the region into several petrotectonic units with different P‐T conditions. The geometry and kinematics of both the detachment zones and the petrotectonic units show that the exhumation of UHP and HP metamorphic rocks in the Dabie‐Sulu region was achieved, at least in part, by non‐coaxial ductile flow in the multi‐layered detachment zones, and by coaxial vertical shortening and horizontal stretching in the metamorphic units, under amphibolite‐ to greenschist‐facies conditions, and in an extensional regime. All ductile extensional deformations occurred at depths below 10 to 15 km, i.e. below the brittle/ductile deformation transition.
Oil Source and Entrapment Epoch of the Ordovician Oil Reservoir in the Kongxi Burial‐Hill Zone, Huanghua Depression, North China
Authors: Tieguan WANG , Feiyu WANG , Hong LU , Chiyin YANG , Qianjin LIAO , Jiansheng ZHOU
Published: September 2010

An oil flow obtained from the Middle Ordovician Fengfeng Formation carbonate reservoir in the well KG‐3, Kongxi burial‐hill zone in 1993 marked a breakthrough in petroleum exploration of the high‐mature Lower Palaeozoic strata, North China. Both the Lower member of the Fengfeng Formation and the Second Member of the Upper Majiagou Formation in the Middle Ordovician are supposed to be the main source beds. Oil generation peaks range from 1.0% to 1.6% in Ro, showing a “lag effect” of oil generation in high‐mature carbonate source rocks under multicyclic tectonic movement conditions. The Kongxi burial‐hill zone adjoins a potential Ordovician source kitchen. The KG‐3 Ordovician burial‐hill reservoir has undergone two oil filling events, i.e., an early event in the Late Carboniferous‐Permian and a more significant late event in the early Eogene.
Integrated P‐T Paths of the High‐Pressure Rocks and Their Tectonic Implications for the Mountain‐Building of the North Qilian, China
Authors: Wei‐Min CHEN , Young‐Ching HUANG , IIZUKA Yoshiyuki , Ching‐Hua LO , Hanquan WU , Shuguang SONG , Jingsui YANG , Zhiqin XU , Houng‐Yi YANG
Published: September 2010

Abstract  After the integration of petrographic study, geothermobarometry and Gibbs method, the synthetic P‐T paths for the rocks from different geological profiles in the North Qilian, China, have been derived. The composite P‐T paths from different methods indicate that all the high‐pressure rocks in the Qilian area recorded P‐T paths with clockwise loops starting at the blueschist facies, later reaching peak metamorphism at the blueschist facies, eclogite facies or epidote‐amphibolite facies and ending up with the greenschist facies. The incremental Ar‐Ar dating shows that the plateau ages for the high‐pressure rocks range from 410 to 443 Ma. The plateau ages could be used as a minimum age constraint for the subduction that resulted in the formation of these high‐pressure rocks in the Qilian area. It is proposed that the late‐stage decompressional and cooling P‐T paths with ends at the greenschist facies for these high‐pressure rocks probably reflect the uplift process which could occur after shifting the arc‐trench tectonic system to the system of continental orogenic belts. The retrograde paths for the high‐pressure rocks in the North Qilian tectonic belt are characterized by dramatic decompression with slight cooling, which suggests very rapid exhumation. Petrography supports that the mountain‐building for the Qilian mountain range could undergo a very fast process which caused rapid uplift and denudation.
Evolution of Chinese Neogene Rhinocerotidae and Its Response to Climatic Variations
Authors: Tao DENG , DOWNS W.
Published: September 2010

Abstract  Chinese Neogene Rhinocerotidae has quite a complete record and its temporal range is the Early Miocene to Late Pliocene. The samples include 25 species in 4 tribes of 2 subfamilies. They are used as a foundation for the study of the evolution of the family and its relation to climatic changes. Taxonomic diversity, new records and extinctions are estimated for each Chinese Neogene mammal faunal unit (NMU). The diversity of Chinese Rhinocerotidae varies noticeably throughout the Neogene and is recognized within five stages: the Middle Miocene and Late Miocene are stages of high diversity and the Early Miocene, early Late Miocene and Pliocene are stages of low diversity. Rhinocerotid diversity and morphology are closely related to environmental factors and particularly sensitive to changes in ambient temperature and humidity. The interpretation of climatic variation reflected in the evolution of Rhinocerotidae corresponds precisely with the conclusions drawn from other workers and provides new evidence for research on the Neogene terrestrial ecosystem in China.
Geochemical Constraints of Sediments on the Provenance, Depositional Environment and Tectonic Setting of the Songliao Prototype Basin
Authors: Quanren YAN , Shanling GAO , Zongqi WANG , Jiliang LI , Wenjiao XIAO , Quanling HOU , Zhen YAN , Haihong CHEN
Published: September 2010

Abstract  The geochemistry of sediments is primarily controlled by their provenances, and different tectonic settings have distinctive provenance characteristics and sedimentary processes. So, it is possible to discriminate provenances, depositional environments and tectonic settings in the development of a sedimentary basin with the geochemistry of the clastic rocks. The analytical results of the present paper demonstrate that sediments in the Songliao prototype basin are enriched in silica (SiO2=66.48–80.51%), and their ΣREE are 30–130 times of that of chondrite with remarkable Eu anomalies. In discriminating diagrams of Eu/Eu* vs ΣREE and (La/Yb)N vs ΣREE, most samples locate above the line Eu/ Eu*=1, on the right of the line Eu/Eu*/ΣREE=1 and under the line La/Yb)N/ΣREE=1/8, which indicates that the depositional environment of sediments in the basin was oxidizing. In addition, variations of MgO, TiO2, Al2O3, FeO+Fe2O3, Na2O and CaO vs SiO2 reflect a tendency of increasing mineral maturity of sediments in the basin. Analyses also show that the protolytes of the sediments in the basin were felsic igneous rocks, and the Songliao prototype basin was in a tectonic setting of an island arc on an active continental margin, with violent sinistral strike‐slip.
Ar‐Ar Dating on the Metallogenesis of the Dongchuang Gold Deposit in the Xiaoqinling Area
Authors: Qiangzhi LI , Yanjing CHEN , Zengqiu ZHONG , Wenliang LI , Shaoru LI , Xiaodong GUO , Baoyi JIN
Published: September 2010

Abstract  The Dongchuang gold deposit in the Xiaoqinling are is an orogenic‐type lode gold deposit. It is one of the few superlarge (>100 t Au) deposits in China. Although it has been argued that it was formed in the Mesozoic, related isotopic age data have not been reported in previous studies. Based on detailed geological study, the authors have carried out isotopic dating on various metallogenic generations. The ore‐forming process of the Dongchuang gold deposit consists of four stages: coarse‐grained pyrite‐bearing quartz veins (stage I), fine‐grained pyrite‐quartz veinlets (stage II), multi‐sulfides (stage III) and carbonate‐quartz veinlets (stage IV). Ar‐Ar dating on mineral separates of stages I, II and III yields plateau ages of 142.9±2.9 Ma, 132.2±2.6 Ma and 128.3±6.2 Ma, respectively. Sericite separates from stage II assemblage also yield an Ar‐Ar isochron age of 132.6±2.7 Ma, similar to the Ar‐Ar plateau age. These results suggest that the Dongchuang gold deposit was mainly formed during 143–128 Ma, coinciding with the authors' geological observations and previous hypothesis. This ore formation is coeval with the regional‐tectonic transition from collisional compression to extension, strongly showing that the decompression‐geothermal increase regime during compression‐to‐extension transition is the most conducive geodynamic environment to orogenic‐type gold mineralization.
Quantitative Modelling of Multiphase Lithospheric Stretching and Deep Thermal History of Some Tertiary Rift Basins in Eastern China
Authors: Changsong LIN , Yanmei ZHANG , Sitian LI , Jingyan LIU , Zhigang TONG , Xiaozhong DING , Xichen LI
Published: September 2010

The stretching process of some Tertiary rift basins in eastern China is characterized by multiphase rifting. A multiple instantaneous uniform stretching model is proposed in this paper to simulate the formation of the basins as the rifting process cannot be accurately described by a simple (one episode) stretching model. The study shows that the multiphase stretching model, combined with the back‐stripping technique, can be used to reconstruct the subsidence history and the stretching process of the lithosphere, and to evaluate the depth to the top of the asthenosphere and the deep thermal evolution of the basins. The calculated results obtained by applying the quantitative model to the episodic rifting process of the Tertiary Qiongdongnan and Yinggehai basins in the South China Sea are in agreement with geophysical data and geological observations. This provides a new method for quantitative evaluation of the geodynamic process of multiphase rifting occurring during the Tertiary in eastern China.
Hydrothermal Alteration Zoning and Kinetic Process of Mineral‐Water Interactions
Authors: Ronghua ZHANG , Shumin HU , Yanfeng SU
Published: September 2010

This study reports the kinetic experimental results of albite in water and in KCl solution at 22 MPa in the temperature range of 25 to 400°C. Kinetic experiments have been carried out in an open flow‐through reaction system (packed bed reactor). Albite dissolution is always incongruent in water at most temperatures, but becomes congruent at 300°C (close to the critical point 374°C). At temperatures from 25 to 300°C, the incongruent dissolution of albite is reflected by the fact that sodium and aluminum are easily dissolved into water, from 300 to 400°C it is reflected by silicon being more easily dissolved in water than Al and Na. Maximum albite dissolution rates in the flow hydrothermal systems have been repeatedly observed at 300°C, independent of flow rates.

The kinetic experiments of albite dissolution in a KCl aqueous solution (0.1 mol KCl) indicate that the dissolution rate of albite increases with increasing temperature. Maximum silicon release rates of albite have been observed at 400°C, while maximum aluminum release rates of albite at 374°C. The reaction rates of albite also depend on the potassium concentration in the aqueous solution.

These results can be used to interpret the mechanism for forming hydrothermal alteration. The kinetic experiments of mineral‐aqueous solutions interactions in the hydrothermal system from 25 to 400°C and at 22 MPa indicate that the formation of the feldspar‐mica‐kaolinite zoning occurring in some ore deposits may depend not only on the mineral stability but also on the kinetics of feldspar hydration, which is affected by the water property variation when crossing the critical point.
Multi‐collector ICP‐MS Analysis of Pb Isotope Ratios in Rocks: Data, Procedure and Caution
Authors: Huaikun LI , Yaoling NIU
Published: September 2010

Abstract  The authors measured Pb isotope compositions of seven USGS rock reference standards, i.e. AGV‐1, AGV‐2, BHVO‐1, BHVO‐2, BCR‐2, BIR‐1/1 and W‐2, together with NBS 981 using a micromass isoprobe multi‐collector inductively‐coupled plasma mass spectrometer (MC‐ICP‐MS) at the University of Queensland. 203T1‐205T1 isotopes were used as an internal standard to correct for mass‐dependant isotopic fractionation. The results for both NBS 981 and USGS rock standards AGV‐1 and BHVO‐1 are comparable to or better than double‐ and triple‐spike TIMS (thermal ionization mass spectrometry) data in precision. The data for BHVO‐2 and, to a lesser extent, AGV‐2 and BCR‐2 are reproducibly higher for 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb than double‐spike TIMS data in the literature. The authors also obtained the Pb isotope data for BIR‐1/1 and W‐2, which may be used as reference values in future studies. It is found that linear correction for Pb isotopic fractionation is adequate with the results identical to those corrected following an exponential law or a power law. Precise 207Pb/206Pb, 208Pb/206Pb and 208Pb/207Pb ratios can be acquired for sample solutions with Pb≥1 ppb. However, Pb isotope ratios involving 204Pb (i.e., 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb) are reliable for solutions with Pb≥40 ppb. The errors for Pb isotope ratio analysis using the MC‐ICP‐MS are dominated by errors in the analysis of 204Pb, which is commonly ascribed to the difficulty and imprecise correction for a 204Hg isobaric interference. It is found however that the major errors on 204Pb come from the tailings of mass 203T1 and mass 205T1. These mass tailings lead to over‐subtraction of the baseline for 204Pb, which is measured at ±0.5 amu on both sides of mass‐204 (i.e., at amu 203.5 and 204.5 respectively). Such errors are insignificant for Pb‐rich sample solutions (i.e., high Pb/T1 ratios), but can be severe for low‐Pb sample solutions when over‐“spiked” with T1. Experiments in this study suggest that a minimum concentration ratio of Pb/T1>5 in T1‐“spiked” solutions be required to ensure reliable 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb isotopic ratios. The tailings of 203T1 and 205T1 can also lead to over‐subtraction of baselines for 202Hg (at amu 202.5) and 206Pb (at amu 205.5). Therefore, the elegance of using 203T1 and 205T1 isotopes for mass fractionation correction becomes a severe problem in low‐Pb rock solutions—caution is required. Alternative internal standards for mass fractionation correction may be considered. Of course, significant instrumental refinement in abundance sensitivity is in demand.
Active Motion of Tectonic Blocks in East Asia: Evidence from GPS Measurement
Authors: Shuanggen JIN , Wenyao ZHU
Published: September 2010

Abstract  The relative Euler vectors of the Pacific, Philippine, Amurian, Okhotsk, N. Honshu and South China plates or blocks are deduced from earthquake slip vectors, transform fault azimuths and spreading rates, which are consistent with new results derived from the International Terrestrial Reference Frame ITRF2000 velocity field, the velocity field of GPS stations in China and the GPS measurement data of the GEONET network in Japan. Based on the two groups of Euler vectors, analysis and comparative study of the relative motions and deformations of the tectonic blocks in East Asia reveal the present‐day motion characteristics of the blocks.
Organic Gases in Fluid Inclusions of Ore Minerals and Their Constraints on Ore Genesis: A Case Study of the Changkeng Au‐Ag Deposit, Guangdong, China
Authors: Xiaoming SUN , NORMAN David I. , Kai SUN , Binghui CHEN , Jingde CHEN
Published: September 2010

Abstract  The newly discovered Changkeng Au‐Ag deposit is a new type of sediment‐hosted precious metal deposit. Most of the previous researchers believed that the deposit was formed by meteoric water convection. By using a high vacuum quadrupole gas mass spectrometric system, nine light hydrocarbons have been recognized in the fluid inclusions in ore minerals collected from the Changkeng deposit. The hydrocarbons are composed mainly of saturated alkanes C1–4 and unsaturated alkenes C2–4 and aromatic hydrocarbons, in which the alkanes are predominant, while the contents of alkenes and aromatic hydrocarbons are very low. The σalka/σalke ratio of most samples is higher than 100, suggesting that those hydrocarbons are mainly generated by pyrolysis of kerogens in sedimentary rocks caused by water‐rock interactions at medium‐low temperatures, and the metallogenic processes might have not been affected by magmatic activity. A thermodynamic calculation shows that the light hydrocarbons have reached chemical equilibrium at temperatures higher than 200°C, and they may have been generated in the deep part of sedimentary basins (e.g., the Sanzhou basin) and then be transported by ore‐forming fluids to a shallow position of the basin via a long distance. Most of the organic gases are generated by pyrolysis of the type II kerogens (kukersite) in sedimentary host rocks, only a few by microorganism activity. The compositions and various parameters of light hydrocarbons in gold ores are quite similar to those in silver ores, suggesting that the gold and silver ores may have similar metallogenic processes. Based on the compositions of organic gases in fluid inclusions, the authors infer that the Changkeng deposit may be of a tectonic setting of continental rift. The results of this study support from one aspect the authors' opinion that the Changkeng deposit is not formed by meteoric water convection, and that its genesis has a close relationship with the evolution of the Sanzhou basin, so it belongs to the sedimentary hot brine transformed deposit.
Geochemical Characteristics and Origin of Natural Gases in the Qaidam Basin, China
Authors: Xiaobao ZHANG , Yong HU , Yi DUAN , Liyuan MA , Zifang MENG , Peng HE , Shixin ZHOU , Dehua PENG
Published: September 2010

Abstract  Sixty‐five natural gas samples were collected from 19 oil‐gasfields in the Qaidam basin, China. The chemical composition and carbon isotope values of the samples were measured, and the geochemical characteristics and origin of the natural gases were studied. The gases can be divided into biogenic gases, sapropelic oil‐type gases, mixed type oil‐type gases, coal‐type gases and mixed gas. The δ13C1 values of the biogenic gases are very small and the C2+ contents of them are very low, ranging from −68.2± to −61.8± and 0.06% to 0.20% respectively. They have heavy δD and δ13Cco2. showing a CO2 reduction pathway. They are distributed in the East depression region and derived from the Quaternary source rocks. The sapropelic oil‐type gases have small δ13C2 values and high C2+ ranging from −36.6± to −28.6± and from 33.01% to 47.15% respectively. The mixed type oil‐type gases have δ13C2 values and C2+ contents varying from −28.6± to −24.8± and from 4.81% to 26.06% respectively. Both sapropelic oil‐type gases and mixed type oil‐type gases are associated with oil‐type oils, distributed in the West depression region and derived from the Tertiary saltwater lacustrine sapropelic source rocks and humic source rocks respectively. The δ13C2 values of the coal‐type gases are extremely high and the C2+ contents are very low, changing from −23.3± to −12.5± and from 0.06% to 18.07% respectively. The coal‐type gases in the Nanbaxian gasfield and the Lenghu oil‐gasfields in the North fault block belt are derived from the Middle Jurassic coal‐measures source rocks, whereas those in the West depression region are derived from the Tertiary saltwater lacustrine humic source rocks. Compared with some other basins in China, the natural gases there have obviously heavier δ13C due to the heavier δ13C of different types of kerogens of the Tertiary saltwater lacustrine source rocks in the West depression region of the basin. The mixing of natural gases is common in the West depression region, but the mixed gases are formed by sapropelic oil‐type gases, mixed type oil‐type gases or coal‐type gases, respectively, of different levels of maturity. Most of the sapropelic oil‐type gases and mixed type oil‐type gases in the west part are thermally immature and low‐mature, but the coal‐type gases in the West depression region and the North fault block belt are mature and high‐ to over‐mature.