bluuebunny/crossref_metadata_2025 huggingface dataset:
Geotectonic Settings of Large and Superlarge Mineral Deposits on the Southwestern Margin of the North China Plate
Authors: Zhongli TANG , Yunlai BAI , Zhilin LI
Published: September 2010

The geotectonic setting refers to the three‐dimensional space and related events based on which a metallogenic system is formed and an ore‐forming process takes place. This paper discusses the tectonic evolution of the southwestern margin of the North China paleocontinent and related geotectonic settings in which large or superlarge deposits are formed. Emphasis is put on the geodynamic conditions of the Jinchuan nickel‐copper deposit, the Baiyin copper‐polymetallic deposit and the Hanshan gold deposit. It is significant that the three deposits occur together as a “trinity” on the same paleocontinental margin. The Jinchuan nickel‐copper deposit was formed during the early stage of rifting of the paleocontinental margin; the Baiyin copper‐polymetallic deposit was formed during the splitting stage of a continental‐margin arc. The continental‐margin arc spitting resulted in an “island arc rift” in the early stage of evolution. The Hanshan gold deposit was formed within the Altun sinistral strike‐slip fault system and its provenance is the “intraoceanic arc” volcanic rocks.
A New Genus of Psittacosauridae (Dinosauria: Ornithopoda) and the Origin and Early Evolution of Marginocephalian Dinosaurs
Authors: Hailu YOU , Xing XU , Xiaolin WANG
Published: September 2010

Abstract  An almost complete juvenile dinosaur skull with lower jaw was discovered from the Early Cretaceous Yixian Formation in Beipiao, Liaoning Province, China. Here, the specimen is described and a cladistic analysis is performed in order to find its phylogenetic relationships. The result shows that this specimen represents a new genus of Psittacosauridae, Hongshanosaurus houi, gen. et sp. nov., and confirms the monophyletic status for Ceratopsia and Marginocephalia. However, Heterodontosaurus is found to be the sister taxon to Marginocephalia, rather than a basal Ornithopoda.
Contrast in Fluid Metallogeny between the Tianmashan Au‐S Deposit and the Datuanshan Cu Deposit in Tongling, Anhui Province
Authors: Yangsong DU , Shihong TIAN , Xuejun LI , Koo LEE Hyun
Published: September 2010

Abstract  A comprehensive contrast of ore‐forming geological background and ore‐forming fluid features, especially fluid ore‐forming processes, has been performed between the Tianmashan and the Datuanshan ore deposits in Tongling, Anhui Province. The major reasons for the formation of the stratabound skarn Au‐S ore deposit in Tianmashan and the stratabound skarn Cu ore deposit in Datuanshan are analyzed in accordance with this contrast. The magmatic pluton in Tianmashan is rich in Au and poor in Cu, but that in Datuanshan is rich in Cu and Au. The wallrock strata in Tianmashan contain Au‐bearing pyrite layers with some organic substance but those in Datuanshan contain no such layers. Moreover, the ore‐forming fluids in Tianmashan are dominantly magmatic ones at the oxide and sulfide stages, but those with high content of Cu in Datuanshan are mainly groundwater fluids. In addition, differences in compositional evolution and physicochemical condition variation of the ore‐forming fluids result in gradual dispersion of Cu or Au in the late stage of the fluid ore‐forming process. This is also an important metallogenic factor for the stratabound skarn Au‐S ore deposit in Tianmashan and stratabound skarn Cu ore deposit in Datuanshan.
First Record of Protorosaurid Reptile (Order Protorosauria) from the Middle Triassic of China
Authors: Chun LI
Published: September 2010

Abstract  A new genus and species of the family Tanystropheidae, Dinocephalosaurus orientalis gen. et sp. nov., is described based on a nearly complete skull. This is the first record of the order Protorosauria from China. It also represents the only known occurrence of Tanystropheidae outside Europe, the Middle East and North America. Dinocephalosaurus is quite similar to Tanystropheus from Monte San Giorgio, Switzerland. Primarily it is distinguished from Tanystropheus in the shape of the premaxilla, maxilla, jugal and parietal. Although the family Tanystropheidae is now referred to the order Protorosauria, the new material from China indicates that the archosauromorph affinities of tanystropheids need further investigation. The discovery of Dinocephalosaurus provides new clues for the study of the evolution and radiation of Protorosauria and Tanystropheidae. It is also important for the study of the eastern Tethyan Fauna and the paleobiogeographical relationship between Europe and southern China in the Triassic.
Polyphase Tectonic Events and Cenozoic Basin‐Range Coupling in the Tianshan Belt, Northwestern China
Authors: Liangshu SHU , Bo WANG , Fan YANG , Huafu LU , CHARVET J. , LAURENT‐CHARVET S.
Published: September 2010

Abstract  Studies show that the Tianshan orogenic belt was built in the late stage of the Paleozoic, as evidenced by the Permian red molasses and foreland basins, which are distributed in parallel with the Tianshan belt, indicating that an intense folding and uplifting event took place. During the Triassic, this orogenic belt was strongly eroded, and basins were further developed. Starting from the Jurassic, a within‐plate regional extension occurred, forming a series of Jurassic‐Paleogene extensional basins in the peneplaned Tianshan region. Since the Neogene, a collision event between the Indian and the Eurasian plates that took place on the southern side of the Tianshan belt has caused a strong intra‐continental orogeny, which is characterized by thrusting and folding. Extremely thick coarse conglomerate and sandy conglomerate of the Xiyu Formation of Neogene System were accumulated unconformably on the Tianshan piedmont. Studies have revealed that the strong compression caused by the Indian‐Eurasian collision had a profound influence over the orogenic belt in the hinterland, and Mesozoic‐Cenozoic brittle deformed structures superposed on the ductile deformed Paleozoic rocks. The Mesozoic extensional basins were converted into Cenozoic compressional basins. The deformation in the basins is featured by step thrusts and fault‐related folds. Statistics of joints show that the principal compressive stress since the Neogene is in a N‐S direction. Meanwhile, owing to the underthrusting of the basin toward the orogenic belt, the Paleozoic strata were thrust on the Meso‐Cenozoic rocks as tectonic slices, revealing distinct kinematic features in different geologic units. The basin‐range coupling zones are characterized by intensive compression, folding and thrusting, accompanied by local sub‐E‐W‐trending strike‐slip faults. In the Tianshan region, Cenozoic thrusting is the most common basin‐range coupling mode. The folding and faulting of Mesozoic sedimentary rocks, spontaneous combustion of Jurassic coal layers and formation of sintered rocks, the Cenozoic earthquakes and active faulting, and the unique mosaic pattern of basin‐range framework of Xinjiang are all products of tectonism since the Neogene.
Thrust Propagation in the Aqqikkol Lake Area, the East Kunlun Mountains, Northwestern China
Authors: Junwen CUI , Wen CHEN , Pengwu LI , Xiaowei ZHANG , Li LI
Published: September 2010

Abstract  The western segment of the East Kunlun Mountains is one of the poorly studied regions in northwestern China. Through a structural analysis of the typical sections, we have the following views: (1) There is a very well developed fault system in the western segment of the East Kunlun Mountains and thrust propagation, normal slip and decoupling are the chief deformation events in this area. (2) Although the thrusting started in the Late Carboniferous and Late Triassic‐Early Jurassic, strong activity took place in the Miocene‐Quaternary when the Kumkol basin was strongly downwarped. (3) The tectonic pattern of coexistence of N‐directed thrust propagation and S‐directed normal slip in this area is consistent with the general tectonic pattern of the northern Qinghai‐Tibet plateau and also very similar to that of the Himalayan region on the southern margin of the Qinghai‐Tibet plateau, but their directions between the thrust propagation are opposite and all the strong thrust propagations occurred from the Miocene‐Pliocene to Quaternary, a period featuring strong collision between the Indian plate and the Eurasian plate and abrupt uplift of the Qinghai‐Tibet plateau. This oppositely directed thrust propagation and normal slip reveal such kinematic characteristics as symmetric propagations of deep‐seated materials towards the north and south beneath the Qinghai‐Tibet plateau and gravitational sliding of superficial materials towards the interior of the plateau. Therefore, the establishment of the fault system in the study area may provide an approach to the study of deep processes of the northern Qinghai‐Tibet plateau and the construction of a unified geodynamic model for the uplift of the Qinghai‐Tibet plateau.
Paleoclimate Changes during the Early Oligocene in the Hoh Xil Region, Northern Tibetan Plateau
Authors: Zhifei LIU , Chengshan WANG , TRENTESAUX Alain , Xixi ZHAO , Haisheng YI , Xiumian HU , Wei JIN
Published: September 2010

Abstract  Sedimentological, cyclic‐stratigraphic, paleomagnetic, and clay‐mineralogical studies on the early Oligocene Yaxicuo Group in the Hoh Xil Basin, the largest Cenozoic sedimentary basin in the hinterland of the Tibetan Plateau, provide abundant information of paleoclimate changes. A 350‐m thick section in the middle‐lower Yaxicuo Group was analyzed to reveal the climatic history that occurred in the Hoh Xil region during the early Oligocene interval 31.30‐30.35 Ma, dated with the paleomagnetic chronostratigraphy. The results indicate that arid and cold climate dominated the Hoh Xil region during the early Oligocene in general, being related to the global cooling and drying events that occurred in the earliest Oligocene. Within this period, relatively warm and wet climate accompanied by strong tectonic activity occurred in the 31.05–30.75 Ma interval; while arid and cold climate and relatively inactive tectonics occurred in the 31.30–31.05 and 30.75‐30.35 Ma intervals. Furthermore, spectral analyses of high‐temporal resolution paleoclimatic records show orbital periods including eccentricity, obliquity, and precession. It is concluded that paleoclimate changes during the early Oligocene in the Hoh Xil region were forced by both tectonic activity and orbital periods.
A New Hadrosauroid Dinosaur from the Mid‐Cretaceous of Liaoning, China
Authors: Hailu YOU , Qiang JI , Jinglu LI , Yinxian LI
Published: September 2010

Abstract A new hadrosauroid dinosaur, Shuangmiaosaurus gilmorei gen. et sp. nov., is described based on a complete left maxilla with articulated premaxilla and lacrimal fragments, and a complete left dentary from the mid‐Cretaceous Sunjiawan Formation of Beipiao, Liaoning, northeastern China. Cladistic analysis shows that Shuangmiaosaurus is a basal hadrosauroid, and comprises the sister taxon to Hadrosauridae. In both Shuangmiaosaurus and Hadrosauridae, the maxilla‐jugal suture is butt‐jointed, rather than finger‐in‐recess articulation as in other basal hadrosauroids. However, Shuangmiaosaurus does not possess such hadrosaurid synapomorphies as the diamond‐shaped maxillary crowns with reduced primary ridges and reduced marginal denticles.
Cobalt Deposits of China: Classification, Distribution and Major Advances
Authors: Chengyou FENG , Dequan ZHANG
Published: September 2010

Abstract  The important strategic metal cobalt has diverse uses and the majority of world cobalt deposits have been found in China. The deposits can be classified into four types, i.e., magmatic Ni‐Cu‐Co sulfide deposits, hydrothermal and volcanogenic cobalt polymetallic deposits, strata‐bound Cu‐Co deposits hosted by sedimentary rocks and lateritic Ni‐Co deposits, of which the former two types are the most important. There are six principal metallogenic epochs and seven important metallogenic belts according to their distribution and tectonic position. Although cobalt generally occurs in nickel‐copper, copper and iron deposits as an associated metal, great developments in exploration for independent cobalt deposits have happened in China, and, in recent years, many independent deposits with different elementary assemblages and different genetic types have been discovered in the eastern part of the northern margin of the North China platform, the Central Orogenic Belt of China, western Jiangxi and northeastern Hunan. In addition, it is inferred that the Kunlun‐Qinling Orogenic Belt has great potential for further exploration of new types of independent cobalt deposits.
Control of Deep Tectonics on the Superlarge Deposits in China
Authors: Liqiang YANG , Jun DENG , Jianguo WANG , Yanguang WEI , Jianping WANG , Qinfei WANG , Ping LU
Published: September 2010

Abstract  Seventy‐three large‐superlarge deposits in China were formed in 4 metallogenic epochs, and located in 6 metallogenic domains. By combing their time‐space distribution and the relevant data of crustal thickness, we discuss the control conditions of deep tectonics on superlarge deposits. The various spatial variation of the crustal thickness where deposits locate is closely related to their different tectonic setting. The crustal thickness of the region where deposits are in the Precambrian metallogenic epoch is 37.1 km and shows double‐peak distribution, which is related to the different tectonic‐mineralization processes in the Tarim‐North China and Yangtze metallogenic domains. The crustal thickness of the region where deposits are in the Paleoproterozoic metallogenic epoch is 43.4 km and shows normal distribution, which is the result of “pure” mineralization setting. The crustal thickness of the region where deposits are in the Late Palaeozoic‐Early Mesozoic metallogenic epoch is about 41.2 km and shows multi‐peak distribution, which can be related with dispersing distribution in the metallogenic domain of these superlarge deposits. The crustal thickness of the region where deposits are in the post‐Indosinian metallogenic epoch is 37.3 km, and shows skew distribution, which resulted from different tectonic settings in eastern and western China.
REE Characteristics of the Kalatongke Cu‐Ni Deposit, Xinjiang, China
Authors: Yuwang WANG , Jingbin WANG , Lijuan WANG , Yong WANG , Caineng TU
Published: September 2010

Abstract  On the basis of the study on the REE geochemistry of the ore minerals and host rocks of the Kalatongke Cu‐Ni deposit, Xinjiang, it is indicated that the major ore minerals, sulfides, were sourced from the host mafic‐ultramafic magma. Characterized by low REE content of sulfide, such a Cu‐Ni sulfide deposit occurring in the orogen is obviously different from that on the margin of the craton. Because the mafic‐ultramafic rocks from the Cu‐Ni sulfide deposit occurring in the orogen is water‐rich and the REEs of some sulfides show a particular “multiple‐bending” pattern, which suggests coexistence of multiple liquid phases (fluid and melt), the sulfide melt possibly contains a great deal of hydrothermal fluids and increasingly developed gases and liquid‐rich ore‐forming fluids after the main metallogenic epoch (magmatic segregation stage).
Geological Characteristics of the Furong Tin Orefield, Hunan, 40Ar‐39Ar Dating of Tin Ores and Related Granite and Its Geodynamic Significance for Rock and Ore Formation
Authors: Jingwen MAO , Xiaofeng LI , Wen CHEN , Xiaoming LAN , Shaoliu WEI
Published: September 2010

Abstract  Furong, Hunan, is a large tin orefield discovered in China in recent years, which is mainly of the skarn‐greisen‐chlorite type. On the basis of the geological characteristics of the orefield, 40Ar‐39Ar dating was performed on muscovite from greisen‐type tin ore and biotite from related amphibole‐biotite granite, which yielded three sets of age data, i.e., a plateau age of 157.5±0.3 Ma and an isochron age of 156.9±3 Ma for amphibole‐biotite granite; a plateau age of 156.1±0.4 Ma and an isochron age of 155.7±1.7 Ma for the Sanmen greisen‐type tin ore; and a plateau age of 160.1±0.9 Ma and an isochron age of 157.5±1.5 Ma for the Taoxiwo greisen‐type tin ore. The three sets of age data coincide well with each other. They not only accurately reflect the timing of rock and ore formation but also indicate close relations between granite and tin deposits. In addition, the plateau ages of all three sets suggest that no subsequent thermal perturbation event occurred after the formation of granite and tin deposits. The Furong tin orefield is a component part of the southern Hunan large tungsten‐tin polymetallic deposit concentration area and also a representative deposit formed in the time interval of 160–135 Ma in four peaks of Mesozoic tungsten‐tin mineralization in the South China region. They might still correspond to the middle and late stages of the major geodynamic transition from a N‐S‐ to an E‐W‐direction in eastern China.
Genesis of the Xinqiao Gold‐Sulfide Orefield, Anhui Province, China
Authors: Wenshuan ZANG , Ganguo WU , Da ZHANG , Jinwen LI , Xiangxin ZHANG , Aihua LIU , Zhongyi ZHANG
Published: September 2010

Abstract  The Xinqiao S‐Fe‐Cu‐Au orefield is located in the Tongling ore cluster in the middle and lower reaches of the Yangtze River in East China. There have been many researches regarding the genesis of the Xinqiao orefield in recent years, showing that it belongs to various types, such as sedimentary‐reformed type, stratabound‐skarn type, sedimentary submarine rocks‐hosted exhalative type. We propose that it was formed in two periods of mineralization base on systematic field observation and Pb and S isotopic analyses in nearly ten years. The first period was formed during a syngenetic sedimentary process, whereas the massive sulphide orebodies are mainly related to the Yanshanian granitic magmatism. Sulfide metallic mineral associations show zoning around a granite intrusion, i.e. magnetite and pyrite → pyrite, chalcopyrite and native gold→pyrite, sphalerite and galena. Gold orebodies occur outside the contact zone of the granite intrusion.
Geochemistry, Geochronology and Genesis of Gold Mineralization in Nurt of Northern Altay, Xinjiang: A Case Study on the Aketishikan Gold Deposit
Authors: Feng YUAN , Taofa ZHOU , Lugui TAN , Xianrong LUO , Shucang YUE
Published: September 2010

Abstract  Gold deposits such as the Aketishikan, Togetobie, Tasbig‐Kokeydlas, Kums and Hongshanzui gold deposits in the Nurt area in Altay of Xinjiang were found in Member 3 rhyolite tufflava, fragmental lava and ignimbrite of the Carboniferous Hongshanzui Group. Trace and rare earth elements, sulfur, lead, oxygen and hydrogen isotopes, and geochronological studies indicate that the ore‐forming material was mostly supplied by the Carboniferous volcanic rocks through water‐rock interaction under a low‐to‐moderate temperature, and the hydrothermal ore‐forming fluid came from meteoric water with some magmatic water input evolved from the granitic magmas. Gold deposits in the Nurt area as well as in the northern Altay might form in multiple stages, and the Yanshanian mineralization period should be paid more attention besides the Variscan mineralization period.
Characteristics of the Composite Metallogenic System along the Jilin Paleocontinental Margin and the Evolution of Continental Dynamic Regimes
Authors: Zhongshi SUN , Yanguo JIANG , Jun DENG , Yingfang CHE , Jianping WANG
Published: September 2010

Abstract  In view of the existing problems about the metallogenic epoch and origin of the complex along the Jilin paleocontinental margin, we propose the composite metallogenic system of the Jilin old land, based on the theory of metallogeny and from the continental dynamics and comprehensive analysis on the metallogenic characteristics. Its scientific theory is demonstrated by the following aspects: (1) Screening and analysis of the multi‐stage superimposition and sequences. The composite ore‐forming system consists mainly of three types: the divergent‐type epicontinental metallogenic system on the southern margin, the convergent‐type epicontinental metallogenic system on the northern margin and the strike‐slip‐type epicontinental metallogenic system on the northeastern margin. Their major metallogenic epochs are Archean‐Proterozoic, Variscan and Yanshanian respectively. (2) Comprehensive analysis of the genetic relations of the complicated deposits. The above‐mentioned three types all indicate a consanguinity among granites, vein rocks and gold deposits, correspondence with geochemical elements, and unicity showing the same activities of mantlederived fluids and multi‐source origin of ore‐forming substances. (3) As to the mechanisms for mineral concentration, in addition to the sources, we also focus on the co‐actions of permeability, vibration, gas‐liquid state alternation and abrupt changes of flow velocity during the movement of ore‐forming liquids, as well as the extraction and communication of multi‐sequence circulating liquids. (4) It is helpful for establishing the relationship between metallogeny and the evolution of continental dynamic regimes, i.e., the ore‐controlling correlations between the ore‐forming elements‐metallogenic series‐metallogenic systems‐composite metallogenic system and ore‐controlling structural features (stratabound, primary and branching types)‐regional faulting or secondary continental extension and collision‐transformation of different continental dynamic types (divergent, convergent and strike‐slip)‐the evolution process of the whole old land for the Jilin old land margin. All these are helpful for further researches on the continental metallogenic dynamics.
Fluid Inclusions of Calcite and Sources of Ore‐forming Fluids in the Huize Zn‐Pb‐(Ag‐Ge) District, Yunnan, China
Authors: Runsheng HAN , Congqiang LIU , Zhilong HUANG , Deyun MA , Yuan LI , Bin HU , Gengsheng MA , Li LEI
Published: September 2010

Abstract  The Huize Zn‐Pb‐ (Ag‐Ge) district is a typical representative of the well‐known medium‐to large‐sized carbonate‐hosted Zn‐Pb‐ (Ag‐Ge) deposits, occurring in the Sichuan‐Yunnan‐Guizhou Pb‐Zn Ore‐forming Zone. Generally, fluid inclusions within calcite, one of the major gangue minerals, are dominated by two kinds of small (1–10 μm) inclusions including pure‐liquid and liquid. The inclusions exist in concentrated groups along the crystal planes of the calcite. The ore‐forming fluids containing Pb and Zn, which belong to the Na+‐K+‐Ca2+‐Cl−‐F− ‐ SO2‐4 type, are characterized by temperatures of 164–221°C, medium salinity in 5–10.8 wt% NaCl, and medium pressure at 410times105 to 661times105 Pa. The contents of Na+‐K+ and Cl−‐F−, and ratios of Na+/K+‐Cl−/F− in fluid inclusions present good linearity. The ratios of Na+/K+ (4.66–6.71) and Cl−/F− (18.21–31.04) in the fluid inclusions of calcite are relatively high, while those of Na+/K+ (0.29–5.69) and Cl−/F− (5.00–26.0) in the inclusions of sphalerite and pyrite are relatively low. The ratio of Na+/K+ increases in accord with those of Cl−/F−, which indicates that ore‐forming fluid of deep source participates in the mineralization. The waters of fluid inclusions have δD values from −43.5‰ to −55.4‰ of calcite. The δ18OV‐SMOW values of the ore‐forming fluids, calculated values, range from 17.09‰ to 18.56‰ of calcite and 17.80‰ to 23.14‰ for dolomite. δ3CV‐PDB values range from −1.94‰ to −3.31‰ for calcite and −3.35‰ to 0.85‰ for the ore‐bearing dolomite. These data better demonstrate that the ore‐forming fluids were mainly derived from metamorphic water and magmatic hot fluid, in relation to the metamorphism of the Kunyang Group in the basement and magmatic hydrothermalism. The deposit itself might have resulted from ascending cycles of ore‐forming fluid, enriched in Pb and Zn. The Huize Zn‐Pb‐ (Ag‐Ge) deposits related to carbonate‐hosted Zn‐Pb sulphides.
Metallogenic Systems on the Paleocontinental Margin of the North China Craton
Authors: Yusheng ZHAI , Jun DENG , Zhongli TANG , Rongge XIAO , Honglin SONG , Runmin PENG , Zhongshi SUN , Jianping WANG
Published: September 2010

Abstract  The North China Craton (NCC) is one of the largest blocks composing the continent. Different types of continental margins well developed around the NCC, along with lots of metallogenic systems of different metals and different times. Based on the study on the structural evolution of the NCC, the authors made a new division of tectonic units of the NCC. Through an analysis of the data of 1:25000 geochemical survey on stream sediments, regional geochemical features of main ore‐forming elements including Au, Ag, Cu, Pb, Zn, W, Ni, Co and Mo of the NCC are discussed in the paper. Then different metallogenic systems and their forming processes and geodynamics are discussed in detail. At last, temporal and spatial distribution regularities are summarized and ten favorable ore‐control factors on the paleocontinental margins are put forward, including (1) abundance of ore sources; (2) rendezvous of ore‐forming fluids; (3) high thermo‐dynamic anomaly; (4) remarkable Earth crust‐mantle interaction; (5) cluster of macroscopic structures and their long activities; (6) diversity of ore‐forming environments; (7) long geohistory; (8) multiforms of critical transitional ore‐forming mechanisms; (9) multi‐staged and superimposed ore‐formation; and (10) suitable preservation condition.
Quantitative Assessment of Hydrocarbon Expulsion of Petroleum Systems in the Niuzhuang Sag, Bohai Bay Basin, East China
Authors: Xiongqi PANG , Sumei LI , Zhijun JIN , Guoping BAI
Published: September 2010

Abstract  Based on a detailed survey of the distribution and organic geochemical characteristics of potential source rocks in the South Slope of the Niuzhuang Sag, Bohai Bay Basin, eastern China, a new approach to assess the amount of hydrocarbons generated and expelled has been developed. The approach is applicable to evaluate hydrocarbons with different genetic mechanisms. The results show that the models for hydrocarbon generation and expulsion vary with potential source rocks, depending on thermal maturity, types of organic matter and paleoenvironment. Hydrocarbons are mostly generated and expelled from source rocks within the normal oil window. It was calculated that the special interval (algal‐rich shales of the Es4 member formed in brackish environments) in the South Slope of the Niuzhuang Sag has a much higher potential of immature oil generation than the other intervals in the area. This suggests that hydrocarbons can definitely be generated in early diagenesis, especially under certain special geological settings. The proportion of hydrocarbons generated and expelled from the Es4 shales in the early diagenetic stage is up to 26.75% and 17.36%, respectively. It was also observed that laminated shales have a much higher expulsion efficiency than massive mudstones. In contrast, the special interval of the Es4 shales proposed from previous studies is probably not the whole rock for oil in the South Slope of the Niuzhuang Sag because of the small proportion of the gross volume and corresponding low percentage of hydrocarbons generated and expelled. A much lower expulsion efficiency of the source rock during the early stage relative to that within the normal oil window has been calculated. Our results indicate that the Es4 mudstones rather than the shales deposited in the Niuzhuang and Guangli Sag are the main source rocks for the oil discovered.
Late‐stage Hydrocarbon Accumulation in the Bozhong Depression of the Bohai Bay Basin as Controlled by Neotectonism
Authors: Zaisheng GONG , Gongcheng ZHANG , Dongsheng CAI , Shibin HE
Published: September 2010

Abstract  Neotectonism occurred intensively in the Bozhong depression in the Bohai Bay Basin, which was reflected vertically by dramatic subsidence and a number of uplifts and laterally by notable fault movements. This particularity has resulted in the special petroleum geological conditions of the Bozhong depression which are different from those of adjacent lands. For example, the source rocks of the Shahejie Formation were overpressured and hydrocarbon generation occurred in the late stage; the Dongying Formation was deeply buried below the hydrocarbon‐generating threshold, therefore there were sufficient oil sources. The rapid subsidence led to starved sedimentation of the Guantao Formation fine sandstone and the regional Minghuazhen Formation lacustrine shale, which formed the Neogene regional reservoir‐caprock association. The active faults formed in the neotectonism became passages for oil to migrate from the Paleogene to Neogene. The traps formed by late fault activity and accompanied anticlines provided spaces for the formation of reservoirs. All the above factors match well with one another in the Bozhong depression, providing favorable conditions for the formation of a series of large oilfields in the region
Ordovician Basement Hydrocarbon Reservoirs in the Tarim Basin, China
Authors: Xiangbin YAN , Tiejun LI , Tao ZHANG
Published: September 2010

Abstract  Ordovician marine carbonate basement traps are widely developed in the paleo‐highs and paleo‐slopes in the Tarim Basin. Reservoirs are mainly altered pore‐cavity‐fissure reservoirs. Oil sources are marine carbonate rocks of the Lower Paleozoic. Thus, the paleo‐highs and paleo‐slopes have good reservoiring conditions and they are the main areas to explore giant and large‐scale oil reservoirs. The main factors for their reservoiring are: (1) Effective combination of fenestral pore‐cavity‐fracture reservoirs, resulting from multi‐stage, multi‐cyclic karstification (paleo‐hypergene and deep buried) and fracturing, with effective overlying seals, especially mudstone and gypsum mudstone in the Carboniferous Bachu Formation, is essential to hydrocarbon reservoiring and high and stable production; (2) Long‐term inherited large rises and multi‐stage fracture systems confine the development range of karst reservoirs and control hydrocarbon migration, accumulation and reservoiring; (3) Long‐term multi‐source hydrocarbon supply, early reservoiring alteration and late charging adjustment are important reservoiring mechanisms and determine the resource structure and oil and gas properties. Favorable areas for exploration of Ordovician carbonate basement hydrocarbon reservoirs in the Tarim Basin are the Akekule rise, Katahe uplift, Hetianhe paleo‐high and Yakela faulted rise.
A Large‐scale Tertiary Salt Nappe Complex in the Leading Edge of the Kuqa Foreland Fold‐Thrust Belt, the Tarim Basin, Northwest China
Authors: Liangjie TANG , Zhijun JIN , Chengzao JIA , Xuejun PI , Shuping CHEN , Huiwen XIE , Ziyu WANG
Published: September 2010

Abstract  The tectono‐stratigraphic sequences of the Kuqa foreland fold‐thrust belt in the northern Tarim basin, northwest China, can be divided into the Mesozoic sub‐salt sequence, the Paleocene‐Eocene salt sequence and the Oligocene‐Quaternary supra‐salt sequence. The salt sequence is composed mainly of light grey halite, gypsum, marl and brown clastics. A variety of salt‐related structures have developed in the Kuqa foreland fold belt, in which the most fascinating structures are salt nappe complex. Based on field observation, seismic interpretation and drilling data, a large‐scale salt nappe complex has been identified. It trends approximately east‐west for over 200 km and occurs along the west Qiulitag Mountains. Its thrusting displacement is over 30 km. The salt nappe complex appears as an arcuate zone projecting southwestwards along the leading edge of the Kuqa foreland fold belt. The major thrust fault is developed along the Paleocene‐Eocene salt beds. The allochthonous nappes comprise large north‐dipping faulting monoclines which are made up of Paleocene‐Pliocene sediments. Geological analysis and cross‐section restoration revealed that the salt nappes were mainly formed at the late Himalayan stage (c.a. 1.64 Ma BP) and have been active until the present day. Because of inhomogeneous thrusting, a great difference may exist in thrust displacement, thrust occurrence, superimposition of allochthonous and autochthonous sequences and the development of the salt‐related structures, which indicates the segmentation along the salt nappes. Regional compression, gravitational gliding and spreading controlled the formation and evolution of the salt nappe complex in the Kuqa foreland fold belt.
Intracontinental Collisional Orogeny During Late Permian—Middle Triassic in South China: Sedimentary Records of the Shiwandashan Basin
Authors: Xinquan LIANG , Xianhua LI , Yuanxi QIU
Published: September 2010

Abstract  Sedimentary response to an orogenic process is important for determining whether South China had compressional or extensional orogeny during the period from the Late Permian to the Middle Triassic besides the tectonic and magmatologic evidence. An intracontinental collision event took place between the Yangtze and Cathaysia blocks in the Late Permian. Beginning at the Late Triassic, the tectonic movement was completely changed in nature and entered a post‐collisional extensional orogenic and basin‐making process. This paper presents sedimentological evidence from the Late Permian to the Middle Triassic in the Shiwandashan basin at the southwestern end of the junction zone between the Yangtze and Cathaysia blocks.
Modern Sedimentation of Phosphorus and Its Microbial Decomposition and Concentration: An Example from Dianchi Lake, Yunnan, China
Authors: Xuehui XIA , Moxing DONGYE , Zhuo ZHANG
Published: September 2010

Abstract  Dianchi Lake is one of the lakes with the richest phosphorus source in the world, in which the P2O5 content in the bottom sediments reaches averagely 0.51 wt % and maximally 1.92%. Studies indicate that this extremely P‐rich state is attributed mainly to the large volume (as high as hundred thousands of tons) of phosphatic matter coming into the lake as many rivers feeding the lake pass through a vast area of phosphate‐mining districts, which then undergo weathering and particularly some human activities, including waste water discharge. When phosphatic matter enters the lake, its grained parts are firstly decomposed by phosphorus‐decomposing bacteria, and finally accumulated in some geographically special parts of the lake, such as a bay area where water flow is much more slower than elsewhere in the lake. With the involvement of phosphorus‐concentrating bacteria, the accumulated phosphates in the bottom sludge ultimately form phosphate minerals through deep‐burial diagenesis.
Microorganisms Linked to Neoproterozoic Microspar Carbonate Sedimentation in the Jilin‐Liaoning Area
Authors: Ming GE , Hongwei KUANG , Xianghua MENG , FURNISS George
Published: September 2010

Abstract  Molar‐tooth carbonate refers to a sort of rock that has ptygmatical folded structure comparable to the ivory. This kind of carbonate exists in a special time range (from Middle to Neoproterozoic). Its origin and the possibility to use it in stratigraphic correlation of the paleocontinent is the key task of the IGCP447, a project on Proterozoic molar tooth carbonates and the evolution of the earth (2001–2005). The importance lies in that the molar‐tooth structure is the key to solving problems related to Precambrian biological and global geochemical events. The molar‐tooth structure is associated with microorganisms. Development and recession of such carbonates have relations with the evolution process of early lives and abrupt changes in sea carbonate geochemistry. In recent years, based on researches on petrology, geochemistry and Sr isotope of molar‐tooth carbonate in the Jilin‐Liaoning and Xuzhou‐Huaiyang area, the authors hold that it can be used as a marker for stratigraphic sequence and sedimentary facies analyses.
Quantitative Analysis of Groundwater Flow near a Partially Penetrating River under Riverside Pumping
Authors: Bingchen WANG , Xilai ZHENG , Hui QIAN , Guoqing LIN , Qian XU
Published: September 2010

Abstract  According to practical geological and hydrogeological conditions of riverside water‐supply well fields in northwestern China, an ideal hydrogeological model has been generalized and a three‐dimensional mathematical model has been set up. A finite difference method was applied to simulating groundwater flow near a partially penetrating river under riverside pumping, and to analyzing the effects of river width, partial penetration and permeability of riverbed sediments on groundwater recharges. Results show that riverside pumping may cause groundwater to flow beneath the partially penetrating river, and that river width, penetration and riverbed permeability obviously influence flows from the partially penetrating river and constant‐head boundaries. However, the pumping output is mainly from the partially penetrating river.
Geoscientific Significance and Classification of National Geoparks of China
Authors: Ting ZHAO , Xun ZHAO
Published: September 2010

Abstract  The conservation of geological remains in China, especially in renowned sites with historical or cultural significance, has long been paid attention to. As the urban residents become more interested in returning to and harmony with the nature, tourism related sciences and knowledge gets more attractive. Geosites and geoparks can definitely play an important role to lead this historic tendency.
Postcranial Anatomy of the Mesozoic Dalinghosaurus (Squamata): Evidence from a New Specimen of Western Liaoning
Authors: Shu'an JI , Qiang JI
Published: September 2010

Abstract The postcranial skeleton of a new specimen of the long‐tailed lizardDalinghosaurus longidigituswas excavated from the Yixian Formation in Lingyuan, western Liaoning. The new specimen provides more anatomical information about this species, especially about the anterior dorsal vertebrae, shoulder girdle and forelimbs. This lizard can be included within the clade Scleroglossa by its 27 or more presacrals, moderately long pubis, and gently notched distal end of tibia. But the detailed systematic position for this taxon remains undetermined. The features of the much longer hind limbs and pes compared with forelimbs and manus, metatarsal IV longer than III, pedal phalanges robust, and penultimate phalanx not longer than other phalanges etc. suggest that this lizard was a running and ground swelling animal.
Modes of Occurrence and Cleaning Potential of Trace Elements in Coals from the Northern Ordos Basin and Shanxi Province, China
Authors: Wenfeng WANG , Yong QIN , Bo JIANG , Xuehai FU
Published: September 2010

Abstract  Based on the analyses of 43 elements in 16 samples of the raw coal and feed coal collected from the northern Ordos basin and Shanxi Province, the modes of occurrence of these elements were studied using the method of cluster analysis and factor analysis, and the cleaning potential of the hazardous elements relatively enriched in the coals was discussed by analyzing six samples of the cleaned coal from the coal‐washing plants and coal cleaning simulation experiments. The results shows that the elements Br and Ba show a strong affinity to the organic matter, Cs, Cd, Pb, Zn and Hg partly to the organic matter, and the other trace elements are mainly associated with the mineral matter. Cs, Mo, P, Pb, Zn and S have positive correlations with the two principal factors, reflecting the complexity of their modes of occurrence. Some elements that were thought to show a faint relationship (Be with S and Sb with carbonates) in other rocks are found to have a strong interrelation in the coals. Clay minerals (mainly kaolinite) dominate in the coals, and Ta, Th, Ti, Sc, REE, Hf, U, Se, W, V, Nb, Mo, Al, P, Cr, Pb and Zn are distributed mostly in kaolinite, while K, Rb, Cs, and Na have much to do with illite. Conventional cleaning can reduce the concentrations of most hazardous elements in various degrees. The hazardous elements S, As, Sb, Se, Mo, Pb, Cd and Hg relatively enriched in some coals from the area studied have a relatively high potential of environmental risks. However, by physical coal cleaning processes, more than 60% of As and Hg were removed, showing a high degree of removal, more than 30% of Sb, as well as S, Pb and Cd partly associated with the inorganic matter were removed. Se and Mo showing a relatively low degree of removal could be further removed by deep crushing of the coal during physical cleaning processes, and the concentrations of S, Pb, Cd and Hg with a partial association with the organic matter could be decreased in such ways as the coal blending. Cluster analysis together with factor analysis is a rapid and effective way to deduce the mode of occurrence of an element from bulk samples, and the removability data of most hazardous elements are basically consistent with their modes of occurrence suggested, which indicates that the statistical analysis could predict the cleaning potential of hazardous elements during the physical coal cleaning.
Textural and Geochemical Characteristics of Proglacial Sediments: A Case Study in the Foreland of the Nelson Ice Cap, Antarctica
Authors: Xiaodong LIU , Liguang SUN , Xuebin YIN
Published: September 2010

Abstract  This paper presents a detailed study on the textural and geochemical characteristics of the proglacial sediments near the edge of modern Nelson Ice Cap, Antarctica. The grain size distributions of the proglacial sediments are characteristic of glacigenic deposits, but very different from those of aeolian and lacustrine sediments. Moreover, the grain size distributions of the proglacial sediments are fractal with a dimension of about 2.9, and the fractal dimensions can be used as another summary statistical parameter for quantifying the relative amounts of coarse and fine materials. Correlations between the absolute element abundances of the proglacial sediments are very weak due to mineral partitioning and other effects of glacial processes, but correlations between the element/Rb ratios are statistically significant. This finding indicates that element/Rb ratios can be used to reduce or eliminate the effects of glacial processes, evaluate geochemical data and determine the sediment provenance in the foreland of Antarctic glacier. Comparisons on the element concentrations among different environments suggest that the proglacial sediments are derived predominantly from local bedrocks and appear to be natural in origin. Thus these natural sediments can be used to study chemical weathering in the proglacial foreland of modern glacier.
U‐Pb Zircon Geochronology and Geochemistry of Granitoids in the Douling Group in the Eastern Qinling
Authors: Chengli ZHANG , Miao LI , Tao WANG , Honglin YUAN , Yunxiang YAN , Xiaoming LIU , Jianqi WANG , Ye LIU
Published: September 2010

Abstract LA‐ICPMS U‐Pb zircon dating of the Sanpinggou, Gangou and Fengzishan granitoids in the Douling Group of the Eastern Qinling yields ages of 760–685 Ma, which represents a strong tectono‐magmatic event in the southern Qinling during the late Neoproterozoic. Geochemical data show that these intrusions have wide compositions ranging from minor gabbros through diorites to granodiorites. They are relatively enriched in LILE, poor in HFSE and strongly depleted in Nb and Ta, displaying affinities of I‐type granites formed in an active continental margin with oceanic subduction. In contrast to granitoids, gabbros and enclaves in the granitoids have higher REE abundances, relatively flat REE patterns, lower LILE, slightly higher HFSE and more depletion in Nb and Ta. All these suggest that the gabbros were formed by partial melting of the upper mantle above the subduction zone and the granitoids by the partial melting of the lower crust. Combined with regional geological data, the subduction‐related granitoids in the Douling Group, together with the Tuwushan A‐type granite with an age of 725 Ma and contemporaneous basic dikes in the Wudang Block, provide evidence for local subduction of oceanic basins between different blocks during the rifting in the Southern Qinling in the Neoproterozoic. Thus, the coexistences of various magmatic rocks formed in different tectonic environments indicate a complicated tectonic evolution and variety of tectonic frameworks in the Qinling area in the Neoproterozoic.
Underplating of Mesozoic Mantle‐derived Magmas in Tongling, Anhui Province: Evidence from Megacrysts and Xenoliths
Authors: Yangsong DU , Hyunkoo LEE , Xinlong QIN
Published: September 2010

Abstract Lithological observations and mineralogical analyses on pyroxene and hornblende megacrysts and pyroxene and hornblende cumulates in xenoliths in the Mesozoic plutons of the Tongling region, Anhui Province, provide evidence for the magmatic underplating of mantle‐derived alkali‐olivine basalt at circa 140 Ma. The pyroxene and hornblende megacrysts and cumulates were formed through the AFC process at depths ranging from 27 to 35 km.
P‐T‐t Path of Mafic Granulite Metamorphism in Northern Tibet and Its Geodynamical Implications
Authors: Daogong HU , Zhenhan WU , Wan JIANG , Peisheng YE
Published: September 2010

Abstract Mafic granulites have been found as structural lenses within the huge thrust system outcropping about 10 km west of Nam Co of the northern Lhasa Terrane, Tibetan Plateau. Petrological evidence from these rocks indicates four distinct metamorphic assemblages. The early metamorphic assemblage (M1) is preserved only in the granulites and represented by plagioclase+hornblende inclusions within the cores of garnet porphyroblasts. The peak assemblage (M2) consists of garnet+clinopyroxene+hornblende+plagioclase in the mafic granulites. The peak metamorphism was followed by near‐isothermal decompression (M3), which resulted in the development of hornblende+plagioclase symplectites surrounding embayed garnet porphyroblasts, and decompression‐cooling (M4) is represented by minerals of hornblende+plagioclase recrystallized during mylonization. The peak (M2) P‐T conditions of garnet+clinopyroxene+plagioclase+hornblende were estimated at 769–905°C and 0.86–1.02 GPa based on the geothermometers and geobarometers. The P‐T conditions of plagioclase+hornblende symplectites (M3) were estimated at 720–800°C and 0.55–0.68 GPa, and recrystallized hornblende+plagioclase (M4) at 594–708°C and 0.26–0.47 GPa. It is impossible to estimate the P‐T conditions of the early metamorphic assemblage (M1) because of the absence of modal minerals. The combination of petrographic textures, metamorphic reaction history, thermobarometric data and corresponding isotopic ages defines a clockwise near‐isothermal decompression metamorphic path, suggesting that the mafic granulites had undergone initial crustal thickening, subsequent exhumation, and cooling and retrogression. This tectonothermal path is considered to record two major phases of collision which resulted in both the assemblage of Gondwanaland during the Pan‐African orogeny at 531 Ma and the collision of the Qiangtang and Lhasa Terranes at 174 Ma, respectively.