bluuebunny/crossref_metadata_2025 huggingface dataset:
The Loess in the Qinling Mountains and Its Records of Palaeoenvironmental Changes
Authors: Xiangyi LEI , Leping YUE
Published: September 2010

Abstract: The Fengzhou loess section is very typical in the Qinling Mountains. The section, which is about 82 m thick and underlain by Neogene red clays, consists of 33 layers of loess and 33 layers of palaeosol. It covers the Brunhes normal polarity zone and Matuyama reversed polarity zone, and the B / M boundary is located in the middle part of loess layer 8 (L8). The loess of the Matuyama reversed polarity zone records the Jaramillo, Olduvai and Reunion normal polarity subchrons. The boundary between the Matuyama reversed polarity zone and Gauss normal polarity zone (M / Ga) appears on the lithological boundary between loess and Neogene red clays. Loess accumulation in the Fengzhou section started before 2.48 Ma B.P. Based on the stratigraphical structure, the material composition and magnetic susceptibility curve of the Fengzhou loess section, the palaeoclimatic changes during the last 2.48 Ma in the Qinling Mountains are subdivided into 66 cold‐dry and warm‐humid stages, equivalent to 33 climatic cycles. The above climatic fluctuations agree very well with those of the oxygen isotopic records from deep—sea deposits.
Formation of the Devonian Fengtai Hydrothermal Brine Basin and the Metallogeny of Gold and Lead‐Zinc Mineralizations in Shaanxi
Authors: Huaping ZHU , Jian GUO , Ping LIU , Falin LI , Changqing HUANG
Published: September 2010

Abstract  The study of the relationships between the hydrothermal sedimentary formations and the gold and lead‐zinc mineralizations in the Devonian Fengtai basin in Shaanxi shows that there was a hydrothermal brine sedimentary event which was inserted into the normal sedimentary background from the late Middle Devonian to the early Late Devonian. This event is closely related to gold and lead‐zinc mineralizations in this area.
Cobalt Deposits in the Central China Orogenic Belt
Authors: Yong XU , Xinyou ZHU
Published: September 2010

Abstract  Cobalt mostly occurs as an associated metal in Cu‐Ni sulphide deposits, skarn Fe‐Cu‐Pb‐Zn deposits and volcanic‐hosted massive sulphide (VHMS) or sedex deposits. There are different types of cobalt deposits in the Central China orogenic belt. In the Tamu‐Kalangu Mississippi‐valley type Pb‐Zn deposits, many cobalt‐nickel sulphide minerals were found. The cobalt content of the ore is 0.064%‐0.46% in sedex‐type Kendekeke Fe‐Pb‐Zn‐Au deposits, and cobalt sulphide veins with Co contents of 4%‐9% have also been found. About 28000 tons of cobalt reserves were delineated in the Dur'ngoi Cu‐Co‐Zn deposit of VHMS type in the A'nyemaqên Mountains. It is considered that the exploration potential for cobalt is attractive in this district, especially in sedex‐type deposits and Co‐rich sulphide veins in sedex‐type Fe, Cu and Pb‐Zn deposits and their surroundings.
Characteristics and Genesis of the Aktubaik Gold Deposit in Altay, Xinjiang
Authors: Yongguan DONG , Chuanlin ZHANG
Published: September 2010

Abstract  The Aktubaik gold deposit lies in the Altay middle‐high mountains area, Xinjiang, hosted by the Palaeo‐ and Mesoproterozoic Xemirxek Group. It is the first gold deposit found in Precambrian rocks in Altay. The deposit is controlled by the NW‐trending fracture‐alteration zone, in which rocks have been strongly altered and bleached. The main wall‐rock alterations include silicification, sericitization (muscovitization), carbonation, pyritization and tourmalinization. Several gold mineralization zones of this type have been found in the study area. The dominant gold mineral is native gold, which is distributed very unevenly, so special methods such as peeling and bulk sampling are required in exploration. The discovery of this gold deposit has laid a foundation for gold exploration in Precambrian rocks in the Altay middle‐high mountains area, Xinjiang.
Uraniferous Black Shale and Related Uranium Mineralization Features in South China
Authors: Qiuying ZHANG
Published: September 2010

Abstract  Black shales are marine sediments with argillaceous, silty and siliceous compositions and high contents of organic materials, disseminated pyrite and uranium. Uraniferous black shale has uranium content of more than 20 ppm.

Black shales are widely distributed in 17 provinces or autonomous regions in northwestern and southern‐central China. Their sedimentary ages are from the Sinian to the Tertiary and uraniferous black shales are mainly exposed in Yunnan, Guizhou, Sichuan, Hunan, Hubei, Jiangxi, and Zhejiang provinces and Guangxi Zhuang Autonomous Region and the economically significant uranium deposits associated with black shale occur in Hunan and Jiangxi provinces and Guangxi Zhuang Autonomous Region.

Uranium mineralization associated with black shale has the following main features: (1) forming stratabound deposits; (2) controlled by structures such as interlayer and intersected faults and fractures; (3) associated with different ore‐forming processes such as leaching and hydrothermal reworking; (4) occurring in five periods, namely 120‐110 Ma, 84‐74 Ma, 75‐65 Ma, 48‐39 Ma and 30‐24 Ma.
Tectonics and Petroleum Potential of the East China Sea Shelf Rift Basin
Authors: Peilian LI , Hongbin HOU , Huifu MA
Published: September 2010

Abstract  There are two Cenozoic sedimentary basins in the East China Sea. They are the East China Sea shelf basin and the Okinawa Trough basin. The former can be divided into a western and an eastern rift region. The development of the shelf basin underwent continental‐margin fault depression, post‐rift and then tectonic inversion stages. Available exploration results show that the distribution of source rocks is controlled by the basin architecture and its tectonic evolution. In the Xihu depression, mudstones and coals are the main source rocks. The eastern rift region has good geological conditions for the formation of large oil and gas fields.
Classification of Mineral Resources Associated and Accompanied with Coal Measures
Authors: Guotai YUAN , Kaifen HUANG
Published: September 2010

Abstract  The paper discusses the concept of mineral resources associated with coal measures. A rational and scientific classification of such mineral resources becomes more necessary with the development of science and technology. A classification scheme is proposed based on compositions and physical properties and the utilization of these associated minerals.
Influences of the Basin Brines on Hydrocarbons of the Anthracosia Shales from Southwestern Poland
Authors: Yuzhuang SUN , Yujie JIN
Published: September 2010

Abstract: Previous studies have shown that the oxidizing brines from the Early Permian Rotliegende sequence have influences on the organic matter of Kupferschiefer. However, inside the Rotliegende sequence there are two other black shales: the Lower and Upper Antracosia shales, which have not been studied as much in detail as in Kupferschiefer. In the present study 12 samples from the Lower and Upper Antracosia shales were analyzed by organic geochemical methods in order to clarify the influences of the oxidizing brines on organic matter. The results indicate that the organic matter of the samples from the Upper Antracosia shale and the bottom of the Lower Antracosia shale was oxidized under the influences of the oxidizing brines. The oxidation resulted in a depletion of saturated hydrocarbons and the alkyls of the aromatic compounds.
Determination of 3‐D Velocity Anomalies of the Nanbei Tectonic Zone of China Based on Local Earthquakes
Authors: Xu CHANG , Yike LIU
Published: September 2010

Abstract: In this paper, 3‐D velocity images of the crust and upper mantle beneath the Nanbei tectonic zone of China are constructed using P‐wave travel time residuals of earthquakes, with the data supplied by China's seismic networks and the International Seismic Centre.

During the model parameterization in the tomographic inversion the interpolation function of grid node velocities is used as the space function of velocity, and the velocity function is allowed to be discontinuous. The difficulties caused by large memory demand and high computing cost in solving the system of equations are avoided by utilizing the least squares QR decomposition algorithm. Thus, the stability of the algorithm is ensured. Though resolution images are not derived in the inversion process based on the resolution theory of Backus and Gilbert, a covariance resolution method is put forward by the authors. The resolution analyses have proved the reliability of the image results. 3‐D ray tracing is conducted to obtain the ray paths in a spherical coordinate system.

The imaging results indicate that there is a significant lateral heterogeneity in the crust and upper mantle beneath the North‐South tectonic zone of China persisting down to 200 km in depth. The velocity images of the upper crust show features closely related to the tectonic features on the surface. A low‐velocity layer exists in a very wide range of the mid‐crust. The lowest velocity value is about 5.60 km/s. In a long narrow area between 25.0°N‐38.0°N and 100.0°E‐103.2°E, a low‐velocity anomaly of about 7.49 km/s appears at the top of the upper mantle. Almost all of the major earthquakes (ML≥6.0) took place in the transitional strips between high and low velocity zones at depths above 20 km in the crust. From the velocity images at 20+0 km and 50+0 km depth respectively, we find that the epicentres of strong earthquakes with magnitudes larger than 6.0 are almost entirely distributed in the low‐velocity zones or on their boundaries.
The Most Complete Sequence of Telychian Graptolite Zones in the World
Authors: Lipu FU , Zifu ZHANG , Liangyu GENG
Published: September 2010

This paper divides the Telychian into 7 graptolite zones, 12 subzones and 4 chitinoans in the Ziyang region, China. The zones and subzones of England are almost totally suitable for the case of Ziyang in China, though they are 10000 km apart. All the above‐mentioned biozones are found only in a unitary continuous section in Ziyang. It has been proved that the Ziyang section is the one with the most complete sequence of Telychian graptolite biozones in the world.
Transgressive Surface as Sequence Boundary
Authors: Hongfu YIN , Jinnan TONG
Published: September 2010

Analysis of the four cases of the sequence boundary (SB)‐transgressive surface (TS) relation in nature shows that applying transgressive surfaces as sequence boundaries has the following merits: it improves the methodology of stratigraphic subdivision; the position of transgressive surface in a sea level curve is relatively fixed; the transgressive surface is a transforming surface of the stratal structure; in platforms or ramps, the transgressive surface is the only choice for determining the sequence boundary; the transgressive surface is a readily recognized physical surface reflected by seismic records in seismostratigraphy. The paper reaches a conclusion that to delineate a SB in terms of the TS is theoretically and practically better than to delineate it between highstand and lowstand sediments as has been done traditionally.
Multi‐mechanism Orogenic Model of the Su‐Jiao Orogenic Belt
Authors: Jintao FAN , Jiongda CHEN , Huogen CHEN
Published: September 2010

The Su‐Jiao orogenic belt is the eastern part of the Central Mountain System of China. Recent studies on its orogenic system indicate that the Su‐Jiao orogenic belt is a complex orogenic belt which suffered at least 3 orogenies of different mechanisms in the Mesoproterozoic, Neoproterozoic and Triassic respectively. The Meso‐Neoproterozoic orogenies belong to the Wilson cycle on the plate margins. The belt is a part of the Late Mesoproterozoic supercontinent Rodinia. The Triassic orogeny belongs to the re‐orogeny of the non‐Wilson cycle. Delamination of mountain roots occurred after both the Wilson and non‐Wilson cycles in the Su‐Jiao orogenic belt. The large‐amplitude isostatic uplift of mountains, magmatic activities and basin‐forming and mountain‐making in the upper crust, all indicate the general significance of delamination in the development of orogenic belts.
Junction and Evolution of the Qinling, Qilian and Kunlun Orogenic Belts
Authors: Yangui SUN , Zhengxing CHEN , Yong'an LIU , Tongqing WANG , Zhiyong ZHANG
Published: September 2010

As the main part of the “central mountain system” in the continent of China, the Qinling, Qilian and Kunlun orogenic belts have been comprehensively and deeply studied since the 1970s and rich fruits have been reaped. However, these achievements were mostly confined to an individual orogenic belt and the study of the mutual relationship among the three orogenic belts was obliged to depend on comparative studies. Different views were produced therefrom. The material composition and structural features of the junction region show that there are several epicontinental and intracontinental transform faults developed in different periods. Restricted by these transform faults, the large‐scale lateral movements and, as a consequence, complicated magmatism and tectonic deformation took place in the orogenic belts. According to these features, the authors put forward a three‐stage junction and evolution model and point out that there is not a single junction zone traversing from west to east but that the three orogenic belts have been joined progressively by the epicontinental and intracontinental transform faults.
Relation of Isotope Geochemical Steep Zones with Geophysical Fields and Tectonics in the Junction Area of the Cathaysian, Yangtze and Indochina Plates
Authors: Bingquan ZHU , Yunpeng Dong , Xiangyang CHANG , Zhengwei ZHANG
Published: September 2010

Through lead isotope geochemical mapping in the Yunnan‐Guizhou area geochemical steep zones (GSZ) have been established, which clearly reveal the junction relationship of the Cathaysian, Yangtze and Indo‐China plates. GSZ are closey related to gravity Moho gradient zones and lithospheric thickness. The GSZ between the Yangtze and Cathaysian plates is consistent with the Shizong‐Mile tectonic belt, where island are basalts are well developed. The Yangtze‐Indo‐China GSZ is parallel to the Jingdong‐Mojiang volcanic belt in rift‐island are environments. The evidence of geology, geophysics and geochemistry all indicates that Cathaysia was subducted towards the Yangtze plate and that the Yangtze plate was underthrust beneath the Indo‐China, which took place from the Early Carboniferous to the Early Triassic.
Sm‐Nd, Pb‐Pb and Rb‐Sr Isotopic Dating and Its Dynamic Implications for the Proterozoic Augen Granite in the Yunkai Area, Western Guangdong Province
Authors: Songbai PENG , Yeming ZHANG , Mingguo ZHAN , Fuwen CHEN , Ruizhao QIU
Published: September 2010

The samples of ductile‐rheologic deformational augen granite from the Yunkai uplift area, western Guangdong province, were determined by the whole‐rock Sm‐Nd, Pb‐Pb and Rb‐Sr isotopic dating to have an Sm‐Nd isochron age of 1414±68 Ma, a Pb‐Pb isochron age of 1388±90 Ma and a Rb‐Sr isochron age of 490±36 Ma. The first two ages are interpreted as the formation age of this suite of granite and the last age represents the timing of the tectono‐thermal event of Caledonian ductile‐rheologic shear partial melting. It is indicated that in the study area not only an orogeny took place in the Caledonian, but also a more important tectono‐magmatic activity occurred in the Meso‐proterozoic there, which may be related to the subduction‐collision between the Yangtze block and Cathaysia block.
Hydrobios and Control of Eutrophication in Dongping Lake, Shandong Province
Authors: Suzhen DOU , Zhaocai SUN , Ying CAO , Yumei MA , Jingfu ZHANG , Guicheng LIU , Xiaoyan KOU
Published: September 2010

The Hydrobios in Dongping Lake, Shandong Province, mainly includes phytoplankton, zooplankton, benthic animals, fishes and hydrophytic vascular plants. Nitrogen and phosphorus are the restrictive factors for the growth and propagation of hydrophyta, therefore the key to the prevention and control of eutrophication in lakes lies in the control of the contents of the two elements in the water. Artificial fishing of algae can reduce the concentrations of trophic substances such as nitrogen and phosphorus in the water bodies, and biological measures may decrease the contents of these trophic substances in the bottom sediments and the water bodies, thereby playing an active role in modifying the eutrophication of the lake.
Biological and Molecular Geochemical Evidence for Dinoflagellate Ancestors in the Upper Sinian‐Cambrian
Authors: Shuichang ZHANG , MOLDOWAN J. Mike , Lizeng BIAN , Baomin ZHANG , Liping ZHANG
Published: September 2010

Dinoflagellates are single celled organisms that reflect the ecological conditions in modern oceans and lakes. Their earliest undisputed fossil record suggests that dinoflagellates originated from the Middle Triassic (c. 240 Ma ago). However, the presence of molecular biomarkers (dinosterane, 4α‐methyl‐24‐ethylcholestane and triaromatic dinosteroids) in rock extracts and coccoid dinoflagellate fossils from the upper Sinian to Cambrian of the Tarim basin confirms the hypothesis that dinoflagellates have an ancient origin, and predate the oldest undisputed dinoflagellate fossils at least by 300 Ma, as early as the late Sinian‐Cambrian.
Ordovician Intrusive‐related Gold‐Copper Mineralization in West‐Central New South Wales, Australia
Authors: Fengjun NIE , Sihong JIANG , Shengmin ZHAO , COOKE David
Published: September 2010

Three major types of Ordovician intrusive‐related gold‐copper deposits are recognized in central‐west New South Wales, Australia: porphyry, skarn and high sulphidation epithermal deposits. These deposits are mainly distributed within two Ordovician volcano‐intrusive belts of the Lachlan Fold Belt: the Orange‐Wellington Belt and the Parkes‐Narromine Belt. Available isotopic age data suggest that mineralization of the three types of deposits is essentially coeval with the Ordovician intrusive rocks (480–430 Ma).

Porphyry gold‐copper deposits can be further divided into two groups. The first group is associated with monzonite showing shoshonitic features, represented by Cadia and Goonumbla. The second group is associated with diorite and dacite, including the Copper Hill and Cargo gold‐copper deposits. Gold skarn is associated with Late Ordovician (430–439 Ma) monzonitic intrusive complexes in the Junction Reefs area (Sheahan‐Grants, Frenchmans, and Cornishmens), Endeavour 6, 7 and 44, Big and Little Cadia. The epithermal gold deposits with high sulphidation including Gidginbung (Temora) and Peak Hill mainly occur within Ordovician andesite and volcaniclastic rocks, and are associated with advanced argillic alteration. Available isotopic age data indicate that both alteration and mineralization of the porphyry, skarn and epithermal gold‐copper deposits are broadly coeval with the Late Ordovician shoshonitic magmatism, which is thought to result from the melting of sub‐continental lithosphere caused by Palaeozoic subduction events.

The Ordovician intrusive‐related gold‐copper deposits are restricted to two longitudinal parallel volcano‐intrusive belts, rarely extending outside them. Diagonal intra‐belt trends of mineralization are common, particularly at the intersections of longitudinal and transverse (oblique) fault/fracture zones based on the authors' review of available geological data. The locations of these gold‐copper deposits are obviously influenced by transverse (oblique) fault/fracture zones that are oriented northwest, eastwest and northeast. The conjunctions of these fault/fractures zones are thought to be zones of structural weakness, and appear to be the favourable locus for the Ordovician intrusive‐related gold‐copper deposits. Differences in structural patterns, intrusive, wall rock types, and depths of ore formation may contribute to the differences among the deposits.
New Early Cambrian Chordates from Haikou, Kunming
Authors: Huilin LUO , Shixue HU , Liangzhong CHEN
Published: September 2010

Abstract  Two new chordates, Cathaymyrus haikouensis Luo et Hu sp. nov. and Zhongxiniscus intermedius Luo et Hu gen. et sp. nov. are studied in this paper. Both display numerous S‐shaped myomeres on their trunk. C. haikouensis shows a long and slim body similar to that of Cathaymyrus diadexus Shu et al., Zhongxiniscus approaches to Myllokunmingia and Haikouichthys in the dorsal fin, but differs in the myomeres. Zhongxiniscus may be the intermediate form between Cathaymyrus and Myllokunmingia and Haikouichthys.
Devonian Frasnian‐Famennian Transitional Milankovitch Cycles and High‐Resolution Stratigraphic Correlation
Authors: Yiming GONG , Baohua LI , Yi WU
Published: September 2010

Abstract  Four hierarchical cyclothems, superbundlesets, bundlesets, bundles and laminae, have been identified from the Devonian Frasnian‐Famennian carbonate strata in Guangxi, South China. Their hierarchical structures, ratio relationships and sequence in conodont zones are continuous and stable and can be traced across different facies zones and sedimentary basins. Our data show that hierarchically organized superbundlesets, bundlesets, bundles and laminae correspond to the long eccentricity, eccentricity, obliquity or precession and sub‐Milankovitch cycles respectively. Their periods were 400,000, 100,000, 33,333, 16,667 and 8,000–17,000 a, respectively. The ratios of long eccentricity to eccentricity, eccentricity to obliquity, and eccentricity to precession in the Devonian are 1:4, 1:3 and 1:6 respectively. Using these hierarchical Milankovitch cyclothems, chronostratigraphical division and correlation can be realized at a resolution of 100 ka or 10 ka at the Frasnian‐Famennian transition. The time intervals of the Upper rhenana Zone, linguiformis Zone, and the Lower, Middle and Upper triangularis Zone are 0.6, 0.8, 0.3, 0.3 and 0.3 Ma, respectively. Sea‐level changes of the Frasnian‐Famennian transition were not coherent and synchronous at the resolution of 100 ka or 10 ka in the basin‐slope carbonate sequences of Guangxi, South China.
Ages and Compositions of the Precambrian High‐grade Basement of the Qilian Terrane and Its Adjacent Areas
Authors: Yusheng WAN , Zhiqin XU , Jingsui YANG , Jianxin ZHANG
Published: September 2010

Abstract  Based on geological, chronological, geochemical and Nd isotopic studies of the high‐grade basement of the Qilian terrane, the authors have drawn the following main conclusions: (1) the high‐grade basement of the Qilian terrane consists mainly of meta‐argillo‐arenaceous rocks and granites and its bulk part was formed in the period of 0.8–1.0 Ga (the Jinningian period); (2) most of the meta‐argillo‐arenaceous rocks and granitic rocks have strong negative Eu and Ba anomalies (Eu/Eu*= 0.47–0.71 and Ba/Ba*=0.16–0.64), with fDM and ENd (1.0 Ga) ranging from 1.87 to 2.26 Ga and from −8.54 to −4.06 respectively, showing relatively high maturity; and (3) the Jinningian granitic rocks are a typical product of continent‐continent collision, being probably related to the formation of the supercontinent Rodinia. These studies, combined with the study of high‐grade basement rocks near the Qilian terrane, suggest that before the Jinningian period, the Qilian‐Qaidam northern‐margin terrane and Dunhuang‐Alxa terrane were separated from each other, belonging to different plate systems of the North China craton and Yangtze platform respectively. The Qilian orogenic belt was the same as or similar to the Qiling orogenic belt in terms of the geological evolution history at least before the Jinningian period.
Silurian Seismites in Hanxia, Yumen, North Qilian Mountains, and Their Tectonic Significance
Authors: Yuansheng DU , Shuyun GONG , Xin HAN , Jiasheng WANG , Songzhu GU , Wenjiao LIN
Published: September 2010

Abstract  The Caledonian orogenic belt of the North Qilian Mountains is an intensely active structure belt. In the process of the Late Caledonian syn‐orogeny, the North Qilian‐Hexi Corridor area was situated on the tectonic background of a syn‐orogenic basin. In response to the orogenic process of the North Qilian Mountains, typical earthquake event deposits—seismites of the Silurian were widely distributed around Hanxia of Yumen City, the Liyuan River of Sunan County and Biandukou of Minle County. In the Hanxia area, where seismites are typically developed, clastic deposits of tidal‐flat facies are the background deposits of the Hanxia Formation. The earthquake event deposits are characterized by sandy mudstone veins, synsedimentary microfractures, micro‐corrugated laminations and earthquake breccias, which in turn constitute complex seismites, featuring seismic corrugation, shattering and liquefied sandy mudstone veins, auto‐clastic breccias and intraclastic parabreccias. The seismites and tidal flat deposits formed typical sequences of earthquake event deposits.
Dating of the Karakorum Strike‐slip Fault
Authors: Yong ZHOU , Ronghua XU , Yuehua YAN , Yusheng PAN , YANG Tsanyao Frank , LO Wei , Chunming WU
Published: September 2010

This paper mainly discusses the timing of the Karakorum strike‐slip fault, and gives a brief introduction of its structures, offset, and deformational style. This fault strikes NNW‐SSE. Asymmetrical folds, stretching lineation, S‐C fabrics, feldspar and quartz s̀‐porphyroclasts, domino structure, shear cleavages and faults in the fault zone are products of tectonic movements. They all indicate a dextral slip sense of faulting. Mylonitic bands are widely developed along this fault. Phengite appears, indicating rather high deformational pressure. Geochronological data indicate that the Karakorum strike‐slip faulting occurred from 6.88±0.36 to 8.75±0.25 Ma. The cumulative displacement from Muztag Ata to Muji is about 135 km.
Early‐Middle Permian Reef Frameworks and Reef‐building Models in the Eastern Kunlun Mountains
Authors: Shugan TIAN , Jiasong FAN
Published: September 2010

Reef frameworks and building models of the Early‐Middle Permian in the eastern Kunlun Mountains have been verified through studies of reef‐building communities, palaeoecology and carbonate facies. The eastern Kunlun reefs are built mainly by 6 reef‐building communities, which include 11 major categories of frame‐building organisms and 6 categories of reef‐associated organisms. Eight types of reef‐frames have been distinguished and eleven kinds of rocks identified to belong to 6 reef facies. Three sorts of reefs classified by previous researchers, namely mudmounds, knoll reefs and walled reefs, are well developed in the study area. Such reef‐facies association and reef distribution show that there are 4 models of reef growth and development, i.e. the tidal‐bank knoll‐reef model, the plateau‐margin wall‐reef model, the composite wall‐reef model and the deep‐water mudmound model. The reefs are mainly constructed by calcareous sponge and calcareous algae, which are similar to all Permian reefs in other areas of South China and the world. Their great scales indicate a secular stable platform‐marginal environment.
Geochemical Characteristics and Genesis of the Granitic Gneisses from the Southeastern Dabie Mountains
Authors: Huaimin XUE , Shuwen DONG , Xiaochun LIU
Published: September 2010

The granitic gneisses from the ultrahigh‐pressure (UHP) metamorphic terrain of the southeastern Dabie Mountains encompass two types: monzonitic granitic gneiss and alkali‐feldspar granitic gneiss, which are characterized by rich alkalis, poor CaO, high FeO/MgO, particularly high Ba, Rb, Th, Ta, REE (except Eu), Ga, Nb and Zn, and low Sr, Eu, Cr, Co and Ni. The gneisses, particularly the alkali‐feldspar granitic gneiss, have typical chemical characteristics of A‐type granites. They resulted from partial melting of crustal materials existing in the rift zone along the northern margin of the South China block during the Neoproterozoic. These gneisses might not have undergone UHP metamorphism during the late Triassic, but were involved into UHP rocks by the tectonic mixing process and kept the exhumation message of the UHP rocks from the middle and upper crust.
Volcanic Event Layers—A Marker Bed of Correlation of Coal Measures
Authors: Bingwen JIA , Anchao ZHOU , Meiling MA , Xiaoyun JIA
Published: September 2010

Upper Carboniferous‐Lower Permian volcanic event deposits from two cross sections in Nanpiao, Liaoning Province, and the Daqing Mountains, Inner Mongolia, were examined by systematic rock and mineral identification, differential thermal analysis, X‐ray diffraction, scanning electron microscopy and trace element and rare earth element quantitative analysis. According to the results, twelve sequences of volcanic event deposits have been distinguished from bottom to top, including 34–39 volcanic event layers. As these layers each have their own distinctive petrological, mineralogical and geochemical characteristics and were derived from the same source, they provide new evidence for further ascertaining the distribution characteristics of volcanic event deposits on the northern margin of the North China plate and carrying out the stratigraphic correlation using volcanic event layers as marker beds.
An Experimental Study of Mixture Corrosion Effects of Carbonate Rocks in the Transitional Zone of Littoral Karst Areas
Authors: Honghan CHEN , Shengzhang ZOU , Yuanfeng ZHU , Congxi CHEN
Published: September 2010

The mechanism for development of littoral karst differs from that of inland karst, and the mixture corrosion effects are one of the most important factors that control the development of littoral karst. Through seven groups of static experiments carried out in a closed CO2‐H2O system, basic conclusions can be drawn as follows: (1) the basic law of corrosion process in a transitional zone of seawater‐freshwater in littoral karst areas is identical with that in the fresh water, i.e., the lithologic characteristics and rock structure are the main factors which control the development of littoral karst; (2) the mixture corrosion rate of the carbonate rock in the above transitional zone is faster than that in fresh water or seawater; (3) the mechanism for development of carbonate rocks differs at various pressures of CO2 in a transitional zone in littoral karst areas.
Characteristics of Karst Ecosystems of Vietnam and Their Vulnerability to Human Impact
Authors: TUYET Do
Published: September 2010

Karst in Vietnam covers an area of about 60,000 km2, i.e. 18 % of the surface of the country. The country has an annual average temperature of 24°C, an annual average rainfall of 2300 mm and a relative humidity of about 90%. Karst in Vietnam is typified by peak cluster‐depression landscapes ranging in elevation from 200 to over 2000 m. Tower and coastal karst landscapes also exit. Because of naturally favourable conditions, karst ecosystems are diverse and very rich. Higher plants (cormophytes) are abundant. They are represented by approximately 2000 species, 908 genera, 224 families, 86 orders and 7 phyla. They form a thick vegetation cover of evergreen tropical rainforest. Knowledge about lower plants is limited. The fauna is rich and diverse. Phyla such as Protozoa, Vermes, Mollusca and Arthropoda are yet ill known. Preliminary results show that the phylum Chordata is represented by 541 species from 80 families, 40 orders and 5 classes. There exist many precious and rare mammals, in particular some endemic species such as Trachypithecus poliocephalus, T. delacouri, Rhinopithecus avanculus, Rhinolophus rouxi, Seotoma dineties and Silurus cuephuongensis. The class Insecta has about 2000 species.

The fast population growth, particularly in the mountainous areas of the country, triggers an increasing demand for land and therefore threatens the ecosystem. To obtain land for farming, people have cut, burned and destroyed natural forest cover; resulting in occurrence of hazards such as soil‐loss, water‐loss, flash floods, mud‐rock flows, rock‐falls, severe drought, water logging and changes of karstic aquifers etc. Poaching precious animals and illegal logging are increasing. In contrast to other natural systems, karst ecosystems cannot be reestablished once damaged. Living karst landscapes will become rocky desert ones without life. Conservation of karstic environmental systems in general and karstic ecosystems in particular should not be the sole vocation of scientists but also a duty and responsibility of authorities and people from all levels. A good example of a multidisciplinary approach to karst‐related problems is the implementation of the Vietnamese‐Belgian Karst Project (VBEKAP): “Rural development in the mountain karst area of NW Vietnam by sustainable water and land management and social learning: its conditions and facilitation”. The aim of this project is to improve living conditions of local people and sustained protection and management of the karst environment and ecosystem.
Karst Collapse Mechanism and Criterion for Its Stability
Authors: Keqiang HE , Changli LIU , Sijing WANG
Published: September 2010

Karst collapse, caused by natural or artificial abstraction of groundwater, has been a focus of environmental geological problems for its ever‐increasing hazardousness. The potential erosion theory and vacuum suction erosion theory, which reveal the origin of karst collapse macroscopically, are popularly accepted. However, a mathematic prediction criterion for karst collapse cannot be established only by these two theories. From a new perspective, this paper attempts to explain the microcosmic mechanism of karst collapse on the basis of these two theories. When the shear stress surpasses the shear strength of soil, a certain point or a certain plane in the unconsolidated soil covering karst caves will fail under the mechanical effects of water and air as well as its load‐pressure, and with the increase of damaged points, a breaking plane appears and the soil on karst caves is completely damaged; as a result, the karst ground collapses. On the basis of the Mohr‐Coulomb failure theory and previous studies, the paper presents a prediction criterion of karst collapse. Finally, by taking, for example, nine typical cases of collapse caused by pumping tests in Guizhou, the paper gives the calculation process of the model and proves its reliability.
Subduction of Continental Crust in the Early Palaeozoic North Qaidam Ultrahigh‐Pressure Metamorphic Belt, NW China: Evidence from the Discovery of Coesite in the Belt
Authors: Jingsui YANG , Zhiqin XU , Shuguang SONG , Jianxin ZHANG , Cailai WU , Rendeng SHI , Haibing LI , BRUNEL Maurice , TAPPONNIER Paul
Published: September 2010

Abstract  Coesite was discovered as inclusions in zircon separates from pelitic gneiss associated with a large eclogite body in the North Qaidam ultrahigh‐pressure (UHP) terrane. Some graphite inclusions were also found. This finding suggested the occurrence of in‐situ UHP metamorphism and that the terrane was most likely recrystallized at pressures below the diamond stability field. It supported other previous indirect UHP evidence, such as polycrystalline quartz inclusions in eclogitic garnet, quartz lamellae in omphacite and P‐T estimates for both eclogite and garnet peridotite. The U‐Pb and Sm‐Nd ages of the North Qaidam eclogite indicated that subduction of continental crust occurred in the Early Palaeozoic, which probably recorded a collision between the Sino‐Korean and Yangtze plates.
Characterizing Fracture Spatial Patterns by Using Semivariograms
Authors: Jiandong XU , Chiente LIN , JACOBI R. D.
Published: September 2010

Abstract  Semivariogram is applied to fracture data obtained from detailed scanline surveys of nine field sites in western New York, USA in order to investigate the spatial patterns of natural fractures. The length of the scanline is up to 36 m. How both fracture spacing and fracture length vary with distance is determined through semivariogram calculations. In this study, the authors developed a FORTRAN program to resample the fracture data from the scanline survey. By calculating experimental semivariogram, the authors found five different types of spatial patterns that can be described by linear, spherical, reversed spherical, polynomial I (for a<0) and polynomial II (for a>0) models, of which the last three are newly proposed in this study. The well‐structured semivariograms of fracture spacing and length indicate that both the location of the fractures and the length distribution within their structure domains are not random. The results of this study also suggest that semivariograms can provide useful information in terms of spatial correlation distance for fracture location and fracture length. These semivariograms can also be utilized to design more efficient sampling schemes for further surveys, as well as to define the limits of highly probable extrapolation of a structure domain.
Relationship between Granite and Eclogite on the Southern Margin of the Qilian Mountains: Evidence from Zircon SHRIMP Ages of the Aolaoshan Granite
Authors: Cailai WU , WOODEN Jone , Jingsui YANG , Haibing LI , IRELAND Trevor , Guang LIOU June , Yusheng Wan , Rendeng Shi
Published: September 2010

Abstract  Zircon SHRIMP ages of the Aolaoshan granite on the south margin of the Qilian Mts. range from 445±15.3 to 496±7.6 Ma (averaging 473 Ma), belonging to the Early Ordovician. Geochemically, the granite is similar to I‐type granite and, tectonically, was formed in an island‐arc environment based on relevant diagrams for structural discriminations. Considering also the regional geology, the authors suggest that the granite is part of an ultrahigh‐pressure belt on the south margin of the Qilian Mts. and that its formation bears a close relationship to this belt.
Discovery of Radiolarian Fossils from the Aiketik Group at the Western End of the South Tianshan Mountains of China and Its Implications
Authors: Yuejun LI , Zhaoming WANG , Haoruo WU , Zhibin HUANG , Zejin TAN , Juncheng LUO
Published: September 2010

Abstract  The Aiketik Group, distributed at the western end of the South Tianshan Mountains, China, is an important lithostratigraphic unit involved in the South Tianshan orogen. It is separated from the adjacent rocks by faults. Generally, the geologists ascribed it to the Upper Carboniferous according to Pseudostaffella sp., Profusulinella sp. and Fusulinella sp. found from the limestone and sandy limestone of Aiketik. Our radiolarian fossils were obtained from the chert samples collected from the Haladaok section located at the upper Tuoshihan River. The fossils mainly include Albaillella undulata Deflandre, Albaillella paradoxa Deflandre, Albaillella sp. aff. A. paradoxa Deflandre, Albaillella sp. cf. A. deflandrei Gourmelon, Albaillella sp., Albaillella excelsa Ishiga, Kito and Imoto (?), Belowea variabilis (Ormiston et Lane), Callella cf. C. parvispinosa Won, Entactinia cf. E. tortispina Ormiston et Lane, Entactinia aff. E. tortispina Ormiston et Lane, Entactinia variospina Won, Entactinia sp., Eostylodictya rota (Won), Latentifistula impella (Ormistone et Lane) (?), Latentifistula turgida Omiston et Lane, Latentifistulidae gen. et. sp. indet. and Polyentactinia cf. aranea Gourmelon. Among them, Albaillella excelsa Ishiga, Kito and Imoto (?) is a Late Permian species with some elements uncertain as there is only one poorly‐preserved fossil of this species found so far. And two radiolarian assemblages can be identified from the other fossils. One is the early Early Carboniferous assemblage represented by Albaillella undulata Deflandre, Albaillella paradoxa and Albaillella sp. cf. A. deflandrei Gourmelon. And the other is the late Early Carboniferous assemblage represented by Eostylodictya rota (Won). This is the first discovery of radiolarian fossils in the Aiketik Group, also the first discovery of Late Permian radiolarian fossils in the South Tianshan Mountains. Meanwhile, this is the current westernmost sampling site of radiolarian fossils in the South Tianshan Mountains.
Conodonts from the Upper Cambrian Sesong and Hwajeol Formations in the Sabuk Area, South Korea
Authors: Byung‐Su LEE
Published: September 2010

Abstract  This paper presents a conodont biostratigraphic study on the Upper Cambrian Sesong and Hwajeol Formations in the Sabuk area, Korea. Two samples near the base of the Sesong Slate at the Pukil section contain lower Upper Cambrian conodonts, comprising Furnishina furnishi, F. kranzae, F. pernical?, F. triangulata, Hertzina elongata, Laiwugnathus doidyxus?, Phakelodus elongatus, Muellerodus? obliquus, Westergaardodina matsushitai and W. moessebergensis. This is the first conodont record of the Upper Cambrian formations recovered yet in the northern limb of the Paekunsan syncline. The faunal assemblage is correlatable with the lower Upper Cambrian W. matsushitai Zone of North China. Four local biozones are recognized in the Hwajeol Formation, i.e. the Proconodontus, Eoconodontus notchpeakensis, Cambrooistodus minutus and Cordylodus proavus Zones in ascending order. This zonal scheme is essentially equivalent to that of the southern limb of the Paekunsan syncline and they are correlatable with zones in other parts of the world, including North America, Australia, Iran and China.
Anomalous Enrichment of Silver in Organic Matter of the Songxi Shale‐hosted Ag‐Sb Deposit in Northeastern Guangdong
Authors: Kai HU , Chensheng YU , Dongsheng MA , Jianping ZHAI , Wenlan ZHANG , Zhenyu XIAO
Published: September 2010

Abstract  The silver contents of organic matter in the host rocks of the Songxi shale‐hosted Ag‐Sb deposit of northeastern Guangdong, South China, have been directly determined using the electron microprobe technique. The silver contents in two types of organic matter, marine vitrinite and solid bitumen, vary in the range from 100times10−6 to 350times10−6, which are from tens of times to thousands of times higher than those of the host rocks in the ore deposit. The average silver content of the organic matter is also several times higher than the pay grade of silver for commercial mining of the ore deposit. It is quite obvious that the organic matter of the host rocks in the ore district is characterized by an anomalous enrichment of silver. The results of this study indicate that the silver anomalies in the organic matter have been derived from both the host rocks and the silver‐bearing fluids of the Songxi black shale ore source. In the course of sedimentation and later hydrothermal reworking, organic matter was able to entrap the element silver from source rocks and silver‐bearing fluids through complexation and reduction, so that silver could be further enriched (or precipitated) in the solid bitumen. The quantitative assessment in this study suggests that the distribution of solid bitumens in the ore district may be considered an indication for mineral exploration.
Paleozoic Accretion‐Collision Events and Kinematics of Ductile Deformation in the Eastern Part of the Southern‐Central Tianshan Belt, China
Authors: Liangshu SHU , CHARVET J. , Huafu LU , LAURENT S.C.
Published: September 2010

The Tianshan range could have been built by both late Early Paleozoic accretion and Late Paleozoic collision events. The late Early Paleozoic Aqqikkudug‐Weiya suture is marked by Ordovician ophiolitic mélange and a Silurian flysch sequence, high‐pressure metamorphic relics, and mylonitized rocks. The Central Tianshan belt could principally be an Ordovician volcanic arc; whereas the South Tianshan belt, a back‐arc basin. Macro‐ and microstructures, along with unconformities, provide some kinematic and chronological constraints on 2‐phase ductile deformation. The earlier ductile deformation occurring at ca. 400 Ma was marked by north‐verging ductile shearing, yielding granulite‐bearing ophiolitic mélange blocks and garnet‐pyroxene‐facies ductile deformation, and the later deformation, a dextral strike‐slip tectonic process, occurred during the Late Carboniferous‐Early Permian. Early Carboniferous molasses were deposited unconformably on pre‐Carboniferous metamorphic and ductilely sheared rocks, implying the end of the early orogeny. The large‐scale ductile strike‐slip along the Aqqikkudug‐Weiya zone was possibly caused by the second tectonic event, the Hercynian collision between the northern Tarim block and the southern Siberian block. Late Paleozoic granitic magmatism and superimposed structures overprinted this Early Paleozoic deformation belt. Results of geometric and kinematic studies suggest that the primary framework of the Southern‐Central Tianshan belt, at least the eastern part of the Tianshan belt, was built by these two phases of accretion events.
Two Contrasting Eclogite Types on the Northern Margin of the Qaidam Basin, Western China
Authors: Jianxin ZHANG , Jingsui YANG , Zhiqin XU , Yusheng WAN , Fancong MENG , Haibing LI , Rendeng SHI , Shuguang SONG
Published: September 2010

Eclogites have been recently discovered in the Xitieshan area in the middle segment of the northern margin of the Qaidam basin. These eclogites, together with those recognized earlier in the Yuka area of the western segment of the northern margin of the Qaidam basin and in the Dulan area of the eastern segment of the northern margin of the Qaidam basin, form an eclogite belt with a length of 350 km. A comparison of the eclogites from the Yuka and Xitieshan areas suggests that they show different country rocks, microtextures, mineral assemblages, and especially, different peak temperatures, PT paths during decompression and isotopic features. Eclogites from the Yuka area bear evidence of prograde metamorphism, such as prograde mineral relics in garnet and growth zoning of garnet, and hairpin‐shaped PT paths with coincidence of the baric and thermal peaks of metamorphism, which reflect rapid burial and uplift. Sm‐Nd isotopic determination shows obvious Sm‐Nd disequilibrium, and no isochron ages of Early Paleozoic metamorphism was obtained. On the contrary, the Xitieshan eclogite was subjected to metamorphism of higher eclogite‐facies and post‐eclogite‐facies temperatures, showing an obvious granulite‐facies overprint. A tentative PT path for the Xitieshan area suggests that the baric peak preceded the thermal culmination. Whole rock‐garnet‐omphacite Sm‐Nd isotopic data give an isochron age in the Early Paleozoic. The differences between the two eclogites imply their different tectonic‐thermal history during their burial and uplift.
Enrichment of Mantle‐derived Fluids in the Formation Process of Granitoids: Evidence from the Himalayan Granitoids around Kunjirap in the Western Qinghai‐Tibet Plateau
Authors: Yaohui JIANG , Hongfei LING , Shaoyong JIANG , Xunruo ZHOU , Xingjian RUI , Wanzhi YANG
Published: September 2010

Taking the Himalayan granitoids around Kunjirap in the western Qinghai‐Tibet plateau as an example, the authors present in this paper the characteristics of the granitoids rich in mantle‐derived fluid components and discuss their rock‐forming mechanism. The research results indicate that the rock assemblage of the studied granitoids involves diopside syenite‐diopside granite‐biotite (monzonitic) granite, consisting mainly of K‐feldspar, oligoclase, quartz, iron‐phlogolite, diopside and edenite. The rocks are rich in mantle‐derived fluid components of volatiles including F, alkali metal elements such as K, Na, Rb, Sr and Ba, and radiogenic heat‐producing elements such as U and Th. They were generated by the influx of mantle‐derived fluids into the lower crust to give rise to partial melting during the lithosphere thinning in the Qinghai‐Tibet plateau.
An Early Cretaceous Avialian Bird, Shenzhouraptor sinensis from Western Liaoning, China
Authors: Qiang Ji , Shu'an Ji , Hailu You , Jianping Zhang , Hongbin Zhang , Nanjun Zhang , Chongxi Yuan , Xinxin Ji
Published: September 2010

Abstract  This paper describes an avialian bird from the Early Cretaceous Jiufotang Formation in Yixian county, western Liaoning, China, which is named as Shenzhouraptor sinensis by Ji et al. on July 15,2002. Shenzhouraptor sinensis is characterized by no teeth in its mouth, the forelimbs longer than the hindlimbs, a long tail with more than 23 caudal vertebrae, U‐shaped wishbone, and remiges longer than the total length of ulna and manus. It is certain that the new avialian bird is really capable of powerful flight, representing a missing link between theropod dinosaurs and birds.