bluuebunny/crossref_metadata_2025 huggingface dataset:
40Ar/39 Ar Age and Geological Significance of Lamprophyres in Pishan on the SW Margin of the Tarim Terrane, NW China
Authors: Huaiyu HE , Zhengfu GUO , Songshan WANG , Jie HAO , Qiang LIU , BOVEN Ariel
Published: September 2010

Abstract  The dike swarm of lamprophyres at Pishan on the SW margin of the Tarim terrane is composed of ultra‐potassic lamprophyres that have intruded into the Proterozoic hornblende schists. 40Ar/39 Ar dating data suggest that the isochron ages for phlogopite and whole rock separates of the lamprophyres are 231.7±0.3 Ma and 228.5±0.3 Ma, respectively. Geochemical data indicate that the dikes were derived from a subduction‐related or metasomatized mantle. During the Middle‐Late Triassic the western Kunlun area entered the post‐orogeny period, and thus the occurrence of the dike swarm in the study area may have been controlled by underplating.
Partial Melting and Its Implications for Understanding the Seismic Velocity Structure within the Southern Tibetan Crust
Authors: Xiaosong YANG , Jin MA , Zhenmin JIN , Shan GAO , Shengli MA
Published: September 2010

Abstract  In order to constrain the crustal wave velocity structure in the southern Tibetan crust and provide insight into the contribution of crustal composition, geothermal gradient and partial melting to the velocity structure, which is characterized by low average crustal velocities and widespread presence of low‐velocity zone(s), the authors model the crustal velocity and density as functions of depth corresponding to various heat flow values in light of velocity measurements at high temperature and high pressure. The modeled velocity and density are regarded as comparison standards. The comparison of the standards with seismic observations in southern Tibet implies that the predominantly felsic composition at high heat flow cannot explain the observed velocity structure there. Hence, the authors are in favor of attributing low average crustal velocities and low‐velocity zone(s) observed in southern Tibet mainly to partial melting. Modeling based on the experimental results suggests that a melting percentage of 7–12 could account for the low‐velocity zone(s).
Exploration of Water Resource and Multiple Model for Water Resource Development in Karst Areas with the Preferred Plane Theory
Authors: Guoyu LUO , Changhong YAN , Xiaozhao LI , Jianping JIANG , Ji MA
Published: September 2010

Abstract  According to the theory of preferred plane, preferred planes (faults) always control the distribution of bedrock fissure water and hold abundant groundwater. Thus, the exploration of fissure or karst water can be converted into searching for the watery preferred plane (WPP). In the paper, the characteristic of watery preferred planes is analyzed and a series of superior indices has been set up. It is introduced that WPPs are determined by the methods of geological analysis, superior index and complex geophysical analysis. Meanwhile, new multiple model for water resource development in the water‐scarce areas of karst mountainous regions are advanced.
Holocene Yellow Silt Layers and the Paleoclimate Event of 8200 a B.P. in Lop Nur, Xinjiang, NW China
Authors: Chenglin LIU , Mili WANG , Pengcheng JIAO , Shude LI , Yongzhi CHEN
Published: September 2010

Abstract  Many yellow silt layers have been identified in the Holocene sediments in the last lake of Lop Nur (playa), Xinjiang, northwestern China. Statistics of drill‐hole cores have revealed more than one hundred layers, which exhibit regularity in time sequence. Study has further verified that these yellow silt layers were deposited through eolian processes. The time‐frequency distribution diagram shows an obvious peak occurring at about 8200 a B.P., which is consistent with the dry, windy and cold climate event occurring at 8200 a in other places around the world. Therefore, this event is regarded as a response to the global climate change.
The Genetic Mechanism and Model of Deep‐Basin Gas Accumulation and Methods for Predicting the Favorable Areas
Authors: Tao WANG , Xiongqi PANG , Xinhua MA , Zhijun JIN , Zhenxue JIANG
Published: September 2010

Abstract  As a kind of abnormal natural gas formed with special mechanism, the deep‐basin gas, accumulated in the lower parts of a basin or syncline and trapped by a tight reservoir, has such characteristics as gas‐water inversion, abnormal pressure, continuous distribution and tremendous reserves. Being a geological product of the evolution of petroliferous basins by the end of the middle‐late stages, the formation of a deep‐basin gas accumulation must meet four conditions, i.e., continuous and sufficient gas supply, tight reservoirs in continuous distribution, good sealing caps and stable structures. The areas, where the expansion force of natural gas is smaller than the sum of the capillary force and the hydrostatic pressure within tight reservoirs, are favorable for forming deep‐basin gas pools. The range delineated by the above two forces corresponds to that of the deep‐basin gas trap. Within the scope of the deep‐basin gas trap, the balance relationship between the amounts of ingoing and overflowing gases determines the gas‐bearing area of the deep‐basin gas pool. The gas volume in regions with high porosity and high permeability is worth exploring under current technical conditions and it is equivalent to the practical resources (about 10%‐20% of the deep‐basin gas). Based on studies of deep‐basin gas formation conditions, the theory of force balance and the equation of material balance, the favorable areas and gas‐containing ranges, as well as possible gas‐rich regions are preliminarily predicted in the deep‐basin gas pools in the Upper Paleozoic He‐8 segment of the Ordos basin.
Re‐Os Age of Cu‐Ni Ores from the Huangshandong Cu‐Ni Sulfide Deposit in the East Tianshan Mountains and Its Implication for Geodynamic Processes
Authors: Jingwen MAO , Jianmin YANG , Wenjun QU , Andao DU , Zhiliang WANG , Chunming HAN
Published: September 2010

Abstract An isochron age of 282±20 (95% conf. limit) Ma of the sulfide ores in the Huangshandong Cu‐Ni sulfide deposit, the East Tianshan Mountains has been obtained through Re‐Os isotopic measurement. The age implies that the Cu‐Ni sulfide deposit and other related deposits in the same area occurred in a Permian extensional environment of post‐collision instead of Devonian‐Early Carboniferous ophiolite‐related oceanic or island arc environments inferred before. It shares the same ages with the orogenic and epithermal gold deposit systems in the same area. An initial 187Os/188Os ratio of 0.25±0.04 (1σ) and a γo8 value of 99 on average display the participation of large quantities of crustal components into the rock‐forming and ore‐forming system during mineralization and magmatic emplacement.
Light Hydrocarbons in Fluid Inclusions and Their Constraints on Ore Genesis: A Case Study of the Songxi Ag (Sb) Deposit, Eastern Guangdong, China
Authors: Xiaoming SUN , NORMAN David I. , Kai SUN , Min WANG , Binghui CHEN , Jingde CHEN , Shoujun YU
Published: September 2010

Abstract The Songxi deposit is a newly discovered large Ag (Sb) deposit. By using a suite of high‐vacuum quadrupole gas mass spectrometer systems, the authors have recognized many kinds of light hydrocarbons in fluid inclusions of minerals. These hydrocarbons are mainly composed of C1‐C4 saturated alkanes, while the contents of C2‐C4 unsaturated alkenes and aromatic hydrocarbons are quite low, suggesting that the metallogenic processes have not been affected by magmatic activities. Chemical equilibrium studies show that these hydrocarbons may be a mixture of organic gases generated by microorganism activity and those by thermal cracking of type‐II kerogens (kukersite) in sedimentary host rocks, and the former may constitute more than two‐thirds, implying that microorganism might have played an important role in the metallogenesis. The equilibrium temperature of the latter is about 300°C, which is much higher than the geothermal temperature at the estimated depth of metallogenesis. Thus, the light hydrocarbons generated by thermal cracking of kerogens probably originated in the deep part of the sedimentary basins and then migrated through a long distance to shallower horizons of the basin. Based on the composition of light hydrocarbons in fluid inclusions, the authors infer that the Songxi deposit was formed in a continental rift. The analytical data presented in this paper support from one aspect the genetic model that the Songxi deposit may be a sedimentary hot brine transformed deposit instead of a submarine basic volcanic exhalation and low‐medium temperature volcanic hydrothermal fluid filling deposit proposed by most previous researchers.
Geochemistry of Mesoproterozoic Volcanic Rocks in the Western Kunlun Mountains: Evidence for Plate Tectonic Evolution
Authors: Chuanlin ZHANG , Yongguan DONG , Yu ZHAO , Aiguo WANG , Kunyi GUO
Published: September 2010

Abstract Mesoproterozoic volcanic rocks occurring in the north of the western Kunlun Mountains can be divided into two groups. The first group (north belt) is an reversely‐evolved bimodal series. Petrochemistry shows that the alkalinity of the rocks decreases from early to late: alkaline→calc‐alkaline→tholeiite, and geochemistry proves that the volcanic rocks were formed in rifting tectonic systems. The sedimentary facies shows characteristics of back‐arc basins. The second (south belt) group, which occurs to the south of Yutian‐Minfeng‐Cele, is composed of calc‐alkaline island arc (basaltic) andesite and minor rhyolite. The space distribution, age and geochemistry of the two volcanite groups indicate that they were formed in a back‐arc basin (the first group) and an island arc (the second group) respectively and indicate the plate evolution during the Mesoproterozoic. The orogeny took place at ∼1.05 Ga, which was coeval with the Grenville orogeny. This study has provided important geological data for exploring the position of the Paleo‐Tarim plate in the Rodinia super‐continent.
Ore‐forming Fluid Systems and Mineralization in the Eastern Jiangnan Uplift in the Border Area of Anhui and Jiangxi Provinces, China
Authors: Taofa ZHOU , Feng YUAN , Mingjin HOU , Yu FAn , Jianguo DU , Guang ZHU , Shucang YUE
Published: September 2010

Abstract  Obvious differences in mineralization characteristics exist between the southern and northern parts of the eastern part of the Jiangnan Uplift in northern Jiangxi Province and southern Anhui Province. The regional metallogeny is discussed, and the ore‐forming fluid systems are classified in this article. It is proposed that the fluid ore‐forming activities in the Jiangnan Uplift both in northern Jiangxi and southern Anhui have close relationships with the crust‐mantle interaction and magmatic‐tectonic activities. The types and scales of the mineralization on the both sides of the eastern Jiangnan Uplift were determined by fluid ore‐forming systems and geological backgrounds.
Fluid Geochemistry and Metallogenesis of the Hatu Gold Deposit in the Junggar Basin, Xinjiang
Authors: Lijuan WANG , Jingbin WANG , Yuwang WANG , Heping ZHU , Lili QU
Published: September 2010

Abstract  The Hatu large gold deposit is located on the western margin of the Junggar basin, Xinjiang. Its mineralization is characterized by auriferous quartz veins and Au‐bearing altered fracturing zones. Studies on mineralogy, inclusions and decrepitation temperature indicate that the gold deposit was formed by overlapping of two kinds of fluid of different origins, instead of gradual evolution of a single fluid. The auriferous quartz veins are related to magmatism‐originated fluid, but the Au‐bearing altered fracturing zones to deep‐derived fluid. Bonanzas in quartz veins were formed and localized at overlapping positions of two types of fluid under intensive compression.
Remote Sensing Technology for Identification of Alteration Information of Gold Deposits in the Eastern Tianshan Area, Xinjiang
Authors: Shuixing FU , Shoulin ZHANG , Chunxia LI , Jianzhong FENG , Tonghui FANG
Published: September 2010

Abstract  Based on specific well‐exposed rocks useful for high‐quality remote sensing interpretation in the gold‐prospecting area in the eastern Tianshan, this paper gives a detailed description of a remote sensing model for metallogenic prediction. The model reveals that multi‐spectral remote sensing data are integrated with high‐resolution remote sensing data, and enhanced extraction and visual description of weak remote sensing information are used for prospecting. This model has tested in the given gold deposit, and used successfully in Au‐Cu prospecting in the Kalatage area.
U‐Pb SHRIMP Dating of Zircon from Quartz Veins of the Yangshan Gold Deposit in Gansu Province and Its Geological Significance
Authors: Jinzhong QI , Shisong YUAN , Zhijie LIU , Dunyi LIU , Yanbin WANG , Zhihong LI , Junhua GUO , Bin SUN
Published: September 2010

Abstract  The Yangshan gold deposit is a super‐large fine‐grained disseminated gold deposit located in southern Gansu Province. Its metallogenic age has been determined by using the cathodoluminescence image and ion probe U‐Pb dating techniques. It is found that zircons from quartz veinlet of the fine‐grained disseminated gold ore show characters of magmatic origin with prism idiomorphism, oscillatory zoning and dominant Th/U ratios of 0.5–1.5. Three main populations of zircons are obtained, giving average 206Pb/238U ages of 197.6±1.7 Ma, 126.9±3.2 Ma and 51.2±1.3 Ma respectively. The first age corresponds to the K‐Ar age of the plagiogranite dike, while the latter two ages indicate that buried Cretaceous and Tertiary intrusives exist in the orefield, suggesting that the Yangshan gold deposit was genetically related to the three magmatic hydrothermal activities. By contrast, zircons from coarse gold‐bearing quartz vein in the mining area are much older than the host rock, indicating that the vein was formed earlier and was not contaminated by later magmatic fluids. It is concluded that the coupling of multiperiodic hydrothermal activities in the mining area has contributed a lot to mineralization of the Yangshan gold deposit.
Re‐Os Dating of Molybdenite from the Nannihu Mo (‐W) Orefield in the East Qinling and Its Geodynamic Significance
Authors: Yongfeng LI , Jingwen MAO , Baojian GUO , Yongjun SHAO , Hongcai FEI , Huabin HU
Published: September 2010

Abstract  Located in the East Qinling molybdenum metallogenic belt on the southern margin of the North China craton, the Nannihu Mo (‐W) orefield comprising Nannihu, Sandaozhuang, and Shangfanggou deposits is a superlarge skam‐porphyry Mo (‐W) orefield in the world. Re‐Os dating was performed of six molybdenite samples from the Mo deposits in the Nannihu Mo orefield with inductively coupled plasma mass spectrometry (ICP‐MS). The results show that the Re‐Os model ages are 145.8±2.1–141.8±2.1 Ma for the Nannihu deposit, 145.4±2.0–144.5±2.2 Ma (averaging 145.0±2.2 Ma) for the Sandaozhuang deposit and 145.8±2.1–143.8±2.1 Ma (averaging 144.8±2.1 Ma) for the Shangfanggou deposit; dating of the six samples yields an isochron age of 141.5±7.8 Ma (2σ), which accurately determines the timing of mineralization. The results also suggest that the ore‐forming materials were mainly derived from the lower crust, mixed with minor mantle components. These Mo deposits were formed during the transition of the Mesozoic tectonic regime in eastern China, and its mineralization was a part of the Late Mesozoic large‐scale mineralization in that region.
A Discussion on the Two‐stage Mineralization of the Baguamiao ‐Shuangwang Gold Orefield, Shaanxi Province, China
Authors: Haishan WANG , Xun LIU
Published: September 2010

Abstract  The gold orefield studied is located on the south border of the underthrust‐collision zone of the Qinling microplate and the North China microplate in the Indosinian epoch. The main ore deposits localized in the area where the WNW‐trending compression‐shear type fault of the Indosinian epoch intersected the NE‐trending tenso‐shear type fault of the Yanshanian epoch. The orebody appeared in a chambered or wedged form. The mineral composition is relatively complex. On the southeastern border of the orefield there have developed intermediate‐acid anatectic magmatites of the Mesozoic Era. Three‐phase inclusions (Lco2, Vco2 and LNaCl‐H2O) comprise over 50%, associated with vapor phase consisting of H2O, CO2, CO, CH4, N2 and H2. The ore‐forming fluids can be divided into 2 stages (the early and the late). The samples are projected in the area of mixture of initial magmatic and meteoric water on the δD‐δ18O diagram, suggesting two types of mineralization, i.e. the re‐equilibrated magmatic‐hydrothermal type and the circulating geothermal water type of a meteoric water source. The mineralization occurring in this orefield might be a superimposition of 2 tectono‐magmatic activities (the Indosinian and Yanshanian movements). Therefore, it is considered a superimposed B‐S type gold orefield.
Post‐Neogene Structural Evolution: An Important Geological Stage in the Formation of Gas Reservoirs in China
Authors: Tingbin WANG
Published: September 2010

Abstract  Tectonic movements since the Neogene have been the major developmental and evolutional stages of the latest global crustal deformation and orogenic movements. China is located in a triangular area bounded by the Indian landmass, the West Siberian landmass and the Pacific Plate, characterized by relatively active tectonic movements since the Neogene, and in this region, natural gas would have been very easy to dissipate, or difficult to preserve. Therefore, the characteristics of post‐Neogene tectonic movements offer important geological factors in researching the formation and preservation of gas reservoirs in China. Summarizing the reservoiring history of gas fields in China, although there are some differences between various basins, they are all affected by the tectonic movements since the Neogene. These movements have certainly caused destruction to the reservoiring and distribution of natural gas in China, which has resulted in a certain dissipation of natural gas in some basins. As a whole, however, they have mainly promoted the reservoiring and accumulation of natural gas: (1) a series of China‐type foreland basins have been formed between basins and ridges in western China, which provide favorable conditions for the formation of large and medium gas fields, as well as controlling the finalization of gas reservoirs in the basins; (2) rows and belts of anticlines have been formed in the Sichuan Basin in central China, which have been the major stages of the formation and finalization of gas reservoirs in that basin; the integral and quick rising and lifting, and a further west‐dipping in the Ordos Basin have resulted in a further accumulation of natural gas in gas fields from Jingbian to Uxin; (3) in eastern China, the Bohai movement in the late Pliocene has provided favorable geological conditions for lately‐formed gas reservoirs in the Bohai Sea area mainly composed of the Bozhong depression; and it also resulted in secondary hydrocarbon generation and formation of secondary gas reservoirs in other basins, as well as the formation of many carbon dioxide gas fields of inorganic origin; (4) in the offshore area, it promoted not only the formation of gas reservoirs of organic origin, but also the formation of inorganic origin non‐hydrocarbon gas reservoirs, as well as the organic and inorganic natural gas of mixed origin, which resulted in the relatively complicated characteristics of gas reservoirs in the area. In short, tectonic movements activated since the Neogene resulted in a reservoiring model mainly characterized by late and superlate hydrocarbon generation and accumulation. These events provide an important geological stage that should not be neglected when studying the formation of gas reservoirs in China.
Application of Biomarkers to Quantitative Source Assessment of Oil Pools
Authors: Sumei LI , Xiongqi PANG , Zhijun JIN
Published: September 2010

Abstract  Recent detailed organic geochemical and geological investigation indicate that oils of the Bamianhe oilfield, Bohai Bay Basin, East China are the mixture of less mature oils and normal oils derived from the Es4 mudstones and shales with a wide range of thermal maturity from immature to middle‐maturity, and most of the oils were proved to be sourced from the depocenter of the Niuzhuang Sag immediately adjacent to the Bamianhe oilfield. Two approaches to quantify the amount of immature oils mixed through quantitative biomarkers were established. One is a relatively simple way only through organic geochemical analysis while the other is to be combined with basin modeling. Selecting biomarkers as proxies is the crucial point in both of them. The results show that the less mature oils mixed in the Bamianhe oilfield is less than 10% and 18% respectively based on the two approaches, which coincide with the results of oil‐source rock correlation.
Sequence Stratigraphy of the Desert System: A Case Study of the Lower Cretaceous in the Kuqa Basin in Xinjiang, Northwestern China
Authors: Mingxiang MEI , Bingsong YU , Weiguang JIN
Published: September 2010

Abstract  The Lower Cretaceous strata in the Kuqa Basin in Xinjiang are marked by a set of arid red beds. Several types of sedimentary facies can be identified in this set of arid red beds: mudstones of the plaza and intracontinental sebkha, aeolian sandstones, sandy conglomerates of the intermittent river, conglomerates of the pluvial fan, etc. These types of sedimentary facies constitute a typical desert system. Therefore, the Cretaceous strata in the Kuqa Basin provide a favorable condition for studies of sequence stratigraphic divisions of the desert system. With the rise and fall of the base level of the sedimentary basin, cyclicity is clearly revealed in stratigraphic records, which helps the identification of the third‐order sequences. Based on the cyclicity in stratigraphic records, 5 third‐order sequences can be found in the strata of the Early Cretaceous in the Kuqa Basin. These sequences comprise a second‐order tectonic sequence. The primary feature of these third‐order sequences is of an upward‐fining sedimentary succession formed by a succession of “coarse sediments of the alluvial system‐fine sediments of the lake system”. The result of this study shows that aeolian sandstones are the best reservoirs of natural gas in the Cretaceous strata in the Kuqa Basin, and that the Kela‐2 gas field is the first large gas field dominated by aeolian sandstone reservoirs in China.
Molar‐tooth Carbonate Sequences and Sr Isotopes in the Neoproterozoic for Stratigraphic Correlation: Research in the Jilin‐Liaoning‐Xuzhou‐Huaiyang Area of the Sino‐Korean Plate and Its Correlation with the Yangtze Plate
Authors: Xianghua MENG , Ming GE , Yanxue LIU , Hongwei KUANG , Weifu LIU , JAN Françoise G. BOURROUILH‐LE , BOURROUILH Robert
Published: September 2010

Abstract  Based on a study of Neoproterozoic carbonates in the Jilin‐Liaoning‐Xuzhou‐Huaiyang area, especially its cyclic sequence stratigraphy and Sr isotopes, two maximum sea flooding events (at 820 Ma and 835 Ma) have been identified. The resulting isochronous stratigraphic correlation proves that these Precambrian strata were connected between the Qingbaikou and the Nanhuan systems with a time range from 750 Ma to 850 Ma. The disappearance of microsparite carbonate and coming of a glacial stage offer important evidence for worldwide stratigraphic correlation and open a window for further correlation of the stratigraphic successions across the Sino‐Korean and Yangtze Plates. A new correlation scheme is therefore provided based on our work.
Ground Subsidence in Areas of Loose Porous Aquifers
Authors: Yixiang LI , Guanhua GAO
Published: September 2010

Abstract  Groundwater is one of the important water resources in northern China's plain areas. Many severe geological hazards have occurred in these areas due to ground subsidence which is caused by over exploitation of groundwater. This paper introduces and analyses the ground subsidence caused by groundwater exploitation and its mechanism in the northern China's plains. A ground subsidence prediction model has been developed based on the consolidation theory. The authors have tested this model in a case study of Fuyang City, Anhui Province, where ground subsidence is a severe environmental problem. In the case study, the model results match very well with those of the actual measurement. Two schemes of groundwater exploitation are assessed. The conclusion from the study could be used in the long‐term water and economical management planning. The strategies for the control of ground subsidence are discussed.
A Titanosaurian Sauropod Dinosaur with Opisthocoelous Caudal Vertebrae from the Early Late Cretaceous of Liaoning Province, China
Authors: Hailu YOU , Qiang JI , LAMANNA Matthew C. , Jinglu LI , Yinxian LI
Published: September 2010

Abstract  We describe a new titanosaurian sauropod dinosaur, Borealosaurus wimani gen. et sp. nov., based on a distinctive mid‐distal caudal vertebra from the early Late Cretaceous Sunjiawan Formation exposed in the Shuangmiao village of Beipiao in Liaoning, China. We provisionally refer an isolated tooth crown, a middle caudal vertebra, and a right humerus from the same locality and horizon to this taxon. Borealosaurus is distinguished from other sauropods in its possession of opisthocoelous mid‐distal caudal vertebrae. The occurrence of opisthocoelous caudals in Borealosaurus and the Mongolian sauropod Opisthocoelicaudia raises the possibility that these taxa pertain to an as‐yet unrecognized titanosaurian subclade endemic to the Cretaceous Asia.
Progress in the Study of Deep Profiles of Tibet and the Himalayas (INDEPTH)
Authors: Wenjin ZHAO , Xun ZHAO , Danian SHI , Kui LIU , Wan JIANG , Zhenhan WU , Jiayu XIONG , Yukun ZHENG
Published: September 2010

Abstract  This paper introduces 8 major discoveries and new understandings with regard to the deep structure and tectonics of the Himalayas and Tibetan Plateau obtained in Project INDEPTH, They are mainly as follows. (1) The upper crust, lower crust and mantle lithosphere beneath the blocks of the plateau form a “sandwich” structure with a relatively rigid‐brittle upper crust, a visco‐plastic lower crust and a relatively rigid‐ductile mantle lithosphere. This structure is completely different from that of monotonous, cold and more rigid oceanic plates. (2) In the process of north‐directed collision‐compression of the Indian subcontinent, the upper crust was attached to the foreland in the form of a gigantic foreland accretionary wedge. The interior of the accretionary wedge thickened in such tectonic manners as large‐scale thrusting, backthrusting and folding, and magmatic masses and partially molten masses participated in the crustal thickening. Between the upper crust and lower crust lies a large detachment (e.g. the Main Himalayan Thrust in southern Tibet, 5–8 km thick) or a very thick shear‐schistose zone (e.g. the Main Qiangtang Thrust—MQT in northern Tibet, up to 20 km thick), which causes the decoupling of the upper crust and lower crust and separation of tectonic activities. (3) During the collision‐compression, the Indian mantle lithosphere was delaminated into two layers from where the crust thickened most rapidly (beneath the High Himalayas). The upper layer extends to 34.5°N and the lower layer to 33.5°. They have been underthrust to depths of 250–300 km into the asthenosphere. Meanwhile the Asian lithosphere (possibly the Qaidam terrane) has also been subducted southwards. Very thick mantle lithosphere does not exist beneath the plateau. (4) The oceanic lithosphere, in light of its lithology and dynamic behaviour, might be close to those of the continental lithosphere and its front might enter the asthenosphere before the continental lithosphere. (5) A 150–200 km deep low‐velocity body below 35°N and a wide low‐velocity zone below the area between 33.5° and 35°N dip north at very steep angles. Volcanism took place frequently in northern Tibet and anisotropy variations are prominent at depths, which might indicate a zone of large‐scale eastward transfer of deep‐seated materials.
New Materials of the Shanita–Hemigordius Assemblage (Permian Foraminifers) from the Baoshan Block, Western Yunnan
Authors: Xiangning YANG , Xiaochi JIN , Zhansheng JI , Yizhao WANG , Jianxin YAO , Hailin YANG
Published: September 2010

Abstract Fossil materials of Shanita and Hemigordius from a section northeast of the Woniusi (the Woniu Temple) of Baoshan, western Yunnan are described and figured in this paper. Field investigation indicates that fossils of these two foraminifer genera are extremely abundant and form a typical Shanita–Hemigordius assemblage in the so‐called “Cracked Limestone” in the Baoshan area. Preliminary study has revealed that the features of this assemblage, which includes Shanita amosi, S. chagouensis, Hemigordius renzi and H. biconcavus, are similar not only to the Shanita fauna previously reported from the Shazipo Formation in the Zhengkang area, west Yunnan, but also to those from the Permian of Burma, Thailand, Iran and Turkey.
Ophiolites from the Mianlüe Suture in the Southern Qinling and Their Relationship with the Eastern Paleotethys Evolution
Authors: Shaocong LAI , Guowei ZHANG , Sanzhong LI
Published: September 2010

Abstract The Mianlüe suture extends from Derni‐Nanping‐Pipasi‐Kangxian to the Lüeyang‐Mianxian area, then traverses the Bashan arcuate structure eastward to the Huashan region, and finally to the Qingshuihe area of the southern Dabie Mountains. From east to west, with a length of over 1500 km, the ophiolitic melangé associations are distributed discontinuously along the suture. The rock assemblages include ophiolite, island‐arc and oceanic island rock series, indicating that there existed a suture zone and a vanished paleo‐ocean basin. The Mianlüe paleo‐ocean basin experienced its main expansion and formation process during the Carboniferous‐Permian and closed totally in the Triassic. It belongs to the northern branch of the eastern paleotethys, separated from the northern margin of the Yangtze block under the paleotethys mantle dynamic system.
Assortment of Deep Mantle Fluids and Their Products in Kimberlites from China
Authors: Lei ZHAO , Jinhua HAO , Yifei DING , Yulong LIU
Published: September 2010

Abstract Based on studies of petrography, mineralogy and mineral chemistry, deep mantle fluids and their products in kimberlites and diamonds can be assorted into the ultradeep fluid‐transmitted minerals with an oxygen‐free feature, the deep fluid metasomatized‐minerals characterized by enrichment in TiO2, K2O, BaO, REE and Fe3+, and the deep fluid‐reformed minerals. The three types show a successive descent in fluid origin depth and metasomatism strength, and they have brought forth a series of corresponding metasomatic products.
Compositions of Upper Mantle Fluids Beneath Eastern China: Implications for Mantle Evolution
Authors: Mingjie ZHANG , Xianbin WANG , Gang LIU , Tongwei ZHANG , Wenrui BO
Published: September 2010

Abstract The composition of gases trapped in olivine, orthopyroxene and clinopyroxene in lherzolite xenoliths collected from different locations in eastern China has been measured by the vacuum stepped‐heating mass spectrometry. These xenoliths are hosted in alkali basalts and considered as residues of partial melting of the upper mantle, and may contain evidence of mantle evolution. The results show that various kinds of fluid inclusions in lherzolite xenoliths have been released at distinct times, which could be related to different stages of mantle evolution. In general, primitive fluids of the upper mantle (PFUM) beneath eastern China are dominated by H2, CO2 and CO, and are characterized by high contents of H2 and reduced gases. The compositions of PFUM are highly variable and related to tectonic settings. CO, CO2 and H2 are the main components of the PFUM beneath cratons; the PFUM in the mantle enriched in potassic metasomatism in the northern part of northeastern China has a high content of H2, while CO2 and SO2 are the dominant components of the PFUM in the Su‐Lu‐Wan (Jiangsu‐Shandong‐Anhui) region, where recycled crustal fluids were mixed with deeper mantle components. There are several fluids with distinct compositions beneath eastern China, such as primitive fluids of upper mantle (CO, CO2 and H2), partial melting fluids (CO2 and CO) and metasomatic fluids mixed with recycled crustal fluids (CO2, N2, SO2 and CH4) etc. Fluids of the upper mantle beneath the North China craton are different from that of the South China craton in total gases and chemical compositions: the contents of the reduced gases of the PFUM in the NCC are higher than those in the SCC.
Theoretical Calculation Model of Heat Transfer for Deep‐derived Supercritical Fluids with a Case Study
Authors: Wenxuan HU , Zhijun JIN , Yucai SONG , Rui SUN , Zhenhao DUAN
Published: September 2010

Abstract Based on a set of equations established by Duan et al. (1992, 1996) for a geofluid system H2O‐CO2‐CH4(‐N2), a formula is obtained to calculate the heat changes. Combining the geological T‐P conditions (geothermal gradients and lithostatic and hydrostatic pressures), the enthalpy of some typical geofluids is figured out. Then the principles of heat transfer of deep‐derived supercritical fluids are discussed. The result shows that deep‐derived geofluids can bring a large amount of thermal heat and release most heat to the shallow surroundings as they move up, because the molar enthalpies vary very greatly from the deep to shallow, increasing with the increases of T and P. Generally, more than tens of kilojoules heat per molar can be released. Furthermore, the molar enthalpy is affected by the compositions of the geofluids, and the molar enthalpy of CO2, CH4, or N2 is greater than that of H2O, being twice, more than twice, and about 140% of H2O, respectively. Finally, a case study is conducted by investigating a source rock sequence affected hydrothermally by magmatic fluids in the Huimin depression of Shengli Oilfield. The thermal heat calculated theoretically of the fluids related to a diabase intrusion is quite large, which can increase the temperature near the diabase to about 300°C, and that can, to some extent, account for the abnormal rise of the vitrinite reflectance, with the highest of about 3.8% (Ro).
What Happened in the Trans‐North China Orogen in the Period 2560‐1850 Ma?
Authors: ZHAO Guochun , Shuwen LIU , SUN Min , Sanzhong LI , WILDE Simon , XIA Xiaoping , ZHANG Jian , HE Yanhong
Published: September 2010

Abstract: The Trans‐North China Orogen (TNCO) was a Paleoproterozic continent‐continent collisional belt along which the Eastern and Western Blocks amalgamated to form a coherent North China Craton (NCC). Recent geological, structural, geochemical and isotopic data show that the orogen was a continental margin or Japan‐type arc along the western margin of the Eastern Block, which was separated from the Western Block by an old ocean, with eastward‐directed subduction of the oceanic lithosphere beneath the western margin of the Eastern Block. At 2550‐2520 Ma, the deep subduction caused partial melting of the medium‐lower crust, producing copious granitoid magma that was intruded into the upper levels of the crust to form granitoid plutons in the low‐ to medium‐grade granite‐greenstone terranes. At 2530‐2520 Ma, subduction of the oceanic lithosphere caused partial melting of the mantle wedge, which led to underplating of mafic magma in the lower crust and widespread mafic and minor felsic volcanism in the arc, forming part of the greenstone assemblages. Extension driven by widespread mafic to felsic volcanism led to the development of back‐arc and/or intra‐arc basins in the orogen. At 2520‐2475 Ma, the subduction caused further partial melting of the lower crust to form large amounts of tonalitic‐trondhjemitic‐granodioritic (TTG) magmatism. At this time following further extension of back‐arc basins, episodic granitoid magmatism occurred, resulting in the emplacement of 2360 Ma, ∼2250 Ma 2110–21760 Ma and ∼2050 Ma granites in the orogen. Contemporary volcano‐sedimentary rocks developed in the back‐arc or intra‐arc basins. At 2150‐1920 Ma, the orogen underwent several extensional events, possibly due to subduction of an oceanic ridge, leading to emplacement of mafic dykes that were subsequently metamorphosed to amphibolites and medium‐ to high‐pressure mafic granulites. At 1880‐1820 Ma, the ocean between the Eastern and Western Blocks was completely consumed by subduction, and the closing of the ocean led to the continent‐arc‐continent collision, which caused large‐scale thrusting and isoclinal folds and transported some of the rocks into the lower crustal levels or upper mantle to form granulites or eclogites. Peak metamorphism was followed by exhumation/uplift, resulting in widespread development of asymmetric folds and symplectic textures in the rocks.
Structures of Syn‐deformational Granites in the Longquanguan Shear Zone and Their Monazite Electronic Microprobe Dating
Authors: Jinjiang ZHANG , Lan ZHAO , Shuwen LIU
Published: September 2010

Abstract: The Longquanguan shear zone is an important structural belt in the North China Craton, separating the underlying Fuping complex from the overlying Wutai complex. This shear zone has experienced three episodes of deformation: the first and main episode is a ductile top‐to‐ESE shear along the gently northwest‐west dipping foliations, while the other two episodes are later collapse sliding. Prolonged granites parallel to the shear foliations make one of the main compositions of the Longquanguan shear zone. These granites experienced deformation to form mylonitic rocks when they emplaced during the first episode of deformation. Structural characters of the granites and their contacts to the country rocks indicate that these granites possibly resulted from in‐situ partial remelting by shearing, i.e., they are syn‐deformational granites. Monazites in these mylonitic granites are magmatic minerals and their crystallization ages may represent ages of the magmatic events, and also the ages for the main deformation of the Longquanguan shear zone. Monazite electronic microprobe dating were carried on two samples of granite, which gives multiple peak ages, among which 1,846 Ma and 1,877 Ma are the main peak ages for the two samples. These ages represent the main deformation of the Longquanguan shear zone, which is consistent with the main regional geological event at about 1,850 Ma caused by the collision between the Eastern and Western Blocks in North China. The good match between the monazite ages and the corresponding regional tectono‐thermal events shows the feasibility and reliability of monazite electronic microprobe dating.
SHRIMP Zircon U‐Pb Chronology and Geochemistry of the Henglingguan and Beiyu Granitoids in the Zhongtiao Mountains, Shanxi Province
Authors: Shengqiang YU , Shuwen LIU , Wei TIAN , Qiugen LI , Yonggang FENG
Published: September 2010

Abstract: Henglingguan and Beiyu metamorphic granitoids, distributed in the northwest of the Zhongtiaoshan Precambrian complex, comprise trondhjemites and calc‐alkaline monzogranites, displaying intrusive contacts with the Archean Zhaizi TTG gneisses. And the Beiyu metamorphic granitoids consist mainly of trondhjemites, distributed at the core of the Hujiayu anticline fold. New SHRIMP zircon U‐Pb dating data show that the weighted mean 207Pb/206Pb ages are 2435.9 Ma and 2477 Ma for the Henglingguan metamorphic calc‐alkaline monzogranites and Beiyu metamorphic trondhjemites, respectively, and reveal ∼2600 Ma inherited core in magmatic zircons. Whole‐rock geochemical data indicate that all the Henglingguan and Beiyu metamorphic trondhjemites and calcalkaline monzogranites belong to the metaluminous medium‐ and high‐potassium calc‐alkaline series. These rocks are characterized by relatively high total alkali contents (Na2O+K2O, up to 9.08%), depleted Nb, Ta, P and Ti, and right‐declined REE patterns with moderate to high LREEs/HREEs fractionation (the mean ratio of (La/Yb)n = 25). The Henglingguan and Beiyu metamorphic trondhjemites display negative Rb, Th and K anomalies in the multi‐element spider diagrams normalized by primitive mantle. Sm‐Nd isotopic data reveal that these granitoids have initial ∍Nd(t)=‐1.2 to +2.4 and Nd depleted mantle model ages of TMD= 2622 Ma‐2939 Ma. All these geochemical features indicate that these granitoids were formed in an continent‐marginal arc, and the trondhjemites mainly originated from partial melting of juvenile basaltic materials and, howbeit, the Henglingguan metamorphic calc‐alkaline monzogranites derived from recycling of materials in the ancient crust under a continent‐marginal arc. The granitic magma underwent contamination and fractional crystallization during their formation.
A New Genus and Species of Sapeornithidae from Lower Cretaceous in Western Liaoning, China
Authors: Chongxi YUAN
Published: September 2010

Abstract: Sapeornithidae is a basal pygostylian family of Early Cretaceous primitive birds, in which only one genus and species, Sapeornis chaoyangensis, was reported before. This paper deals with a new genus and species of this family, Didactylornis jii gen. et sp. nov., which was unearthed from the Early Cretaceous Jiufotang Formation in western Liaoning. According to our phylogenetic analyses, both Didactylornis gen. nov. and Sapeornis form a sister group, which is basal to the clade formed by Confuciusornis and all the more derived birds, and more closely related to the short‐tailed pygostylian birds than to the long‐tailed avialian birds. The early history of pygostylian birds is poorly documented except for the studies of Confuciusornis and Sapeornis. The discovery of Didactylornis jii gen. et sp. nov. adds the new material for the study on the early evolution of birds.
Late Cenozoic Stratigraphy and Paleomagnetic Chronology of the Zanda Basin, Tibet, and Records of the Uplift of the Qinghai‐Tibet Plateau
Authors: Xiangang MENG , Dagang ZHU , Zhaogang SHAO , Chaobin YANG , Jianen HAN , Jia YU , Qingwei MENG , Rongping LU
Published: September 2010

Abstract: The characteristics of Late Cenozoic tectonic uplift of the southern margin of the Qinghai‐Tibet Plateau may be inferred from fluvio‐lacustrine strata in the Zanda basin, Ngari, Tibet. Magnetostratigraphic study shows that the very thick fluvio‐lacustrine strata in the basin are 5.89–0.78 Ma old and that their deposition persisted for 5.11 Ma, i.e. starting at the end of the Miocene and ending at the end of the early Pleistocene, with the Quaternary glacial stage starting in the area no later than 1.58 Ma. Analysis of the sedimentary environment indicates that the Zanda basin on the southern Qinghai‐Tibet Plateau began uplift at ∼5.89 Ma, later than the northern Qinghai‐Tibet Plateau. Presence of gravel beds in the Guge and Qangzê Formations reflects that strong uplift took place at ∼5.15 and ∼2.71 Ma, with the uplift peaking at ∼2.71 Ma.
Synthesis of Mullite from High‐alumina Fly Ash: a Case from the Jungar Power Plant in Inner Mongolia, Northern China
Authors: Jiangfeng CHEN , Longyi SHAO , Jing LU
Published: September 2010

Abstract: In this paper, an experimental study was conducted in order to test the feasibility of sintering mullite directly from the high‐alumina fly ash, without adding any extra material. The results show that the mullite contents in most sintered samples are over 70%. The samples sintered from the beneficiated fly ash have a higher content of mullite than those from the as‐received fly ash under the same synthetic conditions. To obtain an equal amount of mullite, a higher sintering temperature is needed for the beneficiated fly ash than for the as‐received fly ash. Considering the physical properties of sintered mullite, the favorable sintering temperature is 1400 °C for the as‐received fly ash and 1500 °C for the beneficiated fly ash. A higher sintering temperature and a shorter holding time are profitable to sintering mullite. The orthogonal test confirmed that the dominant factor affecting mullite synthesis is sintering temperature, and that the most profitable matching conditions are 200 MPa‐1500 °C‐3 h for the as‐received fly ash and 200 MPa‐1500 °C‐4 h for the beneficiated fly ash.
Geochemistry of the Limahe Intrusion in the Panxi District, SW China: Discussion on the Relationship to the Emeishan Basalts
Authors: Ying LI , Zhaochong ZHANG , Yu AI , Li ZHAO , Tiezheng YANG
Published: September 2010

Abstract: The Limahe intrusion is a typical rock hosting Cu‐Ni sulfide deposit in the Panxi district. The major element, trace element and Sr‐Nd isotopic geochemical data are reported in this study both firstly and systemically. Age‐corrected (87Sr/86Sr), and εNd(t) isotope values, ranging from 0.687062 to 0.709298, from –0.6 to –4.13 respectively, are partly overlap the field of the Emeishan basalt and OIB, and they lie between upper crust and OIB generally. The similar patterns between the Limahe intrusion and the picrites of the Emeishan large igneous province imply the genetic relationship to the Emeishan basalts. Their lower Nb/U (<30), higher (La/Nb)PM and (Th/Ta)PM ratio values (>1) indicate contamination of the upper crust material. The correlation between MgO and major oxides reflects the fractional crystallization of olivine, clinopyroxene and minor plagioclase in the deep‐seated chamber. Therefore increased SiO2 and lowered FeO by the upper crustal contamination may trigger immiscible sulfide melt, which then flowed along the structural fracture and intruded into gabbrodiorite, resulting in the formation of Cu‐Ni sulfide orebody.
Mesoproterozoic Continental Arc Type Granite in the Central Tianshan Mountains: Zircon SHRIMP U‐Pb Dating and Geochemical Analyses
Authors: Tiannan YANG , Jinyi LI , Guihua SUN , Yanbin WANG
Published: September 2010

Abstract: The Central Tianshan belt in northwestern China is a small Precambrian block located in the southern part of the Central Asia Orogenic Belt (CAOB), which is considered as “the most voluminous block of young continental crust in the world” that comprises numerous small continental blocks separated by Paleozoic magmatic arcs. The Precambrian basement of the central Tianshan Mountains is composed of volcanic rocks and associated volcano‐sedimentary rocks that were intruded by granitic plutons. Geochemical analyses demonstrate that the granitic plutons and volcanic rocks were generated in the Andean‐type active continental arc environment like today's Chile, and the zircon U‐Pb SHRIMP dating indicates that they were developed at about 956 Ma, possibly corresponding to the subduction of the inferred Mozambique Ocean under the Baltic‐African super‐continent.