摘要:The rapid identification based on InSAR technology was proved to be effective in our emergency investigation of surface ruptures and geohazards induced by the Yushu earthquake. The earthquake-generating fault of the Yushu earthquake is the Yushu section of the Garzê-Yushu faults zone. It strikes NWW-NW, 23 km long near the Yushu County seat, dominated by left-lateral strike slip, and appearing as a surface rupture zone. The macroscopic epicenter is positioned at Guo-yang-yan-song-duo of Gyegu Town (33°03'11''N, 96°51'26''E), where the co-seismic horizontal offset measured is 1.75 m. Geohazards induced by the Yushu earthquake are mainly rockfalls, landslides, debris flows, and unstable slopes. They are controlled by the earthquake-generating fault and are mostly distributed along it. There are several geohazard chains having been established, such as earthquake, canal damage, soil liquefying, landslide-debris flow, earthquake, soil liquefying, roadbed deformation, etc. In order to prevent seismic hazards, generally, where there is a visible surface rupture induced by the Yushu earthquake, reconstruction should be at least beyond 20 m, on each side, from it. Sufficient attention should also be given to potential geohazards or geohazard chains induced by the earthquake.

摘要:A new sauropod dinosaur, Liubangosaurus hei gen. et sp. nov., is erected based on a specimen represented by five articulated middle-caudal dorsal vertebrae, which was discovered in the Lower Cretaceous Napai Formation of Guangxi Province, southern China. This new taxon is diagnosed by a unique combination of derived features: prezygapophysis closely contacts with parapophysis, with the prdl and prpl absent; presence of cavity on the dorsal surface of the diapophysis; neural spine very low, with its distal end level with that of diapophysis; distal end of the neural spine strongly expanded laterally to form a platform; marked fossa formed between the infradiapophyseal lamina and the parapophysis; broad, flat area of featureless bone on lateral surface of neural arch; vertically directed infradiapophyseal lamina expands or bifurcates ventrally to form a inverted “Y”; highly positioned parapophyses large and tear-drop in shape. The discovery of this new taxon increases the diversity of sauropods in China during the Early Cretaceous.

摘要:A new dinosaur Chuxiongosaurus lufengensis gen. et sp. nov. is erected based on a nearly complete skull. The taxon is characterized by the lacrimal perpendicular to the ventral margin of the upper jaw, which is similar to that of Thecodontosaurus; a depression present on the dorsal profile of the snout behind the naris; the rostral profile of the maxilla slopes continuously towards the rostral tip; and the presence of 25 dentary teeth. It also displays prosauropod characters such as a relatively long skull, the slope of the maxillary rostral profile, and teeth that do not have basically constricted crowns. The new specimen is more basal than Anchisaurus and represents the first basal sauropod dinosaur from the Early Jurassic of China.

摘要:Fourteen graptolite species of the Late Tremadoc and Early Floian are described from the Nanba section in the Yiyang area, Hunan Province. Among them, Paradelograptus onubensis, Kiaerograptus bulmani, K. kutchini and Paratemnograptus isolatus of the Late Tremadoc are first found in China. Based on the current graptolite materials, the correspondingly complete graptolite zones of Upper Tremadocian in China are recognized as follows (in ascending order): the Adelograptus tenellus Zone, the Aorograptus victoriae Zone, the Araneograptus murrayi Zone and the Hunnegraptus copiosus Zone. In the Nanba section, the Hunnegraptus copiosus Zone is overlain directly by the Tetragraptus approximatus Zone, there is no hiatus below the base of Floian.

摘要:Most of the so-called Bayan Obo fine-grained dolomite marbles collected from the main and east orebodies show a microporphyritic texture, namely the microphenocrysts are set in a very fine-grained matrix, although nearly all of them have undergone recrystallization caused either by deformation or alteration. The texture seems likely to have maintained the original features. It is known that one of the most characteristic textures of volcanic rocks is the porphyritic texture, and the microporphyritic texture is a variety in which both the phenocrysts and the matrix are only distinguishable with the microscope. Therefore, the dolomite marbles in the main and east orebodies may be related to the extrusive carbonatites. In addition, there also occur some carbonatite sills and dykes with different textures at Bayan Obo. Thus, the Bayan Obo carbonatites are polyphase intrusive and extrusive carbonatites.

摘要:The Ailaoshan-Red River (ASRR) shear zone is one of the major Southeast Asian tectonic discontinuities that have figured the present tectonic framework of the eastern Tibet. Several metamorphic massifs are distributed linearly along the shear zone, e.g. Xuelongshan, Diancangshan, Ailaoshan and Day Nui Con Voi from north to south. They bear a lot of lines of evidence for the tectonic evolution of the eastern Tibetan at different crustal levels in different tectonic stages. Controversy still exists on the deformation structures, microstructures and their relationship with metamorphisms along the ASRR. In this paper detailed microstructural and EBSD (Electron Backscattered Diffraction) fabric analysis of some highly sheared granitic rocks from different massifs along the ASRR are conducted. High temperature structures and microstructures are preserved in unsheared gneisses, in weakly sheared xenoliths or in some parts of the highly sheared rocks (mylonites). Several types of high temperature quartz c-axis fabrics show symmetrical patterns or transitions from symmetrical to asymmetrical patterns. The former are attributed to coaxial deformation during regional shortening in an early stage of the Indian-Eurasian tectonic interaction and the latter are related to the transitions from coaxial compression to noncoaxial shearing during the post-collisional ASRR left lateral shearing.

摘要:The Tengchong geothermal area, an active tectonic region with frequent earthquakes, is located in Yunnan Province of southwestern China. This area contains abundant active hot springs, which often display high metal concentrations and obvious mineralization phenomena. At 19:19 on 9 July 2009, an earthquake occurred in Yao’an, Chuxiong, Yunnan Province, which is 300 km to the northeast of the Tengchong geothermal area. We sampled water in the hot springs in the Tengchong area from 4 July to 9 July 2009 and from 10 July to 15 July 2009 to study the changes of elemental concentrations before and after the earthquake and discuss the influence of the earthquake on the mineralization of the hot springs. The concentrations of most trace elements increased slightly, but the concentration of REE (rare earth elements) decreased by 50% after the earthquake in the hot springs around a NS-trending fault. The elemental concentrations remained unchanged in Longtan and Suanshuigou, which are related to an inactive crater. The elemental concentrations in other springs controlled by superficial and small-scale faults decreased after the earthquake. The earthquake can stimulate the activity of deep faults and magma chambers, as is responsible for the increase of metal concentrations in the hot springs along the NS-trending deep fault; whereas it can decrease the porosity of permeable rocks, resulting in the decline of the flux of ore-bearing fluids and the corresponding mineralization in the hot springs related to superficial faults.

摘要:The Chang’an gold ore deposit in western Yunnan is located at the southern segment of the Ailaoshan metallogenic belt. The ore bodies are preserved in fractured Ordovician sedimentary clastic rocks. The gold-bearing minerals occur dominantly in sulfide-quartz veins. Fluid inclusion analysis shows that the Chang’an gold ore deposit is characterized by epithermal gold mineralization at temperatures between 200°C and 280°C at a shallow crustal level. The mineralizing fluids have intermediate to low salinity (6%-18%) and low densities (0.72-1.27 g/cm3). The ore minerals have δ34S in a range from -13‰ to 3.57‰, concentrated from -2.06‰ to 3.57‰ with an average of 1.55‰. The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb values are 18.9977-19.5748, 15.7093-15.784, 39.3814-40.2004 respectively. These isotope data suggest that the ore-forming elements were mainly derived from mixed crustal and mantle sources. The Chang’an gold ore deposit and Tongchang Cu-Mo deposit are closely related to each other in their spatial distribution and age of formation. They have similar sources of mineralizing elements and identical ore-forming metal elements, and show a close relationship in physical and chemical conditions of mineralization. The two deposits constitute an epithermal-porphyry-skarn type Cu-Mo-Au mineralization system in the Tongchang-Chang’an area, which is related to the Cenozoic high-K alkaline magmatism.

摘要:Red clay type gold deposits, located in the south of China, are situated not only in orogenic belts, but also in inner cratons, where climate is tropical-subtropical with clear arid and humid. The lateritic weathering crust often can be divided into five zones, including topsoil, siliceous duricrust zone, multi-color zone (or red clay zone in some deposits), pallid zone and saprolite zone from surface to the base rock, several of which are absent in some deposits. The base rocks are composed mainly of carbonate rocks with minor clastic rocks, intermediate-basic volcanic rocks and intermediate-acid and alkalic intrusions. The orebodies are mainly located in the multi-color zone with part of them in the pallid and saprolite zones. The ore sources include orebodies of Carlin-type gold deposits and porphyry gold deposits, as well as gold-rich base rocks. The red clay type gold deposits experienced early-stage endogenic gold mineralization and laterization during the Tertiary and Quaternary. The areas with endogenic gold deposits, especially Carlin-type gold deposits and porphyry gold deposits in karst depressions on the plateau, structual erosional platforms in the middle-lower mountains, and intermountain basins in southern China are well worth studying to trace red clay type gold deposits.

摘要:The western margin of Yangtze Craton is known as a significant sediment-hosted base-metal aggregate cluster, especially for Pb–Zn deposits in China, e.g. Jinding, Daliangzi, Tianbaoshan, Kuangshanchang and Qinlinchang deposits. In comparison with the classic MVT deposits in the world, based on the basic geology of the sediment-hosted Pb-Zn deposits, this paper focuses on temporal–spatial distribution of this deposit to further discuss its large scale mineralization and tectonic evolution history. In the SW Sanjiang Thethys, Jinding deposit is typically thrust fault-controlled and hosted mainly in the sandstones and breccia-bearing sandstones, whereas MVT-type deposits are controlled by lithology and faulting/fracturing with a strong preference for carbonate-hosted rocks. Most importantly, Jinding Pb–Zn deposit differs from the other types of sediment-hosted Pb–Zn deposits in which it was formed in a strongly deformed foreland basin within a continental collision zone. In the Kangdian area, the sediment-hosted Pb–Zn deposits were formed in the extensional basin on the side of the continental orogenic belt along the Yangtze Craton. Compared with classic MVT deposits, the Pb–Zn deposits in the Kangdian area belong to MVT deposits. This paper is significant not only for interpretation of the genesis of sediment-hosted Pb–Zn deposits but also for exploiting large base metal deposits in large sedimentary target areas.

摘要:REE fractionation during the weathering of dolomite has been recognized for decades. A regolith profile on dolomite in southwest Yunnan of China was selected to investigate the behaviors of REE during weathering. The weathering of dolomite is divided into two stages: the pedogenesis stage and soil evolution stage, corresponding to the saprolites and soils respectively in the regolith profile. SiO2, TiO2, P2O5, Zr, Hf, Nb and Ta were immobile components during the weathering by and large, while Al2O3, K2O and Fe2O3 were lost during the soil evolution stage in the physical form (clay minerals probably). REE were fractionated during the whole weathering of dolomite. The field weathering profile and the lab acid-leaching experiments on dolomite indicate that MREE were enriched clearly relative to other REE during the pedogenesis stage in a “capillary ascending-adsorption” mechanism, but they did not fractionate clearly in the soil evolution stage. REE were lost and accumulated in the weathering front of dolomite during the soil evolution stage in a “physical-chemical leaching” mechanism.

摘要:Eocene felsic porphyric rocks and the high-Mg potassic volcanic rocks (HMPR) occur along the Jinshajiang-Ailao Shan-Red River shear zone (JARSZ) in eastern Tibet. Compared with the HMPR, which are generally believed to be sourced from an enriched mantle, the felsic porphyric rocks show similar K2O contents, enrichment in LREE and LILE, particularly radiogenic isotope (e.g. Sr and Nd) features much similar to the former, implying generation of the felsic porphyric rocks most likely related to the HMPR, although they both have clearly different major and trace element compositions. The close relationship in spatial-temporal distribution and similar Sr-Nd characteristics between the felsic porphyric rocks and HMPR in eastern Tibet indicate that both of them were possibly formed by a similar tectonic process (event). Combining the basic dikes in southern and eastern Tibet, we suggest that the break-off of north-dipping Neo-Tethyan slab in southern Tibet during 50-40 Ma, triggered formation of high-Mg potassic magma. This led to developing felsic porphyric magma production by partial melting of underplating HMPR in the lower crust, or fractionation crystallization of the high-Mg potassic magmas. The break-off of slab in the Eocene may also have contributed to the abundant ore-forming material related to earlier subduction events, resulting in formation of the porphyric deposits along JARSZ in eastern Tibet.

摘要:The Nadingcuo high-K calc-alkaline rocks mainly composed of trachyte and trachyandesite are the largest outcrop area of volcanic rocks in southern Qiangtang terrane in the Tibetan plateau. However, their exact source and peterogenesis are still debated. 40Ar-39Ar and LAM-ICPMS zircon U-Pb isotopic dating confirm that these rocks erupted in Eocene. In addition, the Nadingcuo volcanic rocks are characterized by high Sr/Y content ratios, similar with the adakite derived from partial melting of oceanic crust. They can be further classified as high Mg# (Mg#=48–57) and low Mg# (Mg#=33–42) subtypes. The Nadingcuo adakitic rocks have relatively low (87Sr/86Sr)i and high εNd(t), showing a trend of similarity to the Dongcuo ophiolite present in the Bangong-Nujiang oceanic crust. Simple modeling indicates that the Nadingcuo adakitic rocks are a mix resulting from the basalt of Bangong-Nujiang Ocean with 10%–20% crustal material of Lhasa terrane. On these bases we suggest that the low Mg# Nadingcuo adakitic rocks are the product of partial melting of remnant oceanic crust with small sediment, and the high Mg# rocks are the result of reaction between rising melt of remnant oceanic crust with subducted sediment and mantle wedge. Therefore, the origin of Nadingcuo adakitic rocks may be related to intracontinental subduction triggered by collision of India-Asia during Cenozoic.

摘要:The Ailao Shan-Red River fault zone is the boundary between the Yangtze block to the northeast and the Indochina block to the southwest. It is an important tectonic zone due to its role in the southeastward extrusion of the Indochina block during and subsequent to the Indian-Eurasian collision. Diancang Shan (DCS) high-grade metamorphic complex, located at the northwest extension along the Ailao Shan-Red River (ASRR) shear zone, is a representative metamorphic complex of the ASRR tectonic belt. Structural and microstructural analysis of sheared rocks in the high-grade metamorphic rocks reveals that they are coherent with solid-state high-temperature ductile deformation, which is attributed to left-lateral shearing along the ASRR shear zone. New LA-ICP-MS zircon U-Pb geochronological and microstructural studies of the post-kinematic granitic plutons provide a straightforward time constraint on the termination ductile left-lateral shearing and exhumation of the metamorphic massif in the ASRR shear zone. It is suggested that the left-lateral shearing along the ASRR shear zone ended at ca. 21 Ma at relative lower-temperature or decreasing temperature conditions. During or after the emplacement of the young dikes at ca. 21 Ma, rapid brittle deformation event occurred, which makes the DCS massif start fast uplift/exhumation and cooling to a shallow crustal level.

摘要:The Muchang composite intrusion is located about 14 km southeast of the Fengwei town and south of the Baoshan-Zhenkang block. The rift-related intrusion consists of the early-stage riebeckite nordmarkite in the east and west sides and the discontinuous marginal zone, the late-stage main body of dominant riebeckite granite, and minor aegirine granite. Studies on petrological geochemistry and LA-ICP-MS zircon U-Pb dating of the late-stage riebeckite granite, origin and evolution of the Muchang alkali granite and the relationship between the granite and the associated skarn-type Luziyuan Pb-Zn deposit are discussed in this paper. The results show that the Muchang alkali granites belong to A-type granites, which are characterized by enrichment in Al2O3, SiO2 ,total alkali and Fe, depletion in MgO and CaO contents with high FeOT/MgO ratios. The REE concentrations are relatively high, exhibiting highly fractionated LREE patterns with significantly Eu negative anomaly. The Muchang granites are obviously enriched in lithophile elements (e.g., Rb, K, U and Th) and high field strength elements (e.g., Zr, Hf, Nb, Y and Ga) with high 10000×Ga/Al ratios and depleted in Sr, Ba, Ti, Cr and Ni, which are similar to those of the A-type granites and quite different from those of S-type and I-type granites. The LA-ICP-MS zircon dating results of the Muchang granite gave a weighted mean age of 266.2±5.4 Ma (2σ), suggesting that they were formed in the stage of extension at the end of post-collision at Middle Permian and the consumption of Paleo-Tethys ocean took place before 266 Ma. It is suggested that the unexposed intermediate-acid intrusive rocks in the Luziyuan ore district, which is the “sister” rocks material of the Muchang granites and related closely to Luziyuan Pb-Zn mineralization, were the product of Middle Permian.

摘要:The Hadamiao granodiorite, located on the northern margin of the North China platform and acting as the country rock of gold deposits in the Hadamiao region, was formed in the same age and similar tectonic settings with the Hadamiao gold deposit and the large-scale Bilihe gold deposit in the same area. By using the LA-ICP-MS method, the U-Pb age obtained is 267±1.3 Ma, which represents the crystallized age of the granodiorite, and that of the xenolithic zircon is 442.8±5 Ma. Base on the main elements, it exhibits the features of calc-alkaline to high-potassium calc-alkaline series, low silicon, and quasi-aluminous I-type granites, and with high magnesium (Mg#=0.45–0.57) and high sodium contents (Na2O/K2O=0.98–2.29). The SREE values (81.6–110.15 ppm) are relatively low, the fractionations between LREE and HREE are obvious, showing a right-inclined dispersion in the REE distribution diagram. Compared with the primitive mantle, the rock is relatively rich in LREE (La and Ce), LILE (K, Sr, and Th), and intensively depleted in HFSE (Ti, P, Nb and Ta). The ratios of Sr/Y and (La/Yb)N and the contents of Rb, Nb and Y are relatively low, the Sr values are high (436.35–567.26 ppm), and the Yb contents of most samples are low (1.25–1.8), which indicate the features of typical continental margin arc and adakitic rocks. According to the values of εNd(t) (?2.4 to +0.2) and ISr (0.7028–0.7083), and variations of the La/Sm ratios, the Hadamiao granodiorite was formed from mixing of the thickened molten lower crust and the mantle wedge substances. The rock was related to the southward subduction and accretion of the Paleo-Asia Ocean in the Late Paleozoic, being Late Paleozoic magma of the continental margin arc formed on the basement of the Early Paleozoic accretion complexes, and showing a trend of turning into adakitic rocks, which indicates their great metallogenic (Au) potential.

摘要:The Turpan-Hami Basin in eastern Xinjiang is one of the driest regions on Earth and a premier environment to form and preserve nitrate. A large nitrate ore field in this basin was found recently. It is estimated there are about 2.5 billion tons of resources of nitrate, and the amount is as much as the Atacama Desert super-scale nitrate deposit in Chile. Nitrate is one of a few minerals with mass-independent fractionation (MIF), and the oxygen isotope MIF is an effective method to determine the source of nitrate. The δ17O, δ18O of nitrate were measured by fluorination and thermal decomposition method. The date indicated that this is the first time that oxygen isotope MIF has been located in inland nitrate minerals. The results obtained by two methods are similar, Δ17O=δ17O?0.52×δ18O=12‰–17‰. The experiment and observation data proved that oxygen isotope MIF of nitrate are the result of photochemical reactions in the troposphere and stratosphere. Thus, evidence from MIF oxygen isotopic compositions indicate that long term atmospheric deposition of nitrate aerosol particles produced by photochemical reactions is the source of the deposits.

摘要:This study examined spatial variations in the concentration, grain size and heavy mineral assemblages on Cedar Beach (Lake Erie, Canada). Magnetic studies of heavy mineral-enriched, dark-reddish sands present on the beach showed that magnetite (~150 μm) is the dominant magnetic mineral. Surficial magnetic susceptibility values defined three zones: a lakeward region close to the water line (Zone 1), the upper swash zone (Zone 2) and the region landwards of the upper swash zone (Zone 3). Zone 2 showed the highest bulk and mass susceptibility (κ, χ) and the highest mass percentage of smaller grain-size (<250 μm) fractions in the bulk sand sample. Susceptibility (i.e. κ and χ) values decreased and grain size coarsened from Zone 2 lakewards (into Zone 1) and landwards (into Zone 3), and correlated with the distribution of the heavy mineral assemblage, most probably reflecting preferential separation of large, less dense particles by waves and currents both along and across the beach. The eroded western section of Cedar Beach showed much higher concentrations of heavy minerals including magnetite, and finer sand grain sizes than the accreting eastern section, suggesting that magnetic techniques could be used as a rapid, cost-effective way of examining erosion along sensitive coastline areas.

摘要:Zabuye Salt Lake in Tibet, China is a carbonate-type salt lake, which has some unique characteristics that make it different from other types of salt lakes. The lake is at the latter period in its evolution and contains liquid and solid resources. Its brine is rich in Li, B, K and other useful minor elements that are of great economic value. We studied the concentration behavior of these elements and the crystallization paths of salts during isothermal evaporation of brine at 15°C and 25°C. The crystallization sequence of the primary salts from the brine at 25°C is halite (NaCl) → aphthitalite (3K2SO4·Na2SO4) → zabuyelite (Li2CO3)→ trona (Na2CO3·NaHCO3·2H2O) → thermonatrite (Na2CO3·H2O) → sylvite (KCl), while the sequence is halite (NaCl) → sylvite (KCl) → trona (Na2CO3·NaHCO3·2H2O) → zabuyelite (Li2CO3) → thermonatrite (Na2CO3·H2O) → aphthitalite (3K2SO4·Na2SO4) at 15°C. They are in accordance with the metastable phase diagram of the Na+, K+-Cl?, CO32?, SO42?-H2O quinary system at 25°C, except for Na2CO3·7H2O which is replaced by trona and thermonatrite. In the 25°C experiment, zabuyelite (Li2CO3) was precipitated in the early stage because Li2CO3 is supersaturated in the brine at 25°C, in contrast with that at 15°C, it precipitated in the later stage. Potash was precipitated in the middle and late stages in both experiments, while boron was concentrated in the early and middle stages and precipitated in the late stage.

摘要:The pool-forming mechanism of coalbed methane has its own characteristics. In this paper, based on studies on the typical coal-bearing basins in China, it is pointed out that the reservoir formation of medium- to high-rank coalbed methane has experienced three critical stages: the coalbed methane generation and adsorption stage, the coalbed adsorption capacity enhancement stage, and the coalbed methane desorption-diffusion and preservation stage. The regional tectonic evolution, hydrodynamic conditions and sealing conditions play important roles in the stage of coalbed methane desorption-diffusion and preservation. Medium- to high-rank coalbed methane has three types of enrichment models, that is, the most favorable, the relatively favorable, and the unfavorable enrichment models.

摘要:Four coal samples of different ranks are selected to perform the adsorption measurement of high-pressure methane (CH4). The highest equilibrium pressure of the measurement exceeds 20 MPa. Combined with the measuring results and theoretical analyses, the reasons for the peak or the maximum adsorption capacity appearing in the excess adsorption isotherms are explained. The rules of the peak occurrence are summarized. And then, based on the features of coal pore structure, the adsorption features of high-pressure gas, the microcosmic interaction relationship of coal surface and CH4 molecule, and the coalbed methane reservoir conditions, three theoretical assumptions on the coal adsorption high-pressure CH4 are suggested. Thereafter, on the basis of these theoretical assumptions, the Ono-Kondo lattice model is processed for simplification and deformation. Subsequently, the equations modeling the excess adsorption isotherm of high-pressure CH4 adsorption on coal are obtained. Through the verification on the measurement data, the fitting results indicate that it is feasible to use the Ono-Kondo lattice mode to model the excess adsorption isotherm of high-pressure CH4 adsorption on coal.