Enhanced sulfur and nitrogen deposition has been observed in many transect regions worldwide,from urban/agricultural areas to mountains.The Sichuan Basin(SCB),with 18 prefectural cities,is the most economically-develo...Enhanced sulfur and nitrogen deposition has been observed in many transect regions worldwide,from urban/agricultural areas to mountains.The Sichuan Basin(SCB),with 18 prefectural cities,is the most economically-developed region in western China,while the rural Qinghai-Tibetan Plateau(QTP)lies west of the SCB.Previous regional and national atmospheric modeling studies have sug-gested that large areas in the SCB-to-QTP transect region experience excessive deposition of sulfur and nitrogen.In this study,we applied a passive monitoring method at 11 sites(one in urban Chengdu and 10 from fivenature reserves)in this transect region from September 2021 to October 2022 to confirm the high sulfur and nitrogen deposition fluxes and to understand the gaps between the modeling and observation results for this transect region.These observations suggest that the five reserves are under eutrophication risk,and only two reserves are partially under acidification risk.Owing to the complex topography and landscapes,both sulfur and nitrogen deposition and critical loads exhibit large spatial variations within a reserve,such as Mount Emei.Regional atmospheric modeling may not accurately capture the spatial variations in deposition fluxes within a reserve;however,it can capture general spatial patterns over the entire transect.This study demonstrates that a combination of state-of-the-art atmospheric chemical models and low-cost monitoring methods is helpful for ecological risk assessments at a regional scale.展开更多
Xi Jinping Thought on Ecological Civilization contains new concepts,ideas,and strategies that feature Chinese characteristics and the spirit of the times and promote the progress of human civilization.Xi Jinping Thoug...Xi Jinping Thought on Ecological Civilization contains new concepts,ideas,and strategies that feature Chinese characteristics and the spirit of the times and promote the progress of human civilization.Xi Jinping Thought on Ecological Civilization is also the fundamental guide for compliance and action in terms of China’s practices in building an ecological civilization in the new era.Since the 18th National Congress of the Communist Party of China(CPC),Xi Jinping,general secretary of the Communist Party of China Central Committee,has made several inspection tours to Sichuan and given a series of important instructions on green development and building an ecological civilization in Sichuan province.This paper reviews the contemporary meaning and theoretical significance of Xi Jinping Thought on Ecological Civilization and uses them to systematically examine the overall performance of building a beautiful Sichuan,following the guidance of Xi Jinping’s important instructions for the governance of Sichuan.This paper selects and analyzes typical cases that demonstrate the national effect in Sichuan to summarize Sichuan’s unique experiences in the practice of Xi Jinping Thought on Ecological Civilization.展开更多
The recent discovery of natural gas within the fifth member of the Xujiahe Formation(T_(3)x_(5))in the Dongfeng area within the Sichuan Basin highlights the significant exploration potential of this member.However,the...The recent discovery of natural gas within the fifth member of the Xujiahe Formation(T_(3)x_(5))in the Dongfeng area within the Sichuan Basin highlights the significant exploration potential of this member.However,the unconvincing previous understanding of the sedimentary microfacies,combined with a total lack of studies on the sand body architecture and reservoir distribution,hampers the further exploration of this member.Using core data,log curves,and seismic data,along with sedimentary microfacies analysis,this study investigated the interfaces between the sand bodies of various scales in the Dongfeng area.Furthermore,this study explored the morphological characteristics,types,and stacking patterns of these sand bodies and determined the distributions of sand bodies and reservoirs in the area.The results indicate that the first sand group of the T_(3)x_(5) member(T_(3)x^(1)_(5))exhibits delta-front deposits,including subaqueous distributary channels,sheet sands,and interdistributary bays.Seven levels of sand body interfaces are identified in the T_(3)x^(1)_(5) sand group.Among them,the interfaces of the first and second levels were identifed only in cores,those of the third and fourth levels were recog-nizable from cores combined with log curves,while those of the fifth,sixth,and seventh levels were distinguishable using seismic data.Three superimposed subaqueous distributary channel complexes are found in the Dongfeng area.Among them,complex 1 in the northwest exhibits the strongest water body energy,while complex 2 in the south displays the weakest.Complex 2 was formed earlier than com-plexes 1 and 3.Also,complex 1 is further subdivided into three vertically stacked subaqueous distrib-utary channels.The subdivision of sedimentary microfacies in the T_(3)x_(5) member reveals nine lithofacies types.Among them,stacked pancake-shaped,carbonaceous debris-bearing,massive,and cross-bedded medium-grained sandstones are considered favorable lithofacies.These four lithofacies types exhibit high porosity,as well as low natural gamma-ray(GR)values,low-to-medium deep investigate double lateral resistivity(RD),and high interval transit time(AC)on the log curves.Additionally,the reservoir distribution in the Dongfeng area was delineated based on the characterization of the favorable lith-ofacies.This study serves as a guide for future exploration and evaluation of the T_(3)x_(5) member in the Dongfeng area while also augmenting the methodologies for describing tight sandstone reservoirs.展开更多
The Sichuan–Tibet railway construction has received significant attention from both China and abroad.The new section from Ya’an to Nyingchi is about 1018.6 km long,including 69 tunnels with a total length of 841.7 k...The Sichuan–Tibet railway construction has received significant attention from both China and abroad.The new section from Ya’an to Nyingchi is about 1018.6 km long,including 69 tunnels with a total length of 841.7 km.The longest tunnel(Yigong tunnel)is 42.4 km long.The successful construction of the Sichuan–Tibet railway depends largely on tunnel construction.Due to the complex conditions,tunnel construction for the Sichuan–Tibet railway poses great challenges to the research community.This paper aims to illustrate the necessity of interdisciplinary and joint research to solve problems associated with tunnel construction that will be encountered in the immediate future and facilitate the communication and exchange of ideas between disciplines.To this end,based on a systematic analysis of the available data related to Sichuan–Tibet railway tunnels,six major aspects of the geology,environment,and engineering conditions are identified.Next,based on the engineering responses from the Sichuan–Tibet railway tunnels,potential technical problems and risk characteristics are predicted and evaluated.Further,six key scientific issues are identified and discussed based on a coupled multi-layer analysis of essential tunnel engineering issues.Finally,research directions,technical ideas,and research methods that should be carried out for this project are proposed.展开更多
Being constructed in southwestern China, the Sichuan–Tibet Railway(STR) travels across the eastern Tibetan Plateau where there is the most complex terrain and changeable weather in the world. Due to sparse ground-bas...Being constructed in southwestern China, the Sichuan–Tibet Railway(STR) travels across the eastern Tibetan Plateau where there is the most complex terrain and changeable weather in the world. Due to sparse ground-based observations over the Tibetan Plateau, precipitation products retrieved by remote sensing are more widely used;however,satellite-based precipitation products(SPPs) have not yet been strictly and systematically evaluated along the STR.This study aims to evaluate the performance of six SPPs by a series of metrics with available ground observations along the STR during 1998–2020. The six SPPs include the datasets derived from the Tropical Rainfall Measuring Mission(TRMM), Climate Prediction Center morphing technique(CMORPH), Global Precipitation Measurement(GPM), Global Satellite Mapping of Precipitation(GSMaP), Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks(PERSIANN), and Fengyun-2 satellites precipitation estimate(FY2PRE). The results indicate that most of the SPPs can capture the precipitation characteristics on multiple timescales(monthly,daily, hourly, and diurnal cycle) as shown by the evaluated metrics. The probability density functions of the daily and hourly precipitation are also well represented by the SPPs, and 30 mm day^(-1) and 16 mm h^(-1) are identified as the daily and hourly thresholds of extreme precipitation events along the STR. The best SPP varies at different timescales:GPM and GSMaP are suitable for the monthly and daily scale, and FY2PRE and GPM are suited to the hourly scale.In general, GPM is relatively optimum on multiple timescales, and PERSIANN gives the worst performance. In addition, the SPPs perform worse at higher altitudes and for more intense precipitation. Overall, the results from this study are expected to provide essential reference for using the SPPs in meteorological services and disaster prevention in the STR construction and its future operation.展开更多
An earthquake of Ms 8 struck Wenchuan County, western Sichuan, China, on May 12^th, 2008 and resulted in long surface ruptures （〉300 km）. The first-hand observations about the surface ruptures produced by the earth...An earthquake of Ms 8 struck Wenchuan County, western Sichuan, China, on May 12^th, 2008 and resulted in long surface ruptures （〉300 km）. The first-hand observations about the surface ruptures produced by the earthquake in the worst-hit areas of Yingxiu, Beichuan and Qingchuan, ascertained that the causative structure of the earthquake was in the central fault zones of the Longmenshan tectonic belt. Average co-seismic vertical displacements along the individual fault of the Yingxiu-Beiehuan rupture zone reach 2.514 m and the cumulative vertical displacements across the central and frontal Longmenshan fault belt is about 5-6 m. The surface rupture strength was reduced from north of Beichuan to Qingchuan County and shows 2-3 m dextral strike-slip component. The Wenchuan thrust-faulting earthquake is a manifestation of eastward growth of the Tibetan Plateau under the action of continuous convergence of the Indian and Eurasian continents.展开更多
The Qinghai-Xizang (Tibet) Plateau and the 'Sanjiang' area②, where are extensively developed theTethys-type marine Triassic sequences with Indosinian tectonic disturbance and magmatism, provide an impor-tant ...The Qinghai-Xizang (Tibet) Plateau and the 'Sanjiang' area②, where are extensively developed theTethys-type marine Triassic sequences with Indosinian tectonic disturbance and magmatism, provide an impor-tant region for the study of the tectonic evolution and the Indosinian movement of China as well as for thestudy of the boundary between Gondwana and Laurasia and the characteristics of the time-space distributionof the Tethys oceanic crust within the territory of China. Over a long period of time in the past, quite a numberof scholars made substantial studies and discussious from various viewpoints on the geotectonie and regionalgeological evolution of this region. Based on some new data obtained recently and the field observations by theauthor, and by using the plate tectonic theory, the author considers that there developed a Pacific-type (activetype) ancient continental margin bordering the Palaeo-Tethys ocean (or North Tethys ocean) in the south inLate Permian to Triassic times in the region of south-central Qinghai, northeastern Xizang (Tibet), western andsouthwestern Sichuan, and western Yunnan. Its characteristics basically represent the Indosinian tectonic evo-lution of this region.展开更多
Previous studies have shown that the uplift of Tibetan plateau started in response to the collision of Indian plate and Eurasian plate. During this process, the crust of Tibetan plateau has been greatly thickened whic...Previous studies have shown that the uplift of Tibetan plateau started in response to the collision of Indian plate and Eurasian plate. During this process, the crust of Tibetan plateau has been greatly thickened which leads to significant elevations. The elevation gradient is extremely large at the east boundary of Tibetan plateau where Longmenshan fault exists, dropping from 4500 to 500 m within a distance of 100 km, while it is more gentle at the south and north sides of Sichuan basin. Such a difference of elevation gradient has been explained with a crustal channel flow model. However, pre- vious crustal flow models consider the thickness of the lower crust as a constant which is highly simplified. Therefore, it is essential to build a more realistic crustal flow model, in which the thickness of the lower crust is variable and dependent on the inflow velocity of crustal materials. Here we build up both analytical and numerical models to study the mechanism and process of the uplift of Tibetan plateau at the eastern boundary. The results of the analytical model show that if the thickness of the lower crust can vary during the uplift process, the lower crustal viscosity of the Sichuan basin needs to be 1022 Pas to fit the observed elevation gradient. Such a viscosity is one-order magnitude larger than the previous results. Numerical model results further show that the state of stresses at the plateau boundary changes during uplift processes. Such a stress state change may cause the formation of different fault types in the Longmenshan fault area during its uplift history.展开更多
The Earth’s surface kinematics and deformation are fundamental to understanding crustal evolution.An effective research approach is to estimate regional motion field and deformation fields based on modern geodetic ne...The Earth’s surface kinematics and deformation are fundamental to understanding crustal evolution.An effective research approach is to estimate regional motion field and deformation fields based on modern geodetic networks.If the discrete observed velocity field is obtained,the velocity related fields,such as dilatation rate and maximum shear strain rate,can be estimated by applying varied mathematical approaches.This study applied Akaike's Bayesian Information Criterion(ABIC)method to calculate strain rate fields constrained by GPS observations in the southeast Tibetan Plateau.Comparison with results derived from other three methods revealed that our ABIC-derived strain rate fields were more precise.The maximum shear strain rate highlighted the Xianshuihe–Xiaojiang fault system as the main boundary for the outward migration of material in southeastern Tibet,indicating rotation of eastern Tibet material around the eastern Himalaya rather than whole extrusion along a fixed channel.Additionally,distinct dilatation rate patterns in the northeast and southwest regions of the fault system were observed.The northeast region,represented by the Longmenshan area,exhibited negative dilatational anomalies;while the southwest region,represented by the Jinsha River area north of 29°N,displayed positive dilatational anomalies.This indicates compression in the former and extension in the latter.Combined with deep geophysical observations,we believe that the upper and lower crusts of the Jinsha River area north of 29°N are in an entire expanding state,probably caused by the escape-drag effect of material.The presence of a large,low-viscosity region south of 29°N may not enable the entire escape of the crust,but instead result in a differential escape of the lower crust faster than the upper crust.展开更多
The Jiama deposit,a significant porphyry-skarn-type copper polymetallic deposit located within the Gangdese metallogenic belt in Tibet,China,exemplifies a typical porphyry metallogenic system.However,the mineral chemi...The Jiama deposit,a significant porphyry-skarn-type copper polymetallic deposit located within the Gangdese metallogenic belt in Tibet,China,exemplifies a typical porphyry metallogenic system.However,the mineral chemistry of its accessory minerals remains under-examined,posing challenges for resource assessment and ore prospecting.Utilizing electron microprobe analysis and LA-ICP-MS analysis,this study investigated the geochemical characteristics of apatite in ore-bearing granite and monzogranite porphyries,as well as granodiorite,quartz diorite,and dark diorite porphyries in the deposit.It also delved into the diagenetic and metallogenic information from these geochemical signatures.Key findings include:(1)The SiO_(2) content,rare earth element(REE)contents,and REE partition coefficients of apatite indicate that the dark diorite porphyry possibly does not share a cogenetic magma source with the other four types of porphyries;(2)the volatile F and Cl contents in apatite,along with their ratio,indicate the Jiama deposit,formed in a collisional setting,demonstrates lower Cl/F ratios in apatite than the same type of deposits formed in a subduction environment;(3)compared to non-ore-bearing rock bodies in other deposits formed in a collisional setting,apatite in the Jiama deposit exhibits lower Ce and Ga contents.This might indicate that rock bodies in the Jiama deposit have higher oxygen fugacity.Nevertheless,the marginal variation in oxygen fugacity between ore-bearing and non-ore-bearing rock bodies within the deposit suggests oxygen fugacity may not serve as the decisive factor in the ore-hosting potential of rock bodies in the Jiama deposit.展开更多
[ Objective ] To study economic growth of grassland animal husbandry in Sichuan Tibetan region after the liberation and predict long-term trend and regular features of growth and development of grassland animal husban...[ Objective ] To study economic growth of grassland animal husbandry in Sichuan Tibetan region after the liberation and predict long-term trend and regular features of growth and development of grassland animal husbandry. [ Method] Using econometric models and methods, the gov- ernment statistical data after the liberation on grassland animal husbandry of Sichuan Tibetan region were analyzed, and the factors increasing econ- omy of grassland animal husbandry were determined by analyzing time series data of different periods. [ Result] The grassland animal husbandry of Sichuan Tibetan region had significant characteristics of traditional pastoral economy. Before the reform and opening-up, the increase of animal hus- bandry economy was mainly manifested by increase in amount of livestock and laborers, and the increase in amount of livestock was principal pro- moting factor. After the reform and opening-up, the increase in integrated production factors became the primary cause to push the increase of ani- mal husbandry economy. [ Conclusion] Some new measures must be taken to promote the increase of animal husbandry economy of Sichuan Tibetan region, including transforming traditional production mode of animal husbandry, relying on scientific and technological advances, further improving socio- economic system, cultivating more highly sldlled workforce and effectively guiding rational shift and orderly migration of surplus pasture laborers.展开更多
Rubidium(Rb)deposits mostly occur in the South China and Central Asia orogenic belts and are often closely associated with highly differentiated granites.This study investigates a newly-discovered giant Rb deposit at ...Rubidium(Rb)deposits mostly occur in the South China and Central Asia orogenic belts and are often closely associated with highly differentiated granites.This study investigates a newly-discovered giant Rb deposit at Gariatong in the Central Lhasa terrane in Tibet.Detailed field studies and logging data revealed that the Rb mineralization mainly occurs in monzogranite and is related to greisenization.LA-ICP-MS U-Pb dating of zircon yielded ages of 19.1±0.2 Ma and 19.0±0.2 Ma for greisenized monzogranite and fresh monzogranite,respectively.The monzogranites are characterized as strongly peraluminous,with high contents of SiO2,Al2O3,K2O and Na2O as well as a high differentiation index.They are enriched in light rare earth and large ion lithophile elements with significant negative Eu anomalies and depleted high fieldstrength elements.Petrological and geochemical features of these ore-related monzogranites suggest that they are highly fractionated S-type granites,derived from remelting of crustal materials in a post-collisional setting.The geochemistry of zircon and apatite points to a low oxygen fugacity of the ore-related monzogranite during the magma’s evolution.The discovery of the Gariatong Rb deposit suggests that the Central Lhasa terrane may be an important region for rare metal mineralization.展开更多
The Nuri deposit is the only Cu-W-Mo polymetallic deposit with large-scale WO3 resources in the eastern section of the Gangdese metallogenic belt,Tibet,China.However,the genetic type of this deposit has been controver...The Nuri deposit is the only Cu-W-Mo polymetallic deposit with large-scale WO3 resources in the eastern section of the Gangdese metallogenic belt,Tibet,China.However,the genetic type of this deposit has been controversial since its discovery.Based on a study of the geological characteristics of the deposit,this study presents mineralization stages,focusing on the oxide stage and the quartz-sulfide stage where scheelite is mainly formed,referred to as Sch-A and Sch-B,respectively.Through LA-ICP-MS trace element and Sr isotope analyses,the origin,evolutionary process of the oreforming fluid and genesis of the ore deposit are investigated.Scanning Electron Microscope-Cathodoluminescence(SEMCL)observations reveal that Sch-A consists of three generations,with dark gray homogenous Sch-A1 being replaced by relatively lighter and homogeneous Sch-A2 and Sch-A3,with Sch-A2 displaying a gray CL image color with vague and uneven growth bands and Sch-A3 has a light gray CL image color with hardly any growth band.In contrast,Sch-B exhibits a‘core-rim’structure,with the core part(Sch-B1)being dark gray and displaying a uniform growth band,while the rim part(Sch-B2)is light gray and homogeneous.The normalized distribution pattern of rare earth elements in scheelite and Sr isotope data suggest that the early ore-forming fluid in the Nuri deposit originated from granodiorite porphyry and,later on,some country rock material was mixed in,due to strong water-rock interaction.Combining the O-H isotope data further indicates that the ore-forming fluid in the Nuri deposit originated from magmatic-hydrothermal sources,with contributions from metamorphic water caused by water-rock interaction during the mineralization process,as well as later meteoric water.The intense water-rock interaction likely played a crucial role in the precipitation of scheelite,leading to varying Eu anomalies in different generations of scheelite from the oxide stage to the quartz-sulfide stage,while also causing a gradual decrease in oxygen fugacity(fO2)and a slow rise in pH value.Additionally,the high Mo and low Sr contents in the scheelite are consistent with typical characteristics of magmatic-hydrothermal scheelite.Therefore,considering the geological features of the deposit,the geochemical characteristics of scheelite and the O-H isotope data published previously,it can be concluded that the genesis of the Nuri deposit belongs to porphyry-skarn deposit.展开更多
Production performance of the Wufeng-Longmaxi shales varies significantly among Fuling,Weirong,and Wulong fields in the Sichuan Basin.Total organic carbon(TOC)content,mineralogy,and organic matter(OM)pore characterist...Production performance of the Wufeng-Longmaxi shales varies significantly among Fuling,Weirong,and Wulong fields in the Sichuan Basin.Total organic carbon(TOC)content,mineralogy,and organic matter(OM)pore characteristics are investigated to identify key factors governing sweet spots.Siliceous shales with good preservation conditions in the Fuling Field exhibit large thickness,high TOC content and thin-section porosity(TSP),and well-developed OM macropores,thus high initial production and estimated ultimate recovery(EUR).Thin carbonate-containing siliceous shales with good preservation conditions in the Weirong Field feature medium-to-high TOC and well-developed OM macropores but low TSP,leading to high initial production but low EUR.Siliceous shales with poor preservation conditions in the Wulong Field are characterized by large thickness,high TOC,low TSP and poorly-developed OM macropores,causing low initial production and EUR.Both sedimentary and preservation conditions are intrinsic decisive factors of sweet spots,as they control the mineral composition,TOC,and OM macropore development.Deep-water shales in transgressive systems tracts(TSTs)exhibit better-developed OM macropores and greater TOC compared to highstand systems tracts(HSTs).OM macropores are most prevalent in siliceous shales,followed by carbonate-containing siliceous shales and then argillaceous shales.Furthermore,good preservation conditions are conducive to retain OM macropores with low pore aspect ratio(PAR).Comparison among the three fields shows that high-TOC silicious shales with good preservation conditions are the highest in TSP and EUR.Therefore,organic richness,lithofacies,and preservation conditions are the major factors which determine OM pore development,governing the sweet spots of the Wufeng-Longmaxi shales.展开更多
This study analyzed the petrological characteristics,diagenesis,pore types,and physical properties of the tight coarse-grained siliciclastic sequences in the third member of the Upper Triassic Xujiahe Formation(also r...This study analyzed the petrological characteristics,diagenesis,pore types,and physical properties of the tight coarse-grained siliciclastic sequences in the third member of the Upper Triassic Xujiahe Formation(also referred to as the Xu-3 Member)in the western Yuanba area in the northeastern Sichuan Basin,China,based on the results of 242.61-m-long core description,292 thin-section observations,scanning electron microscopy(SEM),and 292 physical property tests.The types and genetic mechanisms of high-quality tight coarse-grained siliciclastic reservoirs in this member was determined thereafter.The research objective is to guide the exploration and development of the tight coarse-grained siliciclastic sequences in the Xu-3 Member.The results of this study are as follows.Two types of high-quality reservoirs are developed in the coarse-grained siliciclastic sequences of the Xu-3 Member,namely the fractured fine-grained sandy conglomerate type and porous medium-grained calcarenaceous sandstone type.Hydrodynamic energy in the sedimentary environment is the key factor controlling the formation of high-quality reservoirs.These high-quality reservoirs are developed mainly in the transitional zone with moderately high hydrodynamic energy between delta-plain braided channels and delta-front subaqueous distributary channels.The dolomitic debris(gravel)content is the main factor affecting the reservoirs’physical properties.The micritic algal debris and sandy debris in the dolomitic debris(or gravels)tend to recrystallize during burial,forming intercrystalline pores within.In the medium-grained calcarenaceous sandstones,intercrystalline pores in the dolomitic debris are formed at the early diagenetic stage,and a pore system consisting of structural fractures connecting intergranular pores,intergranular dissolution pores,and kaolinite intergranular micropores is developed at the late stage of diagenesis.The formation of intercrystalline pores in dolomite gravels and gravel-edge fractures,a pore system connected by gravel-edge and tectonic fractures,is closely related to the dolomite gravels in the sandy fine-grained conglomerates.展开更多
Based on the situation and progress of marine oil/gas exploration in the Sichuan Basin,SW China,the whole petroleum system is divided for marine carbonate rocks of the basin according to the combinations of hydrocarbo...Based on the situation and progress of marine oil/gas exploration in the Sichuan Basin,SW China,the whole petroleum system is divided for marine carbonate rocks of the basin according to the combinations of hydrocarbon accumulation elements,especially the source rock.The hydrocarbon accumulation characteristics of each whole petroleum system are analyzed,the patterns of integrated conventional and unconventional hydrocarbon accumulation are summarized,and the favorable exploration targets are proposed.Under the control of multiple extensional-convergent tectonic cycles,the marine carbonate rocks of the Sichuan Basin contain three sets of regional source rocks and three sets of regional cap rocks,and can be divided into the Cambrian,Silurian and Permian whole petroleum systems.These whole petroleum systems present mainly independent hydrocarbon accumulation,containing natural gas of affinity individually.Locally,large fault zones run through multiple whole petroleum systems,forming a fault-controlled complex whole petroleum system.The hydrocarbon accumulation sequence of continental shelf facies shale gas accumulation,marginal platform facies-controlled gas reservoirs,and intra-platform fault-and facies-controlled gas reservoirs is common in the whole petroleum system,with a stereoscopic accumulation and orderly distribution pattern.High-quality source rock is fundamental to the formation of large gas fields,and natural gas in a whole petroleum system is generally enriched near and within the source rocks.The development and maintenance of large-scale reservoirs are essential for natural gas enrichment,multiple sources,oil and gas transformation,and dynamic adjustment are the characteristics of marine petroleum accumulation,and good preservation conditions are critical to natural gas accumulation.Large-scale marginal-platform reef-bank facies zones,deep shale gas,and large-scale lithological complexes related to source-connected faults are future marine hydrocarbon exploration targets in the Sichuan Basin.展开更多
The analysis of hydrochemical characteristics and influencing factors of surface river on plateau is helpful to study water hydrological cycle and environmental evolution,which can scientifically guide rational develo...The analysis of hydrochemical characteristics and influencing factors of surface river on plateau is helpful to study water hydrological cycle and environmental evolution,which can scientifically guide rational development and utilization of water resources and planning of ecological environment protection.With the expansion and diversification of human activities,the quality of surface rivers will be more directly affected.Therefore,it is of great significance to pay attention to the hydrochemical characteristics of plateau surface rivers and the influence of human activities on their circulation and evolution.In this study,surface water in the Duoqu basin of Jinsha River located in Hengduan mountain region of Eastern Tibet was selected as the representative case.Twenty-three groups of surface water samples were collected to analyze the hydrochemical characteristics and ion sources based on correlation analysis,piper trigram,gibbs model,hydrogen and oxygen isotopic techniques.The results suggest the following:(1)The pH showed slight alkalinity with the value ranged from 7.25 to 8.62.Ca^(2+),Mg^(2+)and HCO_(3)^(–)were the main cations and anions.HCO_(3)^(-)Ca and HCO_(3)^(-)Ca·Mg were the primary hydrochemical types for the surface water of Duoqu River.The correlation analysis showed that TDS had the most significant correlation with Ca^(2+),Mg^(2+)and HCO_(3)^(–).Analysis on hydrogen and oxygen isotopes indicated that the surface rivers were mainly recharged by atmospheric precipitation and glacial melt water in this study area.(2)The surface water had a certain reverse cation alternating adsorption,and surface water ions were mainly derived from rock weathering,mainly controlled by weathering and dissolution of carbonates,and secondly by silicates and sodium rocks.(3)The influence of human activities was weak,while the development of cinnabar minerals had a certain impact on the hydrochemistry characteristics,which was the main factor for causing the increase of SO_(4)^(2–).The densely populated county towns and temples with frequent incense burning activities may cause some anomalies of surface water quality.At present,the Duoqu River watershed had gone through a certain influence of mineral exploitation,so the hydrological cycle and river eco-environment at watershed scale will still bound to be change.The results could provide basic support for better understanding water balance evolution as well as the ecological protection of Duoqu River watershed.展开更多
Two suites of mafic dykes,T1193-A and T1194-A,outcrop in Gyangze area,southeast Tibet.They are in the area of Comei LIP and have indistinguishable field occurrences with two other dykes in Gyangze,T0902 dyke with 137....Two suites of mafic dykes,T1193-A and T1194-A,outcrop in Gyangze area,southeast Tibet.They are in the area of Comei LIP and have indistinguishable field occurrences with two other dykes in Gyangze,T0902 dyke with 137.7±1.3 Ma zircon age and T0907 dyke with 142±1.4 Ma zircon age reported by Wang YY et al.(2016),indicating coeval formation time.Taking all the four diabase dykes into consideration,two different types,OIB-type and weak enriched-type,can be summarized.The“OIB-type”samples,including T1193-A and T0907 dykes,show OIB-like geochemical features and have initial Sr-Nd isotopic values similar with most mafic products in Comei Large Igneous Provinces(LIP),suggesting that they represent melts directly generated from the Kerguelen mantle plume.The“weak enriched-type”samples,including T1194-A and T0902 dykes,have REEs and trace element patterns showing withinplate affinity but have obvious Nb-Ta-Ti negative anomalies.They show uniform lowerεNd(t)values(−6‒−2)and higher 87Sr/86Sr(t)values(0.706‒0.709)independent of their MgO variation,indicating one enriched mantle source.Considering their closely spatial and temporal relationship with the widespread Comei LIP magmatic products in Tethyan Himalaya,these“weak enriched-type”samples are consistent with mixing of melts from mantle plume and the above ancient Tethyan Himalaya subcontinental lithospheric mantle(SCLM)in different proportions.These weak enriched mafic rocks in Comei LIP form one special rock group and most likely suggest large scale hot mantle plume-continental lithosphere interaction.This process may lead to strong modification of the Tethyan Himalaya lithosphere in the Early Cretaceous.展开更多
In Garze Tibetan autonomous prefecture inSichuan province, China, 41 echinococciasis patientswho had received surgical treatment were recruitedin the study, and 82 health persons who had livedin Garze for at least 10 ...In Garze Tibetan autonomous prefecture inSichuan province, China, 41 echinococciasis patientswho had received surgical treatment were recruitedin the study, and 82 health persons who had livedin Garze for at least 10 years were selected ascontrols. The serum levels of Zn, Se and Cu of thecases and controls were detected. The resultsshowed that most echinococciasis cases weredistributed in Shiqu county （17.1%, 7/41）, and only1 case was distributed in Yajiang county （2.4%）. Themale to female ratio of the cases was 1：1.56. Theechinococciasis patients were mainly aged 30-39years （36.59%, 15/41）. And, the cases aged 20-49years accounted for 68.29% （28/41）. Comparedwith health controls, the serum levels of Zn and Seof the cases significantly declined. However, theserum level of Cu of the cases had no significantlychange. It was confirmed that the serum levels ofZn and Se were interrelated with the prevalence ofechinococciasis.展开更多
Analysis and research of large complex phenomena before and after the devastating earthquake to reduce the threat of natural disasters to human survival environment is of great significance.This paper analyzes the Wen...Analysis and research of large complex phenomena before and after the devastating earthquake to reduce the threat of natural disasters to human survival environment is of great significance.This paper analyzes the Wenchuan earthquake zone characteristics of gravity anomaly distributions,and then use edge detection and Euler deconvolution method to inverse Longmenshan gravity anomaly before earthquake.Fault distribution features and the general depth about the fault top of Longmenshan and its adjacent area before earthquake has been obtained.Morphology difference and possible earthquake formation have been analyzed through the Euler deconvolution result of gravity anomaly profile before and after the earthquake.展开更多
基金Under the auspices of National Natural Science Foundation of China(No.41929002)Science and Technology Department of Sichuan Province(No.2021YFS0338)。
文摘Enhanced sulfur and nitrogen deposition has been observed in many transect regions worldwide,from urban/agricultural areas to mountains.The Sichuan Basin(SCB),with 18 prefectural cities,is the most economically-developed region in western China,while the rural Qinghai-Tibetan Plateau(QTP)lies west of the SCB.Previous regional and national atmospheric modeling studies have sug-gested that large areas in the SCB-to-QTP transect region experience excessive deposition of sulfur and nitrogen.In this study,we applied a passive monitoring method at 11 sites(one in urban Chengdu and 10 from fivenature reserves)in this transect region from September 2021 to October 2022 to confirm the high sulfur and nitrogen deposition fluxes and to understand the gaps between the modeling and observation results for this transect region.These observations suggest that the five reserves are under eutrophication risk,and only two reserves are partially under acidification risk.Owing to the complex topography and landscapes,both sulfur and nitrogen deposition and critical loads exhibit large spatial variations within a reserve,such as Mount Emei.Regional atmospheric modeling may not accurately capture the spatial variations in deposition fluxes within a reserve;however,it can capture general spatial patterns over the entire transect.This study demonstrates that a combination of state-of-the-art atmospheric chemical models and low-cost monitoring methods is helpful for ecological risk assessments at a regional scale.
文摘Xi Jinping Thought on Ecological Civilization contains new concepts,ideas,and strategies that feature Chinese characteristics and the spirit of the times and promote the progress of human civilization.Xi Jinping Thought on Ecological Civilization is also the fundamental guide for compliance and action in terms of China’s practices in building an ecological civilization in the new era.Since the 18th National Congress of the Communist Party of China(CPC),Xi Jinping,general secretary of the Communist Party of China Central Committee,has made several inspection tours to Sichuan and given a series of important instructions on green development and building an ecological civilization in Sichuan province.This paper reviews the contemporary meaning and theoretical significance of Xi Jinping Thought on Ecological Civilization and uses them to systematically examine the overall performance of building a beautiful Sichuan,following the guidance of Xi Jinping’s important instructions for the governance of Sichuan.This paper selects and analyzes typical cases that demonstrate the national effect in Sichuan to summarize Sichuan’s unique experiences in the practice of Xi Jinping Thought on Ecological Civilization.
基金funded by a SINOPEC project entitled Exploration Potential and Target Evaluation of Xujiahe Formation in the Northeastern Sichuan Basin(No.P23130).
文摘The recent discovery of natural gas within the fifth member of the Xujiahe Formation(T_(3)x_(5))in the Dongfeng area within the Sichuan Basin highlights the significant exploration potential of this member.However,the unconvincing previous understanding of the sedimentary microfacies,combined with a total lack of studies on the sand body architecture and reservoir distribution,hampers the further exploration of this member.Using core data,log curves,and seismic data,along with sedimentary microfacies analysis,this study investigated the interfaces between the sand bodies of various scales in the Dongfeng area.Furthermore,this study explored the morphological characteristics,types,and stacking patterns of these sand bodies and determined the distributions of sand bodies and reservoirs in the area.The results indicate that the first sand group of the T_(3)x_(5) member(T_(3)x^(1)_(5))exhibits delta-front deposits,including subaqueous distributary channels,sheet sands,and interdistributary bays.Seven levels of sand body interfaces are identified in the T_(3)x^(1)_(5) sand group.Among them,the interfaces of the first and second levels were identifed only in cores,those of the third and fourth levels were recog-nizable from cores combined with log curves,while those of the fifth,sixth,and seventh levels were distinguishable using seismic data.Three superimposed subaqueous distributary channel complexes are found in the Dongfeng area.Among them,complex 1 in the northwest exhibits the strongest water body energy,while complex 2 in the south displays the weakest.Complex 2 was formed earlier than com-plexes 1 and 3.Also,complex 1 is further subdivided into three vertically stacked subaqueous distrib-utary channels.The subdivision of sedimentary microfacies in the T_(3)x_(5) member reveals nine lithofacies types.Among them,stacked pancake-shaped,carbonaceous debris-bearing,massive,and cross-bedded medium-grained sandstones are considered favorable lithofacies.These four lithofacies types exhibit high porosity,as well as low natural gamma-ray(GR)values,low-to-medium deep investigate double lateral resistivity(RD),and high interval transit time(AC)on the log curves.Additionally,the reservoir distribution in the Dongfeng area was delineated based on the characterization of the favorable lith-ofacies.This study serves as a guide for future exploration and evaluation of the T_(3)x_(5) member in the Dongfeng area while also augmenting the methodologies for describing tight sandstone reservoirs.
基金the financial support by the National Natural Science of China(Grant No.51738002)the National Key R&D Program of China(Grant No.2017YFC0805401).
文摘The Sichuan–Tibet railway construction has received significant attention from both China and abroad.The new section from Ya’an to Nyingchi is about 1018.6 km long,including 69 tunnels with a total length of 841.7 km.The longest tunnel(Yigong tunnel)is 42.4 km long.The successful construction of the Sichuan–Tibet railway depends largely on tunnel construction.Due to the complex conditions,tunnel construction for the Sichuan–Tibet railway poses great challenges to the research community.This paper aims to illustrate the necessity of interdisciplinary and joint research to solve problems associated with tunnel construction that will be encountered in the immediate future and facilitate the communication and exchange of ideas between disciplines.To this end,based on a systematic analysis of the available data related to Sichuan–Tibet railway tunnels,six major aspects of the geology,environment,and engineering conditions are identified.Next,based on the engineering responses from the Sichuan–Tibet railway tunnels,potential technical problems and risk characteristics are predicted and evaluated.Further,six key scientific issues are identified and discussed based on a coupled multi-layer analysis of essential tunnel engineering issues.Finally,research directions,technical ideas,and research methods that should be carried out for this project are proposed.
基金Supported by the National Natural Science Foundation of China(42030611 and 42165005)the Second Tibetan Plateau Scientific Expedition and Research(STEP)Program(2019QZKK0103 and 2019QZKK0106)Key Research and Development Plans of Tibet Autonomous Region in 2022(XZ202201ZY0008G)。
文摘Being constructed in southwestern China, the Sichuan–Tibet Railway(STR) travels across the eastern Tibetan Plateau where there is the most complex terrain and changeable weather in the world. Due to sparse ground-based observations over the Tibetan Plateau, precipitation products retrieved by remote sensing are more widely used;however,satellite-based precipitation products(SPPs) have not yet been strictly and systematically evaluated along the STR.This study aims to evaluate the performance of six SPPs by a series of metrics with available ground observations along the STR during 1998–2020. The six SPPs include the datasets derived from the Tropical Rainfall Measuring Mission(TRMM), Climate Prediction Center morphing technique(CMORPH), Global Precipitation Measurement(GPM), Global Satellite Mapping of Precipitation(GSMaP), Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks(PERSIANN), and Fengyun-2 satellites precipitation estimate(FY2PRE). The results indicate that most of the SPPs can capture the precipitation characteristics on multiple timescales(monthly,daily, hourly, and diurnal cycle) as shown by the evaluated metrics. The probability density functions of the daily and hourly precipitation are also well represented by the SPPs, and 30 mm day^(-1) and 16 mm h^(-1) are identified as the daily and hourly thresholds of extreme precipitation events along the STR. The best SPP varies at different timescales:GPM and GSMaP are suitable for the monthly and daily scale, and FY2PRE and GPM are suited to the hourly scale.In general, GPM is relatively optimum on multiple timescales, and PERSIANN gives the worst performance. In addition, the SPPs perform worse at higher altitudes and for more intense precipitation. Overall, the results from this study are expected to provide essential reference for using the SPPs in meteorological services and disaster prevention in the STR construction and its future operation.
文摘An earthquake of Ms 8 struck Wenchuan County, western Sichuan, China, on May 12^th, 2008 and resulted in long surface ruptures （〉300 km）. The first-hand observations about the surface ruptures produced by the earthquake in the worst-hit areas of Yingxiu, Beichuan and Qingchuan, ascertained that the causative structure of the earthquake was in the central fault zones of the Longmenshan tectonic belt. Average co-seismic vertical displacements along the individual fault of the Yingxiu-Beiehuan rupture zone reach 2.514 m and the cumulative vertical displacements across the central and frontal Longmenshan fault belt is about 5-6 m. The surface rupture strength was reduced from north of Beichuan to Qingchuan County and shows 2-3 m dextral strike-slip component. The Wenchuan thrust-faulting earthquake is a manifestation of eastward growth of the Tibetan Plateau under the action of continuous convergence of the Indian and Eurasian continents.
基金A subject of Project Nos.85001 and 851287 funded by the State National Science Foundation.
文摘The Qinghai-Xizang (Tibet) Plateau and the 'Sanjiang' area②, where are extensively developed theTethys-type marine Triassic sequences with Indosinian tectonic disturbance and magmatism, provide an impor-tant region for the study of the tectonic evolution and the Indosinian movement of China as well as for thestudy of the boundary between Gondwana and Laurasia and the characteristics of the time-space distributionof the Tethys oceanic crust within the territory of China. Over a long period of time in the past, quite a numberof scholars made substantial studies and discussious from various viewpoints on the geotectonie and regionalgeological evolution of this region. Based on some new data obtained recently and the field observations by theauthor, and by using the plate tectonic theory, the author considers that there developed a Pacific-type (activetype) ancient continental margin bordering the Palaeo-Tethys ocean (or North Tethys ocean) in the south inLate Permian to Triassic times in the region of south-central Qinghai, northeastern Xizang (Tibet), western andsouthwestern Sichuan, and western Yunnan. Its characteristics basically represent the Indosinian tectonic evo-lution of this region.
基金supported by the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (XDB18000000)Natural National Science Foundation of China (41374102 and 41422402)
文摘Previous studies have shown that the uplift of Tibetan plateau started in response to the collision of Indian plate and Eurasian plate. During this process, the crust of Tibetan plateau has been greatly thickened which leads to significant elevations. The elevation gradient is extremely large at the east boundary of Tibetan plateau where Longmenshan fault exists, dropping from 4500 to 500 m within a distance of 100 km, while it is more gentle at the south and north sides of Sichuan basin. Such a difference of elevation gradient has been explained with a crustal channel flow model. However, pre- vious crustal flow models consider the thickness of the lower crust as a constant which is highly simplified. Therefore, it is essential to build a more realistic crustal flow model, in which the thickness of the lower crust is variable and dependent on the inflow velocity of crustal materials. Here we build up both analytical and numerical models to study the mechanism and process of the uplift of Tibetan plateau at the eastern boundary. The results of the analytical model show that if the thickness of the lower crust can vary during the uplift process, the lower crustal viscosity of the Sichuan basin needs to be 1022 Pas to fit the observed elevation gradient. Such a viscosity is one-order magnitude larger than the previous results. Numerical model results further show that the state of stresses at the plateau boundary changes during uplift processes. Such a stress state change may cause the formation of different fault types in the Longmenshan fault area during its uplift history.
基金supported by grants from the Ministry of Science and Technology(Grant Nos.2021FY100101,2019QZKK0901)the National Natural Science Foundation of China(Grant Nos.41941016,42230312,42020104007)China Geological Survey(Grant No.DD20221630).
文摘The Earth’s surface kinematics and deformation are fundamental to understanding crustal evolution.An effective research approach is to estimate regional motion field and deformation fields based on modern geodetic networks.If the discrete observed velocity field is obtained,the velocity related fields,such as dilatation rate and maximum shear strain rate,can be estimated by applying varied mathematical approaches.This study applied Akaike's Bayesian Information Criterion(ABIC)method to calculate strain rate fields constrained by GPS observations in the southeast Tibetan Plateau.Comparison with results derived from other three methods revealed that our ABIC-derived strain rate fields were more precise.The maximum shear strain rate highlighted the Xianshuihe–Xiaojiang fault system as the main boundary for the outward migration of material in southeastern Tibet,indicating rotation of eastern Tibet material around the eastern Himalaya rather than whole extrusion along a fixed channel.Additionally,distinct dilatation rate patterns in the northeast and southwest regions of the fault system were observed.The northeast region,represented by the Longmenshan area,exhibited negative dilatational anomalies;while the southwest region,represented by the Jinsha River area north of 29°N,displayed positive dilatational anomalies.This indicates compression in the former and extension in the latter.Combined with deep geophysical observations,we believe that the upper and lower crusts of the Jinsha River area north of 29°N are in an entire expanding state,probably caused by the escape-drag effect of material.The presence of a large,low-viscosity region south of 29°N may not enable the entire escape of the crust,but instead result in a differential escape of the lower crust faster than the upper crust.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFC2905001)the National Natural Science Foundation of China(Grant Nos.42272093,42230813)a geological survey project(Grant No.DD20230054).
文摘The Jiama deposit,a significant porphyry-skarn-type copper polymetallic deposit located within the Gangdese metallogenic belt in Tibet,China,exemplifies a typical porphyry metallogenic system.However,the mineral chemistry of its accessory minerals remains under-examined,posing challenges for resource assessment and ore prospecting.Utilizing electron microprobe analysis and LA-ICP-MS analysis,this study investigated the geochemical characteristics of apatite in ore-bearing granite and monzogranite porphyries,as well as granodiorite,quartz diorite,and dark diorite porphyries in the deposit.It also delved into the diagenetic and metallogenic information from these geochemical signatures.Key findings include:(1)The SiO_(2) content,rare earth element(REE)contents,and REE partition coefficients of apatite indicate that the dark diorite porphyry possibly does not share a cogenetic magma source with the other four types of porphyries;(2)the volatile F and Cl contents in apatite,along with their ratio,indicate the Jiama deposit,formed in a collisional setting,demonstrates lower Cl/F ratios in apatite than the same type of deposits formed in a subduction environment;(3)compared to non-ore-bearing rock bodies in other deposits formed in a collisional setting,apatite in the Jiama deposit exhibits lower Ce and Ga contents.This might indicate that rock bodies in the Jiama deposit have higher oxygen fugacity.Nevertheless,the marginal variation in oxygen fugacity between ore-bearing and non-ore-bearing rock bodies within the deposit suggests oxygen fugacity may not serve as the decisive factor in the ore-hosting potential of rock bodies in the Jiama deposit.
基金funded by the Soft Science Project of Sichuan Province ( 2010ZR0033)
文摘[ Objective ] To study economic growth of grassland animal husbandry in Sichuan Tibetan region after the liberation and predict long-term trend and regular features of growth and development of grassland animal husbandry. [ Method] Using econometric models and methods, the gov- ernment statistical data after the liberation on grassland animal husbandry of Sichuan Tibetan region were analyzed, and the factors increasing econ- omy of grassland animal husbandry were determined by analyzing time series data of different periods. [ Result] The grassland animal husbandry of Sichuan Tibetan region had significant characteristics of traditional pastoral economy. Before the reform and opening-up, the increase of animal hus- bandry economy was mainly manifested by increase in amount of livestock and laborers, and the increase in amount of livestock was principal pro- moting factor. After the reform and opening-up, the increase in integrated production factors became the primary cause to push the increase of ani- mal husbandry economy. [ Conclusion] Some new measures must be taken to promote the increase of animal husbandry economy of Sichuan Tibetan region, including transforming traditional production mode of animal husbandry, relying on scientific and technological advances, further improving socio- economic system, cultivating more highly sldlled workforce and effectively guiding rational shift and orderly migration of surplus pasture laborers.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFC2905001)the National Natural Science Foundation of China(Grant Nos.42272093,42230813)+1 种基金the Basic Research Fund of the Chinese Academy of Geological Sciences(Grant Nos.JKYZD202316,KK2116)the China Scholarship Council project and the Geological Survey project(Grant No.DD20230054).
文摘Rubidium(Rb)deposits mostly occur in the South China and Central Asia orogenic belts and are often closely associated with highly differentiated granites.This study investigates a newly-discovered giant Rb deposit at Gariatong in the Central Lhasa terrane in Tibet.Detailed field studies and logging data revealed that the Rb mineralization mainly occurs in monzogranite and is related to greisenization.LA-ICP-MS U-Pb dating of zircon yielded ages of 19.1±0.2 Ma and 19.0±0.2 Ma for greisenized monzogranite and fresh monzogranite,respectively.The monzogranites are characterized as strongly peraluminous,with high contents of SiO2,Al2O3,K2O and Na2O as well as a high differentiation index.They are enriched in light rare earth and large ion lithophile elements with significant negative Eu anomalies and depleted high fieldstrength elements.Petrological and geochemical features of these ore-related monzogranites suggest that they are highly fractionated S-type granites,derived from remelting of crustal materials in a post-collisional setting.The geochemistry of zircon and apatite points to a low oxygen fugacity of the ore-related monzogranite during the magma’s evolution.The discovery of the Gariatong Rb deposit suggests that the Central Lhasa terrane may be an important region for rare metal mineralization.
基金financially supported by the National Key Research and Development Program of China(Grant No.2021YFC2901903)the Geological Comprehensive Research Project of China’s Metallurgical Geology Bureau(Grant No.[2022]CMGBDZYJ005),the National Natural Science Foundation of China(Grant No.42002097)the Geological Investigation Project(Grant Nos.DD20230031,DD20221690,DD20230049,DD20230337).
文摘The Nuri deposit is the only Cu-W-Mo polymetallic deposit with large-scale WO3 resources in the eastern section of the Gangdese metallogenic belt,Tibet,China.However,the genetic type of this deposit has been controversial since its discovery.Based on a study of the geological characteristics of the deposit,this study presents mineralization stages,focusing on the oxide stage and the quartz-sulfide stage where scheelite is mainly formed,referred to as Sch-A and Sch-B,respectively.Through LA-ICP-MS trace element and Sr isotope analyses,the origin,evolutionary process of the oreforming fluid and genesis of the ore deposit are investigated.Scanning Electron Microscope-Cathodoluminescence(SEMCL)observations reveal that Sch-A consists of three generations,with dark gray homogenous Sch-A1 being replaced by relatively lighter and homogeneous Sch-A2 and Sch-A3,with Sch-A2 displaying a gray CL image color with vague and uneven growth bands and Sch-A3 has a light gray CL image color with hardly any growth band.In contrast,Sch-B exhibits a‘core-rim’structure,with the core part(Sch-B1)being dark gray and displaying a uniform growth band,while the rim part(Sch-B2)is light gray and homogeneous.The normalized distribution pattern of rare earth elements in scheelite and Sr isotope data suggest that the early ore-forming fluid in the Nuri deposit originated from granodiorite porphyry and,later on,some country rock material was mixed in,due to strong water-rock interaction.Combining the O-H isotope data further indicates that the ore-forming fluid in the Nuri deposit originated from magmatic-hydrothermal sources,with contributions from metamorphic water caused by water-rock interaction during the mineralization process,as well as later meteoric water.The intense water-rock interaction likely played a crucial role in the precipitation of scheelite,leading to varying Eu anomalies in different generations of scheelite from the oxide stage to the quartz-sulfide stage,while also causing a gradual decrease in oxygen fugacity(fO2)and a slow rise in pH value.Additionally,the high Mo and low Sr contents in the scheelite are consistent with typical characteristics of magmatic-hydrothermal scheelite.Therefore,considering the geological features of the deposit,the geochemical characteristics of scheelite and the O-H isotope data published previously,it can be concluded that the genesis of the Nuri deposit belongs to porphyry-skarn deposit.
文摘Production performance of the Wufeng-Longmaxi shales varies significantly among Fuling,Weirong,and Wulong fields in the Sichuan Basin.Total organic carbon(TOC)content,mineralogy,and organic matter(OM)pore characteristics are investigated to identify key factors governing sweet spots.Siliceous shales with good preservation conditions in the Fuling Field exhibit large thickness,high TOC content and thin-section porosity(TSP),and well-developed OM macropores,thus high initial production and estimated ultimate recovery(EUR).Thin carbonate-containing siliceous shales with good preservation conditions in the Weirong Field feature medium-to-high TOC and well-developed OM macropores but low TSP,leading to high initial production but low EUR.Siliceous shales with poor preservation conditions in the Wulong Field are characterized by large thickness,high TOC,low TSP and poorly-developed OM macropores,causing low initial production and EUR.Both sedimentary and preservation conditions are intrinsic decisive factors of sweet spots,as they control the mineral composition,TOC,and OM macropore development.Deep-water shales in transgressive systems tracts(TSTs)exhibit better-developed OM macropores and greater TOC compared to highstand systems tracts(HSTs).OM macropores are most prevalent in siliceous shales,followed by carbonate-containing siliceous shales and then argillaceous shales.Furthermore,good preservation conditions are conducive to retain OM macropores with low pore aspect ratio(PAR).Comparison among the three fields shows that high-TOC silicious shales with good preservation conditions are the highest in TSP and EUR.Therefore,organic richness,lithofacies,and preservation conditions are the major factors which determine OM pore development,governing the sweet spots of the Wufeng-Longmaxi shales.
文摘This study analyzed the petrological characteristics,diagenesis,pore types,and physical properties of the tight coarse-grained siliciclastic sequences in the third member of the Upper Triassic Xujiahe Formation(also referred to as the Xu-3 Member)in the western Yuanba area in the northeastern Sichuan Basin,China,based on the results of 242.61-m-long core description,292 thin-section observations,scanning electron microscopy(SEM),and 292 physical property tests.The types and genetic mechanisms of high-quality tight coarse-grained siliciclastic reservoirs in this member was determined thereafter.The research objective is to guide the exploration and development of the tight coarse-grained siliciclastic sequences in the Xu-3 Member.The results of this study are as follows.Two types of high-quality reservoirs are developed in the coarse-grained siliciclastic sequences of the Xu-3 Member,namely the fractured fine-grained sandy conglomerate type and porous medium-grained calcarenaceous sandstone type.Hydrodynamic energy in the sedimentary environment is the key factor controlling the formation of high-quality reservoirs.These high-quality reservoirs are developed mainly in the transitional zone with moderately high hydrodynamic energy between delta-plain braided channels and delta-front subaqueous distributary channels.The dolomitic debris(gravel)content is the main factor affecting the reservoirs’physical properties.The micritic algal debris and sandy debris in the dolomitic debris(or gravels)tend to recrystallize during burial,forming intercrystalline pores within.In the medium-grained calcarenaceous sandstones,intercrystalline pores in the dolomitic debris are formed at the early diagenetic stage,and a pore system consisting of structural fractures connecting intergranular pores,intergranular dissolution pores,and kaolinite intergranular micropores is developed at the late stage of diagenesis.The formation of intercrystalline pores in dolomite gravels and gravel-edge fractures,a pore system connected by gravel-edge and tectonic fractures,is closely related to the dolomite gravels in the sandy fine-grained conglomerates.
基金Supported by the National Natural Science Foundation of China(42090022)。
文摘Based on the situation and progress of marine oil/gas exploration in the Sichuan Basin,SW China,the whole petroleum system is divided for marine carbonate rocks of the basin according to the combinations of hydrocarbon accumulation elements,especially the source rock.The hydrocarbon accumulation characteristics of each whole petroleum system are analyzed,the patterns of integrated conventional and unconventional hydrocarbon accumulation are summarized,and the favorable exploration targets are proposed.Under the control of multiple extensional-convergent tectonic cycles,the marine carbonate rocks of the Sichuan Basin contain three sets of regional source rocks and three sets of regional cap rocks,and can be divided into the Cambrian,Silurian and Permian whole petroleum systems.These whole petroleum systems present mainly independent hydrocarbon accumulation,containing natural gas of affinity individually.Locally,large fault zones run through multiple whole petroleum systems,forming a fault-controlled complex whole petroleum system.The hydrocarbon accumulation sequence of continental shelf facies shale gas accumulation,marginal platform facies-controlled gas reservoirs,and intra-platform fault-and facies-controlled gas reservoirs is common in the whole petroleum system,with a stereoscopic accumulation and orderly distribution pattern.High-quality source rock is fundamental to the formation of large gas fields,and natural gas in a whole petroleum system is generally enriched near and within the source rocks.The development and maintenance of large-scale reservoirs are essential for natural gas enrichment,multiple sources,oil and gas transformation,and dynamic adjustment are the characteristics of marine petroleum accumulation,and good preservation conditions are critical to natural gas accumulation.Large-scale marginal-platform reef-bank facies zones,deep shale gas,and large-scale lithological complexes related to source-connected faults are future marine hydrocarbon exploration targets in the Sichuan Basin.
基金financially supported by the Geological Survey Project of China Geological Survey(DD20230077,DD20230456,DD20230424)。
文摘The analysis of hydrochemical characteristics and influencing factors of surface river on plateau is helpful to study water hydrological cycle and environmental evolution,which can scientifically guide rational development and utilization of water resources and planning of ecological environment protection.With the expansion and diversification of human activities,the quality of surface rivers will be more directly affected.Therefore,it is of great significance to pay attention to the hydrochemical characteristics of plateau surface rivers and the influence of human activities on their circulation and evolution.In this study,surface water in the Duoqu basin of Jinsha River located in Hengduan mountain region of Eastern Tibet was selected as the representative case.Twenty-three groups of surface water samples were collected to analyze the hydrochemical characteristics and ion sources based on correlation analysis,piper trigram,gibbs model,hydrogen and oxygen isotopic techniques.The results suggest the following:(1)The pH showed slight alkalinity with the value ranged from 7.25 to 8.62.Ca^(2+),Mg^(2+)and HCO_(3)^(–)were the main cations and anions.HCO_(3)^(-)Ca and HCO_(3)^(-)Ca·Mg were the primary hydrochemical types for the surface water of Duoqu River.The correlation analysis showed that TDS had the most significant correlation with Ca^(2+),Mg^(2+)and HCO_(3)^(–).Analysis on hydrogen and oxygen isotopes indicated that the surface rivers were mainly recharged by atmospheric precipitation and glacial melt water in this study area.(2)The surface water had a certain reverse cation alternating adsorption,and surface water ions were mainly derived from rock weathering,mainly controlled by weathering and dissolution of carbonates,and secondly by silicates and sodium rocks.(3)The influence of human activities was weak,while the development of cinnabar minerals had a certain impact on the hydrochemistry characteristics,which was the main factor for causing the increase of SO_(4)^(2–).The densely populated county towns and temples with frequent incense burning activities may cause some anomalies of surface water quality.At present,the Duoqu River watershed had gone through a certain influence of mineral exploitation,so the hydrological cycle and river eco-environment at watershed scale will still bound to be change.The results could provide basic support for better understanding water balance evolution as well as the ecological protection of Duoqu River watershed.
基金supported by National Science Foundation of China(42102059 and 92055202)the China Geological Survey(DD20221817 and DD20190057)+1 种基金the basic scientific research funding in CAGS(J2204)the Second Tibetan Plateau Scientific Expedition and Research(2019QZKK0702).
文摘Two suites of mafic dykes,T1193-A and T1194-A,outcrop in Gyangze area,southeast Tibet.They are in the area of Comei LIP and have indistinguishable field occurrences with two other dykes in Gyangze,T0902 dyke with 137.7±1.3 Ma zircon age and T0907 dyke with 142±1.4 Ma zircon age reported by Wang YY et al.(2016),indicating coeval formation time.Taking all the four diabase dykes into consideration,two different types,OIB-type and weak enriched-type,can be summarized.The“OIB-type”samples,including T1193-A and T0907 dykes,show OIB-like geochemical features and have initial Sr-Nd isotopic values similar with most mafic products in Comei Large Igneous Provinces(LIP),suggesting that they represent melts directly generated from the Kerguelen mantle plume.The“weak enriched-type”samples,including T1194-A and T0902 dykes,have REEs and trace element patterns showing withinplate affinity but have obvious Nb-Ta-Ti negative anomalies.They show uniform lowerεNd(t)values(−6‒−2)and higher 87Sr/86Sr(t)values(0.706‒0.709)independent of their MgO variation,indicating one enriched mantle source.Considering their closely spatial and temporal relationship with the widespread Comei LIP magmatic products in Tethyan Himalaya,these“weak enriched-type”samples are consistent with mixing of melts from mantle plume and the above ancient Tethyan Himalaya subcontinental lithospheric mantle(SCLM)in different proportions.These weak enriched mafic rocks in Comei LIP form one special rock group and most likely suggest large scale hot mantle plume-continental lithosphere interaction.This process may lead to strong modification of the Tethyan Himalaya lithosphere in the Early Cretaceous.
基金financially supported by the Grant for the National Major Science and Technology Project(grant No.2012ZX10004-220,No.2008ZX10004-011)
文摘In Garze Tibetan autonomous prefecture inSichuan province, China, 41 echinococciasis patientswho had received surgical treatment were recruitedin the study, and 82 health persons who had livedin Garze for at least 10 years were selected ascontrols. The serum levels of Zn, Se and Cu of thecases and controls were detected. The resultsshowed that most echinococciasis cases weredistributed in Shiqu county （17.1%, 7/41）, and only1 case was distributed in Yajiang county （2.4%）. Themale to female ratio of the cases was 1：1.56. Theechinococciasis patients were mainly aged 30-39years （36.59%, 15/41）. And, the cases aged 20-49years accounted for 68.29% （28/41）. Comparedwith health controls, the serum levels of Zn and Seof the cases significantly declined. However, theserum level of Cu of the cases had no significantlychange. It was confirmed that the serum levels ofZn and Se were interrelated with the prevalence ofechinococciasis.
基金funded by the National Natural Science Foundation of China(Grant Nos.42304153,42104138 and U2244220)China Geological Survey(Grant Nos.DD20221715,DD20243057,DD20243216).
文摘Analysis and research of large complex phenomena before and after the devastating earthquake to reduce the threat of natural disasters to human survival environment is of great significance.This paper analyzes the Wenchuan earthquake zone characteristics of gravity anomaly distributions,and then use edge detection and Euler deconvolution method to inverse Longmenshan gravity anomaly before earthquake.Fault distribution features and the general depth about the fault top of Longmenshan and its adjacent area before earthquake has been obtained.Morphology difference and possible earthquake formation have been analyzed through the Euler deconvolution result of gravity anomaly profile before and after the earthquake.
