The regular hydrochemical monitoring of groundwater in the Mila basin over an extended period has provided valuable insights into the origin of dissolved salts and the hydrogeochemical processes controlling water sali...The regular hydrochemical monitoring of groundwater in the Mila basin over an extended period has provided valuable insights into the origin of dissolved salts and the hydrogeochemical processes controlling water salinization.The data reveals that the shallow Karst aquifer shows an increase in TDS of 162 mg L^(-1) while the ther-mal carbonate aquifer that is also used for drinking water supply exhibits an increase of 178 mg L^(-1).Additionally,significant temperature variations are recorded at the sur-face in the shallow aquifers and the waters are carbo-gaseous.Analysis of dissolved major and minor elements has identified several processes influencing the chemical composition namely:dissolution of evaporitic minerals,reduction of sulphates,congruent and incongruent car-bonates’dissolution,dedolomitization and silicates’weathering.The hydrogeochemical and geothermometric results show a mixing of saline thermal water with recharge water of meteoric origin.Two main geothermalfields have been identified,a partially evolved water reservoir and a water reservoir whosefluid interacts with sulphuric acid(H_(2)S)of magmatic origin.These hot waters that are char-acterized by a strong hydrothermal alteration do ascend through faults and fractures and contribute to the contamination of shallower aquifers.Understanding the geothermometry and the hydrogeochemistry of waters is crucial for managing and protecting the quality of groundwater resources in the Mila basin,in order to ensure sustainable water supply for the region.A conceptual model for groundwater circulation and mineralization acquisition has been established to further enhance under-standing in this regard.展开更多
Huaihe River Basin(HRB) is located in China’s north-south climatic transition zone,which is very sensitive to global climate change.Based on the daily maximum temperature,minimum temperature,and precipitation data of...Huaihe River Basin(HRB) is located in China’s north-south climatic transition zone,which is very sensitive to global climate change.Based on the daily maximum temperature,minimum temperature,and precipitation data of 40 meteorological stations and nine monthly large-scale ocean-atmospheric circulation indices data during 1959–2019,we present an assessment of the spatial and temporal variations of extreme temperature and precipitation events in the HRB using nine extreme climate indices,and analyze the teleconnection relationship between extreme climate indices and large-scale ocean-atmospheric circulation indices.The results show that warm extreme indices show a significant(P < 0.05) increasing trend,while cold extreme indices(except for cold spell duration) and diurnal temperature range(DTR) show a significant decreasing trend.Furthermore,all extreme temperature indices show significant mutations during 1959-2019.Spatially,a stronger warming trend occurs in eastern HRB than western HRB,while maximum 5-d precipitation(Rx5day) and rainstorm days(R25) show an increasing trend in the southern,central,and northwestern regions of HRB.Arctic oscillation(AO),Atlantic multidecadal oscillation(AMO),and East Atlantic/Western Russia(EA/WR) have a stronger correlation with extreme climate indices compared to other circulation indices.AO and AMO(EA/WR) exhibit a significant(P < 0.05) negative(positive)correlation with frost days and diurnal temperature range.Extreme warm events are strongly correlated with the variability of AMO and EA/WR in most parts of HRB,while extreme cold events are closely related to the variability of AO and AMO in eastern HRB.In contrast,AMO,AO,and EA/WR show limited impacts on extreme precipitation events in most parts of HRB.展开更多
The concept of load-carrying capacity of the soil can be evaluated by two main components: permissible stress and permissible depth;and therefore, running it begins its assessment that allows an outline of exploitatio...The concept of load-carrying capacity of the soil can be evaluated by two main components: permissible stress and permissible depth;and therefore, running it begins its assessment that allows an outline of exploitation. Nevertheless, the assessment of the load-carrying capacity made the object of several works of research and many models, based on the multi-criteria analysis, have been established. This work examines the contribution of GIS approach to assessment load-carrying capacity of the soil. This one has been finished in two practicums: 1) Assessment of the capacity of soil by a multi-criteria approach, using the Weighted Sum Model (WSM);2) It brought to use the GIS approach to evaluate and spatialize degree of soil bearing stresses resulting from the buildings, as well as load distribution. The method has been applied to the Berhoum area of Hodna Basin, in eastern Algeria, where each is characterized by its various natural properties and density of equipment. Final results are better in the classification of the degree of load-carrying capacity possible in each site. This results in allowing exploiters to program their optimal designs for the rational management of the area.展开更多
Global ecosystems and public health have been greatly impacted by the accumulation of heavy metal(loid)s in water.Source-specific risk apportionment is needed to prevent and manage potential groundwater contamination ...Global ecosystems and public health have been greatly impacted by the accumulation of heavy metal(loid)s in water.Source-specific risk apportionment is needed to prevent and manage potential groundwater contamination with heavy metal(loid)s.The heavy metal(loid)s contamination status,water quality,ecological risk,and health risk apportionment of the Shule River Basin groundwater are poorly understood.Therefore,field sampling was performed to explore the water quality and risk of heavy metal(loid)s in the groundwater of the Shule River Basin in northwestern China.A total of 96 samples were collected from the study area to acquire data for water quality and heavy metal(loid)s risk.There was noticeable accumulation of ferrum in the groundwater of the Shule River Basin.The levels of pollution were considered to be moderately low,as evaluated by the degree of contamination,heavy metal evaluation index,heavy metal pollution index,and Nemerow pollution index.The ecological risks were also low.However,an assessment of the water quality index revealed that only 58.34%of the groundwater samples had good water quality.The absolute principal component scores-multiple linear regression model was more suited for this study area than the positive matrix factorization model.There were no obvious noncarcinogenic or carcinogenic concerns for all types of receptors according to the values of the total hazard index and total carcinogenic risk.The human activities and the initial geological environment factor(65.85%)was the major source of noncarcinogenic risk(residential children:87.56%;residential adults:87.52%;recreational children:86.77%;and recreational adults:85.42%),while the industrial activity factor(16.36%)was the major source of carcinogenic risk(residential receptors:87.96%;and recreational receptors:68.73%).These findings provide fundamental and crucial information for reducing the health issues caused by heavy metal(loid)s contamination of groundwater in arid areas.展开更多
Based on the measurements of petrological, petrophysical and elastic properties of the samples of different sedimentary facies in the fourth member of Sinian Dengying Formation (Deng 4 Member) in the Sichuan Basin, th...Based on the measurements of petrological, petrophysical and elastic properties of the samples of different sedimentary facies in the fourth member of Sinian Dengying Formation (Deng 4 Member) in the Sichuan Basin, the diagenetic processes of reservoirs of different sedimentary facies and their controls on the petrophysical properties were discussed. The results show that cracks and mineral composition jointly control the petrophysical properties, and both are significantly influenced by sedimentary environment and diagenesis. The microbial dolomite of mound-shoal facies mainly experienced multi-stage dolomitization, penecontemporaneous dissolution, tectonic rupture and hydrothermal/organic acid dissolution processes, giving rise to cracks and dissolved pores. The grannular dolomite of inter-mound-shoal bottomland or dolomitic lagoon facies mainly underwent mechanical compaction, burial dolomitization and tectonic-hydrothermal action, creating cracks and intercrystalline pores. The diagenesis related to crack development increases the pressure- and saturation-dependent effects of samples, leading to significant decrease in the compressional wave impedance and Poisson's ratio. Dolomitization changes the properties of mineral particles, resulting in a Poisson's ratio close to dolomite. The muddy, siliceous and calcareous sediments in the low-energy environment lead to the decrease of impedance and the differential change of Poisson's ratio (significantly increased or decreased). The samples with both cracks and dissolved pores show high P-wave velocity dispersion characteristics, and the P-wave velocity dispersion of samples with only fractures or pores is the lowest.展开更多
The upper Paleozoic natural gas reservoirs in the Ordos basin are generally characterized by a large gas-bearing area and low reserve abundance. On such a geological background, there still exist gas-enriched zones, w...The upper Paleozoic natural gas reservoirs in the Ordos basin are generally characterized by a large gas-bearing area and low reserve abundance. On such a geological background, there still exist gas-enriched zones, with relatively high outputs, high reserve abundance and stably distributed gas layers. The gas-enriched layers with relatively high permeability (the lower limit permeability is 0.5×10^-3μm^2) are key factors for the enrichment and high output of natural gas. Based on core observation, analytic results of inclusions, and a great deal of drilling data, we proposed the following four mechanisms for the formation of high-quality reservoirs: (1) in the source area the parent rocks are mainly metamorphic rocks and granites, which are favorable to keeping primary porosity; (2) under the condition of low A/S (accommodation/sediment supply) ratios, sandstone complex formed due to multistage fluvial stacking and filling are coarse in grain size with a high degree of sorting, low content of mud and good physical properties; (3) early-stage recharge of hydrocarbons restricted compaction and cementation, and thus are favorable to preservation of primary pores; (4) microfractures caused by the activity of basement faults during the Yanshan Movement stage can not only improve the permeability of tight sandstones, but also afford vertical pathways for hydrocarbon gas migration.展开更多
The Lhasa River Basin is one of the typical distribution regions of alpine wetlands on the Tibetan Plateau. It is very important to get a better understanding of the background and characteristics of alpine wetland fo...The Lhasa River Basin is one of the typical distribution regions of alpine wetlands on the Tibetan Plateau. It is very important to get a better understanding of the background and characteristics of alpine wetland for monitoring, protection and utilization. Wetland construction and distribution in the basin were analyzed based on multi-source data including field investigation data, CBERS remote sensing data and other thematic data provided by 3S technology. The results are (1) the total area of wetlands is 209,322.26 hm^2, accounting for 6.37% of the total land area of the basin. The wetlands are mainly dominated by natural wetland, with artificial wetland occupying only 1.09% of the wetland area; marsh wetland is the principal part of natural wetland, dominated by Kobresia littledalei swampy meadow which is distributed in the river source area and upstream of Chali, Damshung and Medro Gongkar counties. The ratio and type of wetlands in different counties differ significantly, which are widely distributed in Chali and Damshung counties (accounting for 62% of the total wetland area). (2) The concentrated vertical distribution of wetlands is at an elevation of 3600-5100 m The wetlands are widely distributed throughout the Yarlung Zangbo River Valley from river source to river mouth into the Yarlung Zangbo River. Marsh wetland is dominant in the source area and upstream of the river, with the mosaic distribution of lakes, Kobresia litUedalei and Carex moorcroftii swampy meadow, shrubby swamp and river; as for the middle-down streams, the primary types are river wetland and flooded wetland. The distribution is in a mosaic pattern of river, Kobresia humilis and Carex moorcroftii swampy meadow, Phragmites australis and subordinate grass marsh, flooded wetland and artificial wetland.展开更多
The concentration of hydrogen sulfide gas (H2S) varies greatly in the oil-bearing basins of China, from zero to 90%. At present, oil and gas reservoirs with high H2S concentration have been discovered in three basin...The concentration of hydrogen sulfide gas (H2S) varies greatly in the oil-bearing basins of China, from zero to 90%. At present, oil and gas reservoirs with high H2S concentration have been discovered in three basins, viz. the Bohai Bay Basin, Sichuan Basin and the Tarim Basin, whereas natural gas with low H2S concentration has been found in the Ordos Basin, the Songliao Basin and the Junggar Basin. Studies suggest that in China H2S origin types are very complex. In the carbonate reservoir of the Sichuan Basin, the Ordos Basin and the Tarim Basin, as well as the carbonatedominated reservoir in the Luojia area of the Jiyang depression in the Bohai Bay Basin, Wumaying areas of the Huanghua depression, and Zhaolanzhuang areas of the Jizhong depression, the H2S is of Thermochemical Sulfate Reduction (TSR) origin. The H2S is of Bacterial Sulphate Reduction (BSR) origin deduced from the waterflooding operation in the Changheng Oilfield (placanticline oil fields) in the Songliao Basin. H2S originates from thermal decomposition of sulfur-bearing crude oil in the heavy oil area in the Junggar Basin and in the Liaohe heavy oil steam pilot area in the western depression of the Bohai Bay Basin. The origin types are most complex, including TSR and thermal decomposition of sulfcompounds among other combinations of causes. Various methods have been tried to identify the origin mechanism and to predict the distribution of H2S. The origin identification methods for H2S mainly comprise sulfur and carbon isotopes, reservoir petrology, particular biomarkers, and petroleum geology integrated technologies; using a combination of these applications can allow the accurate identification of the origins of H2S. The prediction technologies for primary and secondary origin of H2S have been set up separately.展开更多
Many of the sedimentary basins in western China were formed through the superposition and compounding of at least two previously developed sedimentary basins and in general they can be termed as complex superimposed b...Many of the sedimentary basins in western China were formed through the superposition and compounding of at least two previously developed sedimentary basins and in general they can be termed as complex superimposed basins. The distinct differences between these basins and monotype basins are their discontinuous stratigraphic sedimentation, stratigraphic structure and stratigraphic stress-strain action over geological history. Based on the correlation of chronological age on structural sections, superimposed basins can be divided into five types in this study: (1) continuous sedimentation type superimposed basins, (2) middle and late stratigraphic superimposed basins, (3) early and late stratigraphic superimposed basins, (4) early and middle stratigraphic superimposed basins, and (5) long-term exposed superimposed basins. Multiple source-reservoir-caprock assemblages have developed in such basins. In addition, multi-stage hydrocarbon generation and expulsion, multiple sources, polycyclic hydrocarbon accumulation and multiple-type hydrocarbon reservoirs adjustment, reformation and destruction have occurred in these basins. The complex reservoirs that have been discovered widely in the superimposed basins to date have remarkably different geologic features from primary reservoirs, and the root causes of this are folding, denudation and the fracture effect caused by multiphase tectonic events in the superimposed basins as well as associated seepage, diffusion, spilling, oxidation, degradation and cracking. Based on their genesis characteristics, complex reservoirs are divided into five categories: (1) primary reservoirs, (2) trap adjustment type reservoirs, (3) component variant reservoirs, (4) phase conversion type reservoirs and (5) scale-reformed reservoirs.展开更多
The Taixinan Basin is one of the most potential gas hydrate bearing areas in the South China Sea and abundant gas hydrates have been discovered during expedition in 2013. In this study, geochemical and microbial metho...The Taixinan Basin is one of the most potential gas hydrate bearing areas in the South China Sea and abundant gas hydrates have been discovered during expedition in 2013. In this study, geochemical and microbial methods are combinedly used to characterize the sediments from a shallow piston Core DH_CL_11(gas hydrate free) and a gas hydrate-bearing drilling Core GMGS2-16 in this basin. Geochemical analyses indicate that anaerobic oxidation of methane(AOM) which is speculated to be linked to the ongoing gas hydrate dissociation is taking place in Core DH_CL_11 at deep. For Core GMGS2-16, AOM related to past episodes of methane seepage are suggested to dominate during its diagenetic process; while the relatively enriched δ18O bulk-sediment values indicate that methane involved in AOM might be released from the "episodic dissociation" of gas hydrate.Microbial analyses indicate that the predominant phyla in the bacterial communities are Firmicutes and Proteobacteria(Gammaproteobacteria and Epsilonproteobacteria), while the dominant taxa in the archaeal communities are Marine_Benthic_Group_B(MBGB), Halobacteria, Thermoplasmata, Methanobacteria,Methanomicrobia, Group C3 and MCG. Under parallel experimental operations, comparable dominant members(Firmicutes and MBGB) are found in the piston Core DH_CL_11 and the near surface layer of the long drilling Core GMGS2-16. Moreover, these members have been found predominant in other known gas hydrate bearing cores, and the dominant of MBGB has even been found significantly related to gas hydrate occurrence. Therefore,a high possibility for the existing of gas hydrate underlying Core DH_CL_11 is inferred, which is consistent with the geochemical analyses. In all, combined geochemical and microbiological analyses are more informative in characterizing sediments from gas hydrate-associated areas in the South China Sea.展开更多
From the near-field records of aftershock of Datong earthquakes in October 1989 and March 1991,an extra phase between P and S arrivals is found. High-precision epicenter location shows that some of these records are o...From the near-field records of aftershock of Datong earthquakes in October 1989 and March 1991,an extra phase between P and S arrivals is found. High-precision epicenter location shows that some of these records are obtained with the incidental angle less than the critical angle. This excludes the possibility that the extra wave phase is a refractive wave from ground surface. Particle motion analysis shows that the characteristic of the extra wave is similar to that of wave, so it is possible that the extra phase is an S to P convert wave from the bottom of sediment basin. Suppose a low velocity layer covers a high velocity basement. Successful simulation by the synthetic seismogram confirms that the extra phase is an S-P convert wave from the interface of the basin bottom. Modifying the depth of interface at each ray path to match the waveform, we obtain an interface distribution in space. In this way, a brief bottom image could be shown, and the Datong basin has a 'V' shaped bottom.展开更多
Based on the information from forest resources distribution maps of Luoning County of 1983 and 1999, six indices were used to analyze spatial patterns and dynamics of forest landscapes of t...Based on the information from forest resources distribution maps of Luoning County of 1983 and 1999, six indices were used to analyze spatial patterns and dynamics of forest landscapes of the typical region in the middle of the Yihe-Luohe river basin. These indices include patch number, mean patch area, fragment index, patch extension index, etc. The results showed that: (1) There was a rapid increase in the number of patch and total area from 1983 to 1999 in the study area. The fragment degree became very high. (2) The area of all the forest patch types had witnessed great changes. The fractal degree of each forest patch type became big from 1983 to 1999. The mean extension index of Robinia pseudoacacia forest, non-forest, shrub forest, sparse forest, and Quercus species forest increased rapidly, but that of economic forest became zero. The fractal dimension each showed that forest coverage has been promoted. (3) The changes of landscape patterns were different in different geomorphic regions. From 1983 to 1999 the vegetation cover area, the gross number and the density of patch, diversity and evenness of landscape were all reduced greatly in gullies and ravines, but the maximum area and the mean area of patch types were increased. In hilly region, both the forest cover area and the number of patch increased from 1983 to 1999, but the mean area of patch was reduced greatly. In mountain region, even though the area under forest canopy reduced from 1983 to 1999, the patch number was increased greatly, the mean area of all patch types was reduced, the extension index, diversity index and evenness index of landscape were all increased. Furthermore, because of different types of land use, human activity and terrain, the vegetation changes on northern and southern mountain slopes were different. According to these analyses, the main driving forces, such as the policies of management, market economy, influence of human activities etc. are brought out.展开更多
The Junggar Basin in the northern part of Xinjiang is the second largest inland basin in China. It is located between the Altai and Tianshan Mountains, which is bounded by the Junggar bounded Mountain in the northwest...The Junggar Basin in the northern part of Xinjiang is the second largest inland basin in China. It is located between the Altai and Tianshan Mountains, which is bounded by the Junggar bounded Mountain in the northwest, the Altai Mountains in the northeast and the North Tianshan Mountains in the south. It belongs to a triangular close inland basin, and extends 700 km in EW and 370 km in NS, covering an area of 38x104 km2. The elevation is about 400 m, high in the east (about 1000 m) and low in the west. The central basin is the Guerbantonggute desert, which accounts for 36.9% of the total basin area.展开更多
On July 20, 1995 an M_L= 4.1 earthquake occurred in Huailai basin, northwest of Beijing, with epicenter coordinates 40.326°N, 115.448°E and focal depth 5.5 km. Following the main shock, microseismicity sharp...On July 20, 1995 an M_L= 4.1 earthquake occurred in Huailai basin, northwest of Beijing, with epicenter coordinates 40.326°N, 115.448°E and focal depth 5.5 km. Following the main shock, microseismicity sharply increased in the basin. This earthquake sequence was recorded by Sino-European Cooperative Huailai Digital Seismograph Network (HDSN) and the hypocenters were precisely located. Using 8 aftershocks as empirical Green(s function (EGF) we calculated the source time function (STF) of the ML=4.1 event respectively, and by superposing these results, we obtained the average time function which has better signal to noise ratio. The final result shows that the ML=4.1 earthquake consisted of two events, one of which was stronger, the other was weaker, STFs from each station demonstrate an obvious (seismic Doppler effect(. Through a trial-and-error method, the following results were drawn: for the 1st event, the rupture length is 0.44 km, rupture velocity is 4.0 km/s, while for the 2nd event those parameters are 0.25 km, 3.0 km/s, the two events ruptured in the direction of 140° and 90° respectively (measured from the strike of the fault, anticlockwise positive), the two events were separated by 0.57 km in space, and 0.09 s in time. Using single EGF, we also retrieved the source time function of other 13 events with ML(2.1 in the Huailai earthquake sequence. These results were reached: each of the 13 events consisted of single event, with the duration of the source time functions ranging between 0.05~0.16 s. Using far-field ground displacement measurement method, the scalar seismic moment, stress drop and rupture radii of 25 events with 0.95(ML(4.1 were obtained. The trend that scalar seismic moment and stress drop increase with magnitude was obvious. In the magnitude range 0.9(ML(2.4, the obtained radii show no correlativity with magnitude, we tend to believe, in such small magnitude range, precise measurement for radii of such small events is beyond the data used in this study.展开更多
Based on the continuous strain data recorded in Xinjiang since 1985, we discuss the mechanisms of Tianshan' s uplift and Tarim basin' s clockwise rotation. The results indicate : 1 ) The principal - compression di...Based on the continuous strain data recorded in Xinjiang since 1985, we discuss the mechanisms of Tianshan' s uplift and Tarim basin' s clockwise rotation. The results indicate : 1 ) The principal - compression directions in Tianshan are nearly NS, and their intersection angles with regional structures and mountains are nearly perpendicular, which is in accordance with Tianshan' s uplift and crustal shortening. 2)The principal compressions around Tarim basin tend to facilitate the regional faults' left-lateral strike-slip movements and the basin' s clockwise rotation. These phenomena of uplift/shortening and rotation are fundamentally the re- suits of India plate' s northward push on Euro-Asia plate, and the associated Pamir arc ' s rapid northward movement and regional blocks' interaction.展开更多
The natural gas components and geochemistry of 38 ultra-deep gas wells(burial depth greater than 6 000 m) in the Sichuan Basin were analyzed to determine the genesis of ultra-deep natural gas in the basin. The ultra-d...The natural gas components and geochemistry of 38 ultra-deep gas wells(burial depth greater than 6 000 m) in the Sichuan Basin were analyzed to determine the genesis of ultra-deep natural gas in the basin. The ultra-deep natural gas components of the basin have the following characteristics: Methane has an absolute advantage, which can be up to 99.56% with an average of 86.6%; ethane is low, with an average of 0.13%; there is nearly no propane and butane. So it is dry gas at over-mature thermal stage. The content of H2 S can be up to 25.21%, with an average of 5.45%. The alkane gas isotopes are: the carbon isotope varies from-32.3‰ to-26.7‰ for methane and from-32.9‰ to-22.1‰ for ethane. There is nearly no carbon isotopic reversal among methane and its homologues. Hydrogen isotope varies from-156‰ to-114‰ for methane, and from-103‰ to-89‰ for some ethane. The carbon isotope of CO_2 varies from-17.2‰ to 1.9‰ and most of them fall within the range of 0±3‰. According to the δ^(13)C_1-δ^(13)C_2-δ^(13)C_3 plot, except some wells, all other ultra-deep gas wells are dominated by coal-derived gas. Based on the CO_2 origin distinguishing plot and δ^(13)C_(CO_2), except some individual wells, most of the ultra-deep CO_2 are of carbonate metamorphic origin. H2 S in the ultra-deep layer of Longgang and Yuanba gas fields belongs to thermochemical sulfate reduction(TSR), while H2 S from Well Shuangtan belongs to thermal decomposition of sulfides(TDS).展开更多
The Xinjiang Geology and Mineral Resources Exploration and Development Bureau have conducted a detailed investigation project of the Xigobi soda-niter deposit in Hami, Xinjiang Province, which was completed at the end...The Xinjiang Geology and Mineral Resources Exploration and Development Bureau have conducted a detailed investigation project of the Xigobi soda-niter deposit in Hami, Xinjiang Province, which was completed at the end of 2011. The project put much emphasis on research of soda-niter mineralization rules, stratum classification, ore-forming展开更多
文摘The regular hydrochemical monitoring of groundwater in the Mila basin over an extended period has provided valuable insights into the origin of dissolved salts and the hydrogeochemical processes controlling water salinization.The data reveals that the shallow Karst aquifer shows an increase in TDS of 162 mg L^(-1) while the ther-mal carbonate aquifer that is also used for drinking water supply exhibits an increase of 178 mg L^(-1).Additionally,significant temperature variations are recorded at the sur-face in the shallow aquifers and the waters are carbo-gaseous.Analysis of dissolved major and minor elements has identified several processes influencing the chemical composition namely:dissolution of evaporitic minerals,reduction of sulphates,congruent and incongruent car-bonates’dissolution,dedolomitization and silicates’weathering.The hydrogeochemical and geothermometric results show a mixing of saline thermal water with recharge water of meteoric origin.Two main geothermalfields have been identified,a partially evolved water reservoir and a water reservoir whosefluid interacts with sulphuric acid(H_(2)S)of magmatic origin.These hot waters that are char-acterized by a strong hydrothermal alteration do ascend through faults and fractures and contribute to the contamination of shallower aquifers.Understanding the geothermometry and the hydrogeochemistry of waters is crucial for managing and protecting the quality of groundwater resources in the Mila basin,in order to ensure sustainable water supply for the region.A conceptual model for groundwater circulation and mineralization acquisition has been established to further enhance under-standing in this regard.
基金Under the auspices of National Natural Science Foundation of China(No.52279016,51909106,51879108,42002247,41471160)Natural Science Foundation of Guangdong Province,China(No.2020A1515011038,2020A1515111054)+1 种基金Special Fund for Science and Technology Development in 2016 of Department of Science and Technology of Guangdong Province,China(No.2016A020223007)the Project of Jinan Science and Technology Bureau(No.2021GXRC070)。
文摘Huaihe River Basin(HRB) is located in China’s north-south climatic transition zone,which is very sensitive to global climate change.Based on the daily maximum temperature,minimum temperature,and precipitation data of 40 meteorological stations and nine monthly large-scale ocean-atmospheric circulation indices data during 1959–2019,we present an assessment of the spatial and temporal variations of extreme temperature and precipitation events in the HRB using nine extreme climate indices,and analyze the teleconnection relationship between extreme climate indices and large-scale ocean-atmospheric circulation indices.The results show that warm extreme indices show a significant(P < 0.05) increasing trend,while cold extreme indices(except for cold spell duration) and diurnal temperature range(DTR) show a significant decreasing trend.Furthermore,all extreme temperature indices show significant mutations during 1959-2019.Spatially,a stronger warming trend occurs in eastern HRB than western HRB,while maximum 5-d precipitation(Rx5day) and rainstorm days(R25) show an increasing trend in the southern,central,and northwestern regions of HRB.Arctic oscillation(AO),Atlantic multidecadal oscillation(AMO),and East Atlantic/Western Russia(EA/WR) have a stronger correlation with extreme climate indices compared to other circulation indices.AO and AMO(EA/WR) exhibit a significant(P < 0.05) negative(positive)correlation with frost days and diurnal temperature range.Extreme warm events are strongly correlated with the variability of AMO and EA/WR in most parts of HRB,while extreme cold events are closely related to the variability of AO and AMO in eastern HRB.In contrast,AMO,AO,and EA/WR show limited impacts on extreme precipitation events in most parts of HRB.
文摘The concept of load-carrying capacity of the soil can be evaluated by two main components: permissible stress and permissible depth;and therefore, running it begins its assessment that allows an outline of exploitation. Nevertheless, the assessment of the load-carrying capacity made the object of several works of research and many models, based on the multi-criteria analysis, have been established. This work examines the contribution of GIS approach to assessment load-carrying capacity of the soil. This one has been finished in two practicums: 1) Assessment of the capacity of soil by a multi-criteria approach, using the Weighted Sum Model (WSM);2) It brought to use the GIS approach to evaluate and spatialize degree of soil bearing stresses resulting from the buildings, as well as load distribution. The method has been applied to the Berhoum area of Hodna Basin, in eastern Algeria, where each is characterized by its various natural properties and density of equipment. Final results are better in the classification of the degree of load-carrying capacity possible in each site. This results in allowing exploiters to program their optimal designs for the rational management of the area.
基金This work was supported by the Kunlun Talent Action Plan of Qinghai Province(E140 WX42)National Natural Science Foundation of China(52179026)Strategy for Water Resource Security in Yellow River Sources。
文摘Global ecosystems and public health have been greatly impacted by the accumulation of heavy metal(loid)s in water.Source-specific risk apportionment is needed to prevent and manage potential groundwater contamination with heavy metal(loid)s.The heavy metal(loid)s contamination status,water quality,ecological risk,and health risk apportionment of the Shule River Basin groundwater are poorly understood.Therefore,field sampling was performed to explore the water quality and risk of heavy metal(loid)s in the groundwater of the Shule River Basin in northwestern China.A total of 96 samples were collected from the study area to acquire data for water quality and heavy metal(loid)s risk.There was noticeable accumulation of ferrum in the groundwater of the Shule River Basin.The levels of pollution were considered to be moderately low,as evaluated by the degree of contamination,heavy metal evaluation index,heavy metal pollution index,and Nemerow pollution index.The ecological risks were also low.However,an assessment of the water quality index revealed that only 58.34%of the groundwater samples had good water quality.The absolute principal component scores-multiple linear regression model was more suited for this study area than the positive matrix factorization model.There were no obvious noncarcinogenic or carcinogenic concerns for all types of receptors according to the values of the total hazard index and total carcinogenic risk.The human activities and the initial geological environment factor(65.85%)was the major source of noncarcinogenic risk(residential children:87.56%;residential adults:87.52%;recreational children:86.77%;and recreational adults:85.42%),while the industrial activity factor(16.36%)was the major source of carcinogenic risk(residential receptors:87.96%;and recreational receptors:68.73%).These findings provide fundamental and crucial information for reducing the health issues caused by heavy metal(loid)s contamination of groundwater in arid areas.
基金Supported by the National Natural Science Foundation of China(41774136)。
文摘Based on the measurements of petrological, petrophysical and elastic properties of the samples of different sedimentary facies in the fourth member of Sinian Dengying Formation (Deng 4 Member) in the Sichuan Basin, the diagenetic processes of reservoirs of different sedimentary facies and their controls on the petrophysical properties were discussed. The results show that cracks and mineral composition jointly control the petrophysical properties, and both are significantly influenced by sedimentary environment and diagenesis. The microbial dolomite of mound-shoal facies mainly experienced multi-stage dolomitization, penecontemporaneous dissolution, tectonic rupture and hydrothermal/organic acid dissolution processes, giving rise to cracks and dissolved pores. The grannular dolomite of inter-mound-shoal bottomland or dolomitic lagoon facies mainly underwent mechanical compaction, burial dolomitization and tectonic-hydrothermal action, creating cracks and intercrystalline pores. The diagenesis related to crack development increases the pressure- and saturation-dependent effects of samples, leading to significant decrease in the compressional wave impedance and Poisson's ratio. Dolomitization changes the properties of mineral particles, resulting in a Poisson's ratio close to dolomite. The muddy, siliceous and calcareous sediments in the low-energy environment lead to the decrease of impedance and the differential change of Poisson's ratio (significantly increased or decreased). The samples with both cracks and dissolved pores show high P-wave velocity dispersion characteristics, and the P-wave velocity dispersion of samples with only fractures or pores is the lowest.
基金This research is part of a project carried out during 2002-2004 and supported by the National Basic Research Program(Grant No.2001CB209100).
文摘The upper Paleozoic natural gas reservoirs in the Ordos basin are generally characterized by a large gas-bearing area and low reserve abundance. On such a geological background, there still exist gas-enriched zones, with relatively high outputs, high reserve abundance and stably distributed gas layers. The gas-enriched layers with relatively high permeability (the lower limit permeability is 0.5×10^-3μm^2) are key factors for the enrichment and high output of natural gas. Based on core observation, analytic results of inclusions, and a great deal of drilling data, we proposed the following four mechanisms for the formation of high-quality reservoirs: (1) in the source area the parent rocks are mainly metamorphic rocks and granites, which are favorable to keeping primary porosity; (2) under the condition of low A/S (accommodation/sediment supply) ratios, sandstone complex formed due to multistage fluvial stacking and filling are coarse in grain size with a high degree of sorting, low content of mud and good physical properties; (3) early-stage recharge of hydrocarbons restricted compaction and cementation, and thus are favorable to preservation of primary pores; (4) microfractures caused by the activity of basement faults during the Yanshan Movement stage can not only improve the permeability of tight sandstones, but also afford vertical pathways for hydrocarbon gas migration.
基金The National Key Technology Research and Development Program,No.2007BAC06B03National Basic Research Program of China,No.2005CB422000
文摘The Lhasa River Basin is one of the typical distribution regions of alpine wetlands on the Tibetan Plateau. It is very important to get a better understanding of the background and characteristics of alpine wetland for monitoring, protection and utilization. Wetland construction and distribution in the basin were analyzed based on multi-source data including field investigation data, CBERS remote sensing data and other thematic data provided by 3S technology. The results are (1) the total area of wetlands is 209,322.26 hm^2, accounting for 6.37% of the total land area of the basin. The wetlands are mainly dominated by natural wetland, with artificial wetland occupying only 1.09% of the wetland area; marsh wetland is the principal part of natural wetland, dominated by Kobresia littledalei swampy meadow which is distributed in the river source area and upstream of Chali, Damshung and Medro Gongkar counties. The ratio and type of wetlands in different counties differ significantly, which are widely distributed in Chali and Damshung counties (accounting for 62% of the total wetland area). (2) The concentrated vertical distribution of wetlands is at an elevation of 3600-5100 m The wetlands are widely distributed throughout the Yarlung Zangbo River Valley from river source to river mouth into the Yarlung Zangbo River. Marsh wetland is dominant in the source area and upstream of the river, with the mosaic distribution of lakes, Kobresia litUedalei and Carex moorcroftii swampy meadow, shrubby swamp and river; as for the middle-down streams, the primary types are river wetland and flooded wetland. The distribution is in a mosaic pattern of river, Kobresia humilis and Carex moorcroftii swampy meadow, Phragmites australis and subordinate grass marsh, flooded wetland and artificial wetland.
基金supported by the National Natural Science Foundation of China (Grant Nos 4060201640773032)the National Basic Research Program of China (contract No.2007CB209500)
文摘The concentration of hydrogen sulfide gas (H2S) varies greatly in the oil-bearing basins of China, from zero to 90%. At present, oil and gas reservoirs with high H2S concentration have been discovered in three basins, viz. the Bohai Bay Basin, Sichuan Basin and the Tarim Basin, whereas natural gas with low H2S concentration has been found in the Ordos Basin, the Songliao Basin and the Junggar Basin. Studies suggest that in China H2S origin types are very complex. In the carbonate reservoir of the Sichuan Basin, the Ordos Basin and the Tarim Basin, as well as the carbonatedominated reservoir in the Luojia area of the Jiyang depression in the Bohai Bay Basin, Wumaying areas of the Huanghua depression, and Zhaolanzhuang areas of the Jizhong depression, the H2S is of Thermochemical Sulfate Reduction (TSR) origin. The H2S is of Bacterial Sulphate Reduction (BSR) origin deduced from the waterflooding operation in the Changheng Oilfield (placanticline oil fields) in the Songliao Basin. H2S originates from thermal decomposition of sulfur-bearing crude oil in the heavy oil area in the Junggar Basin and in the Liaohe heavy oil steam pilot area in the western depression of the Bohai Bay Basin. The origin types are most complex, including TSR and thermal decomposition of sulfcompounds among other combinations of causes. Various methods have been tried to identify the origin mechanism and to predict the distribution of H2S. The origin identification methods for H2S mainly comprise sulfur and carbon isotopes, reservoir petrology, particular biomarkers, and petroleum geology integrated technologies; using a combination of these applications can allow the accurate identification of the origins of H2S. The prediction technologies for primary and secondary origin of H2S have been set up separately.
基金the National Key Fundamental Research Plan "973" Project(2006CB202308) for funds for this paper
文摘Many of the sedimentary basins in western China were formed through the superposition and compounding of at least two previously developed sedimentary basins and in general they can be termed as complex superimposed basins. The distinct differences between these basins and monotype basins are their discontinuous stratigraphic sedimentation, stratigraphic structure and stratigraphic stress-strain action over geological history. Based on the correlation of chronological age on structural sections, superimposed basins can be divided into five types in this study: (1) continuous sedimentation type superimposed basins, (2) middle and late stratigraphic superimposed basins, (3) early and late stratigraphic superimposed basins, (4) early and middle stratigraphic superimposed basins, and (5) long-term exposed superimposed basins. Multiple source-reservoir-caprock assemblages have developed in such basins. In addition, multi-stage hydrocarbon generation and expulsion, multiple sources, polycyclic hydrocarbon accumulation and multiple-type hydrocarbon reservoirs adjustment, reformation and destruction have occurred in these basins. The complex reservoirs that have been discovered widely in the superimposed basins to date have remarkably different geologic features from primary reservoirs, and the root causes of this are folding, denudation and the fracture effect caused by multiphase tectonic events in the superimposed basins as well as associated seepage, diffusion, spilling, oxidation, degradation and cracking. Based on their genesis characteristics, complex reservoirs are divided into five categories: (1) primary reservoirs, (2) trap adjustment type reservoirs, (3) component variant reservoirs, (4) phase conversion type reservoirs and (5) scale-reformed reservoirs.
基金The Natural Science Foundation of China under contract Nos 91128101,41273054 and 41373007the China Geological Survey Project for South China Sea Gas Hydrate Resource Exploration under contract No.DD20160211+1 种基金the Fundamental Research Funds for the Central Universities under contract No.16lgjc11the Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme under contract No.2011
文摘The Taixinan Basin is one of the most potential gas hydrate bearing areas in the South China Sea and abundant gas hydrates have been discovered during expedition in 2013. In this study, geochemical and microbial methods are combinedly used to characterize the sediments from a shallow piston Core DH_CL_11(gas hydrate free) and a gas hydrate-bearing drilling Core GMGS2-16 in this basin. Geochemical analyses indicate that anaerobic oxidation of methane(AOM) which is speculated to be linked to the ongoing gas hydrate dissociation is taking place in Core DH_CL_11 at deep. For Core GMGS2-16, AOM related to past episodes of methane seepage are suggested to dominate during its diagenetic process; while the relatively enriched δ18O bulk-sediment values indicate that methane involved in AOM might be released from the "episodic dissociation" of gas hydrate.Microbial analyses indicate that the predominant phyla in the bacterial communities are Firmicutes and Proteobacteria(Gammaproteobacteria and Epsilonproteobacteria), while the dominant taxa in the archaeal communities are Marine_Benthic_Group_B(MBGB), Halobacteria, Thermoplasmata, Methanobacteria,Methanomicrobia, Group C3 and MCG. Under parallel experimental operations, comparable dominant members(Firmicutes and MBGB) are found in the piston Core DH_CL_11 and the near surface layer of the long drilling Core GMGS2-16. Moreover, these members have been found predominant in other known gas hydrate bearing cores, and the dominant of MBGB has even been found significantly related to gas hydrate occurrence. Therefore,a high possibility for the existing of gas hydrate underlying Core DH_CL_11 is inferred, which is consistent with the geochemical analyses. In all, combined geochemical and microbiological analyses are more informative in characterizing sediments from gas hydrate-associated areas in the South China Sea.
基金State Key Basic Research Development and Programming Project (95-13-05-02) the Federal Institute for Geosciences and Natural Resources, Germany.
文摘From the near-field records of aftershock of Datong earthquakes in October 1989 and March 1991,an extra phase between P and S arrivals is found. High-precision epicenter location shows that some of these records are obtained with the incidental angle less than the critical angle. This excludes the possibility that the extra wave phase is a refractive wave from ground surface. Particle motion analysis shows that the characteristic of the extra wave is similar to that of wave, so it is possible that the extra phase is an S to P convert wave from the bottom of sediment basin. Suppose a low velocity layer covers a high velocity basement. Successful simulation by the synthetic seismogram confirms that the extra phase is an S-P convert wave from the interface of the basin bottom. Modifying the depth of interface at each ray path to match the waveform, we obtain an interface distribution in space. In this way, a brief bottom image could be shown, and the Datong basin has a 'V' shaped bottom.
基金Prominent Youth Science Foundation of Henan Province No.0003+2 种基金 No.9920 Natural Science Foundation of Henan Province No. 0111070100
文摘Based on the information from forest resources distribution maps of Luoning County of 1983 and 1999, six indices were used to analyze spatial patterns and dynamics of forest landscapes of the typical region in the middle of the Yihe-Luohe river basin. These indices include patch number, mean patch area, fragment index, patch extension index, etc. The results showed that: (1) There was a rapid increase in the number of patch and total area from 1983 to 1999 in the study area. The fragment degree became very high. (2) The area of all the forest patch types had witnessed great changes. The fractal degree of each forest patch type became big from 1983 to 1999. The mean extension index of Robinia pseudoacacia forest, non-forest, shrub forest, sparse forest, and Quercus species forest increased rapidly, but that of economic forest became zero. The fractal dimension each showed that forest coverage has been promoted. (3) The changes of landscape patterns were different in different geomorphic regions. From 1983 to 1999 the vegetation cover area, the gross number and the density of patch, diversity and evenness of landscape were all reduced greatly in gullies and ravines, but the maximum area and the mean area of patch types were increased. In hilly region, both the forest cover area and the number of patch increased from 1983 to 1999, but the mean area of patch was reduced greatly. In mountain region, even though the area under forest canopy reduced from 1983 to 1999, the patch number was increased greatly, the mean area of all patch types was reduced, the extension index, diversity index and evenness index of landscape were all increased. Furthermore, because of different types of land use, human activity and terrain, the vegetation changes on northern and southern mountain slopes were different. According to these analyses, the main driving forces, such as the policies of management, market economy, influence of human activities etc. are brought out.
文摘The Junggar Basin in the northern part of Xinjiang is the second largest inland basin in China. It is located between the Altai and Tianshan Mountains, which is bounded by the Junggar bounded Mountain in the northwest, the Altai Mountains in the northeast and the North Tianshan Mountains in the south. It belongs to a triangular close inland basin, and extends 700 km in EW and 370 km in NS, covering an area of 38x104 km2. The elevation is about 400 m, high in the east (about 1000 m) and low in the west. The central basin is the Guerbantonggute desert, which accounts for 36.9% of the total basin area.
基金National Key Basic Research Project "Mechanism and Prediction of Continental Strong Earthquakes".
文摘On July 20, 1995 an M_L= 4.1 earthquake occurred in Huailai basin, northwest of Beijing, with epicenter coordinates 40.326°N, 115.448°E and focal depth 5.5 km. Following the main shock, microseismicity sharply increased in the basin. This earthquake sequence was recorded by Sino-European Cooperative Huailai Digital Seismograph Network (HDSN) and the hypocenters were precisely located. Using 8 aftershocks as empirical Green(s function (EGF) we calculated the source time function (STF) of the ML=4.1 event respectively, and by superposing these results, we obtained the average time function which has better signal to noise ratio. The final result shows that the ML=4.1 earthquake consisted of two events, one of which was stronger, the other was weaker, STFs from each station demonstrate an obvious (seismic Doppler effect(. Through a trial-and-error method, the following results were drawn: for the 1st event, the rupture length is 0.44 km, rupture velocity is 4.0 km/s, while for the 2nd event those parameters are 0.25 km, 3.0 km/s, the two events ruptured in the direction of 140° and 90° respectively (measured from the strike of the fault, anticlockwise positive), the two events were separated by 0.57 km in space, and 0.09 s in time. Using single EGF, we also retrieved the source time function of other 13 events with ML(2.1 in the Huailai earthquake sequence. These results were reached: each of the 13 events consisted of single event, with the duration of the source time functions ranging between 0.05~0.16 s. Using far-field ground displacement measurement method, the scalar seismic moment, stress drop and rupture radii of 25 events with 0.95(ML(4.1 were obtained. The trend that scalar seismic moment and stress drop increase with magnitude was obvious. In the magnitude range 0.9(ML(2.4, the obtained radii show no correlativity with magnitude, we tend to believe, in such small magnitude range, precise measurement for radii of such small events is beyond the data used in this study.
基金supported by the National Natural Science Foundation of China( 40864003,40562001)
文摘Based on the continuous strain data recorded in Xinjiang since 1985, we discuss the mechanisms of Tianshan' s uplift and Tarim basin' s clockwise rotation. The results indicate : 1 ) The principal - compression directions in Tianshan are nearly NS, and their intersection angles with regional structures and mountains are nearly perpendicular, which is in accordance with Tianshan' s uplift and crustal shortening. 2)The principal compressions around Tarim basin tend to facilitate the regional faults' left-lateral strike-slip movements and the basin' s clockwise rotation. These phenomena of uplift/shortening and rotation are fundamentally the re- suits of India plate' s northward push on Euro-Asia plate, and the associated Pamir arc ' s rapid northward movement and regional blocks' interaction.
基金Supported by the China National Science and Technology Major Project(2016ZX05007-001)
文摘The natural gas components and geochemistry of 38 ultra-deep gas wells(burial depth greater than 6 000 m) in the Sichuan Basin were analyzed to determine the genesis of ultra-deep natural gas in the basin. The ultra-deep natural gas components of the basin have the following characteristics: Methane has an absolute advantage, which can be up to 99.56% with an average of 86.6%; ethane is low, with an average of 0.13%; there is nearly no propane and butane. So it is dry gas at over-mature thermal stage. The content of H2 S can be up to 25.21%, with an average of 5.45%. The alkane gas isotopes are: the carbon isotope varies from-32.3‰ to-26.7‰ for methane and from-32.9‰ to-22.1‰ for ethane. There is nearly no carbon isotopic reversal among methane and its homologues. Hydrogen isotope varies from-156‰ to-114‰ for methane, and from-103‰ to-89‰ for some ethane. The carbon isotope of CO_2 varies from-17.2‰ to 1.9‰ and most of them fall within the range of 0±3‰. According to the δ^(13)C_1-δ^(13)C_2-δ^(13)C_3 plot, except some wells, all other ultra-deep gas wells are dominated by coal-derived gas. Based on the CO_2 origin distinguishing plot and δ^(13)C_(CO_2), except some individual wells, most of the ultra-deep CO_2 are of carbonate metamorphic origin. H2 S in the ultra-deep layer of Longgang and Yuanba gas fields belongs to thermochemical sulfate reduction(TSR), while H2 S from Well Shuangtan belongs to thermal decomposition of sulfides(TDS).
文摘The Xinjiang Geology and Mineral Resources Exploration and Development Bureau have conducted a detailed investigation project of the Xigobi soda-niter deposit in Hami, Xinjiang Province, which was completed at the end of 2011. The project put much emphasis on research of soda-niter mineralization rules, stratum classification, ore-forming