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The karst geological conditions of the Yunnan–Guizhou Plateau have led to serious rocky desertification and fragile ecological environment. Evaluating the ecosystem service function of the region can help to improve ecological environment problems. Based on the InVEST model and PLUS model, the carbon stock and habitat quality of the Yunnan–Guizhou Plateau from 2000 to 2030 are quantitatively evaluated. Combined with natural resource zoning, the temporal and spatial variation characteristics and driving factors of carbon stock and habitat quality in the region from 2000 to 2030 are analyzed. The results show that from 2000 to 2030, the average carbon stock of the Yunnan–Guizhou Plateau is 7.323 × 109 t, showing a downward trend over the years, with a total reduction of 0.471 × 109 t. Spatially, it was characterized by high in the west and low in the east. The highest fourth-level zoning was the subdivision of the northern part of Chuxiong in the eastern part of Lijiang City. The land type with the highest contribution to carbon stock was the forest land (>60%), followed by cultivated land (>28%). The factor with the strongest explanatory power for the spatial differentiation of carbon stocks was elevation, and the factor with the strongest interaction was land use and slope direction. From 2000 to 2030, the average habitat quality of the Yunnan–Guizhou Plateau is 0.755, showing a downward trend over the years, with a total reduction of 0.016. Spatially, it was characterized by high in the west and low in the middle and east. The highest fourth-level zoning was the subdivision in the west of Lijiang City and the southeast of Nujiang Lisu Autonomous Prefecture. The habitat quality of forest land is the highest, with an index of 0.83. The research results reveal the evolution law and distribution pattern of carbon stock and habitat quality on the Yunnan–Guizhou Plateau, which can provide a scientific basis for the ecological environment construction of the region.
Soil microbial biomass carbon is the most active component of soil organic matter. Studying the microbial biomass carbon in the rhizosphere soil is of great significance.
The study took Ma’an Forest Park in Wuhan City as the research object, and four different plant types (trees, small trees, shrubs, and herbs) were selected to randomly set up 33 sampling points to study the main drivers of the distribution characteristics of rhizosphere soil microbial mass carbon in different plant communities.
① Soil microbial biomass carbon was significantly different in the plant rhizosphere of different plant communities. The fluctuation range of soil microbial biomass carbon in the plant rhizosphere was 270.76 ~ 908.44 mg/kg. ② Soil microbial biomass carbon was significantly and positively correlated with soil organic carbon (r = 0.662, p < 0.01), inorganic nitrogen (r = 0.510, p < 0.01), carbon−to−phosphorus ratio (r = 0.519, p < 0.01), ammonium nitrogen (r = 0.355, p < 0.01), and nitrate nitrogen (r = 0.485, p < 0.01), while it was significantly and negatively correlated with soil quick−acting phosphorus (r =− 0.134, p < 0.05). ③ The variation of soil microbial biomass entropy carbon in the rhizosphere of different plant communities ranged from 1% to 4%, among which the rhizosphere of the Dryopteris fuscipes C. Chr. was the highest, and that of the osmanthus sp was the lowest. ④ Soil organic carbon, carbon to phosphorus ratio and inorganic carbon were the main factors affecting soil microbial biomass carbon, while carbon to nitrogen ratio (36.36%, p < 0.01) and organic carbon (24.42%, p < 0.05) were the key determinants of entropic carbon content of soil microbial biomass.
Soil carbon to nitrogen ratio and organic carbon were the main influencing factors of soil microbial biomass entropy carbon. There were significant differences between the soil microbial biomass carbon in the inter−root soils of different plants, compared to the Dryopteris fuscipes C. Chr, which had the highest inter−root soil microbial carbon sequestration capacity.
Using geochemical data obtained from black soil quality surveys, this study investigates the geochemical baseline values and background values of soil in the northernmost Xunke Plain of China, as well as their differences from the national and Songliao Plain soil baseline values and background values. This provides a reference basis for studying soil baseline values and background values in different climates and geographical environments, and has reference significance for enriching the study of soil geochemical characteristics in different regions of China. By comparing the geochemical background values of elements with the baseline values, it was found that among the 54 analyzed indicators, 41 elements or indicator soil background values were equivalent to the baseline values, indicating that the vast majority of elements in the surface soil inherited the level of parent material content, and the influence of soil formation and human activities on the enrichment or depletion of surface soil elements was relatively small. Nine elemental indicators, including Cl, Mn, P, I, S, Br, N, TC, and Corg, were significantly enriched in the surface soil; Cd and Ag are locally enriched due to mining activities; The significant depletion of Au and Hg elements indicates that these elements are greatly influenced by epigenetic processes and human activities. Compared with the background values in other regions, the soil nutrient indicators N, P, TC, and Corg in the Xunke Plain are significantly higher than those in the national soil and Songliao Plain soil background values, indicating that the soil in the Xunke Plain is fertile and high-quality black soil resources. However, there is also a risk of heavy metal pollution in some areas, and attention should be paid to protection and utilization.
Core logging is crucial for obtaining deep geological information about the earth. Currently, manual logging remains the primary method for acquiring lithological and other information, but it is time−consuming, labor−intensive, and prone to incomplete results and subjectivity.
Therefore, this study focuses on the ZKH3 of sandstone−type uranium deposits in the southwest of the Ordos Basin, applied deep learning and imaging spectroscopy techniques to core lithology identification. This study constructed a CNN model consisting of 7 one−dimensional convolutional layers, 2 pooling layers, 1 one−dimensional CBAM, and 3 fully connected layers.
Additionally, a total of 26877 spectral samples from 7 types of rocks were collected, and model optimization and training were completed. Finally, the performance of the model was evaluated through comparison with Support Vector Machine (SVM) and its application in the whole borehole.The results show that the overall accuracy (OA) of deep learning model reached 94.6%, among which the producer’s accuracy (PA) of mudstone, fine sandstone, siltstone, medium sandstone, coarse sandstone, glutenite and background were 95.07%, 72.02%, 97.50%, 97.37%, 96.65%, 97.33%, and 99.01%, respectively. The Kappa coefficient was 0.94, which was better than SVM overall and achieved comparable results to geological logging.
This indicates that deep learning model based on imaging spectral data demonstrates excellent lithology classification and identification capabilities for core samples. And this approach enables non-destructive and rapid lithology identification while reducing the subjectivity inherent in manual geological logging to some extent, which provides valuable reference for digitization and automated logging research of core samples reference for research on digitalization and automation of core logging.
The development and utilization of urban underground space is an important part of urban construction, and urban three-dimensional geological model is one of the bases to evaluate the difficulty of development and utilization of underground space. In order to meet the needs of current urban construction, this paper designs a reasonable calculation method of stratigraphic pinchout position based on the influencing factors of model accuracy. This method determines the pinchout position when tracking stratigraphic division by considering factors such as stratum thickness, borehole spacing, stratum burial depth, and single-hole control range, so as to construct a stratum surface with higher accuracy, and solve the problem of inaccurate stratigraphic division range in 3D geological modeling. In this paper, Beihai City is taken as the research area to establish a unified stratigraphic sequence, generate stratigraphic zoning constraints, and establish a three-dimensional geological structure model of Beihai City by using drilling and profile data. In order to verify the reliability of the constructed model, this paper evaluates the model quality based on drilling and profile. The results show that the three-dimensional geological model constructed by this method is highly consistent with the actual situation, which can deal with the modeling problem of unconformity strata containing complex strata and has certain credibility.
The composition and age of metamorphic rocks provide a crucial window into understanding the nature, formation, and evolution of orogenic belt basements. Based on an analysis of zircon age and trace elements from the Xingeer Formation in the eastern part of the South Tianshan Orogenic Belt, this paper explores the age of meta−rhyolite and its significance for the tectonic evolution of the Southern Tianshan orogenic belt.
The lithology, LA−ICP−MS zircon U−Pb dating, and zircon trace element analysis of the meta−rhyolite in the Xingeer Formation, located in the eastern part of the South Tianshan Orogenic Belt, have been systematically conducted. The data have been comprehensively analyzed in conjunction with regional research findings.
LA−ICP−MS zircon U−Pb dating results indicate that the protolith was formed in the Early Devonian (418~412 Ma). The zircon exhibits a relative depletion in light rare earth elements (LREE) and enrichment in heavy rare earth elements (HREE), characterized by a negative Eu anomaly and a positive Ce anomaly. Trace element analysis reveals positive anomalies of U and Hf, along with negative anomalies of Nb, La, Pr, and Ti. Based on zircon trace element analysis, it is inferred that the crustal thickness at the time of rhyolite eruption was less than 35 km, with evidence of plagioclase fractionation and crystallization in the magmatic source region. The zircon Ti thermometer indicates a high magmatic crystallization temperature (>800°C), suggesting a high−temperature magmatic origin. This implies that the rhyolite's development may be associated with continental rifting.
Based on previous studies, it is inferred that the South Tianshan Orogenic Belt may have been part of the Tarim Craton during the Early Paleozoic, with its northern margin representing an active continental margin. Influenced by subduction and retreat along the northern margin, the South Tianshan region experienced significant back−arc extension during the Late Silurian to Early Devonian. The meta−rhyolite identified in this study is likely to have formed within the tectonic setting of Early Devonian back−arc extensional rifting.
Extracting useful geochemical information from land quality geochemical survey data, which often consists of numerous testing indicators and abundant information, is a challenging task. Factor analysis, as a multivariate statistical analysis method, is commonly used in the analysis of geochemical data to condense complex geochemical indicators into a few key factors that reflect most of the information in the original data. By applying factor analysis to the surface soil data from a 1: 250, 000 land quality geochemical survey in Pingguo City, Guangxi, seven factors representing the main geochemical information of the study area were identified. These factors were used to establish seven geochemical zones based on combinations of indicators, and a geochemical zoning map was created. By considering the characteristics of each geochemical zone, along with the regional geological background and the geochemical properties of the element combinations, the geological and geochemical significance of each geochemical zone was explored.
Xinjiang Qixin Ni-Co mineralized intrusion is located in the south-central of the Beishan orogenic belt. It is one of the important new discoveries in nickel, cobalt other strategic minerals in Beishan orogenic belt in recent years. The intrusion is mainly composed of lherzolite, olivine pyroxenite, troctolite, norite gabbro, olivine-gabbro and gabbro, and mineral bodies are mainly hosted by peridotite and gabbronorite. In this study, we carried out the in-situ composition analysis of olivine major and trace elements in four small ultramafic intrusion of Qixin to identify the nature of mantle source and portray the processes of sulfide segregation. The results show that olivine of peridotite in each intrusion has Ni losses of varying degrees ( the Fo value and Ni concentration of olivine in the No. I and II intrusion are 84.0~87.5 and 134~2562 ppm, the No. III and IV intrusion are 82.3~86.1 and 581~2970 ppm). However, the olivine have high Mn/Zn ratio (>15) and 100*Mn/Fe ratio (1.4~1.7), and low 10000*Zn/Fe ratio (3.5~9.4), Ni/Co ratio (7.3~14.0), and Li concentration (1.8~9.8 ppm).The trace element characterization of olivine indicates that mantle origin of the Qixin intrusion is a peridotite mantle with water-rich component in the source origin and was no added the material from oceanic crust, but mixed by material from continental crust during magmatic evolution. The characteristics of olivine Fo value, Ni concentration and other components suggest that the sulfide segregation of the deep in the intrusion No. I and II are more significant, and there is potential to search for Ni-Co deposit in the deep. Therefore, ore prospecting and exploration need to focus appropriately on intrusion No. I and II, and need to pay attention to the deep and periphery of the intrusion No. I and II.
Southeast of Sulige gas field, through statistical analysis of the chemical properties and characteristics of formation water samples of Majiagou Formation 1 sub-section in Southeastern Sulige, revealing its results found that the formation water in Southeastern Sulige is highly mineralized, with an average of 148905.46mg/L, much larger than normal seawater, without a long time of intra-stratum circulation, highly metamorphosed evaporated brine after water-rock action with high concentration, and the water type of CaCl2 type. pH value is between The pH value is between 5.0 and 6.3, which is weakly to moderately acidic, mainly related to the high content of residual organic acid in the formation water. The results of the analysis of various stratum water chemical parameters show that the stratum of Majiagou Formation 1 subsection in Southeastern Sulige is well closed, which is favorable for the preservation of the gas reservoir. Stratigraphic water is characterized by gas-water mixing, which is mainly distributed in five areas, with the west relatively "water-rich" and the east relatively "gas-rich". Vertically, according to the differences in genesis and spatial distribution pattern, the stratum water is divided into tectonic low-part water, isolated lens water, and low-permeability zone stagnant water. Tectonic low water is commonly found in the western part of the study area where the tectonic structure is relatively low and in the nasal concave area where the tectonic structure is relatively low in the southeast direction; the isolated lenticular water is relatively undeveloped. The study concludes that three factors, namely, tectonic pattern, reservoir inhomogeneity, and paleomorphic pattern, jointly control the distribution of gas and water in Southeastern Sulige, which is mainly affected by reservoir inhomogeneity and paleomorphic pattern, and the tectonic influence on the anisotropic effect of gas and water is limited.
This study investigates the distribution characteristics of debris flow in Jinsha River and conducts a hazard assessment to provide data support and a scientific basis for understanding regional variations in debris flow and disaster prevention in the Hengduan Mountain area.
Based on the field investigation and GIS spatial analysis, 2551 debris flows in the Jinsha River were identified. Hazard assessment was performed based on the activity characteristics of these debris flows. Using ROC analysis and spatial clustering, the debris flow hazard zoning in the Jinsha River was established.
① Debris flows in the upper reaches of Jinsha River are not active, predominantly of low to medium frequency, while high−frequency debris flows are concentrated in the lower reaches, especially between Yarmou and Qiaojia. ② The primary factors influencing debris flow formation include slopes ranging from 15° to 35°, frequent seismic activity, and the presence of both soft and hard clastic rocks. ③ Medium− and high−hazard debris flows cover 47.48% of the area, nearly half of the studied region. ④ The high−hazard zone in the Dongchuan−Qiaojia section shows high concentration, closely correlating with active faults and abundant sediment supply, largely controlled by tectonic activity.
High−hazard debris flow zones are concentrated in the downstream of Jinsha River. The hazard zoning map provides a reference for risk mitigation in hydropower development and transportation infrastructure planning.
Xuefeng gold field, located at the southern section of Jiangnan Orogenic belt, including Chanziping, Daping, Hengbidong gold deposits. It is of great significance to study the ore-controlling structure characteristics and ore-controlling rules in Xuefeng gold field for the study of the southern section of Jiangnan Orogenic belt and the deep peripheral prospecting. By analyzing and studying the metallogenic geological background, ore-body characteristics and ore-controlling structural characteristics of Chanziping and Daping gold deposit, combined with the previous published data, the study summarizes the ore-controlling structural characteristics of the gold deposit and its relationship with gold mineralization, and tries to estimate the stress system and deformation process in the metallogenic period. According to the study, the NE schistoscopic zone in the ore field is the ore guide structure, and the NW schistoscopic zone is the associated structure of the NE fault, which often develops in or near the NE schistoscopic zone, and is the main ore-bearing geological body of the gold deposits in the area..In the late Indosinian period, the principal stress of Xuefeng gold field is in the NW-SE direction. Based on the structure, vein characteristics, it is considered that a good prospecting space is located in the deep of Xuefeng gold field.
The five counties and cities of Baiquan, Yi'an, Fuyu, Keshan, and Kedong in Qiqihar, Heilongjiang Province, are famous as the hometown of black soil and also the most important grain producing areas in China. In recent years, there has been relatively little research on the density and storage of organic carbon (Corg) and total carbon (TC) in this region. This article relies on the soil organic carbon and soil total carbon test results obtained from the investigation of the black soil ground substrate in the Qiqihar area of the Songnen Plain to study the Corg and TC reserves, carbon density, spatial distribution, and carbon sequestration potential in the plain areas in the study area of Qiqihar, Heilongjiang Province, with a depth of less than 20 cm, and then use principal component analysis to analyze the factors affecting changes in organic carbon storage. It is found that the TC reserves in five counties of Qiqihar City, Heilongjiang Province is 82.17 Mt, and the Corg reserves is 67.93 Mt, which are at a relatively high level. The results of geostatistical analysis indicate that the Corg reserves in the region have a certain spatial autocorrelation, and the main controlling factor is the water erosion of the Nenjiang River, followed by changes in soil type and land use type. It exhibits a strong carbon sink effect, with a carbon sequestration potential of 20.10 Mt for surface soil Corg, which is at a relatively high level. As a result, it has been found that a stable and good soil environment is conducive to the enrichment and aggregation of carbon. The enrichment of elements such as N, S, Se, and P has extremely high value for carbon sequestration. The increase of inorganic salts such as K2O and Na2O and ecological fragile phenomena such as soil desertification have a significant impact on carbon storage and carbon sink phenomena.
The Tarim Basin, situated as a significant oil and gas exploration and development research region within China, has undergone a multifaceted tectonic evolution over time. Nonetheless, the existing studies have not adequately acknowledged the potential reservoirs within the Silurian-Devonian system in the central and western sectors of the basin. In this research paper, our focus is on core samples extracted from the Donghetang Formation, obtained from Batan 6 well, Kangtan 1 well and Yu 2 well. Our objective is to identify the depositional characteristics, material source evolution and age attribution of the Donghetang Formation. This analysis combines various factors, including the clastic fractions of sandstones, heavy minerals, zircon U-Pb ages, and rare earth elements. Our study reveals that the Donghetang Formation belongs to the coastal-shallow sandy coastal phase. The zircon U-Pb ages are distributed into three groups: 485-393 Ma, 995-665 Ma, and 2064-1560 Ma. Heavy minerals and detrital zircon data show that the host rocks are primarily composed of acidic magmatism, with a smaller presence of intermediate-basic magmatism or granitic pegmatites. The sources of the Donghetang Formation are primarily attributed to the West Kunlun Orogenic Belt and the Tabei Uplift. By comprehensively determining the sedimentary features, stratigraphic assignment, and source evolution of the Devonian Donghetang Formation in the western Tarim Basin, we can not only provide information on the evolution of the basin, but also provide crucial data support for future oil and gas exploration endeavors.
Using modern information technology, based on the integration and analysis of data from three aspects: global geology, mineral resources, and mining policies and investment environments, we can build a global mineral resources information system. This system can use multiple data sources to discover potential mineral resource-rich areas around the world, make dynamic assessments of global investment environments, and enhance geological research capabilities at global and regional scales. It is of great significance in ensuring national resource security. In recent years, based on the construction of global geological and mineral databases, we have restructured the system's architecture framework using techniques such as network resource services, data application services interfaces, spatial analysis, and web data crawlers. This has resulted in a relatively complete work process system for data retrieval, processing, management, sharing, services, and analysis at the global level. We have developed various application systems, including a global geological and mineral big data platform based on an intranet, a global geological and mineral information website based on internet services, a global mineral resources management system, a mining project investment environment evaluation system, a mining policy management system, and a strategic mineral reserves filling information system. These systems provide functions such as multi-source data correlation, remote resource sharing and retrieval, investment environment evaluation analysis, basic data collection and management, and mineral resource visualisation. They have practical significance for studying the distribution of mineral resources, analysing different mineralisation laws, evaluating the investment environment of mineral resource countries, and planning key areas for global mineral exploration and development. Ultimately, they support national energy and resource security, support bureau-level decision-making and benefit mining companies.
The "Pingxi type" sedimentary Mn deposits are developed in the middle-lower Cambrian Qiujiahe Formation in the Ningqiang-Qingchuan-Pingwu-Beichuan area on the western Yangtze margin. They are transformed from primarily iron and manganese deposits by regional metamorphism and epigenetic oxidation. Analyzing the genesis of Mn-carbonates is the key to understanding the genesis and mineralization process of this type of deposit and also helps regional prospecting and prediction. This study takes target form well ZK0202 in the Liangshang manganese exploration area of Chenjiaba field in Beichuan County to carry out sedimentology and mineralogy research. Research has shown that Fe/Ti, (Fe+Mn)/Ti, Al/(Al+Fe+Mn), SiO2/Al2O3 ratios, and Eu/Eu* anomalie indicate that hydrothermal fluids provided the Mn source. pyrite framboid laminations or thin layers are commonly developed in black shale, indicating the presence of iron and manganese separation processes before the Mn-carbonates deposition, which helps to increase the concentration of Mn2+ in anoxic water bodies. However, the high Fe/Mn ratio of Mn-bearing strata indicates that the separation process is incomplete and the water column redox condition is continuous anoxia. Mn-carbonate minerals coexist with pyrite framboids. The pyrite diameters are mostly less than 5 μm, suggesting that the Mn-carbonates were deposited in a anxic water column. Mn-carbonates are characterized by microcrystalline textures distributed in black shales as block-like and layered structures. Mn-carbonates are often idiomorphic and semi-idiomorphic with calcium cores. The calcium cores are diamond-shaped or feature a dissolved texture. It is vital evidence for the Mn-carbonates direct precipitation mechanism induced by calcite. Based on the above sedimentary evidence, the Mn-carbonates of the Qiujiahe Formation were deposited directly in anoxic Mn-rich water columns. When calcite is injected into the Mn-rich anoxic water, it suffers dissolution but increases the alkalinity of water, and the residual calcite provides nucleations to induce the Mn-carbonate precipitation.
The Baizhangzi gold deposit in western Liaoning is among the largest gold deposits within the Jidong−Liaoxi metallogenic belt, where Mesozoic magmatism has led to the formation of granitic rock mass closely associated with gold ore. On the basis of field investigation, we have identified that the Baizhangzi granite consists of biotite monzogranite, biotite−bearing monzogranite, monzogranite and granitic porphyry dykes, and studied petrology, petrogeochemistry, chronology and Hf isotopic characteristics. The zircon U−Pb ages of granitic porphyry dykes were determined to be 231.0 ± 1.3 Ma and 231.7 ± 2.7 Ma, indicating formation in the Late Triassic. The major elements of Baizhangzi granitic rock mass exhibit characteristics of a high−K calc−alkaline series, displaying quasi−aluminum to weakly peraluminous granite composition; while the trace elements show enrichment in Rb, Th, U, K, Hf and depletion in Nb, Ba, P, Ti without obvious Eu and Ce anomalies. Additionally, there is relative enrichment in light rare earth elements and depletion in heavy rare earth elements placing it within the Post−COLG on tectonic setting discrimination diagrams. The Harker diagram and rare element covariant relationship indicate fractional crystallization of biotite, potassium feldspar, apatite, ilmenite and spar from biotite monzogranite to granitic porphyry dykes. The zircon Hf isotope analysis of the granitic porphyry dykes reveals εHf(t) values ranging from −9.02 to −5.62 (average −7.43), with two−stage Hf model ages (TMD2) ranging from 1592 Ma to 1810 Ma (average 1710 Ma), suggesting derivation of the magma through partial melting of Late Paleoproterozoic crust. The zircon rare elements in the granitic porphyry dykes show a △FMQ range from −1.23 to 4.65. The enrichment of alkali, high oxygen fugacity(fO2), and medium degree of evolution in granite porphyry dykes are favorable conditions for gold mineralization, indicating a strong potential for mineralization.
Based on Python and Paraview software, the 3D suitability evaluation of 0~-100m underground space of Zhongshan city was realized by bilinear interpolation method and analytic hierarchy process. The data of 8192 bore holes was collected and analyzed, and five 3D data of single factor (spt blow count, water content, internal friction angle, compression modulus and compressive strength) was obtained. In addition, the geotechnical conditions, hydrogeological conditions, adverse geological conditions, resource sensitivity and development value were selected as theme layer, them contain 21 signal factor 2D data. The coupling calculation of 2D and 3D data is realized based on the Variable weight method. According to the sensitivity of different engineering types to single factor, the architectural engineering and tunnel engineering are evaluated respectively. This evaluation was wide area, large depth and many evaluation factors, which can provide reference for the suitability evaluation of underground space development and utilization in other cities.
The northern Alxa block is the key area for studying the closing of the Paleo-Asian Ocean, Owing to the Carboniferous granites have been rarely investigated in the Yagan area, Leading to importartly restriction for the time of the closing of the Paleo⁃Asian Ocean in northern Alxa block. In this paper, we carried out a systematic study of the petrography, geochemistry, zircon U-Pb dating for the Weibozhan intermediate-acid granites, which are located in the north of the Yagan Fault. The Weibozhan intermediate-acid granites have mainly composed of monzogranite and pyroxene diorite. The zircon LA-MC-ICP-MS U-Pb dating results show that the monzogranite and pyroxene diorite are formed during the Late Carboniferous in 320±1.7Ma, 323 ±4 Ma.The Weibozhan intermediate-acid granites are characterized by high K calc-alkaline or calc-alkaline. are relatively enriched in large in lithophile elements, such as Rb , Th, Hf and depletions in high field strength elements, such as Nb, P and Ti. They show right-leaning chondrite-normalized patterns, which means enrichment in LREE and depletions in HREE. Based on the formation age and geochemical characteristics, it is concluded that the the Weibozhan intermediate-acid granites are likely formed in a continental margin arc setting, and products of the subduction of the paleo-Asian ocean during Late Carboniferous. Combined with regional geological background, it is inferred that the closure of the paleo-Asian ocean in the northern margin of the Alxa block should postdate the Early period of Late Carboniferous.
In order to research the evolution law of land subsidence and its subsidence potential,take the Wangsiying area in Beijing as an example,the characteristics of land subsidence in Wangsiying area "from point to surface" are analyzed and compared with multi−source fine monitoring data.
The growth curve land subsidence model is introduced, and the land subsidence potential evaluation model based on multi−source data fusion is constructed by MATLAB.Based on Wangsiying ground land subsidence station, the mechanism analysis and prediction of layered land subsidence are carried out on "point"; Based on the regional leveling and dynamic monitoring data of regional groundwater level, the regional land subsidence evolution characteristics and land subsidence potential are evaluated.
(1) The land subsidence mainly occurs in the cohesive soil layer, and the development of land subsidence is directly proportional to the content of cohesive soil. The land subsidence amount and the land subsidence ratio of the shallow strata in Wangsiying area are getting smaller and smaller, while the land subsidence amount and the land subsidence ratio of the deep strata are getting larger and larger with time; The land subsidence rate slows down in the wet season and increases significantly in the dry season; After fitting the data of land subsidence and groundwater level, it is found that there is a certain correlation between them. The correlation increases with the increase of water level decline, and the correlation is positive; The development of land subsidence in Wangsiying area is relatively high,and the differential subsidence in the whole area is also very obvious. (2) The error values of the static leveling system of bedrock level and layered level and the manual leveling system for the data of the same monitoring point are very close to each other and conform to the normal distribution law. (3) It is predicted that the future land subsidence will be vertical. With the increase of time, the land subsidence of each layer will gradually decline, but the overall residual subsidence of the stratum still has a development space of about 100 mm. The middle and deep strata are the main "dominant strata" for the future land subsidence, and the land subsidence potential is large; Horizontally, the trend of land subsidence in the future is consistent with that in the current stage, but the overall rate is slowing down.
The deep strata in Wangsiying area are the main subsidence "advantageous" layers, and the seasonal deformation characteristics of land subsidence are highly correlated with the dynamic changes in groundwater level. In the future, the land subsidence in this area will continue to slow down.
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