Loess mudflow is a frequent geological hazard in the Loess Plateau region, characterized by strong mobility, long-distance movement, and massive impact and destructive force, often causing major disasters. A scientific understanding of the mechanism of mudflow disasters on the Loess Plateau is of great significance for reducing disaster risks and adopting scientifically effective disaster reduction measures. This article first reviews the latest progress in research on the environmental characteristics, fluid properties, disaster mechanisms, and monitoring and early warning of loess mudflow disasters. Then, it analyzes the key scientific issues in the research of loess mudflow disasters. Finally, it is proposed that the future research on mudflow disasters on the Loess Plateau should still take "field investigation - experimental research - theoretical analysis - practical application" as the research paradigm, and adopt new theories, new methods, new technologies and new equipment, and focus on the following research directions considering the multi-scale, multi-time series and multi-stage perspectives of mudflow on the loess Plateau: Study the temporal and spatial development characteristics of loess mudflow and its advanced identification technology under complex disaster-prone environment, build a dynamic model of loess mudflow evolution mechanism and disaster mechanism, establish a real-time monitoring and early warning model of loess mudflow disaster and a comprehensive evaluation method, and form a comprehensive technical system of loess mudflow toughness prevention and control and emergency rescue.

The Yellow River Delta wetland represents one of the most typical ecosystems in the temperate zone. Influenced by human activities, frequent channel shifts of the Yellow River, and rapid changes in sediment discharge to the sea, the vegetation cover and community structure of the wetland have undergone rapid changes, subsequently affecting soil nutrient components. In order to elucidate the ecological stoichiometry of carbon, nitrogen, and phosphorus in typical vegetation soils of the Yellow River Delta, this study focused on the Dongying City region in Shandong Province. Soil samples (0 to 30 cm) were collected from typical natural vegetation, bare soil, and crops, and the concentrations of organic carbon, total nitrogen, and total phosphorus were determined. The results indicated that: ① Total organic carbon content in soils of different vegetation types followed the order: Glycine max ＞ Zea mays ＞ Gossypium spp. ＞ bare soil ＞ Sorghum bicolor ＞ Suaeda salsa ＞ Spartina alterniflora ＞ Phragmites australis ＞ Tamarix chinensis; Total nitrogen content showed the order: Glycine max ＞ Gossypium spp. ＞ Sorghum bicolor ＞ Spartina alterniflora ＞ Suaeda salsa ＞ bare soil ＞Zea mays ＞ Tamarix chinensis ＞Phragmites australis. ② In the 0 to 10 cm soil layer, the soil ω(C)/ω(N) ratios were in the order: bare soil ＞Phragmites australis ＞ Suaeda salsa ＞ Spartina alterniflora ＞ Tamarix chinensis ＞ Gossypium spp. ＞ Sorghum bicolor ＞ Glycine max ＞Zea mays; ω(N)/ω(P) ratios followed the order: Glycine max ＞Zea mays ＞ Gossypium spp. ＞ Spartina alterniflora ＞ Sorghum bicolor ＞ Suaeda salsa ＞ Tamarix chinensis ＞ bare soil ＞Phragmites australis; ω(C)/ω(P) ratios were in the order: Glycine max ＞ Gossypium spp. ＞Zea mays ＞ bare soil ＞ Spartina alterniflora ＞ Suaeda salsa ＞ Sorghum bicolor ＞Phragmites australis ＞ Tamarix chinensis. ③ Agricultural utilization had an enriching effect on total nitrogen and total phosphorus in the soil. The nutrient content in Glycine max soil was higher than that in the soils of other crops. The organic carbon content in natural vegetation was lower than that in bare soil. Spartina alterniflora and bare soil had double the total nitrogen content in the 20 to 30 cm soil layer compared to other natural vegetation. Different vegetation types had a significant impact on soil nitrogen accumulation, and Spartina alterniflora exhibited an inhibitory effect on nitrogen accumulation in different soil layers. In conclusion, the influence of natural vegetation and crops on soil nutrient components is complex, with natural vegetation consuming more nutrients than accumulating, while crops and agricultural utilization contribute more to nutrient enrichment than depletion.

The relationship between groundwater and vegetation is crucial to achieve a harmonious balance between human and the natural environment. Groundwater-dependent vegetation (GDV) is extensively distributed in the arid and semi-arid regions of Northwest China. In certain areas, the decline in water table levels due to human activities has fallen below ecological water level thresholds, leading to the degradation of ecological functions and, in some cases, widespread vegetation die-off. Therefore, the sustainable development of the region's economy and society is under significant threat. A comprehensive review was conducted concerning GDV mapping, ecological resilience assessment, groundwater-vegetation co-evolution, and ecological water table. Through this review, the main challenges and urgent issues that need to be addressed in current research have been summarized, and future research directions were outlined. The review revealed limited research on GDV mapping at the watershed scale in Northwest China, highlighting the need for further refinement on the stable isotope method for ground validation of mapping results. Current studies on resilience focus on surface ecology and ecological indicators overlook underground indicators, such as groundwater and root distribution, and lack a comprehensive evaluation based on resistance, recovery, and adaptability. Qualitative assessments of ecological resilience prevail in current research, falling short of meeting the requirements for effective ecological conservation and restoration. Challenges in researching the co-evolution of vegetation and groundwater arise from the difficulty in accurately detecting changes in root systems. Further studies are warranted to develop root detection methods and three-dimensional models for simulating the co-evolution of roots and water sources. Concerning ecological water tables, the focus remains on static water levels determined by current conditions, with insufficient consideration of spatial variations in precipitation and lateral groundwater flow as well as plant self-adaptation. Additional research is essential to establish dynamic ecological water levels under varying external conditions. This review aims to summarize the progress and future prospects of research on eco-hydrological processes of GDV, addressing the weak research areas. By doing so, it aims to provide a robust scientific foundation for further theoretical research and practical applications on eco-hydrology in NW China.

The LA–ICP–MS U–Pb dating technique is a crucial tool that has been widely employed in geological sciences. Despite its relative maturity, several critical issues still require attention in practical applications. This article provides a brief discussion of five critical aspects of this technique, including sample preparation, selection of dating results, lead loss, common lead, and presentation and interpretation of dating results. Firstly, for the U–Pb dating of complex minerals, it is recommended to employ mineral identification and location techniques in combination with LA–ICP–MS instruments for in–situ analysis directly on rock thin sections or polished sections, without mineral separation. However, attention must be paid to Pb contamination in sample preparation. Secondly, for the selection of dating results for detrital minerals, the ²⁰⁶Pb/²⁰⁷Pb age is utilized to represent the crystallization age of grains older than 1.5 Ga, while the ²⁰⁶Pb/²³⁸U age is employed for grains younger than 1.5 Ga. The determination and selection of the maximum depositional age of sedimentary rocks mainly rely on statistical methods and sometimes require the combination of geochemical data and geological background information as supplementary criteria. Thirdly, for young samples with continuous age distribution on the concordia line, various methods such as the concordia diagram, weighted mean diagram, CL images, and element contents should be used to identify whether there is an inconsistent lead loss line or not. Furthermore, this article focuses on a rarely used common lead correction method for detrital mineral U–Pb dating. Finally, this article emphasizes the theoretical basis that, when evaluating the quality of the weighted mean value, the closer the MSWD is to 1, the higher the data quality is. In summary, to conduct U–Pb dating studies on minerals using LA–ICP–MS technology, it is essential to consider multiple factors comprehensively to obtain accurate, reliable, and geologically meaningful dating results.

Helium is widely used in the fields of national defense, military industry, high−tech industry development and so on, as a rare gas related to the national security and development. China is short of helium resources and highly dependent on foreign countries. There is a good prospect of helium resources in Ordos basin. However, there are fewer study on the characteristics of the helium source rocks and the faults related closely to the helium distribution, which limits the evaluation of the helium resource potential in the basin. In this thesis, the gravity and magnetic data in the southeast of Ordos basin are processed by using the normalized vertical derivative of the total horizontal derivative (NVDR−THDR), vertical derivative and potential field date separation techniques, and inferred the main faults and potential helium source rocks (strong magnetic metamorphic rocks). The distribution of helium resources is controlled by the basement faults and the distribution of helium source rocks. The strong magnetic metamorphic rocks provide gas source conditions for helium enrichment in the basin, and fault activity provides channels for helium migration. There are a large number of metamorphic rocks distributed in Fuxian−Yichuan−Huanglong area. Most of them are located near faults and their intersection areas, which may be potential favorable areas for helium resources.

A large number of mineral resources related to granite−pegmatite system that are found in the traditional Mesoproterozoic Kibaran belt in Central Africa, especially characterized by the distinctive mineralization of rare metals (Nb−Ta−Li), tungsten, tin and gold. The metallogenic events can be associated with the process of Rodinia amalgamation. Most of these mineral occurrences are linked to the early Neoproterozoic G4 leucogranitic intrusions, also termed “tin (−bearing) granites”. G4 granites have been extensively scrutinised because they are considered as the parental rocks to the ore mineralization in the region. The field identification criteria, timing, geochemical characteristics for G4 granites in different parts of Kibaran belt, however, have been shown to vary in previous studies. As a result, the type of rock, the petrogenesis of these parental granites and the geodynamic context is still a matter of debate. Combined with the disparate nature of datasets in the literature (e.g. field outcrops, petrography, geochronology, geochemistry and isotopes), the results show that the derivation of G4 granite is consistent with a meta−pelitic source, and these leucocratic granites could be considered more like anatectic migmatites rather than actual highly fractionated granites formed by fractionation out of large magma chambers. It has been largely established via the research of diagenetic and metallogenic processes that the protracted differentiation of G4 granites is the primary driver of diverse mineralization in the Kibaran belt. It’s hypothesized that the G4 granite was probably emplaced in the syncollisional to post−collisional stage of Kibaran orogeny when considering the regional tectonic background.

The area surrounding the Qaidam basin, Qinghai Province, is characterized by occurrences of a large number of gold deposits, which is an importance source of gold deposits in China. This area is thus called the “Qinghai Gold Belt”. Based on regional geology, geophysical and geochemical features, this study reveals that the “Qinghai Gold Belt” was formed by two stages of orogenies. During the Caledonian– Hercynian, the collision between the Qaidam and Oulongbuluke blocks resulted in the closure of Proto–Tethys ocean, forming the Tanjianshan gold district and Saibagou gold deposit; during the Indosinian, the collision between the East Kunlun and Bayakara Block resulted in the closure of Proto–Tethys ocean, forming the Wulonggou, Dachang and Gouli gold districts and the Manzhanggang gold deposit. Combined with previously published data, it is deduced that the formation of gold deposits in this area is closely related to crustal–mantle interaction, with mantle materials contributing a lot for the ore–forming fluids and materials. This is further demonstrated by the spatial and temporal correlation between gold deposits and mafic–ultramafic rocks. Therefore, the locations where mafic–ultramafic rocks occur are potential for the orogenic gold exploration.

Mountainous urbanization, new rural construction, rural revitalization and poverty alleviation are facing the threat of geo-hazards. It has a great strategic significance to carry out large-scale geo-hazards investigation and risk assessment to control geo-hazards risks from their source. Based on the pilot survey and assessment, this paper puts forward a set of ideas and technical methods for the investigation and risk assessment of geo-hazards in mountainous towns. Investigation and risk assessment of geo-hazards in mountain towns can be divided into 3 levels according to the purpose and scale accuracy. ① Investigation and risk assessment of regional remote geo-hazards, assessing the possibility of remote geo-hazards in mountainous towns, at scale of 1:50,000. ② Investigation and risk assessment of urban geo-hazards to investigate and assess the possibility and consequence of deformation and instability of surveying each slope and valley in the surrounding areas of mountain towns, with a scale of 1:10,000. ③ Investigation and risk assessment of important site geo-hazards to assess the possibility and consequence of deformation and damage of slopes and valleys around important sites, such as major construction projects and tourist attractions and evaluating the possibility of instability and the degree of damage. with scale range from 1:5,000 to 1:2,000. Each level has been explained in this paper from the aspects of contents, methods and processes of geo-hazards investigation and risk assessment. Taking the typical mountainous towns the Qinba Mountain Area in Southern Shaanxi and Loess Plateau Area in Northern Shaanxi, as the study areas the demonstrative application demonstration of geo-hazards investigation and risk assessment in mountainous towns was established.

The geological environment of Longchuan County, Yunnan Province, is fragile and vulnerable to landslides. Analyzing the susceptibility of regional landslide hazards is of great significance to prevent and control the landslides in this area. Ten evaluation factors are established. They are elevation, slope, slope direction, section curvature, plane curvature, normalized vegetation index, distance from water system, fault distance, lithology and road distance. Landslide susceptibility evaluation is assessed by using information value model and Geographic Information System(GIS). The results show that the high landslide susceptibility zones are mainly located in the north, southeast and southwest of the study area; the moderate landslide susceptibility zones are mainly in the central, eastern and western parts of the study area; the low landslide susceptibility zones are mainly in Longba Township, most of Chengzizhen and northwest of Hu Sa Achang; the extremely low landslide susceptibility zones are mainly located in the central and urban areas of Qingping,part of the central part of Chenzi and most of Zhangfeng. 83.56% of the landslide hazards are in the middle and high susceptible zones, and the area of landslide increases with the increase of the susceptibility grade. The area of the middle and the high landslides susceptible zones accounts for 22.79% and 58.13% respectively of the total study area.The results are consistent with the actual distribution of landslide hazards, which can provide theoretical reference for disaster prevention and mitigation in the study area.

The national territory development plan needs to evaluate the resource environmental carrying capacity, which can provide basis for the delineation of so-called "three zones and three lines", that is the spaces for urban, agriculture and ecology, as well as the red lines of environmental protection, permanent basic farmland protection and urban development. The theory and method of resource environmental carrying capacity evaluation have received more and more attention from all stakeholders, but a complete theoretical framework has not yet been formed. This study introduces short-board theory, risk theory and marginal theory, develops the theoretical framework of resource environmental carrying capacity evaluation, and conducts empirical research with the Suide County of the Loess Plateau in Northern Shaanxi as the research area. Based on the short-board theory, we identify the major resource environmental problems in this region, and select 1-3 restrictive factors; On the basis of the marginal theory, we take the maximum profit or no-profit of resource development and utilization as the evaluation standards to carry out the evaluation of resource carrying capacity; According to the risk theory, the allowable standards of environmental issues brought about by human activities or of life and property risks caused by disasters are taken as the evaluation standards to carrying out the evaluation of environmental carrying capacity; By using the single factor carrying capacity evaluation results to carry out the comprehensive carrying capacity evaluation, the results can be classified as safe, overload or unacceptable three categories. The comprehensive carrying capacity evaluation results are overlapped with the regional terrestrial space development status or planning results, which can be used to delineate the "three districts and three lines" of regional development. The resource environmental carrying capacity evaluation results of Suide County show that the theoretical framework and technical method system are simple and easy to promote, and the evaluation results are credible, which can provide support for the optimization of terrestrial space development and the scientific delineation of the "three red lines".

This paper takes Lingtai County, Pingliang City of Gansu Province as target research area. Based on the geospatial and historical landslide data, four machine learning models were used to construct the landslide susceptibility evaluation model. The four models are BP neural networks model, Random Forest classification model, support vector machine model, and logistic regression model which were optimized by GMM cluster model. In this paper, seven factors are selected as the landslide susceptibility influence factors, including elevation, slope, aspect, loess erosion intensity, vegetation coverage and geological structure. The influence factor of the geospatial database is established with 30m grid. The target area is divided into 1.8 million grid cells, and the grid cells of the whole area are clustered by the GMM model to obtain the preliminary subarea of landslide susceptibility map. 500 grid cells in the lowest-susceptibility category are selected as non-landslide units randomly, and 203 landslide grid units were used as landslide units according to historical landslide data. trained model is used to simulate and predict the whole research area, and to draw the ROC curve of each algorithm. Then compare the prediction results of each algorithm. The results of the analysis showed that the landslide susceptibility map of each algorithm is consistent with the actual landslide development. The random forest model has the largest area of 0.96 under the ROC curve, and the highest prediction accuracy of 0.93. It is followed by the BP-neural-network model with 0.89 under the ROC curve and 0.87 of the prediction accuracy. The area under the ROC curve and prediction accuracy of the support-vector-machine-model is 0.86, 0.81; and the logistic regression model is and 0.85, 0.80 respectively. The latter are lower than the first two models.