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    2021, Volume 28 Issue 4
    25 July 2021
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    The major issues in ecological restoration of China’s territorial space
    BAI Zhongke
    2021, 28(4): 1-13. 
    DOI: 10.13745/j.esf.sf.2021.6.20

    Abstract ( 639 )   HTML ( 22 )   PDF (3552KB) ( 530 )  

    Ecological restoration of China’s territorial space is fundamental to sustainable development of the Chinese nation in building a beautiful country. The research methods used in this study included comprehensive literature analysis, systematic review, empirical and analogous analyses, trend extrapolation, and environmental impact assessment. This paper systematically examined the territorial ecological restoration from the aspects of national strategy and top-level design, expounded the research methodology from the perspectives of project planning, technical route and method, field station, and plot, analyzed the problems of “pseudo-ecology” and “fake technology”, and pointed out the strategic guidelines, objectives, directions, principles, priorities, and countermeasures for improving ecological restoration. In addition, from five aspects of ecological restoration including the major scientific issues and hotspots, context analysis, zoning classification, differential management, and ecological compensation mechanism, this research advocated scientific and technological support to boosting ecological restoration of China’s territorial space, and discusses the issues of “two (ecological) barriers and three (protection) zones”, scientific advancement of ecological restoration, and integration of management and technical ideas. The study results provide a scientific basis for solving the three major contradictions—interconnectedness of ecological elements and departmentalization of management authorities, continuity of ecological space and division of local administrations, and long-term nature of ecological engineering and temporariness of administrative tenures—in the “overall protection, systematic restoration and comprehensive management” of territorial space.

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    A technical framework for ecosystem conservation and restoration
    ZHOU Yan, CHEN Yan, YING Lingxiao, YANG Chongyao
    2021, 28(4): 14-24. 
    DOI: 10.13745/j.esf.sf.2020.10.23

    Abstract ( 679 )   HTML ( 21 )   PDF (2388KB) ( 514 )  

    Faced with the severe resources, environmental and ecological pressures, President XI Jinping proposed the concept of community of life consisting a full range of ecosystems, including mountains, rivers, forests, farmlands, lakes and grasslands. By the end of 2019, 25 pilot projects for ecosystem conservation and restoration had been carried out in China. Although the previous efforts had achieved some results, there are still many problems, such as unclear conservation and restoration goals, insufficient scientific characterization, excessive engineering measures, lack of dynamic monitoring and evaluation, and difficulty in realizing harmonious coexistence between human and nature. In the current research, we built a four-level—regional (province), landscape, ecosystem and subproject level—technical framework for ecosystem conservation and restoration, based on the theories in landscape and restoration ecology and the concepts of nature-based solution, adaptive management, complex socio-economic-natural ecosystem, and ecosystem services. Under this framework, the technical requirements related to monitoring and managing the entire project implementation process were proposed, so as to provide the theoretical and technical supports toward integrated conservation, systematic restoration, and comprehensive management of a full range of ecosystems.

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    Ecosystem conservation and restoration through Nature-based Solutions
    YANG Chongyao, ZHOU Yan, CHEN Yan, WANG Liwei
    2021, 28(4): 25-34. 
    DOI: 10.13745/j.esf.sf.2020.10.3

    Abstract ( 813 )   HTML ( 27 )   PDF (1583KB) ( 344 )  

    In order to solve the complex problems we face in ecosystem management in China, 25 pilot projects for ecosystem protection and restoration were implemented from 2016 to 2018 with positive outcomes. However, problems still exist, such as lacking a good understanding of the internal controls of ecosystems, overly relying on engineering approach and inadequate management policies. As one of the most accepted measures addressing societal challenges, Nature-based Solutions (NbS) have developed rapidly, with emerging concepts, principles and practices. This paper systematically sorts out the concepts, core theories and typical cases of NbS, and interprets, from the perspective of NbS, the problems in the pilot projects in terms of their spatio-temporal scale, goal setting, technical measures, and implementation and management strategies. We propose using NbS as reference to improve the ecosystem protection and restoration projects in China, which entails adopting a multi-scale, multi-objective design, setting multi-objective goals, and establishing a scientific technical framework and standard. Meanwhile, we aim to promote multi-party participation, economic sustainability, adaptive management and so on.

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    Land consolidation and ecological restoration in Horqin: Land use planning strategy based on geosciences knowledge
    ZHANG Fengrong, ZHOU Jian, XU Yan, CHEN Jingyuan
    2021, 28(4): 35-41. 
    DOI: 10.13745/j.esf.sf.2020.10.12

    Abstract ( 338 )   HTML ( 8 )   PDF (2384KB) ( 164 )  

    The Horqin sandy land in Inner Mongolia is the largest sandy land in China with a mean annual precipitation of 380 mm. Historically the sandy land was a prairie and nowadays it is a mixed farming and grazing zone. Today, farmlands occupy a large portion of the entire region, which has major implications for ecological security, national food security, and farmers’ livelihoods. Soil water content is conspicuously different at the dune top and in the inter-dune depression. Based on the large interannual variation in precipitation and the topographical features of sand dunes, the research objective was to overlay the soil and land use maps interpreted by satellite imagery to delineate the dominant and hidden sandy lands. Using NDVI data of different precipitation years as the discrimination criteria, cultivated land with low NDVI can be transferred to grassland to avoid the risk of desertification in the drier years. Adapted to the regional geographic environment in semi-arid regions, this method of optimizing spatial allocation of land use could be consistent with ecological and production needs while being uncomplicated. The study could be used as a functional model for reducing desertification in semi-arid areas by using sand dunes as wind protection, abandoning large-scale land leveling engineering and developing rain-fed agriculture. In other words, land-use allocation and farmland consolidation should be in harmony with the regional geographical environment. Combining agricultural production and desertification prevention is a sustainable land use planning strategy.

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    Essentials for soil and water conservation in ecosystem management
    JIANG Dewen
    2021, 28(4): 42-47. 
    DOI: 10.13745/j.esf.sf.2020.10.4

    Abstract ( 467 )   HTML ( 15 )   PDF (1442KB) ( 249 )  

    The mountain, river, forest, farm, lake and grassland ecosystems are an integral part of the life community, and their systemic management is essential to soil erosion control and ecological restoration. The occurrence and development of soil erosion is a complex issue, thus soil and water conservation needs an interdisciplinary scientific approach. The widespread soil erosion has long been existed in China, yet the current level and annual progress of erosion control are relatively low and do not meet the demands of ecological civilization. To prevent and control soil erosion and to establish and develop the discipline of soil and water conservation, we need to focus on systems thinking and overall measures and develop a comprehensive erosion control strategy. We should fully engage the nature’s self-repair ability, support key management, rely on small scale restoration then expand to large areas, and restore vegetation rapidly on a grand scale to reduce erosion rate. We should integrate water resources protection, water environmental improvement, surface source pollution prevention and control, rural sewage and garbage treatment, and village appearance and welfare improvement into ecosystem management. Equally important are to promote the construction of ecologically viable small watersheds as a way of system governance, and pay attention to the development of mountainous lands into fruit forests as part of the comprehensive and systematic measures for soil erosion control. It is necessary to implement comprehensive water and soil conservation measures to promote high quality socioeconomic developments in the ecologically damaged areas caused by industrialization, urbanization, and agricultural modernization.

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    Strategies for biodiversity conservation in agricultural landscape during land rehabilitation and ecological restoration
    LIU Yunhui, YU Zhenrong, LUO Ming
    2021, 28(4): 48-54. 
    DOI: 10.13745/j.esf.sf.2020.10.6

    Abstract ( 219 )   HTML ( 10 )   PDF (2648KB) ( 248 )  

    As ecological civilization has become a national strategy, land rehabilitation and ecological restoration need more support from ecological science and environmental technology. Biodiversity in a agricultural landscape is an important natural resource, which provides important ecosystem services for sustainable development of the human society and helps humans to cope with risks like climate change. In this paper, we analyzed the importance of biodiversity conservation in agricultural landscape in China and the challenges involved in land rehabilitation and ecological restoration. We systematically summarized the relevant conservation experiences and methods reported by the European Union. Finally, we proposed four strategies integrating the biodiversity conservation into land rehabilitation and ecological restoration in accordance with the national strategy for pursuing ecological civilization. The four strategies are: the “ecological restoration and management-ecological compensation-human welfare improvement” strategy in ecological space; the “ecological infrastructure-ecosystem services enhancement-green development” strategy in agricultural space; the “multifunctional landscape-green livable space construction” strategy in urban and rural living space; and the “biodiversity conservation network” strategy in overall territorial space.

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    Territorial land zoning for ecological restoration in Jiangxi Province based on dominant ecological function
    CAI Haisheng, ZHA Dongping, ZHANG Xueling, CHEN Yi, ZENG Heng, SHAO Hui, HONG Tulin
    2021, 28(4): 55-69. 
    DOI: 10.13745/j.esf.sf.2020.10.7

    Abstract ( 179 )   HTML ( 12 )   PDF (4883KB) ( 313 )  

    In conderations of the regional differentiation characteristics, dominant ecological functions and typical ecological problems, this article explores the territorial land zoning for ecological restoration in Jiangxi Province to provide scientific and technological supports for the preparation and implementation of ecological restoration plans as well as for the realization of land management and control in Jiangxi Province. Guided by the ideas of life community, harmonious rural development, and suitable management, by delineating the principle and ecological functional spaces, and taking into account both the practical ecological problems associated with rural development and the demands for comprehensive development, we use the multi-factor comprehensive spatial analysis method, combined with the “top-down”, “bottom-up” approach, to achieve the three-level ecological restoration of territorial land. The territorial land zoning divides the plains and lakes in northern Jiangxi and the hills and basins in central, western, southern, and eastern Jiangxi into 5 level-1, 24 level-2, and 70 level-3 ecological restoration zones. Through the three-level zoning, the characteristics of the territorial land are clarified, the leading ecosystem function are specified, and the key areas of ecological restoration are identified. It provides a decision-making basis for the implementation of ecological restoration projects and land governance as well as a scientific and technological approach for the overall protection, systematic restoration, and comprehensive governance of territorial land.

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    The relationships between vegetation dynamics and environmental factors on the Qinghai-Tibet Plateau: A review of research progress and prospect
    WANG Jun, ZHANG Xiao, GAO Yan
    2021, 28(4): 70-82. 
    DOI: 10.13745/j.esf.sf.2020.10.20

    Abstract ( 247 )   HTML ( 12 )   PDF (2157KB) ( 142 )  

    The Qinghai-Tibet plateau is one of the regions most sensitive to climate change both in China and in the world at large. In recent years, local vegetation has been under the dual pressure from climate change and human activities. Its physiological and ecological characteristics, in response to climate change and human interference, were analyzed in this paper based on literature research, and the impact of change in vegetation coverage on soil physical and chemical properties were quantitatively summerized based on meta-analysis. On this basis, this paper reviewed the research scales and methods in studying the relationship between vegetation and environmental factors on the Qinghai-Tibet plateau and summerized the results as the follows: 1) Natural factors such as temperature, precipitation and radiation, and human activities such as grazing, farming and road construction, significantly affected the carbon exchange, water use efficiency, elemental content and distribution pattern, phenological period and diversity of vegetation. The change of vegetation also affected the water heat exchange, hydrological process and physical and chemical properties of soil. 2) In the process of vegetation degradation, the changes in vegetation coverage from high to medium had a stronger negative effect on the physical and chemical properties of soil than changes from medium to low; therefore, more attention should be paid to vegetation protection in the high coverage area. 3) Previous researches mainly focused on the impact of a single factor and a single scale. In future, more attention should be paid to multi-factor coupling by considering the intra- and out-of-domain effects on the ecosystem. Besides, multi-scale comparison and scale-effect research should be conducted to explore the ecological restoration strategies and climate change coping mechanisms at different scales based on data compiled through cooperation and data sharing. To implement further research, it is also necessary to integrate multi-source, multi-point, long-term series monitoring data to establish an observational network covering the whole Qinghai-Tibet plateau. In addition, data sharing should be strengthened to save research resources while reducing damage caused by unnecessary repeated sampling to the fragile plateau ecosystem. The systematic review of the relationships between vegetation and environmental factors could be applied to the planning, design and monitoring of ecological protection and restoration projects, so as to develop the ecological protection and restoration technology and management system suitable for the Qinghai-Tibet plateau region, and also provide support for policy-making in this region.

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    Land destroyed by mining in China: Damage distribution, rehabilitation status and existing problems
    YANG Jinzhong, XU Wenjia, YAO Weiling, SUN Yaqin
    2021, 28(4): 83-89. 
    DOI: 10.13745/j.esf.sf.2020.10.8

    Abstract ( 640 )   HTML ( 12 )   PDF (1497KB) ( 343 )  

    A national mine monitoring system using remote sensing technology has been in service to meet the “strict source control, strict process management, severe punishment for consequences” chain management requirements. The monitoring system revealed that by the end of 2018, 3.61 million hm2, or 0.37% of the total land in China, had been destroyed by mining. Of which, the excavation damaged land, occupied land and subsidence land were 1.46, 1.31 and 0.84 million hm2, respectively. The total and abandoned mine areas were 1.34 and 2.27 million hm2, respectively. Meanwhile, the nationwide mine rehabilitation area was 0.93 million hm2 by the end of 2018. During the year 2018, 48.1 thousand hm2 additional land in the country were destroyed by mining while 65.2 thousand hm2 rehabilitated. This research provides a preliminary analysis of the national ecological rehabilitation status of land destroyed by mining and existing problems, with discussions on countermeasures and suggestions for land management.

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    Ecological restoration of the Dabaoshan Mine based on IUCN biodiversity management guidelines
    LUO Ming, ZHANG Shiwen, WEI Hongbin, ZHOU Pengfei, ZHOU Yan, CHEN Yan, LI Zhuochao, ZHANG Jintao
    2021, 28(4): 90-99. 
    DOI: 10.13745/j.esf.sf.2020.10.9

    Abstract ( 250 )   HTML ( 10 )   PDF (5126KB) ( 175 )  

    In order to study biodiversity management in mine restoration, this paper applies the relevant theories and methods presented in the IUCN “Mining and Biodiversity Management Guideline Series” to the restoration practice in the Dabaoshan Mine in Guangdong Province. First, the main content of IUCN Integrated Biodiversity Management System (IBMS) is introduced as the basis for the restoration practices. Next, the paper discusses IBMS application in the restoration project, and puts forward a restoration framework for biodiversity management in the Dabaoshan Mine. The framework includes the full cycle management scheme, focusing on biodiversity investigation, monitoring, evaluation, protection, damage control and restoration. Finally, the paper discusses the inspiration for biodiversity protection and restoration in China’s mining areas where IUCN guidelines play an important role.

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    Spatio-temporal dynamics of landscape ecological risk in resource-based cities: A case study of Wuhai
    LI Shaoling, XIE Miaomiao, LI Hanting, WANG Huihui, XU Meng, ZHOU Wei
    2021, 28(4): 100-109. 
    DOI: 10.13745/j.esf.sf.2020.10.24

    Abstract ( 139 )   HTML ( 8 )   PDF (4283KB) ( 133 )  

    Large-scale open-pit coal mining has a great impact on the ecological environment. This paper aimed to study the impact of resource mining on landscape ecological risk in the arid desert areas of Northwest China and the spatio-temporal dynamics of such risk in the context of resource-based city transformation. We chose the resource-declining city, Wuhai, Inner Mongolia, and its surrounding areas as the study area. The threat index was added to the disturbance and vulnerability measures in assessing landscape ecological risk in order to develop a comprehensive risk assessment model for resource-based cities. The sequential variation and temporal distribution features of risk were analyzed using the 2005-2015 Wuhai landscape data. The results show: (1) The landscape change was greater between 2010-2015 than 2005-2010, and the annual change intensities were 7.43% and 3.44%, respectively, with most activities in industrial/mining and urban construction lands but with reduced annual intensity increase. (2) The degree of forest, water area and wetland losses worsened slightly initially then improved dramatically; other land and grassland losses increased while industrial/mining land use decreased first then increased slightly. On the other hand, the threat indexes of urban construction and industrial/ming lands were the highest. Other landscape types displayed an upward tendency, but the rise in “other land”, water area and wetland gradually slowed down. (3) From 2005-2015, the ecological risk index increased, and the risk level was higher in the west and middle than in the south and north. The low risk areas shifted from the edge to the center, while the high-risk area expanded from the original high-risk area. The change in the risk area during the study period is evident in the high-risk western sandy land, and the risk in other lands is always lower in the east than in the west of the mining area because of bush and grassland covers. Depending on the proportion of industrial/mining land use in different risk grades, risk management can be accomplished by controlling the proportion under 5%. The study provides a basis for ecological risk management in resource-based cities through proper land planning.

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    Spatio-temporal impact and the scope of vegetation disturbance from coal mining: A case of the Ningdong mining district
    YUAN Tao, NI Xuan, ZHOU Wei
    2021, 28(4): 110-117. 
    DOI: 10.13745/j.esf.sf.2020.10.11

    Abstract ( 351 )   HTML ( 17 )   PDF (3946KB) ( 356 )  

    Coal mining is a large-scale, high-intensity ecologically disruptive activity causing considerable ecological and environmental problems, such as land occupation, land damage, and vegetation destruction. The northwest region of China has an arid climate, sparse vegetation, and an extremely fragile ecological environment. The Ningdong mining district is a typical arid coal mining area and has important research value. Therefore this area, along with a reference area with similar natural conditions, were selected as the study area. A total of 276 MODIS NDVI remote sensing images from 2008 to 2019 were used for this study. In the temporal dimension, seasonal and trend decomposition using Loess (STL), functional principal component analysis (FPCA), pixel binary model calculation of vegetation coverage, and other methods, were applied to analyze the temporal variation characteristics of NDVI. The results show that the prolonged mining operation caused noticeable stress to vegetation growth around the mining district compared with the reference area. In the spatial dimension, FPCA was used to analyze the correlation of NDVI data across different buffer zones. We found that the boundary of the ecological impact area lies about 7 km from the mining district. In addition, we analyzed the variation in vegetation coverage at the pixel level and performed a hierarchical statistical analysis of vegetation coverage for different variation ranges. It was found that although the average value of NDVI remained stable over time, the moderate to severely degraded vegetation areas have increased significantly.

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    Temporospatial distribution and influencing factor analysis of dust concentration in Wuhai, Inner Mongolia
    ZHANG Minghao, ZHAO Tingning, XIAO Huijie
    2021, 28(4): 118-130. 
    DOI: 10.13745/j.esf.sf.2020.10.5

    Abstract ( 138 )   HTML ( 8 )   PDF (4119KB) ( 103 )  

    In January and July, 2018, the mobile monitoring method was used to collect dust particles from Wuhai, Inner Mongolia. Together with data from the monitoring station, the temporospatial distribution pattern and influencing factors of dust concentration for different particle sizes were studied. The results show that the dust pollution level is much higher in spring and winter than in summer and autumn, with the highest level in spring and relatively low level in summer. The worst month for PM2.5 pollution March and for PM10 is April. The daily dust concentration peaks between 10-noon and drops to the lowest level between 4:00-6:00 in the afternoon. Areas with high dust concentration are distributed in strips in the east while spread out radially from point sources in the central, south and west. Dust concentration in the industrial, mining and urban areas is higher than in forest and unused lands, while arable land and water body have the lowest dust level. In Wuhai City, the industrial and mining lands are the main source of coarse particulate, while the urban area is the main source of summer fine dust. Water bodies and arable and forest lands can significantly reduce the concentration of airborne particulates. The total suspended particulate(TSP)and individual particulate concentration are positively correlated with wind speed and humidity and negatively correlated with temperature and altitude. Among the influencing factors, air pressure is the most important one affecting TSP concentration, while humidity affects PM1-10 concentrations the most. The dust particle concentration for different particle sizes is constrained by multiple factors, such as normalization index, meteorology and topography, whereas a single condition has only limited impact on atmospheric dust.

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    Ecological evaluation of the Tongling pyrite mining district in Anhui Province
    JIA Han, LIU Junxing, YIN Xianyang, WANG Chunguang, GENG Hao, CHI Haoxuan, TANG Shijie
    2021, 28(4): 131-141. 
    DOI: 10.13745/j.esf.sf.2020.10.16

    Abstract ( 232 )   HTML ( 8 )   PDF (7089KB) ( 404 )  

    The Tongling area of Anhui Province is a typical pyrite mining district in China. Long-term mining in several pyrite mines in the research area, including the Xinqiao pyrite mine, has greatly damaged the local ecological environment. Ecological evaluation of the Tongling area can provide a basis for mine restoration. Based on data analysis and field investigation, we constructed 20 evaluation indexes for the four influential elements: geoenvironmental background, mine development, geoenvironmental setback, and geohazard. We used the analytical hierarchy process (AHP) to determine the weight value of each element and index layers. On this basis, the geoenvironement of mine is evaluated by fuzzy comprehensive evaluation, and the evaluation scores were compared and verified by grid interpolation using ArcGIS. The resulting weight values of the four elements were 0.10, 0.14, 0.37, and 0.39, respectively. The primary judgment of second level fuzzy comprehensive evaluation indicates geoenvironmental setback has greater influence on the geoenvironment of mine in the research area, most prominently from soil and water pollutions; while the first level evaluation shows the geoenvironment of the study area is generally good. By grid interpolation assessment, the extent of mining-induced geoenvionmental impact on the study area can be classified as extreme, moderate and mild, representing 4.62%, 32.04% and 63.34% of the study area, respectively. The fuzzy comprehensive evaluation and grid interpolation yielded similar results, whereas AHP and fuzzy comprehensive evaluation are more applicable to the pyrite mining district. The evaluation results can provide a basis for the geoenvironmental protection and governance in local mining areas.

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    Gravel curtain layer in the desert open-pit mining area of Xinjiang: Ecological damage and reconstruction method
    ZHANG Junjie, BAI Zhongke, YANG Boyu
    2021, 28(4): 142-152. 
    DOI: 10.13745/j.esf.sf.2020.10.15

    Abstract ( 539 )   HTML ( 12 )   PDF (4516KB) ( 326 )  

    The large scale topsoil stripping and land acquisition during open-pit mining lead to destructions of land surface, vegetation, and underground water systems as well as alteration of landscape patterns, causing a series of ecological environmental problems. Open-pit mining in the desert area of northwestern China, an important successor mining location in China’s future coal resources strategy, can severely threaten the country’s land and ecological securities if there are no targeted countermeasures for ecosystem restoration. In this study, seven typical open-pit coal mines in the northwest desert area were selected for the landform remodeling, gravel layer reconstruction, and desert vegetation restoration studies through field investigation, empirical analysis, remote sensing imaging, and comparative analysis. The results are as follows: (1) The seven open-pit mines caused a variety of land disturbances. Among all mines, the land destruction in Baishihu is most severe, reaching 1190.3 hm2; the occupied land in Wucaiwan is the largest at 2251.0 hm2; the land excavation in Jungjun Gobi is most severe, reaching 1007.3 hm2; the bare land area in Dananhu is the largest at 20164.2 hm2; the vegetation around Yili is most abundant at 343.3 hm2; and the traffic land around Xiheishan is the largest, reaching 194.3 hm2. (2) The area of the gravel layer in Wuheishan, the most representative open-pine mine selected for gravel layer study, decreased from 60.12% in 2000 to 31.28% in 2010, then increased to 42.75% in 2017. (3) For the Wucaiwan mine, the estimated biomass was 12.53 g/(m2·a); the landscape diversity index was 0.2193; the landscape dominance was 1.7807; and the landscape evenness was 0.1097. This area has insufficient ecological carrying capacity, weak resistence to ecological disturbance, and low ecological integrity. (4) The vegetation coverage of the Wucaiwan mining area showed an upward trend from 2000 to 2005, reaching 7.72% in 2005, followed by a downward trend from 2005 to 2015, reaching 3.89% in 2015. It can be concluded that the desert open-pit mining area in northwestern China has suffered relatively severe ecological damage. Therefore, the reconstruction of gravel curtains in this area is most urgent, and human support and guidance should be adopted to improve the rate and effectiveness of natural ecological restoration, so that the damaged habitats can spontaneously shift towards recovery and virtuous cycle through active self-feedback.

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    The undergrowth developmental dynamics of plantations in an open-pit coal mine waste dump in loess area
    ZHAO Bingqing, BAI Zhongke, GUO Donggang, CAO Yingui
    2021, 28(4): 153-164. 
    DOI: 10.13745/j.esf.sf.2020.10.18

    Abstract ( 676 )   HTML ( 5 )   PDF (1651KB) ( 93 )  

    To study the community dynamics of artificial vegetation in reclaimed land of mining areas, a 1-hm2permanent monitoring plot was established in 2010 with mixed forestry of Robinia pseudoacacia+Ulmus pumila+Ailanthus altissima at the Antaibao open-pit coal mine in Shanxi Province. Based on two datasets obtained in 2010 and 2015, we measured the species diversity using multiple indices, and analyzed the overall interspecific association and main species interspecific association in the herbal layer of the community using variance ratio (VR) tests, χ2tests, and Spearman’s rank correlation coefficient tests from the 17th to 22nd year since reclamation. The results indicated the following: (1) A total of 62 species, belonging to 20 families and 46 genera, and 53 species, belonging to 18 families and 39 genera of herbaceous plants were investigated after 17 and 22 years of reclamation, respectively. The dominance of the Compositae was the most exaggerated in 2010, and this level of dominance gradually decreased, while the dominance of Gramineous plants gradually increased. During this five-year period, the dominant component changed from Artemisia sieversiana to Roegneria kamoji. Similar to the natural vegetation in the original landform, the perennial and mesophyte plants dominated the two surveys of herbaceous plants under artificial vegetation. The importance of annual or annual/biennial and mesophytic herbs decreased, while the dominance of perennial, xerophyte, meso-xerophyte, and xero-mesophyte herb increased along with succession. (2) After 17 years of reclamation, the species richness index of herbaceous plants under artificial vegetation has significantly exceeded that of the original landform. The species richness index decreased with succession, while the Shannon-Wiener index and Pielou evenness index showed an increasing trend. The species diversity of the herbaceous plants under artificial vegetation was restored to 94.12% of the natural vegetation in the original landform after 22 years of reclamation. (3) The overall correlation of herbaceous plants under artificial vegetation changed from a significant negative correlation to no significant negative correlation. The positive-negative correlation ratio of the main species increased from 0.30 to 0.79, but both were less than 1, and the interspecific association of most species pairs was not significant (P>0.05), reflecting the interspecific competition relationship of herbaceous species in the community. With the succession of the community, the structure of the herbaceous community gradually became stable. The main species pairs of Stipa capillata and U. pumila showed a significant positive correlation. These zonal species have strong ecological adaptability for tolerating drought and poor soil fertility, and could therefore be used as preferred plant species pairs for mixed planting in future waste dump revegetation in the Antaibao open-pit coal mine. This study can provide a theoretical basis for vegetation reconstruction and biodiversity conservation in mining areas.

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    Visual evaluation of land reclamation aesthetics: An example of the Loess Plateau mining area
    CHENG Jiyuan, BAI Zhongke, YANG Boyu, ZHANG Jianan
    2021, 28(4): 165-174. 
    DOI: 10.13745/j.esf.sf.2020.10.14

    Abstract ( 178 )   HTML ( 6 )   PDF (1760KB) ( 128 )  

    At present, the national and global level studies on land reclamation from the perspective of esthetics are scarce. In fact, the concept of land reclamation esthetics has not yet been proposed, and the visual evaluation system of land reclamation esthetics is not yet mature. To study this concept in depth, we discuss in this article the esthetic expression of land reclamation in reference to the experience of land reclamation and ecological restoration in the Pingshuo mining area. Following the idea of “ecosystems are a life community”, a nested evaluation system composed of element and system evaluations is proposed. By deconstructing some well established landscape visual evaluation systems, including the United States Forest Service visual management system (VMS), Land Administration visual resource management (VRM) system, and Federal Highway Administration visual impact assessment (VIA) system, and combining with the theory of five-stage reclamation for mine ecological restoration, we constructed a indicator system for evaluating land reclamation esthetics applicable to the mining area of the Loess Plateau. The system has 21 indicators: 8 related to structure, 7 for vegetation reconstruction and biodiversity, and 6 for landscape reproduction. All indicators have complete qualitative or semi-quantitative interpretations, with revisions of interpretation criteria for 4 indicators: rock formation, topography, lake, and adjacent landscape. The esthetic evaluation of land reclamation cannot ignore the influence of subjective factors, and it should emphasize diversity and difference in the esthetic expression of landscapes so that the visual expression of land reclamation esthetics is more selective.

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    Water quality analysis and pollution evaluation of the main rivers in the Tongling mining area
    WANG Chunguang, LIU Junxing, GENG Hao, JIA Han, YIN Xianyang, CHI Haoxuan
    2021, 28(4): 175-183. 
    DOI: 10.13745/j.esf.sf.2020.10.1

    Abstract ( 186 )   HTML ( 11 )   PDF (3215KB) ( 293 )  

    The Tongling mining area is an important copper and iron resource base in the lower reaches of the Yangtze River and also a typical sulphur-containing polymetallic mining area, where acid mine drainage is an unavoidable environmental problem affecting especially surface water. Here, we studied the main rivers in the Tongling mining area. Through field investigation and laboratory analysis, the water quality status, in terms physical and chemical properties, acid mine drainage, and heavy metal elements, was evaluated; and the pollution status was assessed using the Nemerow water quality index method. The results show: (1) Organic waste and mine acid drainage were the primary source of river pollution, followed by heavy metals. (2) According to the comprehensive pollution index, 93.48% of the 46 river sections were polluted with the following water quality grades: 4.35% seriously polluted, 13.04% heavily polluted, 65.22% polluted, and 10.87% lightly polluted. Only 6.52% of the river sections had good quality clean water. (3) The three most polluted rivers, ranked by pollution index, were Xinqiao River, Shun’an River, and Red Star River, all, except the Shun’an River, were polluted by acid mine dranage. Hence, we should pay more attention to the pollution mechanism and risk assessment of acid mine drainage and strengthen water environmental protection and restoration in the mining area.

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    The hydrogeochemical evolution of groundwater in the middle reaches of the Heihe River Basin
    WANG Wenxiang, LI Wenpeng, CAI Yuemei, AN Yonghui, SHAO Xinmin, WU Xi, YIN Dechao
    2021, 28(4): 184-193. 
    DOI: 10.13745/j.esf.sf.2021.5.28

    Abstract ( 186 )   HTML ( 11 )   PDF (3968KB) ( 180 )  

    The Heihe River is the second largest inland river in China. Studies on the hydrochemical evolution of the Heihe River Basin play an important role in utilizing and managing regional water resources as well as ensuring downstream ecological security and safety of drinking water. In this study, the hydrochemical and isotopic variation patterns of two typical profiles of the Heihe and Fengle River mainstreams were studied using data from a 1∶50000 hydrogeological survey conducted in the Heihe River Basin from 2014 to 2018. The study suggests that groundwater in the middle reaches of the Heihe River Basin mainly recharged via precipitation from the Qilian Mountain. Deuterium and oxygen-18 isotope were more enriched in the groundwater of the Heihe River than in the Fengle River mainstream, demonstrating the altitude effect for stable isotopes. Ancient water, different from modern water, was found in the Fengle River Basin drainage area, indicating the current salt lake basin was the groundwater retention area during its early stage. After an extended leaching period, groundwater TDS in the Gobi belt was low, and the hydrochemical type was mainly the bicarbonate type; downstream, TDS increased gradually and the sulfuric acid and sulfuric acid-chlorine types became dominant. Chemical evolution of groundwater in this area followed two distinctive patterns: one is gypsum dissolution-carbonate precipitation-chloride dissolution incomplete silicate dissolution followed by cation exchange, the other is sodium sulfate dissolution after the first. The primary reason for the TDS increase in the recharge/runoff area is leaching, the same reason for the TDS increase in the Fengle River discharge area, where the main source mineral, salt, primarily originated from the surface. In the discharge area of the Heihe River mainstream, owing to the thin aquifer and shallow groundwater, evaporation had a greater influence on groundwater salinization.

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    Hydrochemical characteristics and evolution of groundwater in the Dachaidan area, Qaidam Basin
    ZHANG Jingtao, SHI Zheming, WANG Guangcai, JIANG Jun, YANG Bingchao
    2021, 28(4): 194-205. 
    DOI: 10.13745/j.esf.sf.2020.6.40

    Abstract ( 561 )   HTML ( 8 )   PDF (2891KB) ( 424 )  

    Groundwater plays an important role in the ecological environmental protection in arid and semi-arid areas. The Dachaidan Lake in the northern margin of the Qaidam Basin is located in the arid, ecologically sensitive northwestern region. For sustainable use of groundwater in this region, it is crucial to understand its hydrochemical evolutionary characteristics. In this study, we collected 28 representative water samples from this area and analyzed the distribution characteristics of groundwater chemical types by using mathematical statistics, Piper chart, Gibbs chart, ion ratio, saturation index and reverse hydrogeochemical simulation; we also discussed the water-rock interaction in the groundwater hydrochemical evolutionary process. The main results are: (1) From the piedmont alluvial fan to the Dachaidan Lake, the hydrochemical type changed from HCO3·Cl·SO4-Na·Ca to SO4·Cl-Ca·Na and Cl-Na while TDS increased from 1 to 380 g/L or more. (2) The gibbs diagram, major ion ratio and saturation index showed the hydrochemical characteristics of groundwater in the study area were mainly controlled by the water-rock interaction and evaporation-crystallization effect, with halite, gypsum and feldspar dissolution and calcite and dolomite deposition along the groundwater flow path. The relationship between chlor-alkali index and [(Na++K+)-Cl-] or [(Ca2++Mg2+)-( HCO 3 -+ SO 4 2 -)] showed the cation exchange also affected the chemical composition of groundwater in the area. (3) Through reverse hydrogeochemical simulation, the main water-rock effect of the groundwater runoff process revealed by qualitative analysis was quantitatively verified.

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    Iron and manganese in shallow groundwater in Shijiazhuang: Distribution characteristics and a cause analysis
    ZHANG Xiaowen, HE Jiangtao, HUANG Guanxing
    2021, 28(4): 206-218. 
    DOI: 10.13745/j.esf.sf.2020.7.4

    Abstract ( 392 )   HTML ( 7 )   PDF (13293KB) ( 372 )  

    Iron and manganese ions, as the main indicator contributing to the sub-Class III classification of shallow groundwater in Shijiazhuang, pose serious risks to local water safety and residents’ health. Here, based on previous researches and a new hydrogeological survey, 138 groundwater samples were collected and analyzed to reveal the spatial distribution characteristics of high Fe/Mn groundwater influenced by hydrogeological conditions as well as human factors, such as groundwater development and ground pollution input. Multivariate regression was used to establish the mathematical relationship between the influencing factors and high Fe/Mn presence, and to determine the main controlling factors for the Fe/Mn distribution in the area. The results showed that the average Fe and Mn concentrations in the study area were 0.2 and 0.04 mg/L, respectively, with 15.2% and 5.8% water samples being classified as sub-Class III, respectively. The low level Fe/Mn is mainly found in the top unit of the alluvial-proluvial fan and groundwater dropping funnel areas, impacted by groundwater mining. The over-mining area is liable to form an oxidizing environment, where low oxidation state Fe/Mn are oxidized to form insoluble Fe-Mn compounds resulting in a decrease in Fe/Mn concentration. The median level Fe/Mn is mainly found in the central unit of the alluvial fan. As its lithology becomes finer and hydraulic gradient becomes smaller, the central unit is easy to form a reducing environment where Fe/Mn are concentrated as a result of such natural advantage. The high level Fe/Mn is mainly found in spots or bands in the northern part of the Shijiazhuang urban area, Zhengding County, and in southern Lingshou County, caused mainly by surface pollution. The input of pollutants leads to changes in the redox and acid-base environments and an increase in the Fe/Mn concentration.

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    Estimating biomass of reclaimed vegetation in prairie mining area: Inversion method based on Worldview-3 and Sentinel-1 SAR data
    LIU Yanhui, YANG Xiaoyu, BAO Nisha, GU Xiaowei
    2021, 28(4): 219-228. 
    DOI: 10.13745/j.esf.sf.2020.10.10

    Abstract ( 173 )   HTML ( 6 )   PDF (7882KB) ( 149 )  

    Quantitative inversion of reclaimed vegetation biomass in prairie mining area based on the remote sensing technology is the basis of dynamic monitoring and evaluation of mining ecological environment. In this research, focussing on the reclaimed vegetation in the grassland open-pit coal mine in Inner Mongolia, we combine the advantages of optical and radar remote sensing to explore the inversion method for biomass estimation based on Worldview-3 and Sentinel-1 SAR data. The principal component-wavelet transform algorithm was selected for data fusion. We revealed the correlation between parameters such as band reflectivity, vegetation index, backscatter coefficient or texture feature and biomass, established multivariate biomass inversion models, and analyzed the spatial uncertainty of different biomass models. The results are as follows: (1) After image fusion using W-PCA method, both data entropy and average gradient of the fusion data were significantly improved, and the fused 8th band (NIR2) had the highest correlation coefficient, the lowest spectral distortion, and the highest spectral fidelity. (2) Correlation analysis revealed a significant positive correlation between biomass and EVI, NDVI, VH polarization scattering coefficient, VH mean texture or the 8th band after fusion. Compared with a single variable, using the joint variables, NDVI of WV-3 and VH mean texture of Sentinel-1, it achieved the highest model accuracy (R2=0.8340, RMSE=16.4646 g/m2, Ac=81.52%), while the 8th band after fusion gave the highest verification accuracy (R2=0.7983, RMSE=22.8283 g/m2, Ac=74.64%). (3) According to the residual uncertainty analysis of different models, the Sentinel-1 variables are more prone to overestimation and saturation, whereas the joint variables can achieve complementary advantages. Using fusion data significantly improved the biomass overestimation for biomass below 40 g/m2 and saturation for biomass greater than 100 g/m2, reducing the model uncertainty by 2.42-9.68 g/m2 on average. It can be seen that the combination of optical and microwave cooperative remote sensing can effectively improve the estimation accuracy of vegetation biomass, thereby providing effective data support for fine monitoring of reclaimed vegetation in mining areas.

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    Application of data mining algorithm in correlation analysis of the driving factors for alpine grassland degradation
    MA Rongrong, YANG Guozhu, HU Yueming, ZHOU Wei
    2021, 28(4): 229-237. 
    DOI: 10.13745/j.esf.sf.2020.10.19

    Abstract ( 262 )   HTML ( 7 )   PDF (4028KB) ( 148 )  

    The degradation of alpine grassland is affected by a range of natural and human activities, and the coupling relationship between degradation and its driving factors is complex. To study the relationship between the influencing factors and indicators for alpine grassland degradation, this paper refers to Duo County as the research area, extracts the NDVI time series data from 2005 to 2014, combines the temperature, precipitation and socio-economic factors, and uses the data mining-based lift caluation in the correlation analysis. The relationships between the three levels of NDVI, food availability or plant height and the corresponding temperature, precipitation, rodent or grazing intensity were examined, so as to more accurately analyze the contribution rate of each driving factor to different grades of grassland degradation. The conclusions are: (1)The low vegetation coverage in grassland is negatively correlated with temperature and precipitation. (2)The low food availability in grassland is negatively correlated with temperature and population, and positively correlated with livestock. (3)The low plant height is positively correlated with livestock.

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    Assessments of heavy metal pollution in soils of the southwestern Xiong’an District and its ecological risk
    ZHANG Surong, WANG Changyu, LIU Jihong, XING Yi, LIU Qingxue, YANG Junquan, HE Fuqing
    2021, 28(4): 238-249. 
    DOI: 10.13745/j.esf.sf.2020.7.1

    Abstract ( 258 )   HTML ( 12 )   PDF (4819KB) ( 298 )  

    Heavy metal pollution in soil is tremendously hazardous and poses great risks to the ecosystem. In this study, we focus on the topsoils and staple crops, wheat and maize, in southwestern Xiong’an District. We assessed the heavy metal pollution in soil and its ecological risks based on the metal concentration analysis of eight heavy metals, As, Ni, Cu, Cr, Pb, Hg, Cd and Zn. The results show that the concentration of heavy metals in the topsoils of certain areas exceeded the standard value. The degrees of heavy metal pollution were Cd>As>Cu>Zn>Pb>Hg, while Cr and Ni were below the hazardous level for clean soil environment. The heavy metal pollution in topsoils of the area is caused by human activity. Numerous nonferrous metal smelting activities in Laohetou Township and adjacent area might be the major pollutant source. The degrees of potential ecological risk of the eight heavy metals were Cd>Hg>As>Cu>Pb>Zn>Cr>Ni. The average value of polymetallic potential ecological risk index (RI) was 252, indicating an intermediate risk level of overall potential hazard from heavy metals. Among the eight heavy metals, Cd contributed the most to RI, for it has the strongest chemical activity and strong migration ability and is easily absorbed by plants. These results would provide an important basis for the land use planning in Xiong’an District.

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    Petrogenesis and tectonic significance of OIB- and arc-type volcanic rocks in the western Yangtze Block: From intracontinental rifting to subduction
    ZHANG Jibiao, DING Xiaozhong, LIU Yanxue
    2021, 28(4): 250-266. 
    DOI: 10.13745/j.esf.sf.2020.12.4

    Abstract ( 362 )   HTML ( 8 )   PDF (8152KB) ( 249 )  

    The late Mesoproterozoic to early Neoproterozoic magmatism in the western margin of the Yangtze Block played an important role in the geodynamics and crustal evolution of the Yangtze Block during the assembly and breakup of the Rodinia supercontinent. In this study, new SHRIMP zircon U-Pb dating yielded ages of (1035±15) and (884±9) Ma for the Tianbaoshan basaltic tuff and Yanbian hornblende andesite in the western Yangtze Block, respectively. The Tianbaoshan basaltic tuffs are of alkali basalt, exhibit OIB-like geochemical affinity and enrichments of LILE and HFSE, and have a positive εNd(t) (4.6) value, with geochemical characteristics similar to ocean island balsalt. They are presumably derived from low-degree (1%-5%) partial melting of the upwelling asthenospheric mantle in an intra-plate rifting setting in the garnet+spinel stability field. The Yanbian hornblende andesites have calc-alkaline arc rocks signature, characterized by the enrichments of LILE and LREE and depletion of HFSE, significantly negative Nb, Ta and Ti anomalies, and positive εNd(t) (1.1-2.8) values. They are derived from 5%-10% partial melting of mantle wedge in a subduction setting in the garnet+spinel stability field. On the basis of these results, we propose that the late Mesoproterozoic rifting-early Neoproterozoic subduction related volcanic rocks record a tectonic switch, from a continental-rifting basin to an convergent environment in the western Yangtze Block.

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    Characterization of the Xiaokelehe granite porphyry in the Northern Great Xing’an Range
    CHEN Zhigang, LI Yongsheng, YU Xiaofei, WANG Ying, ZHEN Shimin, GONG Fanying
    2021, 28(4): 267-282. 
    DOI: 10.13745/j.esf.sf.2020.12.6

    Abstract ( 255 )   HTML ( 9 )   PDF (8869KB) ( 195 )  

    The Xiaokelehe Mo(Cu) deposit is a newly discovered porphyry deposit in the Northern Great Xing’an Range and related to the granodiorite porphyry. The granite porphyry veins, intruding into the granodiorite porphyry, are superimposed with new alteration and mineralization. Potash feldspathization, silicification and sericitization are developed in the wall rock contacting the granite porphyry. In this alteration zone, it developed veinlet-disseminated pyrite, chalcopyrite and molybdenite—specially abundant, indicating an medium to high temperature of alteration and mineralization. In this paper, LA-ICP-MS zircon U-Pb geochronology, whole-rock geochemistry and Hf isotope were used to constraint the magmatic source and tectonic setting. The zircon U-Pb age obtained for granite porphyry was 131.42±0.39 Ma, corresponding to the Early Cretaceous. The Xiaokelehe granite porphyry is mainly composed of orthoclase, albite, microcline and quartz. No mafic alkaline and peraluminous minerals were observed. The granite porphyry belongs to high-K calc-alkaline series, characterized by high contents of SiO2(76.24-77.55%) and (K2O+Na2O) (8.12-8.44%), and low contents of MgO (0.09-0.16%) and CaO (0.30-0.65%). The A/CNK ratio ranged between 0.94-1.04. The rocks also showed pronounced depletions of Nb, P and Ti, and enrichments of Rb, Th and U. The (Zr+Nb+Ce+Y) content and 10000 Ga/Al ratio were below the lower limits of the A-type granite. Integrated mineralogical, geochemical data suggest that the granite porphyry is a highly differentiated I-type granite. Hafnium isotopic analysis of zircons from the granite porphyry yielded εHf(t) value of -0.2 to 4.0 and two-stage model age (TDM2) of 931 to 1199 Ma, indicating the magmas were derived from partial melting of juvenile crustal material, with addition of ancient crustal materials. It is believed that the porphyry deposit was formed under the extensional environment related to the paleo-Pacific and Mongol-Okhotsk Plates. The Late Jurassic-Early Cretaceous was an important period of Mo(Cu) mineralization in the middle and northern Great Xing’an Range. The shallow high-K calc-alkaline granitic intrusion is important for exploring porphyry Mo(Cu) deposit.

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    Characteristics and tectonic significance of the early Paleozoic syenite granite from Jinchuan, Gansu Province
    ZHANG Xiaoxu, SU Shangguo, LIU Meiyu, WANG Weizhu
    2021, 28(4): 283-298. 
    DOI: 10.13745/j.esf.sf.2020.7.7

    Abstract ( 249 )   HTML ( 13 )   PDF (5844KB) ( 271 )  

    In this paper, the petrology, zircon SHRIMP U-Pb age and whole rock geochemical data of the Jinchuan syenite granite in Gansu Province were examined in order to determine the formation age, petrogenesis and tectonic environment of the pluton. The SHRIMP U-Pb weighted average age of magmatic zircons from syenite granite samples is (425.7±2.5) Ma (MSWD=1.07), belonging to the early Paleozoic Silurian and similar to the age of the exposed dolerite dikes in the Jinchuan area. The syenite granite is low in silicon (SiO2, 66.71 to 70.05%), rich in alkalis ((Na2O+K2O), 10.00 to 10.70%; K2O/Na2O ratio, 1.88-2.41), high in total iron (FeOT, 1.79 to 2.62%), low in titanium (TiO2, 0.34 to 0.52%), and metaluminous (A/CNK ratio, 0.82-1.05). Its petrology and chemical composition show that it belongs to the quasi-aluminous alkaline series A1 type granite, with a relatively high zircon saturation temperature (TZr, 878-1015 ℃). It has high contents of rare earth elements (REE) (ΣREE, (374.4-529.4)×10-6, averaging 428.7×10-6). The REE distribution curve shows relative enrichment of light REE and depletion of heavy REE by the right-inclined distribution; (La/Yb)N ranges between 28.07 and 41.28, with negative Eu anomaly (δEu, 0.53-0.66). The standardized primitive mantle spider diagram shows depletions of Nb, Ta, Ti and P. The rocks have relatively high Rb/Sr (0.81-1.27, averaging 1) and Rb/Nb (4.72-9.75, averaging 7.15) ratios, showing the compositional characteristics of crust-derived magma. Combined with regional tectonic evolution and tectonic discrimination, it is considered that the Jinchuan syenite granite is formed from partial melting of felsic material in the upper crust at high temperature, and the bimodal intrusive rocks, composed of dolerite dikes of the same age, are formed in an extensional intraplate rift environment and related to the subduction plate break-up and exhumation and asthenosphere mantle upwelling caused by the ~426 Ma Alashan block and the Qilian-Qaidam block. The Jinchuan syenite granite is formed by partial melting of felsic material in the upper crust at high temperature, and the bimodal intrusive rocks is formed in the extensional intraplate rift environment. The structural activity and hydrothermal mineralization of the Jinchuan Cu, Pt-rich orebody may be related to this magmatic activity.

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    Discussion on the characteristics of the Jurassic-Cretaceous boundary correlation in the Songliao Basin and adjacent areas
    QU Xuejiao, GAO Youfeng, LIN Zhicheng, WANG Pujun, WU Kangjun
    2021, 28(4): 299-315. 
    DOI: 10.13745/j.esf.sf.2020.7.3

    Abstract ( 210 )   HTML ( 4 )   PDF (6493KB) ( 217 )  

    The Songliao Basin and adjacent areas, one of the largest Cretaceous sedimentary landmass, is an excellent candidate for recovering a complete terrestrial sedimentary record from the top of the Upper Jurassic to the Cretaceous. However, the Jurassic-Cretaneous (J/K) boundary bearing areas and beds in the region have not been confirmed because of discontinuous outcrops and deep burial depth. It is important to note that the terrestrial J/K boundary division and correlation is a complex issue with no quick solutions. A set of framework characteristics of inter-region correlation need to be devised. In this report, we discuss the framework characteristics of the J/K boundary correlation in the Songliao Basin and adjacent area and summarize the basis of tectonic setting, magmatic events and biotic macroevolution from the Late Jurassic to the Early Cretaceous. The region west and south of the Songliao Basin has a post-collision extensional setting related to the closure of the Mongol-Okhotsk Ocean in the Jurassic, and an extensional setting in the Cretaceous caused by continental crustal thickening and delamination related to N-S thrust. The Songliao Basin was in a post-collision orogeny setting related to the closure of the Mongol-Okhotsk Ocean in the Jurassic, and in an extensional setting in the Cretaceous caused by plate reorganization involving the active northern and eastern continental margins. The region east of the Songliao Basin was in a strike-slip setting from the Late Jurassic to the Early Cretaceous. The Yanliao and Jehol Biotas are two big fossil groups representing the Jurassic and the Cretaceous, respectively. The Jurassic palynological assemblage is dominated by gymnosperm pollens with high abundance of Classopollis, while the Cretaceous one is dominated by bisaccate pollens of conifers with low Classopollis abundance. The Tuchengzi Formation in northern Hebei and western Liaoning, the Donganzhen Formation in Raohe, and the Dongrong Formation in Suibin are the most probable J/K boundary bearing beds. The J/K boundary may also present in the Daxing’anling Manketouebo Formation, Changjiaweizi Fault Depression and the area between the Changjiaweizi Fault Depression and Daxing’anling.

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    Crude oil geochemical features, charging model and exploration practice in slope zone of the Oriente Basin
    ZHANG Zhiwei, MA Zhongzhen, ZHOU Yubing, YANG Xiaofa, WANG Dandan, LIU Yaming, ZHAO Yongbin
    2021, 28(4): 316-326. 
    DOI: 10.13745/j.esf.sf.2020.6.38

    Abstract ( 221 )   HTML ( 6 )   PDF (4822KB) ( 85 )  

    The slope zone of the Oriente Basin has a complex crude oil distribution according to °API. Heavy oil extraction in the basin is difficult and costly, accompanied by unclear distribution of medium and light crude oil, which greatly hinders oil and gas exploration in this area. In this paper, starting with geochemical analysis of crude oil, we clarified the formation mechanism of heavy oil and established a charging model for crude oil by analyzing its distribution and geochemical characteristics. We also identified the favorable prospecting areas for medium and light crude oil to provide effective guidance for oil and gas exploration. The results show: (1) Crude oil samples from the slope zone had a front peak in their n-Alkane distribution, indicating marine source. (2) The group composition of crude oil displayed a “double low+double high” feature, suggesting the crude oil comes from the low maturity-maturity stage of source rocks. (3) Biodegradation is the major reason for heavy oil formation, evidenced by (i) the well developed UCM phenomenon in the total carbon ion flow chart; and (ii) the detection of 25-norhopane marker compounds. (4) Degraded and normal crude oil co-exist in the same oil sample according to geochemical analysis, indicating crude oil is the results of mixing two stages of oil charging. Based on the results, a two-stage oil filling model is established: After early oil charging, crude oil is generally degraded and becomes heavier in the mid-stage; then after late-stage oil charging, the mixing of later stage normal oil and degraded crude oil controls the planar distribution of crude oil. The area in the down dip direction of shale belt in the slope zone is the favorable area for normal oil exploration as proved by successful drilling of exploration wells.

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    Origin and evolution of gypsum dolomite as a favorable reservoir in the Ordos Basin, China
    HE Mingqian, HUANG Wenhui, JIU Bo
    2021, 28(4): 327-336. 
    DOI: 10.13745/j.esf.sf.2020.5.6

    Abstract ( 466 )   HTML ( 9 )   PDF (12446KB) ( 141 )  

    Gypsum dolomite is the most favorable natural gas reservoir in M51 of the Paleozoic Majiagou Formation in the middle eastern Ordos basin while its properties are mostly affected by dissolution. On the basis of past studies, the composition and genesis of gypsum dolomite and geopetal structure of M51 were determined by core data, cathodoluminescence and geochemical analyses. Thin section and physical property studies show that the numerous cast holes and other secondary pores from gypsum dissolution form the main reservoir space. In addition, a large number of geopetal structures are found in gypsum dolomite. Cathodoluminescence and elemental analysis show that the upper part of the geopetal structure is filled with calcite formed during the burial period; while the lower clastic dolomite is filled with clastic dolomite that has similar geochemical characteristics with the penecontemporaneous mud-powder dolomite outside the geopetal structure, but are obviously different from the fine-mesocrystalline dolomite formed in the deep burial period. The evolution of geopetal structural is an important component of gypsum dolomite as a favorable reservoir. Governed by the principle of chemical and ionic equilibrium, dissolution and filling alternate and repeat throughout the different diagenetic stages, demonstrating that chemical instability is the intrinsic cause of gypsum dissolution, the key to the formation of gypsum dolomite reservoir.

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    Soil mass domination in debris-flow disasters and strategy for hazard mitigation
    CHEN Ningsheng, TIAN Shufeng, ZHANG Yong, WANG Zheng
    2021, 28(4): 337-348. 
    DOI: 10.13745/j.esf.sf.2020.6.39

    Abstract ( 239 )   HTML ( 12 )   PDF (5112KB) ( 199 )  

    According to the traditional view, debris-flow disasters are mainly caused by precipitation, and the runoff, confluence process is a physical process that can be simulated by hydrological processes. However, based on the current observation that debris-flow disasters are concentrated in seismic zones and arid valleys, combining with the existing evidence on debris flow formation and prevention, we found that in human inhibited mountainous areas, the slope and precipitation conditions are prone to causing debris-flow hazards and consequently soil mass dominates the initiation, formation and evolution of debris-flow disasters. The dynamic variation of soil mass affects the feasibility of debris flow formation and also controls the scale and frequency of debris flow. Soil mass at the source region undergoes a loosening or compacting process depending on the internal and external dynamic geological effects, as debris flows of different scales, frequencies and properties are triggered by the failure of soil mass of different densities. And soil mass controls the debris flow enlargement process. It has been proven that the source control theory-based technologies, including regional prediction, multi-level, multi-indicator warning system, and engineering control technology, are scientific and effective in the prevention and mitigation of mountain hazards. Thus, catastrophic debris flows are a geological process and characterization of this process requires more consideration of empirical models based on geological conditions. In addition, the prediction, early warning and high-efficiency mitigation of debris-flow disasters should take into account the mechanism and process that are dominated by soil mass.

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    Research progress on the morphology and sedimentology of long runout landslides
    CHEN Jian, CHEN Ruichen, CUI Zhijiu
    2021, 28(4): 349-360. 
    DOI: 10.13745/j.esf.sf.2020.7.2

    Abstract ( 229 )   HTML ( 14 )   PDF (6583KB) ( 356 )  

    Rapid and long runout landslides, characterized by huge volume, long travel distance and high speed, threaten the personal and property safety for people living in mountainous areas and piedmont plains. The movement process of this type of landslide is difficult to observe or record directly because it occurs quickly—often at high altitude—and always generates a lot of dust. Therefore, the morphology and sedimentary features of long runout landslide deposits become important evidence for inverting the movement process and helping us understand the kinematic and dynamic characteristics of these hazardous events, which are important for disaster prevention and reduction. This paper reviews the hypothesized long runout mechanism, and discusses the significance of geomorphology and sedimentology in this field. The classification of plan view shape and profile of the long runout landslide deposits are associated with the kinematic information presented in this paper. The characteristics and causes of the geomorphic features (toreva block, hummock, ridge, fault) are also discussed and analyzed. These features are resulted from the uneven movement of the landslide material, and such movement is not only related to the terrain but also affected by cohesive force. The sedimentological characteristics of rapid and long runout landslides are obviously affected by lithology, topography, substrates, etc. In view of the literature on sedimentary structures, the facies model (carapace facies, body facies, basal facies, some sub-facies), preserved stratigraphic sequence and inverse grading of long runout landslides are discussed. Finally, this paper analyzes some research problems on the geomorphology and sedimentology of long runout landslides. It proposes that the priority should be given to investigating the formation mechanism of the sedimentary and geomorphic features of these landslides through a combination of analogue modeling and numerical stimulation, helping to clear the current controversies and improving the understanding of the kinematics of rapid and long runout landslides.

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    Hydrogeochemical characteristics and genetic analysis of the Chaluo hot springs and geysers in the Batang County of Sichuan Province
    CAO Ruwen, ZHOU Xun, CHEN Binghua, LI Zhuang
    2021, 28(4): 361-372. 
    DOI: 10.13745/j.esf.sf.2020.6.35

    Abstract ( 439 )   HTML ( 6 )   PDF (3114KB) ( 210 )  

    Hydrochemical and genetic investigations of hot springs are of great significance for the exploitation of geothermal resources. The Chaluo hot springs are located along a river valley in the Batang County of Sichuan Province. The occurrence of the springs is controlled by the Chaluo-Songduo fault. Triassic limestone, conglomerate and granite of the Yanshan Period occur near the hot spring. There are about twenty spring vents on both sides of the river, some are boiling vents and at least two are geysers. Hot water samples were taken from 10 vents. Due to different rock conditions and cold water mixing status, the temperatures of the two vents in the northeastern region ranged from 45 to 51 ℃, while in the central and western areas the vent temperatures ranged from 77 to 89 ℃. The discharge of the vents ranged from 0.01 to 1.8 L/s. The main chemical characteristics of the hot spring water are: pH=6.1-8.1, TDS=0.39-1.06 g/L, [F-]=15-22 mg/L, and [H2SiO3]= 69-356 mg/L. The major cations in the hot springs are Na+, K+ and Ca2+, and the major anions are CO 3 2 -, HCO 3 -, Cl- and SO 4 2 -. Most of the hot water samples are of HCO3-Na type. The δ2H and δ 18O of the hot spring water samples indicate that the hot water is meteoric in origin. The recharge altitude was estimated to be 4400-4800 m, and the average temperature of the recharge area is about -10 ℃. The estimated temperature of the geothermal reservoir is 150-200 ℃, and the calculated depth of the thermal ground water is 2810-3480 m. The geothermal waters of the Chaluo hot springs receive recharge from precipitation infiltration. Heated by heat flow during the deep circulation process, the hot waters emerge along the fault zones in the river valley. Thick limestones near the springs are dissolved by groundwater to form cavities, inside which the shallow cold and deep hot waters are mixed and heated to boiling temperature forming geysers.

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    Research on 3D modeling method for evaluation of urban underground space resources: A case study in Shanghai
    XUE Tao, SHI Yujin, ZHU Xiaodi, WANG Jun, LIU Ting
    2021, 28(4): 373-382. 
    DOI: 10.13745/j.esf.sf.2020.11.1

    Abstract ( 519 )   HTML ( 20 )   PDF (4006KB) ( 315 )  

    The development and utilization of urban underground space is an important part of smart city development in China. The 3D geological structural and property models of urban underground space can reveal the underground structures, river channels, water systems, etc.; by integrating with 3D models, they can better show the quality of underground space resources. In this paper, taking the underground space resources evaluation in the Central District of Shanghai as an example, we designed and established the integrated method for 3D modeling of geological structure and property, constructed the 3D geological model of underground space in the Central District of Shanghai, and realized the automatic fusion of 3D geological model and underground structure model. Finally, according to the suitability evaluation model for the development and utilization of urban underground space resources in Shanghai, we constructed the 3D evaluation model for urban underground space resources. The results of this paper have been applied to the overall and localized planning and engineering construction projects of underground space in the Central District of Shanghai.

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