Abstract:In order to improve the cognition of hydrogeology and groundwater resources in the Yangtze River Basin and break through the limitations of previous evaluation from the point of view of surface water or groundwater, the hydrogeology survey project in the Yangtze River Basin was guided by the earth system science theory and water cycle theory. Based on the full consideration of the transformation relationship between surface water and groundwater, hydrogeology unit and surface water basin were organically combined to divide groundwater evaluation units in the Yangtze River Basin. A new round of groundwater resource evaluation in the Yangtze River basin was carried out through the establishment of typical groundwater resource evaluation model. The evaluation results show that the spatial and temporal distribution of water cycle elements in the Yangtze River basin is uneven, with the highest precipitation in the middle reaches and decreasing from southeast to northwest. Surface runoff is mainly concentrated in summer, the north bank is higher than the south bank in summer concentration surface runoff. Evapotranspiration is generally higher in the east than in the west, and the maximum value is concentrated in the middle reaches of the Yangtze River. The groundwater level in the Yangtze River basin remains stable on the whole, and the water level changes little in the peak and dry seasons, generally less than 2 m. The area of groundwater funnel in the Yangtze River Delta over-exploitation area has been significantly reduced, and the related environmental geological problems have been effectively controlled. In 2020, the total groundwater resources in the Yangtze River Basin was 242.170 billion m³/a, including 209.279 billion m³/a in hilly areas and 33.135 billion m³/a in plain areas. Compared with 2019, the groundwater storage increased slightly, especially in Sichuan Basin, with a total increase of 2.372 billion m³. The water quality in the upper reaches of the Yangtze River basin is better than that in the lower reaches, and the high-quality groundwater is mainly distributed in southern Jiangxi and the western foothills of Dabie Mountains. The main reason for poor water quality in some areas is the widespread distribution of primary inferior water. The development and utilization level of groundwater in the Yangtze River Basin is very low as a whole. The environmental geological problems caused by unreasonable development in some areas have been greatly solved, and karst collapse and land subsidence have been well controlled. It is suggested that high-quality bedrock fissure water should be properly developed and utilized in southern Jiangxi and south Dabie Mountains.

Abstract:The Yellow River basin is an important ecological barrier and economic zone in China. The upper, middle and lower reaches of the Yellow River are faced with different ecological environmental problems. Water plays an important role in the formation and evolution of ecological environmental problems. Based on the quantities, qualities, settlements and dynamic characters of groundwater, the groundwater resources and the drinking water safety of the YRB were analyzed. The results show that total avenue groundwater resource of the YRB in 2019 is 3.93×10¹⁰ m³. Groundwater resources in seven key plain regions, such as Yinchuan plains and Hetao plains, is 8.19×10⁹ m³, contributing more than 20% groundwater resources of the whole basin. The groundwater qualities in YRB dominated is mainly classified as I-IV grade. The concentration of total hardness, sulfate, iron, TDS and Cl-exceed the groundwater standard at high rate. Excessive arsenic, fluoride, selenium, iodine and other primary components threaten the local drinking water safety. Compared with the same period in 2019, the groundwater table kept stable in the upper reach, local rising in the middle reach and decreasing in the lower reach in 2020. The morphological characters of main groundwater depression cone kept basically stable. Focusing on the key regions of the YRB, such as the sources area, Hetao Basin, etc., based on the analysis of the eco-environmental problems, it is proposed to carry out the whole basin resource survey and assessment, deeply develop water balance research in the whole basin and key regions.

Abstract:On the basis of the current situation and history of groundwater resources evaluation in the Pearl River Basin, the water resources evaluation methods and zoning principles were discussed, and 129 four level groundwater systems are divided. Taking the groundwater system as the evaluation unit, based on the full consideration of different hydrogeological parameters, this paper analyzes and evaluates the amount of groundwater resources and the existing problems, discusses the characteristics of different flow movement in the three terraces of the Pearl River Basin, and expounds the accuracy of the evaluation and the influence of water conservancy projects on groundwater circulation. Through this evaluation, the natural groundwater resources in the Pearl River Basin are 137.416 billion m³, the exploitable amount is 57.87 billion m³, and the development and utilization rate is only 9.8%. The Pearl River Basin has a large span, and its hydrodynamic characteristics are quite different, characterized by the deep valley area in the upper reaches of Yunnan-Guizhou Plateau, the peak cluster depression area in the middle reaches of Guangxi, and the alluvial proluvial plain area in the lower reaches. According to incomplete statistics, there are 32 reservoirs in the Pearl River basin with a storage capacity of more than 1 million m³. The construction of water conservancy projects and the regulation and distribution of water resources by reservoirs bring some difficulties to the evaluation of groundwater resources. The main problems are the inconsistency of the basin boundaries between surface water and groundwater caused by the differences in the concepts of surface water and groundwater between different ministries and commissions. Therefore, the countermeasures and methods to solve the problems are put forward, so as to provide reference for the development, utilization, control and protection of groundwater.

Abstract:There is serious shortage of water resources in the Haihe River Basin, and long-term over exploitation of groundwater is the bottleneck for the sustainable social and economical development. Therefore, it is of great significance to carry out study on groundwater resources and utilization potential of the river basin, for dealing with the groundwater overexploitation, and ensuring the sustainable use of groundwater resources and the protection of the ecological environment. The systematic evaluation shows that there is 252.99×10⁸ m³ of groundwater natural resources in the Haihe River Basin, and 172.98×10⁸ m³ of exploitable resources under ecological water level constraints,and 4.68×10⁸ m³ availability of deep water. The quality of groundwater in the mountainous areas of Haihe River Basin is generally good, type I-III groundwater accounting for 40.83%, and the quality of the shallow groundwater in the plain area is worse; type I-III groundwater accounts for 14.10%, meanwhile the quality of deep groundwater is better than the shallow groundwater; and type I-IV groundwater accounts for 74.25%. The overall potential of groundwater exploitation in the mountainous areas of Haihe River Basin is relatively small. There is almost no exploitation potential in Yanshan and the north part of Taihang Mountain because of poor groundwater resource. There is no or little exploitation potential in the central part of Taihang Mountain because of a high degree of groundwater exploitation. There is comparatively great exploitation potential in the southern Taihang Mountain because of abundant groundwater resource. The exploitation potential of shallow groundwater in different hydrogeological units in the plain area is quite different. Because of large-scale groundwater drop funnel caused by long-time over exploitation, the shallow groundwater in the piedmont plain has no more exploitation potential. Meanwhile,there is little exploitation potential in the central and eastern plain,with mainly brackish water. Because of a low degree of groundwater exploitation in the Lubei plain, the exploitation potential of Liaocheng-Dezhou is comparatively great. There is no exploitation potential in Xiong'an New District. There is no exploitation potential of deep groundwater in the plain area.

Abstract:The per capita water resources of Huaihe River Basin are 475 cubic meters, which is less than one quarter of the national per capita water resources (2100 m³), and the quality of groundwater is poor. The contradiction between supply and demand of water resources is prominent, which seriously restricts the high-quality development of regional social economy. Based on the theory of water cycle, the study analyzes the groundwater resources, influencing factors, sustainable development and utilization potential in Huaihe River Basin by using the data of multi-stage groundwater resources survey. The results as follows:(1) The water circulation process in Huaihe River Basin is mainly affected by artificial mining, which leads to the continuous decline of groundwater level and the weakening of effective evaporation; The natural resources of groundwater in Huaihe River Basin are 32.697 billion m³ per year; (2) The quality of groundwater in the basin is generally average, and the proportion of Type Ⅰ-Ⅲ water in pore groundwater is less than 30%; At the same time, the water quality is deteriorating compared with the historical data; (3) The exploitation potential characteristics of shallow groundwater in the basin can be summarized as the south is greater than the north and the mountain area is greater than the plain; Jiangsu and Anhui is relatively larger in the Huaihe River Basin; On the contrary, the shallow groundwater in some areas of Eastern Henan and southwestern Shandong has been over exploited and has no potential for development and utilization; Finally, the surplus of shallow groundwater in other areas is small; (4) The results provide a geological basis for the scientific development and utilization of regional groundwater resources.

Abstract:The Songhua River-Liaohe River Basin is an important commodity grain base in China, and groundwater resources play an important role in maintaining China's food security. In 2019, the amount of groundwater resources in Songliao Basin was 797.31×10⁸ m³, and the exploitation amount of groundwater was 276.4×10⁸ m³. Groundwater in Songliao River Basin is faced with resource, environmental and ecological problems such as local shortage of water resources, continuous decline of local water level, aggravation of "three nitrogen" pollution, and wetland shrinkage, land desertification, salinization etc. Based on the analysis of the driving factors of these problems, the main driving force is summarized as the increase of temperature leading to the expansion of rice suitable area, the change of land use pattern, and the substantial increase of cultivated land area, especially paddy field area,resulting in excessive exploitation of groundwater and aggravation of groundwater surface source pollution. The construction of a large number of reservoirs led to the reduction of river runoff in arid and water shortage areas, the lack of groundwater recharge sources, the decline of groundwater supply capacity and the decline of groundwater level. In view of these problems, some suggestions are put forward, including investigation and monitoring of water resources, research on the rational allocation of water resources, joint dispatching of surface water and groundwater, construction of water resources management system, rigid restriction of the system, and adjusting the agricultural planting structure, promoting water-saving irrigation and improving water resources utilization efficiency.

Abstract:Guangdong-Hong Kong-Macao Greater Bay Area (GBA) is one of the areas with the highest degree of openness and the strongest economic vitality in China. It has an important strategic position in the overall situation of national development. The future development of the bay area is inseparable from the support of water resources and a good water ecological environment. In recent years, with the rapid economic development of GBA, the population is increasing rapidly, the water demand is increasing. As a result, the water environment is deteriorating obviously, and many cities have a single water source, the local water resources storage capacity is limited, and the degree of water security is insufficient. Groundwater is an important part of water resources, with the characteristics of stable water quantity and good water quality, which can be used as an important emergency standby water source. Starting from the groundwater resources, based on the systematic summary of groundwater resources status, characteristics, development and utilization potential, some suggestions in water source of GBA were put forward. It is concluded that groundwater can be divided into three categories:pore water of loose rock, karst water of carbonate rock and fissure water of bedrock, among which pore water of loose rock and fissure water of bedrock are the most widely distributed. The hydro chemical types of groundwater in the bay area are relatively complex, with HCO₃-Na、HCO₃-Ca and HCO₃-Na+Ca as the main types in the hilly area, HCO₃+Cl-Na and HCO₃ +Cl-Na+Ca as the main types in the alluvial plain and intermountain basin, and Cl-Na brackish water as the main type in the delta area. The main streams of Xijiang, Beijiang and Dongjiang constitute the main drainage channels of groundwater in the bay area. The tributaries are the local discharge datum of groundwater. The groundwater changes dynamically with the seasons. The overall quality of groundwater is good, class I-III water of which accounts for 66.25%. From hilly areas to delta plain, the water quality shows a trend of deterioration, especially in Guangzhou, Jiangmen, Zhongshan, Dongguan and other cities. The main factors exceeding the standard are ammonia nitrogen, chloride, fluoride, sulfate, etc. The degree of groundwater development and utilization is very low. Groundwater has basically not been developed and utilized in Dongguan and Zhongshan. Of all kinds of groundwater, carbonate karst fissure water has the potential of large-scale exploitation and utilization. Based on the comprehensive analysis of relevant data, 10 water-rich blocks such as Guanghua basin are proposed as emergency water sources, which can provide 418 million m³ of emergency water supply guarantee for GBA every year. In order to deal with the sudden water pollution and extreme arid climate and other large-scale water supply crisis, ensure the water safety of GBA, and promote the high-quality development of GBA, it is suggested to strengthen the basic hydrogeological survey of GBA, master the dynamic change of groundwater level, water quality and water quantity, and accurately calculate the groundwater storage that can be used for emergency exploitation.

Abstract:Based on the systematic synthesis of previous studies, main aquifers in inland catchments in northwestern China were summarized, groundwater circulation in mountains, plains and deserts were described, and groundwater flow systems in plains were specifically analyzed. Due to the tight connection between groundwater and surface water, aquifers and rivers are hydraulically connected to form a system. Therefore, either groundwater or surface water exploitation in the upper stream can result in significant changes in water resources in the entire catchment. Groundwater resources assessment shows that the total groundwater resources are 78.3 billion m³/a, of which it is 48.7 billion m³/a in plains, 19.9 billion m³/a in mountainous areas and plains, and the current mining rate is 12.8 billion m³/a. Groundwater resource potential analysis indicates that groundwater potential is limited except the Cadam basin and the southern marginal areas of the Tarim basin. Hence, groundwater carrying capacity can only be increased by enhancing groundwater utilization efficiency. In the further, saline or brackish water utilization, research on underground water reservoirs, studies on groundwater ecological function and ecological water requirements should be enhanced to provide technical support for the rational development of water resources.

Abstract:Groundwater resources have played an important role in the national social and economic development, especially in the northern region where surface water resources are relatively scarce. It is very important for security guarantee of water supply to understand hydrogeology, dynamic characteristics of groundwater, and exploitation potential of groundwater resources in a certain area. The Xiong'an New Area was selected as pilot area to analyze and summarize the regional hydrogeology and dynamic characteristics of groundwater based on hydrogeological survey and groundwater monitoring in recent years as well as the previous achievements. Aiming at recovering groundwater depression cones as the sustainable exploitation strategy of groundwater, different scenarios were put forward, including current condition, river recharge, water-saving from agricultural and industrial water consumption, and decrease or prohibition of groundwater pumping. Using groundwater numerical simulation technology, the prediction results of different scenarios after 30 years were comprehensively analyzed, and the sustainable exploitation and utilization scheme of groundwater in plain area of Baiyangdian Watershed was put forward. The results show that the hydrogeology is relatively simple in Xiong'an New Area with normal water-bearing capacity in shallow aquifers and good in deep aquifers. The groundwater level has been declining for many years, and getting stable or rising up in the past one or two years. The quality of groundwater is good and stable both in shallow and deep aquifers. According the assessment, the exploitation potential of groundwater in Xiong'an New Area is about 1.80×10⁸ m³/a, with 1.50×10⁸ m³/a in shallow aquifers and 0.30×10⁸ m³/a in deep aquifers.

Abstract:Since the implementation of the Yangtze River Economic Zone strategy, the economy of provinces and cities along the Yangtze River has developed rapidly. At the same time of economic growth, the ecosystem has been strongly disturbed. The ecological environment of the Yangtze River Economic Zone is facing a severe challenge, which seriously restricts the sustainable development of the Yangtze River Economic Zone. The MODIS and Landsat remote sensing images in 2001 and 2020 were selected as the evaluation indexes of humidity, greenness, dryness and heat to calculate the Remote Sensing Ecological Index (RSEI) by means of principal component analysis method, and finally to quantitatively analyze and evaluate the ecological environment status and changes of 11 provinces and cities in the Yangtze River Economic Zone. The results show that the overall ecological environment grade of the Yangtze River economic zone is optimal, and especially it maintained the overall stable and slightly better trend from 2001 to 2020. The optima ecological environment regions are mainly distributed in Wuyi Mountain, Luoxiao Mountain, Xuefeng Mountain, Wuling Mountain, Wushan Mountain, Dabie Mountain, Xishuangbanna and other areas, while the poor and poor ecological environment regions are mainly distributed in large, medium and small towns, Hengduan Mountain Area in Western Sichuan. The eco-environment grade declining areas are mainly concentrated in the Yangtze River Delta, Taihu Lake, Jianghan Plain, Dongting Lake, Northwest Anhui, southern Hunan and Sichuan Basin. While, the eco-environment grade rising areas are mainly concentrated in most of Sichuan Basin, Chongqing mountain area and Three Gorges Reservoir area, most of Guizhou, Southeast Yunnan, central and Northern Anhui and Northern Jiangsu.

Abstract:As one of the three great plains in China, North China Plain is also one of the main grain-producing areas. As Beijing-Tianjin-Hebei coordinated development zone and the Xiongan New Area are both located in the region, its geographical location is extremely important. Groundwater is the main source of water supply in North China Plain, accounting for about 70% of the total water supply. The increasing exploitation of groundwater since the end of 1970s enables it to be in a state of serious overexploitation for a long time, forming a huge groundwater depression cone leading to a series of environmental and geological problems such as land subsidence, ground cracks, wetland degradation, seawater intrusion, etc., restricting the sustainable development of society and economy. The analysis and research on the evolution of groundwater level can provide support for the treatment of groundwater overrun and the restoration of falling funnels. Based on the high-density simultaneous measurement of groundwater level from 2019 to 2020 and historical groundwater level data, the flow field and funnel distribution of the current groundwater level in 2020 were clarified, and the variation characteristics of the groundwater level in the last 40 years were systematically analyzed. The results show that the shallow groundwater in the eastern and western parts of the North China Plain develops in different ways, the shallow groundwater in the west of the plain continued to decline rapidly from the 1980s to 2014 with a cumulative decline of 20-60 meters. The water level in the edge of alluvial and diluvial fan in the piedmont of Taihang Mountain declined the most. After the South-to-North Water Transfer Project began supplying water in 2014, water levels in major western piedmont cities stopped falling and rose. The groundwater level in the central and eastern regions fluctuated naturally. From the 1980s to 2014, the deep groundwater level showed a general downward trend, and the water level in the central and eastern regions dropped the most, reaching 40-90 m accumulatively. After 2014, the deep groundwater level in urban areas and agricultural areas developed differently, and the water level in urban areas recovered obviously, while the surrounding agricultural areas still showed a rapid downward trend. Additionally, based on the analysis of groundwater evolution, aiming at the balance of groundwater mining and recharge and water level recovery, some suggestions are put forward to carry out the research on the threshold of target water level for the prevention and control of overexploitation areas, formulate the groundwater abatement and recharge scheme, and optimize the groundwater level monitoring network. The research results are of great significance to support the accurate management of groundwater overexploitation in the North China Plain, the restoration of groundwater depression cone, and the rational development and management of groundwater resources.

Abstract:Water resource is an important factor to ensure regional development and a key factor to maintain ecological environment. As an important region in Beijing-Tianjin-Hebei, the water resource carrying capacity of Baoding Plain is of great significance to regional ecology and social and economic development. Based on the basic concept of ecological priority, according to the supply and utilization relationship of different water sources and different water types, the water resource carrying capacity of Baoding Plain was evaluated separately by using the method of combination of quota calculation and linear weighted objective programming, and compared with the local planning, the water resource carrying capacity was classified. The results show that on the basis of guaranteeing ecological water and agricultural irrigation water, under conditions of persistent dry years, total available water of urban life and industrial production will be 463 million m³ in 2025, lacking of 52 million m³, and total available water will be 696 million m³ in 2030, lacking of 56 million m³. Under conditions of persistent median water years, total available water of urban life and industrial production will be 581 million m³ in 2025, surplus 66 million m³, and total available water will be 814 million m³ in 2030, surplus 62 million m³. This research can provide scientific basis for development planning in Baoding Plain.

Abstract:The multi-objective geochemical survey in Shiyan-Danjiangkou area of Hubei Province was organized by the Institute of Geophysical and Geochemical Exploration, Chinese Academy of Geological Sciences during 2013-2015. It aimed to determine the geochemical distribution characteristics of elements in the survey area, conduct land resource environmental assessment and basic geological research, and provide basic data for the sustainable development of national and local economic and social sciences. The investigation revealed the accumulation of cadmium in the bottom sediments of Danjiangkou Reservoir and soil along the Hanjiang River. In order to protect the water source area of Danjiangkou and the water quality and safety of the South-to-North Water Transfer Project, the characteristics of cadmium content in soil and bottom sediments in different ecological areas of Danjiangkou reservoir area were systematically studied, and the background value and enrichment coefficient of cadmium content were calculated, which provided information for reservoir cadmium pollution prevention and ecological restoration. The eco-geochemical risk assessment of cadmium show that 100% of the water-fluctuating zone soil, 100% Hanjiang bottom sediment, 99.45% deep soil and 92.14% top soil belong to the agricultural land with low risk of cadmium pollution. The proportions of low, medium, and high-potential ecological risks in reservoir sediment samples account for 15.52%, 20.69%, and 63.79%, respectively. Based on the analysis of the relationship between the content of cadmium in soil and bottom product and the content of pH, Corg, and major elements, it is recommended to cut off upstream pollution sources, prevent soil erosion, prevent soil acidification, and carry out ecological restoration measures to prevent cadmium pollution of bottom sediments in the reservoir area and reduce its ecological risks.

Abstract:Leizhou Peninsula is located in the southernmost part of mainland China,which is an important agricultural production area of pineapple, banana, sugarcane,ect. Nitrogen, phosphorus, potassium and other nutrients in the soil are the most needed nutrients for crop growth, which is very important for agricultural development.In this paper,the background characteristics of soil nitrogen, phosphorus and potassium in Leizhou Peninsula were analyzed for the first time.The content levels of nitrogen, phosphorus and potassium in different soil parent materials and land use types were studied.The man-made influencing factors and temporal and spatial variation of nitrogen, phosphorus and potassium were discussed,and the evaluation of their abundance and deficiency was carried out.It is found that the distribution of nitrogen, phosphorus and potassium in the soil is restricted by geological background and strongly disturbed by human activities. nitrogen, phosphorus are significantly affected by human activities,and potassium is slightly disturbed by human actibities.Compared with th 1990s,the content of phosphorus in surface soil increased greatly,dan potassium was equivalent to that in the earlier stage. The results of soil fertility evaluation showed that the soil in Leizhou Peninsula was rich in phosphorus, deficient in potassium and locally deficient in nitrogen.

Abstract:Based on the core datas of A27 borehole and the characteristics of micropaleontology and sporopollen in the east of Langfang, combined with the AMS14C datas, analyzed the stratum,established the stratigraphic framework, since the MIS7,in the middle and lower region of the Yongding River. In addition, the stratigraphic and environmental effects under the oxygen isotope staging climate are discussed.The results show that stratigraphy can be divided into 8 sedimentary units(U1~U8), respectively, and have a good correspondence with the marine isotope stage, which correspond to the MIS1~MIS7 and late MIS8, in the Late Quaternary of the middle and lower region of the Yongding River. U1 unit is the lacustrine-valley-floodplain sediment formed during MIS1, U2 unit is the hard clay (the first hard clay) -incised valley-lacustrine sediment formed during MIS2, U3 unit is the lacustrine -valley-floodplain sediment formed during MIS3, U4 unit is massife sediment formed during MIS4 (including the second hard clay, exposed dewatered sediment), U5 unit is lacustrine and branch channel sediment formed during MIS5, U6 unit is incised valley during MIS6 with ephemeral Lake and marsh deposit, U7 unit is a lake-marsh deposit formed by MIS7, U8 is floodplain sediment formed during the late MIS8. It reshaped the sedimentary environment model since MIS7 and defined the geologic time scale in the late Quaternary.It is believed that rivers and lakes are coexisted in the Neolithic period, the lake reached its peak, and peat layer appears in its late era, in the middle and lower reaches of the Yongding River.Until the Shang-Zhou dynasties, the limnetic facies fade away and transform into flood plain facies under the influence of climate change.It can provide an important reference for regional palaeogeographic environment and ecological restoration.

Abstract:The Lenghu sandstone-type uranium deposit is the newly discovered industrial deposit in the northern margin of Qaidam basin. Based on the field geological survey, the ore-bearing rocks in the Dameigou Formation in this area were studied by means of polarizing microscope and electron probe analysis to further clarify the characteristics of uranium source, petrology and mineralogy of Lenghu sandstone-hosted uranium deposit. Results show that the ore-bearing rocks in the Dameigou Formation are mainly (silty) sandy mudstone and thin layer coal and fine-grained quartz greywacke, accompanied with a series of epigenetic alteration phenomena. The Lower Proterozoic Dakendaban Group and Hercynian granite in the northeastern part of the study area provide abundant uranium sources for uranium mineralization. The uranium minerals in this deposit are mainly pitchblende and minor adsorption state of uranium. In general, the pitchblende occurs in irregular granular, stellate, "beadlike, linear" and powdery forms at the edge of pyrite, in the crack or on the contact between pyrite and calcite. The adsorbed uranium mainly occurs in the carbon chips and coal lines. The pitchblende deposit is the first exposed and discovered independent uranium mineral in the northern margin of Qaidam basin, which generally fills the blank of no independent uranium mineral exposed in this area. The presence of calcite in ore-bearing layer indicates that the uranium mineralization fluid is rich in CO₂, H₂O etc. volatile and mineralizer. In addition, many exposed reducing medium (oil and gas, carbon and pyrite, etc.) provides reductant required for REDOX reaction of this type of deposit, which eventually reduces U⁶⁺ to U⁴⁺ and results in precipitation of pitchblende.

Abstract:The tungsten deposits in the Chuankou orefield occur in the outer contact zone and the inner part of the Chuankou pluton. The deposit types are mainly quartz-veinlet belt type and quartz-big vein type of magmatic-hydrothermal origin. In recent years, a breakthrough in prospecting has been made in the Chuankou orefield, and a new type of intrusion-related tungsten deposits has been found. In this paper, LA-ICP-MS zircon U-Pb dating and rock geochemical characteristics of biotite adamellite and ore-hosting rock muscovite monzogranite are studied. The diagenetic age of the Chuankou pluton is (223.1±0.78) Ma, MSWD=0.98, n=24, and the ore-forming age of the intrusion-related tungsten deposit is (224.6±1.31) Ma, MSWD=0.33, n=9, all of which are in Indosinian period. The Chuankou granite is characterized by high SiO₂ and K₂O + Na₂O, low CaO and MgO. It belongs to the peraluminous high-K calc-alkaline series S-type granites, which was formed under the weak compression tectonic system in the collision environment. The Chuankou pluton is characterized by low total REE (∑REE), relatively rich LREE, strong negative Eu anomaly, enrichment of large ion lithophile elements Ba, K, and high field strength element Ta, and depletion of large ion lithophile elements Sr and compatible elements P, Ti, which indicates that the granites of each stage of the granites came from the same magma source and experienced a high degree of evolution. Compared with other granites, the ore-bearing granite (muscovite monzogranite) with lower δEu value and (La/Yb)_N value has a higher crystallization differentiation degree.

Abstract:The research on uranium geology in the northern Songliao Basin is relatively weak. Based on the sedimentology, basin analysis and sandstone-type metallogenic theories, the characteristics of sedimentary formation in the Northeast Uplift Zone (NUZ), Songliao Basin, is systematically researched by means of core and well logging. Firstly, the stratigraphic architecture of NUZ and the temporal-spatial distribution of infiltration window for oxygen water with dissolved uranium are clarified. The strata below Nenjiang Formation on the north of Suiling City are overlap structure. Only the Quantou Formation in Hailun Uplift has a truncated-structure at the basin margin, so it has an infiltration window. In contrast, the late Cretaceous strata on the south of Suiling City are all truncated-structure, so all late Cretaceous strata have infiltration windows. Secondly, seven sedimentary facies, including alluvial fan, fan delta, meandering river, braided river, delta, beach bar and semi-deep to deep lake facies, can be recognized. There are different sedimentary filling patterns among Hailun Uplift, Suiling Anticline and Qing'an Uplift. Thirdly, the main exploration formation, prospecting type and prospecting direction of sandstone-hosted uranium deposits in NUZ, Songliao basin, are discussed as follows. The braided channel sand body in the alluvial fan of Quantou Formation in Qing'an area is the most favorable exploration object, followed by the fan delta sand body of Yaojia Formation in Tieli area and the braided channel sand body of Quantou Formation in Hailun area, and finally the delta front sand body of the first Member of Nenjing Formation in Suiling area. This study can provide a new idea for the progress of uranium exploration in NUZ.

Abstract:A new set of basic rocks was discovered in the Heishidun in South Kangurtag, Eastern Tianshan. Its lithology mainly consists of gabbro and olive gabbro. The rocks are characterized by relatively low contents of SiO₂ (47.59%-50.79%), K₂O (0.26%-1.15%) and MgO (3.94%-12.55%), high contents of Na₂O (2.72% -4.42%) and Al₂O₃ (14.75% -19.65%), and moderate content of Mg^# (47.6-66.64). Light rare earth is enriched ((La/Yb)_N of 1.83-2.12) with a bit of Eu positive anomaly (1.00-1.25). LILE (Ba, U, Sr) is enriched, while HFS (Ta, Nb, Th, and Ti) is depleted, and Pb is strongly enriched. LA-ICP-MS zircon U-Pb dating yields 342.6±3.2 Ma, indicating that this basic rock is a product of Early Carboniferous magmatic activity. Rocks have lower Sr ratio (⁸⁷Sr/⁸⁶Sr)_i (0.703421-0.704551), positive ε_Nd (t) (7.6-8.1) and ε_Hf (t) (9.82-13.74). Geochemical characteristics and petrography show that it is originated from the lithospheric mantle source of the loss, and the source area was affected by the metamorphism of the dehydration and melting fluids resulted from the subduction of marine sediments rich in large ionic lithophile and light rare earth elements. The separation and crystallization of olivine, pyroxene and plagioclase took place during the emplacement of magma, the degree of contamination by the crustal material during the emplacement was very low. The structural and dynamic background shows that the Heishidun basic rock is the product of the Northern Tianshan Ocean's northward subduction along the Kangugtag-Huangshan fault in the Early Carboniferous.

Abstract:Southwestern Guizhou is one of the main producing areas of Carlin-type gold deposits in China. The Jiadi gold deposit is a newly discovered Carlin-type one hosted in basalt in southwestern Guizhou in recent years, and the occurrence state of gold has long been the focus of attention. Previous studies have shown that arsenic-bearing pyrite is the main gold-bearing mineral in the Jiadi gold deposit. However, there has been a lack of in-depth research on the gold-bearing pyrite and the gold occurrence law in the Jiadi gold deposit. Based on the field investigation and indoor microlithographic observation, the pyrites in the mine were divided into different phases first; then, the electronic probe analysis method was used to study the pyrites of different phases. The results show that S and As of pyrite have an obvious negative correlation, and Au and As have a certain positive correlation. Ore-predating pyrite, ore-forming pyrite and post-ore pyrite share similarity of high contents of S, Fe and low contents of As, Au. The ring of the ore-forming pyrite has the characteristics of high As and Au, different that of the post-ore pyrite (high As without Au), indicating that two types of pyrites belong to different hydrothermal events. The crystallization sequence of the gold-bearing pyrite in the mine is summarized as follows:Strawberry-like acyclic pyrite of low-arsenic→arsenic, ringing pyrite (containing gold) and homogeneous apyrite fine-grained pyrite→high-arsenic ring pyrite (without gold). This conclusion has certain directive significance for the prospecting and exploration in the Jiadi gold deposit.

Abstract:Geochronological data of 2.10-1.90 Ga tectonic thermal events in the Yangtze block are widely documented, but the magmatic rocks of this period in the Dabie area have not been reported. On the basis of field geological survey, the geochronological and zircon Hf isotopes of the metamorphic granite from the Jinpan pluton in western Dabie Mountains were analyzed. U-Pb dating of magmatic zircons from the metamorphic granite yielded age of (2022±17)Ma (MSWD=2.3), which represents Paleoproterozoic magmatic event in the Dabie orogenic belt. The negative ε_Hf(t) values (-10.6--7.6) and T_DM2 ages (2.95-3.12 Ga) of zircons indicate that the Jinpan granite might be derived from the reconstruction of ancient continental crust. The previous Hf isotope results also indicate that the widely-distributed Archean continental crust (2.95-3.18 Ga) in the Yangtze Block provided material source for the magmatic evolution of the Jinpan metamorphic granite. The Jinpan pluton was formed in the period of Paleoproterozoic collisional orogeny (2.03-1.93 Ga), and it might be the response to the convergent of Columbia supercontinent. The identification of the~2.0 Ga granite provides a new evidence for the evolution of Precambrian tectonic-magmatic events in the Dabie orogenic belt.

Abstract:The Dawa area is adjacent to the Qingshui large oil-generating sag, where the composite hydrocarbon migration system constituted by multi-stage faults and unconformities provides a favorable condition for hydrocarbon accumulation. However, the volcanic lithology and lithofacies are complex with changeable eruption environment in this area. In order to clarify the reservoir characteristics and the main controlling factors of hydrocarbon accumulation, based on 107.73 m core, 270 thin sections and logging data from 15 wells, the volcanic lithology and lithofacies are classified. It is suggested that the Mz-ⅠMember was formed in underwater eruption environment with overflow hyaloclastite subfacies basaltic volcanic breccia and overflow lava subfacies basalt. The Mz-Ⅱ Member was developed in abovewater eruption environment with explosive tuff subfacies rhyolitic tuff and overflow lava subfacies andesite. Among the volcanic lithofacies, the basaltic volcanic breccia shows the best physical property with porosity of 19.3% and permeability of 6.71×10^-3μm²,and the basalt shows the worst physical property with porosity of 9.2% and permeability of 0.23×10^-3μm². Based on the logging and seismic data, it is recognized that the Dawa area possesses a favorable source-reservoir matching and composite hydrocarbon migration system constituted by multi-stage faults and unconformities. The hydrocarbon reservoir distribution is determined by production test data to definite the main controlling factors of hydrocarbon accumulation and establish accumulation models. The study shows that the reservoir quality is controlled by lithology, lithofacies, volcanic eruption environment and tectonic movement. The hydrocarbon accumulation is mainly controlled by source-reservoir configuration and migration system. The reservoir type is structural-lithologic composite reservoir. The favorable exploration target area is on the west side of the study area which develops favorable lithology and lithofacies and locates near oil source and Dawa fault. The west side of the study area and localities near oil source and Dawa fault are the priority prospects for exploration, where favorable lithology and lithofacies are developed.

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