Abstract:This paper is the result of geothermal geological survey engineering. [Objective] The hydrochemical formation and evolution of the geothermal water in the Xiong'an New Area have great significant implications to understand the formation mechanism of geothermal resource. [Methods] Geothermal water and cold groundwater in the Rongcheng uplift, Niutuozhen uplift, Baxian depression, Baoding depression, and Gaoyang low uplift were sampled for hydrochemical analyses. [Results] There are two thermal reservoirs: Sandstone and karst thermal reservoirs. The main hydrochemical types were Cl·HCO₃-Na and Cl-Na. The TDS values of geothermal water increased with well depths. Mixing of the geothermal water of the Wumishan Formation and the Guantao Formation was observed in the fault zone. The metamorphic coefficients and desulfurization coefficients of geothermal water in the Wumishan Formation were low, indicating a relatively closed thermal reservoir and reduced state, while the sealing of the reservoirs in the Guantao Formation and Minghuazhen Formation was relatively poor. [Conclusions] The chemical field of geothermal water in the study area is controlled by the extent of water-rock interaction, faults, the sealing of the reservoirs, and so on. Our result is of great significance for understanding the geothermal resources in Xiong'an New Area and promoting clean heating in winter in northern China.

Abstract:The paper is the result of geothermal geology survey engineering. [Objective]The heat flow values in Xiong'an New Area are mostly measured from the Neogene sedimentary cap and dolomite strata. The previous geothermal exploration and utilization horizons are mainly karst thermal reservoirs shallower than 1800m in the Jixian System and the boreholes exposing the Archean are scarce in Xiong'an New Area. Heat flow determinations and analyses from Archean under the karst thermal reservoir are rarely reported by previous researchers. Since 2018, D01 deep geothermal parameter well with a depth of 3403.67m has been implemented in Niutuozhen geothermal field in Xiong'an New Area. The karst thermal reservoir of the whole Gaoyuzhaung Formation was exposed and the Archean of 1723.67m was drilled by D01 well. The D01 well provides the conditions for the heat flow study from Archean under the karst thermal reservoir in this area. [Methods]Based on borehole temperature measurement and thermal conductivity tests, the study on the heat flow from the Archean of D01 well was carried out. [Results]The results showed that the Archean of D01 well has significant geothermal characteristics of conduction type, and the geothermal gradient is 18.3℃/km, which is lower than the Neogene geothermal gradient of 48.6℃/km. The thermal conductivity values of 25 Archean gneiss core samples of D01 well were measured with an average value of (2.41±0.40) W/(K·m). Based on the temperature measurement curve and thermal conductivity data of 2300-2700m section of D01 well, the Archean heat flow of D01 well was calculated to be (44.1±7.0) mW/m². The heat flow of the Neogene sedimentary cap of D01 well was estimated to be 84.6 mW/m². [Conclusions]The higher part 40.5 mW/m² than Archean of D01 well was considered to be mainly contributed by the lateral convection heat transfer of groundwater in high pore-permeable karst dolomite and the vertical convection heat transfer of groundwater in the Niudong fault. The research results can provide the basic data for the previous heat accumulation mechanism of the groundwater transport and the heat conduction fault. And the results are of great significance to the genetic mechanism of deep geothermal resources and the geothermal field of Archean in Xiong'an New Area.

Abstract:This paper is the result of geothermal resource survey engineering. [Objective]Tianjin is abundant in geothermal resources with high utilization level, and section 4-3 in Wumishan Formation of Jixian system is the main development dolomite reservoir at present. With the development intensity of geothermal fluid increasing, the exploitation potential of some areas has reached the limit. Exploring the deep geothermal resources and increasing the allowable productions have become one of the effective ways to ensure the sustainable development of geothermal resources in Tianjin. [Methods] Donglihu area is the key research region in this study. Deep geophysical detection had been carried out and geothermal scientific exploration well CGSD-01 had been drilled. [Results] The main results are listed as follows: (1)CGSD-01 drilling encountered the section 2 of Wumishan Formation at 3715 m, a set of purplish red argillaceous dolomite with light gray fine-grained dolomite is developed at the bottom of the section 3 of Wumishan Formation overlying, the thickness is about 73 m, and the fissures are not developed, which can be considered as aquiclude or aquitard; (2)The completion depth of CGSD-01 is 4051.68 m, and the bottom temperature is 106℃, specific field is 1.53 m³/h·m, permeability is 0.40 m/d, conductivity is 48.69 m²/d; (3)The geothermal fluid type of the section 2 of Wumishan Formation is Cl·SO₄·HCO₃-Na, salinity is 1.7 g/L. It is preliminarily inferred that the geothermal water is originated from atmospheric precipitation, and mainly occurs mixing, cation alternating adsorption, carbonate dissolution, sulfate reduction, and does not reach equilibrium state; (4)The maximum outflow rate of CGSD-01 can be reach to 130 m³/h, and the temperature is 100℃, which can meet the heating load of 300 thousand square meters building area. [Conclusions] The high-yield new reservoir section 2 in Wumishan Formation of Jixian system was exposed for the first time in the second space of deep thermal reservoir in Tianjin area, and the thermal reservoir structure and main parameters of the reservoir were proved up, showing a good resource prospect.

Abstract:This paper is the result of geothermal geological survey engineering. [Objective] The characteristics and development potential of geothermal resources is an important basis for the development of regional geothermal resources. [Methods]Combined the previous research results with the latest drilling data, the geothermal reservoir model is established based on the analysis of the main factors such as geothermal geological background, thermal reservoir distribution, geothermal field characteristics and hydrochemical resource types in the northern Cangxian uplift. [Results] Under the background of high heat flow value in the extensional sedimentary basin of Bohai Bay, the atmospheric precipitation received by the bedrock in the exposed area of Yanshan Mountain in the north is used as the near source water supply. The cold water enters the bedrock, is heated by the deep heat source in the deep circulation process, and migrates and enriches along the fracture zone and unconformity surface, and forms the geothermal heat transfer mechanism dominated by conduction system. [Conclusions] The geothermal resources in this area are characterized by many types thermal reservoirs, high geothermal gradient of caprock, rapid recharge rate and huge resources. It is mainly shown as follows: Three sets of main hot water reservoir, sandstone thermal reservoir of Guantao Formation, karst thermal reservoir of Ordovician and Jixian Wumishan Formation are distributed in the area; the distribution of geothermal field is mainly controlled by basement structure, and the average geothermal gradient in bedrock uplift area is 45 ℃/km; with the increase of groundwater depth, the groundwater type changes from HCO₃-Na, HCO₃·SO₄-Na to mature Cl-Na; the recoverable geothermal resources in this area is 1.67×10¹⁰ GJ, equivalent to 5.72×10⁸t of standard coal. The annual exploitable geothermal resources can meet the heating area of 2×10⁸ m², considering the balance of exploiting and irrigation, the annual exploitable resource of geothermal fluid in the northern part of Cangxian uplift is 7.06×10⁷ GJ, equivalent to 2.41×10⁶t of standard coal, which can meet the heating area of 8.5×10⁷ m², which has a good prospect of geothermal market development.

Abstract:This paper is the result of geothermal resource survey engineering. [Objective]The geothermal resources in Anhui of Yangtze River Economic Zone are abundant, which has good prospects for city development and utilization. The evalution of geothermal resources can provide a scientific basis for the optimization of energy structure, sustainable development and utilization of geothermal resources in this area. [Methods]Through analyzing the geological and hydrogeological conditions, e.g., geological structure, formation lithology, and hydrochemical composition of geothermal fluids, this study reveals the distribution characteristics of geothermal resources in Anhui of Yangtze River Econmic Zone, discusses the storage feature of geothermal resources in uplift mountain convective area and conductive-type sedimentary basins, and evaluates its reserves, development, and utilization potential. [Results] The geothermal resources mainly occurred in the uplift mountain including the Chaohu-Hexian bedrock, the Dabie mountain, the bedrock along the Yangtze River, the Jiangnan, and at the sedimentary basin including the Dingyuan, the Feidong, the Huoshan-Jijing, the Luzong, the Anqing, and the Xuancheng, etc. The thermal storage of the former uplift mountain is zonal-type, dominated by granite in the fractured zone of the area. The thermal storage of the latter sedimentary basin is layered and layered-zonal type, dominated by lithologic sandstones and carbonate rocks. The thermal storage is mainly metasilicic acid-fluorine thermal mineral water. The hydrochemical type of the geothermal fluid in uplift-mountain type are mainly SO₄ and HCO₃ type. The hydrochemical type of geothermal fluid in sedimentary-basin type is mainly HCO₃ type. According to the potential evaluation results, the utilization potential of geothermal resources in uplift mountain type is relatively small and is basically in over-exploitation situation while that in sedimentary-basin type is relatively large. There are 4, 6, and 10 basins with big, medium, and small potential in sedimentary-basin type geothermal resources. [Conclusions] The potential distribution of geothermal resources in Anhui of Yangtze River Economic Zone is uneven, and the geothermal resources need to be planned and utilized in different zones. It is necessary to consider the surface water pollution caused by the utilization of high fluoride and high salinity hot mineral water.

Abstract:This paper is the result of groundwater survey engineering. [Objective] The study on the temporal and spatial law of groundwater under changing environment is helpful to the fine management of water resources and the guarantee for regional water resources security. [Methods] Based on the rainfall data of typical weather stations in the Huaibei Plain from 1953 to 2019, the wavelet analysis and M-K test method was used to study the periodic changes and trend of rainfall on a multi-year scale. Combined with 395 national monitoring wells and groundwater monitoring data, the principal components analytical method was used to optimize the evaluation of monitoring wells. [Results]The results show that the rainfall in Huaibei Plain appears multiple temporal and spatial scales variation characteristics: The shallow groundwater level has declined continuously in the northwest, while fluctuated greatly in the other regions; In 1970, 2003 and 2019, the shallow groundwater level in the southern region decreased firstly and then recovered, and on the contrast, the shallow groundwater level in the northern region increased firstly and then decreased; The groundwater level in the study area has generally declined; And since 2000, the water level has somewhat risen; The 277 monitoring wells (221 water wells and 56 natural resource wells) optimized by principal component analysis can represent the overall water level changes of 395 original national monitoring wells. [Conclusions] The long-term monitoring data of the national groundwater monitoring project can well serve the evaluation and management of water resources at the basin scale, but still need to be optimized and densified at the provincial, municipal scales or key areas. The artificial observation in unified time period can also make up for this deficiency which should be densified in the high hydraulic gradient areas such as both sides of important rivers and lakes, the north bank of Huaihe River, and the piedmont plain in the northeast.

Abstract:This paper is the result of mineral exploration engineering. [Objective] Inertinite-rich coal is characterized by the high inertinite content, and several coal properties are personalized accordingly, which affecting its clean utilization. In this paper, we focus on both the determination of the time-space distribution of the inertinite-rich coals in China and the induction of the coal properties, clean potential and utilization mode of the low rank inertinite-rich coals in Northwest China. [Methods] We sort out a large number of exploration data and research results, and coal macerals and coal properties data were analyzed and summarized. The determination of inertinite-rich coal's time-space distribution in China and their coal properties were based on the data. The clean potential and utilization mode of the low rank inertinite-rich coal in Northwest China were carried out along the coal properties combined with the indexes for various purposes. [Results] It shows that the inertinite-rich coals are mainly distributed in the Early-Middle Jurassic in Northwest China. The low rank inertinite-rich coals in Northwest China are characterized by low ash, low sulfur, low harmful elements, low cohesiveness, low hydrogen content, low volatile matter, high carbon dioxide reactivity and high calorific value, among which, the hydrogen content, cohesiveness, volatile matter and carbon dioxide reactivity are obviously related to the high inertinite content. The coal properties show that the Jurassic coals in Northwest China are of high cleanliness and high calorific value, which is a high-quality power coal. The relatively low volatile matter and hydrogen content in the same coal rank make it not conducive to be used as coal for direct liquefaction. The low ash, low sulfur, low cohesiveness, strong reactivity with carbon dioxide are conducive to being used as coal for gasification, which is suitable for a variety of gasification processes. In addition, part of the low rank inertinite-rich coals represented by the northern part of Shaanxi Province are of high tar yield, which is suitable for low temperature retorting. [Conclusions] The low rank inertinite-rich coals in Northwest China are suitable for power coal and gasification coal, and the tar-rich coal should be given priority to low temperature retorting.

Abstract:This paper is the result of oil and gas exploration engineering. [Objective] Continental shale oil is an important replacement field of energy in China, and precise drilling of long horizontal wells is a key technology to achieve commercial development of shale oil. However, due to the characteristics of continental shale such as high clay mineral content, strong heterogeneity and bedding development, serious instability of horizontal well wall and difficulties in precise steering of thin target layer are caused. [Methods] Taking the shale of the first member of Qinghe Formation in the south of Songliao Basin as the research object, the integrated research of geological engineering is carried out by comprehensively using geochemical, geophysical, rock mechanics, geostress analysis and other means. [Results] The shale in the upper part of Qing-1 Member is bedding shale, which is not suitable for horizontal wells to pass through. The thin oil-bearing sand bars in the lamellar shale in the middle and lower part of Qing-1 Member are both oil-bearing, drillable and compressible, which can be used as the crossing target layer; For shale formation, strong inhibition KCL polyamine drilling fluid system and oil-based drilling fluid system should be selected for horizontal well drilling. The mud density window increases with the increase of horizontal stress difference and well trajectory inclination angle; Logging GR and logging total hydrocarbon can accurately reflect the lithological heterogeneity change of target layer, and combined with high-precision geophysics, it can accurately control the drilling trajectory in real time. [Conclusions] Through application and practice, Jiye 1HF well has safely drilled 1252m along 1.94m ultra-thin target bed, with a penetration rate of 100%, which has achieved a technical breakthrough in accurate drilling of long horizontal section of continental shale oil, laid a foundation for Jiye 1HF well to obtain high-yield industrial oil flow, and has guiding and reference significance for accurate drilling of long horizontal section of continental shale oil of the same type in China.

Abstract:This paper is the result of mineral exploration engineering. [Objective]Rare earth is not only important natural non-renewable resources, but also a key strategic resource. Based on the field geological survey and indoor comprehensive study of sedimentary rare earth resources in the eastern Yunnan and western Guizhou area, this paper reveals the advantages and development and utilization potential of the rare earth resources, which not only enriches the industrial types of the global rare earth resources, but also supports the national strategic reserve of key rare earth resources. [Methods]Based on the research on the characteristics of ore-bearing strata, typical ore characteristics, the partition characteristics of rare earth elements and the potential of rare earth resources, this paper discusses the genetic types of the rare earth resources, the occurrence state of rare earth elements and the potential of development and utilization. [Results]The ore-bearing stratum is identified as Xuanwei Formation of Upper Permian (P₃x); the lithology of rare-earth rich ore is gray- white aluminite claystone and silty claystone; the origin of rare earth ore belongs to sedimentary type; in Weining County Heishitou—Mazha—Zhejue area, the thickness of ore body varies from 2m to 18m, the ore body extension is relatively continuous, the content of rare earth oxide (TREO) is up to 1.6%, the weighted average grade of ore body block (TREO) is 0.18% to 0.46%, and the inferred resource is over 300,000 tons; the proportion of "Critical rare earth elements (CREE)" in the rare earth resources is up to 22.6% (∑CREO), which is higher than most of the rare earth deposits under development and utilization at domestic and overseas. In addition, the new selective leaching technology is used in the dressing and metallurgy test, and the results indicate that the recovery of rare earth can reach more than 90%. This new type of rare earth mine is expected to realize large-scale industrial utilization. [Conclusions]The sedimentary rare earth resource has the advantages of large ore thickness, high ore grade, large resource potential, low mining cost, high proportion of critical rare earth elements (CREO) in ore, and good development and utilization prospect.

Abstract:This paper is the result of mineral exploration engineering. In recent years, with the large-scale exploitation of mica-type lithium deposits in the Northwest of Jiangxi Province, hard-rock-type lithium deposits, such as greisen-type and altered granite-type in south China block, have gradually attracted more and more attention. Southern Jiangxi Province is a world-famous quartz vein-type wolframite mining district and producing base. In the past, exploration and research work mainly focused on the tungsten and tin deposits. [Objective]In order to further understand whether lithium mineralization exists in quartz vein type tungsten tin ore and its geological characteristics. [Methods]This study was conducted through systematic microscope identification and laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) analysis. [Results]Greisen-type lithium ore was found in the deep part of Shilei tungsten and tin deposit in Chongyuyou Ore cluster located in the Southern Jiangxi Province. The lithium ore body occurred at the top of the deep concealed granite body, and distributed on two sides of W-Sn-bearing quartz-vein and feldspar quartz-vein. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis and microscope identification show that lithium mainly found in muscovite-phengite. The average Li₂O content of greisen in hornfelsic sandstone is 0.25%, the average Li₂O content of quartz (feldspar) vein greisen in mica granite is 0.21%, and the average Li₂O content of mica vein-bearing greisen developed in mica granite is 0.22%, which shows potential comprehensive utilization value. [Conclusions]In this study, lithium mineralization of industrial significance is identified in Shilei quartz vein-type tungsten tin deposit. The discovery enriched the metallogenic theory of tungsten and tin deposits in the Southern Jiangxi Province, broadened the prospecting and exploration ideas of greisen-type lithium deposits in Chongyuyou ore cluster, and provided a basis for further expanding the prospecting space of hard-rock-type lithium deposit in South China Block.

Abstract:This paper is the result of the geological survey engineering. [Objective]The genesis of Pb-Zn deposit in Sichuan, Yunnan and Qianhai is diverse, especially the relationship with the Emei Mountain basalt is more controversial. In this paper, we study the source of ore-forming material, starting from Pb-Zn deposit in Permian carbonate rocks, which has received less attention from previous authors. [Methods]Using experimental data of S, Pb, C, H, and O isotopes and fluid inclusion temperature measurements, the source of mineralized materials and the characteristics of mineralized fluids were investigated in the Taipingzi Pb-Zn deposit in Xundian County, Yunnan Province. [Results]The Pb isotopic compositions of the ore are relatively homogeneous and concentrated, with the variations of ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb ranging from 18.543 to 18.584, 15.646 to 15.694 and 38.799 to 38.958, respectively. These suggest that the Pb in Taipingzi Pb-Zn deposit belongs to normal common Pb with crustal origin. The metal-forming materials are mainly from the basement rocks, and the water-rock reaction may make the mineralized enclosing rocks contribute a small number of mineralized materials. The δ³⁴S in ore sulfide varies from -13.6 ‰ to -7.3 ‰ and δ³⁴S of the galena is higher than that in sphalerite. Sulfur isotope fractionation has not reached equilibrium, sulfur is mainly from crustal source. Biogenic sulfate reduction （BSR） is the main mechanism of sulfur reduction. A large amount of biogenic sulfur reduction has accumulated in the mineralized area before mineralization. The hydrothermal calcite δ¹³C_V-PDB ranges from 3.8 ‰ to 4.7‰ and δ¹⁸O_V-SMOW ranges from 12.0 ‰ to 16.7 ‰ with obvious low δD and high δ¹⁸O_fluid characteristics compared to other important Pb-Zn deposits in northeast Yunnan. The water in the mineralizing fluid mainly originates from a mixture of magmatic and organic water, with medium-high temperature and low salinity characteristics. [Conclusions]Taipingzi Pb-Zn deposit is significantly different from other typical Pb-Zn ores in the region in terms of metallogenic material, fluids and metallogenic temperature, and has typical magmatic-hydrothermal genesis characteristics.

Abstract:This paper is the result of the mineral exploration engineering. [Objective] In order to discuss the genesis of the lead-zinc deposits in Hengyang Basin and its surrounding areas, this paper has carried out work on the highly studied Qingshuitang lead-zinc deposit. [Methods] By means of geological survey, fluid inclusion study of quartz, calcite and sphalerite at different stages and Rb-Sr dating of quartz, we discuss the geochemical characteristics, evolution and mineralization processes of ore-forming fluid. [Results] Based on the mineral assemblages and the intercutting relationships between veins, this paper classifies the metallogenesis of the Qingshuitang lead-zinc deposit into three stages: pyrite-quartz stage (I), quartz-galena-sphalerite stage (II) and barite-calcite stage(III). The research of fluid inclusions show that both L- and VL-type primary and secondary fluid inclusions occur in quartzs and sphalerites at stage II; VL-type primary fluid inclusions predominantly occurs in quartzs at stage I and calcites at stage III. The measured temperature results show that primary inclusions of quartz formed at stage II can be subdivided into four groups according to the homogeneous temperature and salinity, which are 258-296℃ and 8.55%-9.21% NaCl eqv, 260-298℃ and 3.61%-4.18% NaCl eqv, 120-160℃ and 12.73%-18.22% NaCl eqv, 145-168℃ and 3.06%-3.87% NaCl eqv, respectively. By comparison, the homogenization temperature and salinity of sphalerite are mainly concentrated in the range of 102-178℃ and 10.24%-19.45%NaCl eqv. The ore-forming fluid belongs to the NaCl-H₂O hydrothermal system of medium-low temperature and medium salinity. Based on occurrence and homogenization temperature of inclusions, the medium and low salinity fluids at stage II may have different sources and evolutionary processes. The former is mostly distributed in groups and might derive from medium temperature (210-312℃) and medium salinity (12.30-19.30%NaCl eqv) fluid at stage I. The latter mostly occurs along mineral fissures, which may be formed by mixing of the late low salinity atmospheric precipitations. In this paper, two quartz Rb-Sr isochron ages are obtained, and they are (88.8±2.4) Ma and (17.86±0.42) Ma, respectively. The former age represents the mineralization age of Qingshuitang lead-zinc deposit, and the latter age records the time of late tectonic superposition. Both of them are significantly later than the diagenetic ages of the Zhoujialing granite ((203.0±1.4) Ma) near the mine site and the adjacent Guandimiao pluton ((223.4±1.9) Ma). [Conclusions]Considering that the metallogenic fluids of lead-zinc in the area are related to magmatic activities, it is inferred that there are the Late Cretaceous concealed intrusions in the deep part of the mining area combined with sulfur and lead isotope characteristics of sulfides from the Qingshuitang and Liushutang mining areas, which provide material and energy sources for lead-zinc mineralization.

Abstract:This paper is the result of mineral exploration engineering. [Objective] The Lekai lead-zinc deposit, located in the Pb-Zn deposit concentration of northwestern Guizhou, is one of the small-scale lead-zinc deposits newly discovered in recent years. Different from most lead-zinc deposits in the Pb-Zn deposit concentration of northwestern Guizhou, the Lekai lead-zinc deposit is controlled strictly by NE trending fault-fold structure, which is similar to most lead-zinc deposits in the Pb-Zn deposit concentration of northeastern Yunnan. The current research provided significant implications for the deep exploration in the Lekai lead-zinc deposit and the Sichuan–Yunnan–Guizhou Triangle area (SYGT). [Methods] This study applied a large deal of detailed structural analysis on mechanical properties for faults and folds in the mining area and tectono-geochemistry method. [Results] The results showed that duo-type and λ-type are the main ore-controlling structural styles in this area. Moreover, three tectonic associations have been divided, which are correspond to four tectonic systems, namely Hercynian to Mid Indosinian, Late Indosinian to Early Yanshanian, Mid-Late Yanshanian, and Himalayan epochs. The trace elements concentrations of tectonites represented three element associations of principal factors, including frontal halo elements (Sb-As-Hg) in low temperature ore-forming stage, mineralization-halo elements (Zn-Pb-Cd) in medium-low temperature ore-forming stage, and tail-halo elements (In-Sn-Ni-Cu) in medium temperature ore-forming stage. [Conclusions] In four tectonic systems, ore-forming tectonic system corresponded with Late Indosinian to Early Yanshanian. According to anomaly features and their distribution regularities, the possible migration direction of ore-forming fluid is from southwest to northeast, and six target prospecting areas have been put forward in the depth of mining.

Abstract:This paper is the result of mineral exploration engineering. [Objective] Laiwu Sanchahe iron-gold deposit is the first skarn type iron-gold deposit (without copper) discovered in western Shandong. Previous research on the Sanchahe deposit is weak. The purpose of this paper is to discuss the age of ore-forming pluton,magma sources, petrogenesis and tectonic setting. [Methods] We carried out LA-ICP-MS zircon U-Pb dating, major and trace elements analysis.[Results] Zircon U-Pb age of pyroxene diorite is (138.4 ±1.2) Ma in the Early Cretaceous. Pyroxene diorite is calc-alkalic (Rittmann index σ = 2.20-2.54) and characterized by high Mg^# and high contents of Na₂O, Sc, Cr, Co and Ni, which demonstrates that it has geochemical affinity with mantle-derived magma. It is enriched in LREE and depleted in HREE, with no obvious Eu anomaly, and shows enrichment in Cs, Ba, Sr and depletition in high field strength elements (Nb, Ta, Zr), indicating involvement of some crustal materials. [Conclusions] Geochemical features of pyroxene diorite combined with geochronological data imply that it may be generated by partial melting of the enriched lithospheric mantle which had been metasomatized by the ancient crust materials of the North China Craton, and formed in the strong extensional tectonic background of lithospheric thinning, which may be caused by the retreat of the subducting Paleo-Pacific plate.

Abstract:This paper is the result of mineral exploration engineering. [Objective]The phosphate deposit accumulation scope of Maidiping Formation of the Lower Cambrian covers a wide area from Leibo County (Sichuan) to Yongshan County (Yunnan). The study of phosphorus-bearing strata is not only helpful to the reconstruction of the paleogeographic environment and its varied characteristics, but also can obtain the formation and distribution of phosphate deposits in combination with the study of tectonic background, and provide a thedeposittical basis for the development of phosphate deposit. [Methods]Based on the cdeposit record and section measurement, this paper studies the thickness, lithology, sedimentary facies, sedimentary model, tectonic background, basin properties, genetic mechanism of phosphate deposit, petrological features of phosphorite, and their changes in Maidiping Formation in Leibo area. [Results]The significant difference of lithology and lithofacies of the Maidiping Formation in Leibo area are within 50 kilometers, and the characteristics of phosphorite are well explained. It is pointed out that the Leibo area was an uplift and depression environment during the sedimentary period of Maidiping Formation, and the shallow shelf facies was absent. Dolomite facies area belongs to tidal flat facies, which is a favorable area for the phosphate deposit accumulation. Siliceous rocks belong to deep-water shelf facies and are of hydrothermal origin formed by volcanic activity. The accumulation of phosphorite is the result of volcanic activity in siliceous lithofacies area, biological development, movement of high temperature ocean current from the bottom to the top, sedimentation of the seawater with high P₂O₅ carried by ocean current decomposing biological remains in dolomite facies area on both sides of the sag area and post-sedimentation transformation. Based on the tectonic background, basin nature, source of phosphorus, migration, sedimentation and enrichment of phosphorus, the deposit-forming mechanism of phosphate is described, and the formation of phosphate deposit in Leibo area is suggested by the interaction of many factors, and the corresponding deposit-forming model of phosphate deposit is established. The siliceous rocks in the depression are the result of the hot water activity under volcanism. [Conclusions]The study revealed a new phosphorus mineralization style in the late stage of rift basin development from Late Neoproterozoic to Early Cambrian, i.e., the paleogeographic pattern of alternating uplift and depression with the weak volcanic activity. A new idea of predicting and evaluating the phosphate deposit in dolomite facies area on both sides of the depression is put forward. We suggest that the prospecting space of the Maidiping Formation phosphate deposit should be expanded from the depression area to the surrounding areas.

Abstract:This paper is the result of the geological survey engineering. [Objective]The Simao Basin hosts the only pre-Quaternary solid potash deposit in China, but the genesis of this deposit has been still controversial. An objective understanding of deposit genesis as well as rational construction of a metallogenic model is not only fundamental scientific issues that need to be addressed urgently in the study of potash mineral deposits, but also have a bearing on the choice of the direction for potash resource exploration in the basin. [Methods]This study focuses on Sr isotope geochemical characteristics of the samples from salt rocks, overlying and underlying clastic rocks and clastic rocks within the salt rocks in Wells L-2 and MZK-3 of the Simao Basin. [Results]The results show that: (1) The bulk-rock ⁸⁷Sr/⁸⁶Sr values from the Well L-2 samples are 0.708220-0.727458, with an average of 0.712776; the ⁸⁷Sr/⁸⁶Sr values of water-insoluble matter within the salt rock are 0.711342-0.741999, with an average of 0.716574; (2) The ⁸⁷Sr/⁸⁶Sr values of the clastic rock overlying and underlying the salt layer in Well MZK-3 range from 0.713318-0.723147 and 0.712470-0.738988, with an average of 0.717255 and 0.719307, respectively; (3) The ⁸⁷Sr/⁸⁶Sr values of the clastic rock corrected by 87Rb tore cover their initial sedimentary state are 0.710880-0.727678, with an average of 0.712828; (4) The ⁸⁷Sr/⁸⁶Sr values of salt rock are all significantly lower than the average value of the continental weathering system, with some individual samples having ⁸⁷Sr/⁸⁶Sr values larger than modern seawater. [Conclusions]Based on the existing research results of the basic geology and potash deposit geology in the Simao Basin, combined with the Sr isotope geochemical characteristics of salt rocks and clastic rocks, it can be concluded that: The potash-bearing salt rocks and clastic rocks are in different Sr isotope equilibrium systems; the matter source of potash-bearing salt rock is mainly seawater, and the recharge of terrestrial freshwater into the evaporation basin during the salinization process would increase ⁸⁷Sr/⁸⁶Sr values of the samples. The clastic rocks were deposited in the terrestrial environment and were in the eodiagenesis substage A before contacting with solid salt rock or brine; a more rational potash metallogenic model is that the deep source salt migrated to the surface through faults formed by strike-slip pull-apart process during the deposition period of the Mengyejing Formation, capturing the unconsolidated clastic rocks in the eodiagenesis substage As they migrated from the height to the catchment basin, and forming the present-day clastic-bearing salt rocks. After migrating into the catchment basin, parts of the clastic-bearing salt rocks underwent dissolution and recrystallization, resulting in the formation of salt rock with relatively purer composition. The subsequent deposition of the clastic rocks formed a protective layer against rock salt dissolution. Early-formed potash deposits were influenced by the Cenozoic Himalayan movement, leading to the modification not only in physical structure but also in mineral component.

Abstract:This paper is the result of oil and gas exploration engineering. [Objective] Carbonate strata are susceptible to sea-level changes and thus develop high-frequency sequences. However, the accuracy of geochemical indicators reflecting sea-level changes is insufficient, resulting in poor understanding about the high-frequency sea-level fluctuation. The controls of sea-level changes on the high-frequency sequence and sedimentary evolution of the platform-margin reef-shoal deposits remain unclear. [Methods] Continuous core data from a well in the Upper Ordovician Lianglitage Formation in the Tarim Basin were selected for microfacies analysis, carbon and oxygen isotope analyses by densely-collected samples. [Results] Seven microfacies types developed in the middle and upper part of Lianglitage Formation. The analysis of the sedimentary evolution shows that the sedimentary environment evolved from tidal flat to reef and shoal, and to deeper platform during the middle to late period of deposition. The carbon and oxygen isotope values ranges from: δ¹³C is 0.5993 ‰-1.6228 ‰ (average 1.139 ‰) and δ¹⁸O value is-8.3608 ‰- -5.1452 ‰ (average -6.790 ‰). The changes of the δ¹³C and δ¹⁸O correspond well with the evolution of microfacies and sedimentary cycles. The analysis of paleo-ocean conditions shows that the Lianglitage Formation was deposited under warm climate and the reef and shoal samples recorded high paleo-temperature, representing a high rate of carbonate production. The paleo-salinity reflected by the Z-value is high according to the samples at the bottom of the tidal flat, and it is relatively low at the top of high-frequency cycles, probably indicating the influence of meteoric water. The range of δ¹³C and δ¹⁸O values differ from the Tazhong area, the southern margin of Tabei area, and Bachu area, which is mainly related to the difference in environment and water depth. [Conclusions] At least three cycles of sea-level change and two secondary cycles exit in the middle to upper parts of the Lianglitage Formation. Different levels of sea-level changes are mainly driven by paleoclimate changes that control the formation of high-frequency sequences. Sea level rises slowly and then continues to be stable or oscillate on a small scale, which provide a favorable condition for the deposition and development of thick-bedded bioclasts and carbonate sands. Sea level rose sharply during the late sedimentary period of the Lianglitage Formation, and the sedimentary environment turned into inter-shoal lagoons and deeper platforms. The early-stage karstification caused by the small-scale sea-level drop at the top of the high-frequency sequence is an important factor to improve the reservoir quality of reef and shoal faces.

Abstract:This paper is the result of oil and gas exploration engineering. [Objective]Debris flow represents an important mechanism of sediment transport and dispersal in deep-water environment, the related sandstone reservoir constitute one of the important targets for petroleum exploration in petroliferous basins, while deep-water systems dominated by debris flows are still poorly understand compared to well-studied turbidity currents and turbidite systems. [Methods]The depositional process and model of gravity flows which developed in the Middle Sub-member of the 3rd Member of the Eocene Shahejie Formation, Dongying Depression, Bohai Bay Basin have been studied through the integration of core data examination, well logging data and 3D seismic data interpretation. [Results]It is suggested that nine base types of lithofacies can be recognized in slump-derived gravity flow deposits, which can be summarized into four main origin types, which indicate mass transport and flow transport processes, respectively. Quantitative lithofacies analysis suggests that the slump-derived gravity flow depositional system is dominated by debris flows, while turbidity currents are less important, and sandy debris flows represent the most important debris flow type. The slump-derived gravity flows undergo five evolution stages including slide, slump, sandy debris flow, muddy debris flow and turbidity currents, which correspondingly develop five types of deep-water depositional elements during transportation and evolution, including slide, slump, debrite channel, debrite lobe and turbidite sheet. Sandy debrite channels, lobes and sandy slides constitute the most important deep-water reservoirs in the study area according to their wide distribution and reservoir property. [Conclusions]It is proposed that adequate sediment supply, high depositional rate on delta-front, frequent tectonic activities and short transport distance are the main controlling factors. Accordingly, a depositional model is proposed to depict slump-derived gravity flow systems based on depositional processes, sedimentary patterns and basin morphology. This study seeks to improve deep-water sedimentary theories and provide guidance for petroleum exploration of deep-water sands in deep-lacustrine basins.

Abstract:This paper is the result of the mine environmental geological survey engineering. [Objective] Xin Barag Youqi is located in hulun buir grassland, and mining activities are frequent. Understanding the sources and ecological risks of heavy metals of soil in this area is prerequisite for assessing environmental impact. [Methods] We collected a total of 221 samples of ore, bed rock and soil, and tested contents of 7 elements (Cd, Cr, As, Hg, Ni, Pb and Zn). The pollution degree and distribution characteristics of heavy metals were evaluated by geoaccumulation index method and potential ecological risk index method. The sources of heavy metals in soil were determined by correlation analysis and principal component analysis. [Results] It was found that the heavy metal pollution in the soil of Xin Barag Youqi is mainly mild, and Cd, Ni, As, Cr and Pb are polluted. The contaminated areas are located in Jiawula-Chagan Mining Area, Zhuan Ulanor, northwest shore of Hulun Lake and middle of the Krumlen River. Source analysis results shows that Cr、Ni and Hg are mainly from human activities, Cd, Zn and Pb are affected by both natural factors and human activities, and As is mainly from natural factors. [Conclusions] In general, the ecological risk in Xin Barag Youqi is low, and Cd has the most prominent contribution to the ecological risk of the soil in this area, which should be taken seriously in soil quality monitoring.

Abstract:This paper is the result of geological survey engineering. [Objective]It is of great significance to find out the geochemical and tectonic evolution characteristics of granite in the southeast of the Songpan-Ganze terrane for searching for rare metal minerals in this area. [Methods]we have carried out field geological survey and conducted whole-rock geochemistry and zircons LA-(MC)-ICP-MS U-Pb and Lu-Hf isotope analyses on the monzogranite of the Sudi pluton in the southeast part of the Songpan-Ganze terrane. [Results]The results show that the samples were medium-high potassium, sodium rich and calcium deficiency. The values of AR were 1.44-1.83 and values of A/CNK were 0.98-1.16, which were medium-high potassium calcareous alkaline series. The rocks show relatively enriched large ion lithophile element (LILE), negative high field-strength elements (HFSE), and high REE content (the total amount of REE = 157.16×10^-6-187.88×10^-6) with the LREE enrichement (LREE/HREE = 6.26-9.46) and weak negative Eu anomaly europium anomaly (δEu = 0.62-0.74). The results of zircon U-Pb dating were (221.1±1.5) Ma (MSWD=0.30, n=22) and (214.5±1.5) Ma (MSWD=0.22, n=22), indicating that the primitive magma of the Sudi pluton crystallized in the middle of the Late Triassic. Its zircon Lu-Hf isotope ε_Hf(t) and T_DM2 are -6.56--4.12 and 1.67-1.51 Ga. [Conclusions]According to the comprehensive analysis, we believe that the monzogranite in Sudi pluton is a typical I-type granite and it may be formed by the upwelling and emplacement of the initial magma from the lower crust in the middle of Late Triassic in the process of orogenic collision to post-collisional extensional tectonic setting. The southeastern margin of Songpan-Ganze terrane was under post-collisional orogenic environment in Late Triassic.

Abstract:This paper is the result of geological survey engineering. [Objective] A large amount of ~ 100 Ma magmatic rocks are developed in the southeast margin of South China. Shifting to interior of South China, although the period of magmatism has been reported sparingly, they were often related to metal mineralization. Determination of the distribution of magmatism of ~ 100 Ma in the interior of South China would provide a scientific basis for the study of the late Yanshanian tectonic setting, and related ore prospecting and exploration. [Methods] Based on the 1︰50000 regional geological survey and detailed petrographic study, the granites in Qiashui area, which are located near the Chenzhou-Linwu fault in the interior of South China, were divided into five intrusive episodes, including (1) porphyritic coarse-medium-grained amphibole-biotite monzogranite, (2) porphyritic medium-fine-grained amphibole-bearing biotite monzogranite, (3) porphyritic medium-fine-grained biotite monzogranite, (4) medium-fine-grained biotite monzogranite with rare porphyrites and (5) fine-grained biotite syenogranite with rare porphyrites, respectively. Zircon LA-ICP-MS U-Pb dating was carried out systematically for the representative rocks of these intrusions. [Results]U-Pb dating yield ages of the first to fifth intrusive episodes ranges from 102 Ma to 97 Ma, which is at the transition of the Early and Late Cretaceous. [Conclusions] According to comprehensive analysis and comparison of the ~100 Ma magmatic events in the interior and southeast coastal regions of South China, it shows that the geodynamic mechanism of the magmatism of ~100 Ma in the interior of South China might be related to back arc and intracontinental lithospheric extension resulting from Paleo-Pacific plate subduction retreation. It led to reactivation and extension of ancient deep faults such as the Chenzhou Linwu fault, and then the intensive mantle and crust magmatism.

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