Abstract:This paper is the result of hydrogeological survey engineering.[Objective] The formation and evolution of the Yangtze River and the recurrent flood disasters in the middle and lower reaches of the Yangtze River are the key scientific problems to be solved urgently. [Methods] By using alluvial fan genetic theory, combined sedimentary facies profile correlation method, lithofacies paleogeographic analysis, high-precision dating technology, remote sensing method and so on, from the perspective of the basin, the genesis of gravel layers and lithofacies paleogeographic characteristics along the middle and lower reaches of the Yangtze River, planation surface and terrace characteristics of the Three Gorges and the genesis of the great turn of Yangtze River in Shigu, Yunnan in the upper reaches of the Yangtze River are analyzed. [Results] The understandings of the east-west transconnection time of the Yangtze River at the turn of early-Middle Pleistocene (750,000 years ago) and the Holocene river lake evolution pattern of "one River (Yangtze River) and four lakes (Yunmengze, Penglize, Dongting lake and Poyang Lake)" in the middle reaches of the Yangtze River the are put forward. The present situation and influencing factors of flood disaster in the middle and lower reaches of the Yangtze River in modern times under the natural and man-made effects were analyzed, and the evolution law of the Yangtze River and its enlightenment to flood disaster prevention and control were combined. The prevention and control measures of flood disaster in the middle and lower reaches of the Yangtze River including "rebuilding Yunmengze, expanding Dongting Lake and Poyang Lake", "Sand exploiting expansion lake, removing silt and turned into farmland" and relevant geological suggestions for the next step were put forward. [Conclusions] The major adjustment of geological environment in the early and middle Pleistocene was an important reason for the connection of the east and west lines of the Yangtze River. The flood disaster prevention and control in the middle reaches of the Yangtze River should fully consider the evolution law of rivers and lakes. The research results can provide basic support and theoretical basis for the territorial space planning, geological disaster prevention and ecological environment protection and restoration of the Yangtze River Economic Belt/Yangtze River Basin.

Abstract:This paper is the result of hydrogeological survey engineering.[Objective] Late Holocene sedimentary records along the abandoned channel areas contain lots of paleoflood information in the lower Yellow River, which can help to extend extreme flood records, and are of great value in understanding flood hazard patterns. [Methods] This paper selects Longwangmiao (LWM) profile (located in Daming County), Hebei Province, as the typical paleoflood section in the lower Yellow River. Luminescence dating, radiocarbon dating, gransize, and geochemistry analyses are combined with a synthesis of historical flood records and regional previous works. [Results] The study concluded that: (1) Different facies in LWM profile, including paleosols, lacustrine deposits, overbank deposits, and slackwater deposits, have some close relationships with the others. (2) Four major flood deposits during the late Holocene are corresponding to four abnormal flood events in Zhou Dynasty, Western Han Dynasty, Northern Song Dynasty, and Ming Dynasty in this area. (3) Human activities have a profound impact on flood scale and frequency in the lower Yellow River, from seasonal floods to extreme floods. [Conclusions] The study identified the characteristics of different sedimentary facies on lithology and environmental proxies, and explored the influence of human activities on floods. It provides a reference for paleoflood research along the abandoned channels in the lower Yellow River, and helps to further understand the processes and evolutionary mechanisms of flood hazards in the Yellow River.

Abstract:This paper is the result of hydrogeological survey engineering.[Objective] Evaluation of groundwater resources is essential for the management and sustainable utilization groundwater resources as well as the preservation of the ecological environment. The groundwater resources division serves as the foundation for assessing groundwater resources. [Methods] Based on the groundwater survey engineering, the theory of water cycle and groundwater system and the features of recharge, runoff, discharge and storage, the groundwater resources area of the Songliao River Basin is redivided by combining hydrogeological characteristics with surface water basins. [Results] There are four division levels: 2 first-level subareas, 6 second-level subareas, 17 third-level subareas, and 56 fourth-level subareas. The first-level subarea is divided into the Songhua River Basin and Liaohe River Basin based on the first-level drainage basin of surface water. The secondary zone is centered on a broad plain (basin) and includes nearby mountain recharge zones in order to create a unified groundwater recharge and drainage system. The plains (basins) and surrounding mountain recharge areas are separated in the tertiary division. The fourth level zones in mountainous regions are divided by the fourth surface water basins, the Songnen Plain and Liaohe Plain are divided by the secondary surface water basins, and the Sanjiang Plain and Hailaer Basin remain independent and undivided. [Conclusions] The division scheme of new groundwater resources area in the Songliao River Basin effectively takes into account the basin and groundwater system, and completely reflects the formation and evolution process of groundwater. It is an effective application of groundwater system theory that provides a scientific premise for the next round of groundwater resources evaluation.

Abstract:This paper is the result of geological survey engineering.[Objective] Water conservancy projects are usually located in mountainous areas with steep terrain, inconvenient transportation and harsh environment, so that the survey work is very difficult. Meanwhile, the limitation of horizon makes it impossible for geologists to grasp the features of geological units as a whole, especially in high mountain and canyon areas. The application of hyperspectral remote sensing technology in the geological field mainly focuses on the extraction and identification of geological composition. The types of surface features are determined by similarity of spectral features between unknown geological units and known mineralsand rocks. Using its extremely high spectral resolution, spatial resolution and the advantage of union of imagery and spectrum, the technology can be applied on fine classification of rock types in alpine and canyon areas, so as to improve the efficiency of geological survey and reduce costs and risks. [Methods] This paper introduces Bei Fang Investigation, Design & Research Co., Ltd. adopting the SSMAP-II small short-wave infrared imaging system independently developed by the Nanjing Center, China Geological Survey in the project of "Research on Remote Sensing Geological Interpretation Methods Based on Hyperspectral Image Data", taking a helicopter as platform to carry out hyperspectral ground-based remote sensing surveys in Diebu County, Gannan Tibetan Autonomous Prefecture. The surveys aerial hyperspectral image data of the study area, then used MNF minimum noise fraction(MNF) method and band ratio analysis method to interpret the lithology. [Results] The interpretation result is basically consistent with the lithology distribution of the known regional geological map, providing first-hand information for the water conservancy projects of the dangerous areas. [Conclusions] This research improves the work efficiency and the level of geological exploration, meanwhile it also verifies the reliability and practicability of the domestic hyperspectral imaging spectrometer.

Abstract:This paper is the result of urban geological survey engineering.[Objective] This paper aims to develop the study of natural resources endowment in ecological security, environmental protection, agricultural production and urban construction in Chengdu-Deyang-Meishan-Ziyang urbanization construction area, and propose the protection strategy of territory development preliminarily. [Methods] This paper is carried by systematically organizing the research results of previous geological surveys in the study area. [Results] The research shows that the resources and environmental conditions of the Chengdu-Deyang-Meishan-Ziyang urban groups are generally good, and the most important ecological protection area presents the spatial characteristics of "northeast orientation and three corridors". In the past 30 years, nearly 80% of the area has maintained good ecological space. In addition, the ecological space increase area is slightly larger than the decrease area, and the ecological function is strengthened year by year. The atmospheric environment is relatively good, the water quality of rivers and groundwater is on average, the water quality of rivers presents the spatial characteristics of “good upstream and poor downstream”, and the groundwater which is Grade 5th of NSWS presents the spatial characteristics of “concentrated in urban area and scattered around urban area”. Suitable areas for agricultural production are widely distributed, concentrated and contiguous, with good combination of water and soil resources overall good soil nutrients and environmental quality. Most areas contain selenium, and some are selenium-rich areas. Suitable areas for urban construction are also widely distributed, with good endowment of water and soil resources, but those areas are at the risk of earthquakes and geological disasters. [Conclusions] Based on the similarity of natural geographic patterns, it is suggested that the Chengdu-Deyang-Meishan-Ziyang urban groups should form an integrated land space development, and protection pattern create a regional ecological pilot demonstration area. It also needs to establish a concentrated and contiguous high-standard farmland demonstration area to avoid natural disasters. It is suggested to optimize the spatial pattern and create a multi-center, networked and group-style urbanization system.

Abstract:This paper is the result of mineral exploration engineering.[Objective] China's titanium resources are relatively abundant, but they are mostly co-produced primary ores with low grades, mainly in the form of primary titanium (magnetite) iron ore type. As a major consumer of titanium ore, the study of future titanium resource consumption projections is of great significance. [Methods] Based on a comprehensive analysis of the geological characteristics, application areas, current process and market trade of titanium ore in China, we adopt the sectoral analysis method, the "S" shaped forecasting method and the ARIMA forecasting method to forecast China's titanium consumption from 2021 to 2030. The forecast is based on sectoral analysis, the "S" shaped forecast method and the ARIMA forecast method. [Results] Based on the forecast results, the following observations were made: (1) the consumption of titanium dioxide and titanium concentrate (TiO₂) in China will peak at 3.02 million tons and 4.79 million tons respectively in 2027; (2) the consumption of titanium sponge will continue to grow in the next decade. [Conclusion] By looking ahead to the development direction of the titanium ore resource industry, suggestions are made to ensure a stable supply of titanium ore products, introduce advanced technology and process equipment, promote technological innovation in all aspects of the industry, and incorporate higher environmental and governance standards into the production chain, among other countermeasures.

Abstract:This paper is the result of mineral exploration engineering.[Objective] Zirconium and titanium resources in China are scarce and the market demand is large, heavily dependent on import. Sorting out the distribution of zirconium and titanium resources, metallogenic types and supply and demand status is of great significance for further zirconium and titanium exploration and development. [Methods] This paper systematically collected and sorted out the endowment, deposit types, supply and demand conditions and resource potentials of zirconium and titanium resources in the world. [Results] Zirconium resources in the world are mainly placer-type, titanium resources consist mainly of ilmenite and rutile, and high-quality titanium resources are also dominated by sedimentary placers. Zirconium and titanium resources in the world have the characteristics of concentrated distribution and separation between supply and demand, shown mainly as follows: Zirconium resources are mainly concentrated in Australia (71.43%), South Africa (8.43%) and Mozambique (2.57%) (accounting for more than 80%). China is the world's largest importer of zirconium resources, mainly from Australia and South Africa; Ilmenite resources are mainly distributed in China (32.86%), Australia (22.86%), India (12.14%) and other countries, while rutile resources are mainly distributed in Australia (62.31%), India (14.87%), South Africa (13.07%) and other countries. Although China's titanium resources account for a high proportion of reserves, its resource endowment is poor (high-grade titanium depends on imports), and it is the world's largest net importer of titanium resources, Mozambique and Vietnam are currently the largest overseas sources of titanium resources. [Conclusions] Zirconium and titanium resources are still in short supply in China in the future. We should further increase investment in exploration and development, expand overseas sources, improve the level of industrial chain development, and establish a sustainable development and security system for zirconium and titanium resources as soon as possible.

Abstract:This paper is result of marine geological survey engineering.[Objective] Oyster reef has important ecological value, and studying its present situation is of great significance for coastal ecological protection and restoration. [Methods] This article reviewed the investigation and research data of the natural oyster reefs at home and abroad. In addition, the present situation, historical changes, as well as the major ecological problems of the natural oyster reefs in China were also discussed. On the basis of the results, combined with indigenous and abroad oyster reef ecosystem restoration practices, suggestions on the protection and restoration of the natural oyster reefs in China were put forward. [Results] The results show that the global oyster population has declined by 85% over the past century, with more than 90% of reefs in the Asia-Pacific region have already disappeared. The natural oyster reefs in China are also severely degraded, and the known natural living oyster reefs are mainly distributed in Caofeidian, Hebei, Dashentang, Tianjin, Binzhou Port and Laizhou Bay, Shandong, Xiaomiaohong, Jiangsu, Shenhu Bay and Kinmen, Fujian, etc. The existing oyster reefs in severely degraded areas are less than one-tenth of what they were in the past, causing serious damage to the structure and function of the estuary and coastal ecosystems. Therefore, the protection and restoration work is needed urgently. [Conclusions] The practices of oyster reef restoration at home and abroad show that it is feasible and quite significant to carry out area restoration of oyster reef ecosystem. In order to make full use of the ecological service function of oyster reefs, provide support for the ecological restoration, and improve the carbon sequestration capacity of coastal zones, this paper proposes four suggestions on protection and restoration, including promoting relevant legislation on oyster reef protection, conducting systematical survey and research on the natural living oyster reefs, pilot to carry out oyster reef restoration demonstration projects, and constructing "China Coastal Oyster Reef Eco-Corridor".

Abstract:This paper is the result of oil and gas exploration engineering.[Objective] Residual bay basin was developed during the transition from marine to continental deposition in the Qiangtang Basin. This transition environment enables Qiangtang Basin to generate organic-rich shales. The mechanism of organic matter accumulation is still controversial due to its complicated organism origin. [Methods] In this study, we choose residual bay organic-rich shales from the Changliangshan section to study the mechanism of organic material accumulation. Redox-sensitive indices including EF values, Mn contents and U/Th ratios reveal that the water volume was dyoxic to anoxic condition during the shale deposition. The relatively low primary productivity during deposition is supported by the relatively low biogenic barium concentrations. [Results] Climate change indices including oxygen-isotope, Mg/Ca and Fe/Mn ratio show that a significant climatic change has taken place during the shale deposition. Climate has changed into warm and humid during the shale deposition compared with dry and cold during underlying marl deposition. [Conclusions] Combined with sedimentary rate and type II kerogen, this paper proposed that warm and humid climate conditions, relatively high sedimentation rate, and high input from terrigenous higher plants are the main factors controlling organic matter accumulation in the Changliangshan shales.

Abstract:This paper is the result of oil and gas exploration engineering.[Objective] The second member of Xujiahe formation of the HC area in the Sichuan Basin has great potential for exploration and development, but it is a typical low-porosity and low-permeability tight gas reservoir, which requires in-situ stress refined evaluation to recommend the optimal selection of engineering sweet spots for later vertical fracturing and plane fracturing to increase production. [Methods] Based on experimental test analysis such as 25 groups of acoustic emission and 13 groups of differential strain, combined with hydraulic fracturing, conventional and special logging data, we analyze the applicability of different experimental test methods in tight sandstone reservoirs by performing a fine-scale evaluation of in-situ stress and identified layers and sweet spots conducive to engineering modifications. [Results] The results of the experimental tests of the second member of Xujiahe formation in the HC area showed that the maximum horizontal principal stress values ranged from 50.77 to 75.65 MPa, with a mean value of 59.71 MPa; the minimum horizontal principal stress values ranged from 45.37 to 54.31 MPa, with a mean value of 49.31 MPa; and the vertical stress values ranged from 48.11 to 65.62 MPa, with a mean value of 56.53 MPa. The simulation results show that the smaller the thickness of the stress barrier within the reservoir and the differential coefficient of in-situ stress in both directions, the more favorable the fracture modification. The comparison of the three-dimensional stress relationships between the minor layers indicates that the second member of Xujiahe Formation is in a strike-slip stress state. The dense sandstone in the second member of the Xujiahe Formation is more homogeneous, the acoustic emission test results are more inaccurate. The results of the differential strain test are in better agreement with the results of the in-situ stress magnitude interpretation, making the test method more suitable for more homogeneous sandstone formations. [Conclusions] In combination with the magnitude of in-situ stress, it is recommended vertically that the more favorable combination of compartments, upper middle of the second subsection of Xu-II, be selected as the target layer for fracturing. To achieve a better volume fracturing network, it is recommended to avoid areas near faults with a large differential coefficient of two-dimensional stress. The area of HC102-HC111 well in the central part of the HC area, where high-quality reservoirs are developed and two-dimensional stress difference factor is relatively small, should be selected.

Abstract:This paper is the result of oil and gas exploration engineering.[Objective] Two sets of black shales occurred in the Ordovician Ningguo-Hule period in the Lower Yangzi region have some potential for shale oil and gas resources. However, the planar extension and vertical thickness of the shale are still unclear. Accordingly, petrographic paleogeographic studies are of greatest significance for exploring their hydrocarbon resource prospects. [Methods] A detailed field geological survey and test analysis were carried out regarding the Ningguo-Huleian sedimentary strata in the Lower Yangtze area. Based on the study of lithology, sedimentary structure and paleontological fossil assemblages, we carry out the research of lithofacies paleogeography. [Results] Two types of sedimentary facies are identified: carbonate gentle slope facies and clastic shelf facies. Carbonate gentle slope facies mainly existed in the northern and western parts of the Lower Yangtze region, and can be further divided into shallow water gentle slope and deep water gentle slope according to lithologic and biological characteristics. The shallow water gentle slope is dominated by biological spangled limestone, mud-crystal limestone and argillaceous limestone, while the deep water gentle slope is dominated by nodular limestone, turtle crack biolimestone and shale. The clastic shelf facies mainly developed in the southern and eastern parts of the Lower Yangzi region, and can be further divided into shallow- and deep-water shelves. The main differences between the two subfacies are the increased silica content, biota variation and higher organic matter content in the deep-water shelf. [Conclusions] The study reconstructed three stages of the paleogeographic pattern during the Ningguo-Hule Period initially. The Hule Formation of Jixi-Jingde-Ningguo in Southern Anhui province has large shale thickness and high organic matter abundance, which can become a critical prospective zone of Paleozoic shale oil and gas.

Abstract:The paper is the result of geothermal geological survey engineering.[Objective] D34 well of Gaoyang geothermal field in Xiong'an New Area is the highest temperature geothermal well in North China Basin drilled by Chinese Academy of Geological Sciences and China Geological Survey in 2020. The wellhead temperature is 123.4℃, and the water output is 94.5 m³/h. Obviously, such high temperature corresponds with a relatively low flow. In order to provide important theoretical support for fracturing stimulation, this study intends to clarify the fragmentation law of reservoir carbonate rock under different confining pressures. [Methods] Based on previous studies, this paper takes the deep Gaoyuzhuang Formation reservoir carbonate rocks drilled from D34 well as the research object, and carries out conventional triaxial compression and tensile experiments. [Results] The experimental results show that: (1) The tensile strength characteristics of the reservoir carbonate rock in the Gaoyuzhuang Formation are similar with that of compressive strength, and shows obvious compression failure features. With the increase of the surrounding rock pressure, the compressive strength shows a typical secondary increase. (2) The compressive strength and the distribution of the fractures show differences with the depth. Among them, the uniformly developed multiple fractures and single main fractures are the main forms of expansion. Under the confining pressure of 20 MPa and 40 MPa, the yield strength changes synergistically with the Young's Modulus and Poisson's Ratio, respectively. (3) The expansion methods of tensile fractures are different with different depth. The shallower tensile fractures mainly expand with small amplitude and multi-stage expansion, while the deeper rocks show a uniform expansion trend. [Conclusions] Combined with the result of conventional triaxial compression and tensile experiments, it is concluded that the possibility of forming a complex fracturing network in the shallow part of the reservoir is higher than that in the deep part, but the overall brittleness index is less different, so there is no need to adopt different construction plans for different depths of the reservoir.

Abstract:This paper is the result of geothermal survey engineering.[Objective] Building genetic model of the geothermal system plays an important guiding role in the evaluation of the geothermal resources of the geothermal field and the later selection of favorable zones. Daming Sag is a secondary structural unit at the southern of Guantao Uplift in Linqing Sag, Bohai Bay Basin. The sandstone thermal reservoir of Guantao Formation can form a complete geothermal system. [Methods] Combining previous research results and regional geothermal drilling data, through analysis and research on the main geological factors of the “source, reservoir, migration, and cover”, the conceptual model of the geothermal system was established in Daming Sag, Linqing Depression. On this basis, a evaluation of geothermal resources was carried out. [Results] The thermal reservoirs of the Guantao Formation are uniformly distributed in the area, the floor depth is between 1550-2000 m, the thickness of the reservoir is between 268-324m, the porosity is between 14%-32%, and the reservoir-thickness ratio can reach up to 70%. The geothermal wells drilled into the Guantao Formation in the area, its water temperature is about 54-60℃, and the water chemistry type is mainly Cl×SO₄-Na. The upper Quaternary and Minghuazhen Formation strata have a geothermal gradient between 22-60℃/km, forming a good cap layer. The heat source comes from the high geothermal value background of the Cenozoic rift basin, about 52-57 mW/m². The Linzhang-Daming fault in the south and the Guanxian fault in the east are favorable channels for the upward transportation of deep heat. The geothermal system receives the atmospheric precipitation replenishment from the Taihang Mountains in the west and the southwestern Luxinan uplift in the east. After being warmed by deep heat conduction and local heat convection, it is enriched in the reservoir. [Conclusions] The evaluation results of the geothermal resources in the Damingci Depression show that the sandstone geothermal system resources of the Guantao Formation are more than 127.42×10⁸ GJ, the annual geothermal resources that can be exploited are 31.86×10⁶ GJ equivalent to 1.09×10⁶ t of standard coal. The annual exploitation of geothermal resources can meet the heating area over 3.14×10⁷ m², and the development potential is great.

Abstract:This paper is the result of mineral exploration engineering.[Objective] The Tangqung Co area in Tibet is located in the north of Tangra Yum Co-Xuru Co rift. The presence of geothermal springs in locations like Qurebaima and Zhariqusheng has prompted the need for a comprehensive study of their hydrochemical characteristics and origin, particularly regarding their contribution of Li and Rb substances to the Tangqung Co salt lake. [Methods] This study involved the collection and analysis of six spring water samples to determine their chemical composition and stable isotopes. Various chemical coefficients and mineral saturation indices were calculated, and cluster analysis was performed on the chemical components of the springs. [Results] The findings reveal that Qurebaima spring waters exhibit enrichments in elements such as Li, B, Rb, and Cs. These springs are influenced by atmospheric rainfall and snowmelt, displaying shallow circulation characteristics. The springs' extended flow path and substantial water-rock interaction contribute to the predominance of HCO₃^- originating from carbonate rocks and CO₂ produced by magmatic activity. Moreover, the calculated thermal reservoir temperature based on SiO₂ geothermometers falls within the range of 123.33 to 128.22℃ for Qurebaima samples. [Conclusions] Geothermal activity in the Tangqung Co area is governed by the N-S trending Tangra Yum Co-Xuru Co rift valley, wherein the geothermal water acquires Li, Rb, Cs, and other trace elements through interactions with silicate minerals. Additionally, the water-rock interaction extends to the Permian and Cretaceous carbonate rocks, ascending along active faults in the region, and ultimately mixing with water from the Tangqung Co lake. This phenomenon suggests that the formation of Li and Rb-rich salt lakes in Tibet may be associated with extensive N-S rift activities, which not only provide geographic space for the accumulation and mineralization of salt lakes but also act as conduits between deep sources and surface environments.

Abstract:This paper is the result of mineral exploration engineering.[Objective] Kunshan molybdenum polymetallic deposit is located in Xiushui County, Jiangxi Province, and belongs to eastern segment of the Jiuling uplift from mid-segment of the Jiangnan orogen. This study attempts to precisely constrain the metallogenic age of the Kunshan W-Cu-Mo polymetallic deposit, provide geochronological evidence for the study of mineralization and the summary of the metallogenic regularity of the deposit, study the metallogenic relationship of the deposit and the source of metallogenic material, and divide the metallogenic periods of the Dahutang tungsten polymetallic ore concentration area. [Methods] The Re-Os isotopic geochronology for the molybdenite from the Kunshan molybdenum polymetallic deposit was carried out in this paper. [Results] An isochron age of (148.8±1.0) Ma, and a weighted mean age of (148.7±0.7) Ma for 10 molybdenite samples were obtained, which were approximately simultaneous with each other, and the Re-Os system was closed accordingly. The points of ¹⁸⁷Re and ¹⁸⁷Os are far away along the isochron, which indicates that the geochronology data are reliable. Metallogenesis lags behind the emplacement of porphyritic-like biotitic granite in the Kunshan deposit, caused by Late Jurassic granitic magmatism. Metallogenic materials of the Kunshan molybdenum polymetallic deposit mainly came from crust materials, in addition, there are two samples with higher Re, it shows that partial mantle source metallogenic materials participated in the formation of the deposit. [Conclusions] The intrusion of asthenospheric materials began from the Late Jurassic epoch, through the intersection part of NNE deep faults and NEE ancient faults formed from Late Jinningian. Partial melting of crustal material was caused by the heat conduction effect, which forms a series of intermediate-acid intrusive rocks in the Dahutang area, such as porphyritic-like biotitic granite, fine-grained biotitic granite, and granite-porphyry.

Abstract:This paper is the result of geological survey engineering.[Objective] The formation mechanism of the Xiaowan granitic pluton, located in the magmatic belt of the Lincang terrane in the Fengqing County, western Yunnan province, is very important for constraining the petrogenesis of the Lincang magmatic arc derived from crust, subduction of the ocean basin, and the time of collision closure. [Methods] This paper reports for the first time the zircon U-Pb chronology, petrography, and geochemical characteristics of major and trace elements in the Xiaowan granitic pluton. [Results] The Xiaowan granite is mainly composed of biotite monzogranite. Zircon U-Pb LA-ICP-MS dating shows that its formation age is (260.4±1.3) Ma (MSWD=0.32, n=18), suggesting that the Xiaowan granite was formed in the Late Mid-Permian, rather than the Middle Proterozoic as previously considered. Whole-rock geochemical analysis shows that the A/CNK of biotite monzogranite is greater than 1 (1.02-1.47), indicating that the Xiaowan granitic pluton is composed of weakly peraluminous granite. These rocks are characterized by high silica (SiO₂ = 67.54%-78.66%), alkali rich (K₂O+Na₂O = 6.20%-8.52%), poor in the elements of calcium (CaO=0.25%-3.20%), magnesium (MgO content 0.11%-1.95%) and phosphorus (P₂O₅ content 0.03%-0.16%). Meanwhile, they are enriched in large ion lithophile elements (LILE) such as Rb, Th, Ce, relatively depleted in high field strength elements (HFSE) such as Ta, Nb, Zr, Ti, Hf, Y. In the (Y+Nb) vs. Rb, Yb vs. Ta diagrams, they exhibit dual geochemical characteristics of arc and collisional granite. [Conclusions] Based on regional geological data, we suggest that the Xiaowan granitic pluton is the product of partial melting of the mudstone mixing with sandstone at the upper crustal level, under the setting of the eastward subduction shifting to the convergence of the Changning-Menglian ocean (also called as “Three Rivers” ancient Tethys ocean). This study provides important chronological and petrological evidences for the transition of the Changning-Menglian ocean from arc-continental subduction to collision in the southwestern Qinghai-Tibet Plateau.

Abstract:This paper is the result of geological survey engineering.[Objective] The study aims to further understand the tectonic evolution of the back-arc basin of Bayankera, the northwestern margin of Songpan-Ganzi block, Western Kunlun. [Methods] In this paper, the authors present petrographical, lithogeochemical, LA-ICP-MS zircon U-Pb geochronological and Hf isotopic data for the two-mica monzogranite in Dujianshan. [Results] LA-ICP-MS zircon geochronology study reveals that the monzogranites in the Dujianshan area crystallized at (219.9±1.2)-(227.1±1.5) Ma, indicative of the Late Triassic plutons. The results of major elements, trace elements and Hf isotope reveal that the monzogranites are metaluminous-weakly peraluminous rocks, belongs to the high potassium calcium alkaline series and exhibit characteristics of island arc and collisional granites. The source rocks of granites were generated from partial melting of a mixture of crust-mantle materials. [Conclusions] Combined with the regional tectonic evolution, it is speculated that the Dujianshan area is in a post collision extension environment at the end of the Late Triassic, and the island arc and syn-collision materials formed in the early ocean continent subduction stage partially melted to form post collision granite in the area.

Abstract:This paper is the result of geological survey engineering.[Objective] The Paleo-Proterozoic Pandaoling pluton is a granitic body in the Liaoji active belt, Eastern Block of the North China Craton, which is mainly composed by biotite monzogranite. It has been seldom researched so far, which restricts the recognition of evolution of tectonic setting in North China. [Methods] Based on the field geological characteristics of the Pandaoling pluton, it has been studied in terms of petrography and geochemistry in this paper. [Results] The rocks contain high silicon (74.04%-75.84%), high potassium (3.81% in average) and are rich in alkali (Na₂O+K₂O=7.29%-7.87%), and the average value of K₂O/Na₂O and A/CNK are 1.09 and 1.187-1.394, respectively. The rocks belong to high-K, calc-alkaline series peraluminous I-type granite. The granites have low ΣREE contents (with average of 89.78×10^-6) and obvious negative Eu anomalies (0.19-0.93). They has variable (La/Yb)_N ratios of 2.95 to 50.38, and display enriched LREE patterns, with relatively enrichment of LILEs (Rb, K, U) and HFSEs (Hf), and low contents of Ba, Zr, Nb, Ta, P and Ti. Zircon saturation temperatures (745-774℃) of granite melt are significantly lower than the A-type granites (868℃-928℃). These characteristics suggest that the Pandaoling monzogranite is characteristic of high fractionated I-type granite. [Conclusions] The petrological and geochemical features of the Pandaoling pluton indicate that they were originated from partial melting of the deep crust due to mantle magma intraplating. Based on tectonic history and the diagram of structure environment, the Pandaoling pluton was possibly formed in the continental borderland collision tectonic setting of Liaoji Paleoproterozoic active blet.

Abstract:This paper is the result of geological survey engineering.[Objective] Bluesschist is the product of subduction of ancient oceanic crust and collage of ocean-continental and land-continental collisions. It is of great significance to further explore the subduction metamorphism of oceanic crust or continental crust and the formation and evolution of orogenic belts. In this paper, the newly discovered bluesschist in Damenglong area, Jinghong, western Yunnan, is selected as the research object, and its restriction on the Changning-Menglian Paleo-Tethys Ocean subduction-orogenic setting is discussed. [Methods] Through petrography and mineral chemistry analysis, two different types of bluesschist in the study area are identified according to different mineral combinations, and the P-T trajectory of metamorphic evolution is initially established. Combined with regional geological data, the genetic mechanism and dynamic background of bluesschist are analyzed to constrain the evolution of Changning-Menglian Paleo-Tethys Ocean subduction and orogeny. [Results] The results show that the peak metamorphic temperature and pressure conditions of muscovite-garnet-glaucophane-quartz schists are T =450-490℃, P=0.90-1.45 GPa, and chlorite-epidote-actinolite-glaucophane schist with the low peak metamorphic temperature and pressure conditions are T = 430-470℃, P = 0.69-0.73 GPa. The P-T tracks of metamorphic evolution of two different types of bluesschist are preliminarily established. [Conclusions] The metamorphic differences of the two types of blueschists occur might because the metamorphic rocks subducted to different depths were uplifted to the surface via subduction tunnels through the exhumation mechanism. The results of this study will provide an important basis for further exploring the subduction and closure of the Paleo-Tethys Ocean in the Changning-Menglian suture zone.

Abstract:This paper is the result of agricultural geological survey engineering.[Objective] The purpose of this paper is to screen the crops with low cadmium accumulation, study the influencing factors of cadmium in crops, and guide the safe utilization of agricultural soil lightly contaminated with cadmium. [Methods] Cadmium and other elements in the edible parts of 23 crops and the corresponding root soils from Luoyang City were measured. We studied the reasons of excessive cadmium in soil, enrichment trend of cadmium in different crops and its influencing factors to screenout the crops with low cadmium accumulation by mathema-ticalstatistics and correlation analysiscombined with the information of geology and mineral deposits. [Results] 6.98% of root soil samples exceeded the national standard of Cd in crop soil. 0.84% of crop samples exceeded the national standard of Cd in crops. The rates of crop exceeding the national standard in the soil with cadmium slightly exceeding the national standardis low.The average cadmium concentration in the edible parts of various crops is ranked as: peanut>okra>cowpea>mung bean>soybean>black bean> sesame>apeseed>pepper>wheat>garlic>red bean>millet>edamame>bean>corn> sweet potato>cherry>pomegranate>pear>Chinese artichoke>apple>grape. Different speciation of Cd is significantly correlated with the total Cd in root soil. The main influencing factors affecting cadmium concentration in edible parts of crops is soil pH, followed by cadmium concentration in soil and concentrations of other elements such as Se, Mo and Zn.The correlation between Cd concentration in edible parts of different crops and soil Cd content and pH is not consistent. In areas with weak cadmium pollution, apples, pomegranates, Chinese artichoke, pears, sweet potatoes, corn, garlic, grapes, beans and cherries are recommended to be planted.Sesame, rapeseed, millet, wheat and peanuts can be farmed in alkaline soil.Sesame, rapeseed, millet, sweet potato and corn and fruits such as apple, pear, grape and cherry can be safely grown in areas with excessive cadmium in wheat grains.Increasing soil pH can also reduce the adsorption of cadmium by wheat grains.[Conclusions] The study of cadmium accumulation trends and its influencing factors of different crops could provide scientific basis for the safe utilization of soil with cadmium slightly exceeding the national standard.

Abstract:This paper is the result of environmental geological survey engineering.[Objective] The study of paleo-environmental changes of Mid-to Late-Pleistocene in northwest Tarim Basin is relatively weak. As a sensitive area to climate and environmental change in Asia, the paleoenvironment study of the Southwest Tianshan is of great significance for predicting future climate. The succession law of palaeo-vegetation indicated by the characteristics of palynological assemblage has become an important problem to be solved urgently in paleoclimate research in this area. [Methods] Based on palynological identification and photoluminescence dating of typical river terrace samples from Sepayi-Keping area, Xinjiang, the characteristics of palynological assemblages in the Mid-to Late-Pleistocene and their implications for paleoclimate were discussed in this paper. [Results] Three palynological assemblages of Mid-to Late- Pleistocene were divided. Palynological assemblage zone Ⅰ: Quercus-Graminae- Chenopodiaceae; Ⅱ: Ephedra-Betula-Labiatae; Ⅲ: Pinus-Ephedra-Chenopodiaceae. [Conclusions] They indicate the arid climate of the Southwest Tianshan and the fluctuation trend (dry and cold-warm and wet-dry and cold) during Mid-to Late-Pleistocene. During 65-16 ka before present, there was an obvious humid climate stage with abundant precipitation. The terraces formed by river downcutting were controlled by both tectonic and climatic factors.

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