Local Geological Conditions Research Articles

Discussion on the Main Control Effect of Geological Structures on Coal and Gas Outburst.

Coal and gas outbursts are great natural disasters in underground coal mines, seriously threatening the lives of miners and coal mine safety. The study of the relationship between coal and gas outbursts and geological structures has always been an important component of gas geological work, and it also serves as a foundation for coal mines to develop gas outburst prevention measures. This study considers groups F and E coal seams, mainly mined in the southwest wing of Likou syncline in the Pingdingshan mining area, as the research object. Based on actual outburst data, this study investigates the distribution and intensity characteristics of coal and gas outbursts and the correlation between coal and gas outbursts and geological structures using gas geological analysis methods and taking structural control as the main line. The results depict that the coal and gas outbursts in the study area have obvious district and subband characteristics. The outburst district mainly occurred in the East, and the four outburst zones, I, II, III, and IV, were the concentrated occurrence subband of coal and gas outbursts. The district and subband of coal and gas outburst are mainly controlled by and related to the geological structure. The eastern fold structure has developed more than the middle and western districts, which is why the eastern part of the coal and gas outburst is more severe than in the middle and western regions. Under the structural background of the coal and gas outburst district, the subband outburst characteristics were mainly controlled by local geological structural conditions.

Cause Analysis and Preventive Measures of Guizhou D2809 Train Derailment Accident in Guizhou, China on 4 June 2022.

This paper summarizes the cause of the debris flow impact train accident by investigating the local geological condition, meteorological data and field investigation that happened in Guizhou, China on 4 June 2022. The result showed that the major reason is the continuous heavy rain in the surrounding area, which led to a small landslide at the upper right of the tunnel entrance. Besides, the construction of the Jianrong Expressway in the upper reaches increased the catchment area, which makes the water content of the upper soil increase while the shear strength decreases. Such large-scale catastrophic accidents significantly threaten the local environment and public safety. Therefore, it is urgent to pay special attention to the changes in geological conditions along the line, especially the adverse effects of construction, to improve the early risk warning and post-accident treatment ability.

KORELASI KONDISI GEOLOGI DAN SUMBER PENCEMAR TERHADAP KUALITAS AIR SUMUR DI KECAMATAN VERA CRUZ, DILI, TIMOR LESTE

The research was took place in Post Administrative of Vera Cruz, Dili City, Timor Leste. Vera Cruz is one of the 5 (five) post administrative that located in Dili City. The purpose of this study was to examine the quality of well water in the research area, considering that the government supply of clean water to Dili City could not fulfill the needs of the community. By understanding the quality of well water for the community daily consumption, the community might be more confident or able to treat the well water so that it was safe for consumption. Well water samples were taken randomly from 4 villages of Vera Cruz Post Administrative. Well water quality was analyzed in the laboratory with 6 (six) parameters, including Mn, Fe, and microbiology. In addition, the distance of the well to the source of pollutant and the local geological conditions were studied to find out their influences to the quality of the well water. Referring to several standards of drinking water quality from both Indonesia and Timor Leste, it was known that well water in Vera Cruz Post Administrative has not been yet suitable for direct consumption because it was affected by domestic polluting sources and local geological conditions. Therefore, the well water should be treated before consumption.

Identification of Heavy Metals and Organic Micropollutants in Drinking Water Sources in Typical Villages and Towns in Northeast China.

This study identified and detected the existence of major pollutants in northeast China. As an alpine region and an agricultural base, this region has representative significance in pollution research. We selected 56 samples from drinking water sources of typical villages and towns, focusing on the analysis of heavy metals and organic micropollutants in northeast China. The analysis results showed that Fe and Mn were the main metal elements exceeding the standard. The exceeding rates were 17.9% and 19.6%. Experiments showed that there were 19 kinds of pesticides, 6 kinds of OPEs, 2 kinds of PAEs, 22 kinds of PPCPs. The detection rate of these 49 kinds of organic micro-pollutants were 1.79~82.14%. The characteristics of organic pollution were extensive and varied. Many underground water samples had high level of micropollutants. The water quality parameters of drinking water sources in villages and towns showed close relation to local geological conditions and agricultural activities. Actions must be taken to control these parameters from the source of pollution.

Analysis of Soil Dynamics and Seismic Vulnerability in Kalibening District, Banjarnegara Using the HVSR Method

On April 18, 2018, an earthquake with a magnitude of 4.4 Mw struck the Kalibening district, Banjarnegara. The observations on the damage distribution caused by the earthquake showed something unique: the areas that suffered severe damage were concentrated in villages on hills. This observation may indicate a site-effect phenomenon due to local geological conditions. In this study, we carry out microtremor measurements at 30 stations. The measurement area includes areas that have suffered damage due to the 2018 earthquake and also with minimum damage. We analyze the microtremor observation to estimate the site’s characteristics and map the seismic vulnerability based on predominant frequency (f0 ) and amplification factor (A0 ) using the Horizontal to vertical spectrum ratio (HVSR) method. The results show that the predominant frequency in the Kalibening district area is 0.4 – 3.7 Hz, while the amplification factor is 2.5 – 10.7. The Kalibening Basin has a low f0 (<2.5 Hz) and A0 (<4), which indicates that the Kalibening Basin has a thick and soft soil type but low-density contrast. Areas with a high degree of damage have dominant frequency values in the range of 1.5 – 2.3 Hz and amplification of 5.1 – 9.2. These results suggest that the location has a high-density contrast and thick sediment, causing significant amplification. The seismic vulnerability index (Kg) values are in the range of 3.6 - 46.74. The area around the Kalibening Basin has a low Kg value, While the damaged areas have a moderate to high seismic vulnerability index.

Applicability and improvement of soil classification methods in Delta regions based on the CPTU database

Several soil classification systems have been developed for specific sites based on the CPTU database. However, issues may occur when applying these existing soil classification methods to delta regions, whose construction sites involve deposits that are both weak and compressible. This requires further evaluation and a more detailed dataset. A database has been compiled that includes 85 CPTU soundings from 36 sites in the Yangtze River Delta. This study evaluates the performance of four existing CPTU-based soil classification methods for deltaic soils. The performance of each soil classification method is quantified by the micro F 1 score, the weighted kappa coefficient, and the chi-square value. An analysis and comparison indicate that the SBT chart has the highest accuracy, with a micro F 1 score of 0.72. The weighted kappa values for most of the soil classification methods can reach 0.5, which shows that there is a median degree of consistency in terms of the classified soil type. Hence, current soil classification methods need to be supplemented using local geological conditions and laboratory test results from borehole records. Therefore, a novel modified soil classification chart is presented herein to illustrate the deltaic soil conditions more accurately.

Seismic zoning maps of the National Capital Region (NCR) of India

AbstractWe present seismic zoning maps of the National Capital Region (NCR) of India in terms of uniform hazard spectrum (UHS) amplitudes using three different attenuation equations to model the contributions of local earthquakes around the region and distant earthquakes in northwestern Himalaya (NWH) and Hindu Kush Subduction (HKS) sources. Our results show that the shape of design spectra must depend on the nature of contributing earthquake sources, their relative activity, the potential to create large magnitudes, and their geographical placement relative to the site selected for hazard computation. Our results also show that specifying strong motion amplitudes for use in engineering design by means of peak ground acceleration and a standard spectral shape may result in significant underestimation of intermediate and long‐period ground motions critical for buildings higher than four to five stories and hence should not be used. We present zoning maps for nine possible combinations of three different local geological site conditions (sediments, intermediate sites, and basement rock sites) and three different soil site conditions (“rock,” stiff soil sites, and deep soil sites). One of these maps can be readily used to extract the UHS amplitudes of the pseudo relative velocity spectrum (PSV) at any site in the NCR by specifying the local geological site‐condition parameters from a high‐resolution surface geological map of the region and determining the local soil site conditions by experiments limited to the site alone. The paper also provides a geological map of NCR on a scale of 1:1 million for a rough idea of the local geological parameters for a site of interest.

Ruins and Remains as a Background: Natural Catastrophes, Abandonment of Medieval Villages, and the Perspective of Civilization during the 20th Century in the Central Apennines (Abruzzi Region, Central Italy)

The resettlement of villages strongly damaged by catastrophes during the 20th century played a key role in the modification of the Apennine landscape in Italy. Following their abandonment, the remains of the medieval settlements progressively deteriorated in their ruined condition, becoming ghost villages often made of sparse portions of buildings, traces of outer walls, and isolated vestiges of ancient monuments colonized by vegetation. Five cases of central Apennine abandoned villages in the Abruzzi region (Frattura, Sperone, Albe, Salle, and Gessopalena) were investigated, combining information on the local adverse geological conditions with the historical reconstruction of their abandonment and resettlement, based on archive documents from the 19th and 20th centuries. The history of these localities was conditioned by two strong earthquakes that struck the Abruzzi region in 1915 (magnitude 7.1) and 1933 (magnitude 5.9), and by slope instability. In all cases, abandonment and resettlement produced new villages against the background of ancient ruins and remains. In conclusion, the paper discusses the potential use of the material traces of local histories with educational aims. Geological evidence of natural hazards, remains of the abandoned settlements and resettled villages could be arranged in museums aimed at increasing the awareness of natural hazards and risks.

Evaluation Methods and Indexes for Ultra‐deep Petroleum Reservoir Preservation with Case Studies

AbstractFollowing consideration of the characteristics of high temperature, high pressure and high in‐situ stress in ultra‐deep sedimentary basins, together with the existence of hydrocarbon phase state transformation, hydrocarbon‐water‐rock interaction and rock mechanical property transition at those depths, the evaluation index system for hydrocarbon preservation was established. The physical leakage evaluation indexes can be divided into three categories: the dynamic efficiency indexes of micro‐sealing, caprock integrity and natural gas diffusion. The chemical loss evaluation indexes can be divided into two categories: the thermochemical sulfate reduction (TSR) index in marine gypsum‐bearing carbonate strata and the thermochemical oxidation of hydrocarbons (TOH) index in clastic strata. The slippage angle and overconsolidation ratio (OCR) are the key evaluation indexes in the evaluation of the integrity of shale caprocks. TSR intensity can be quantitatively calculated by use of the ZnPVT state parameter method. The TOH strength can be used to estimate the degree of hydrocarbon chemical loss, based on the TOH‐related authigenic calcite cement content or the degree of negative δ13C of authigenic calcite. For the evaluation of ultra‐deep preservation in specific areas, key indexes can be selected according to the local geological conditions, instead of all indexes needing to be evaluated for every scenario.

Available Legal Regime and The Use of Mercury for Small-Scale Gold Mining in Ghana

The aim of this study was to examine the effects of mercury (Hg) and available laws to regulate its use in the Artisanal and Small-Scale Gold Mining (ASGM) Community in Ghana. Research shows that the use of Hg in the ASGM causes damage to the cognitive and neurological function of the miners, as well as to the physical and mental disabilities to children in the ASGM communities. Furthermore, number of publications also shows that the use of Hg causes significant damage to water bodies and the environment in most mining communities. Additionally, in an attempt to protect the environment from these high levels of Hg in these mining sites and beyond, has led to some conflict and military intervention. Even though, Ghana has adequate laws to regulate Hg use by reducing and where feasible eliminate the use of Hg for small-scale mining. However, due to some legal limitations to the current situation there is the need to amend some of these laws to help address these challenges. In addition, certain policies, technological and educational initiatives taken to address the use of Hg in our environment, have proven largely ineffective. The results of this study shows that the implementation of mining regulation without careful analysis of mine community dynamics, the organization of activities, operators’ needs and local geological conditions has resulted in some challenges. However, significant improvements can only be achieved in this area if the state and the organs of government tackle the illegal mining “galamsey” menace; introducing cost-effective techniques for the reduction of the use of Hg in mining; effective government sponsored participatory training exercises as mechanisms for communicating information about appropriate technologies and the environment; and strengthening compliance and enforcement of existing laws. In conclusion there is the urgent need to properly regulate the use of Hg in mining communities in Ghana.

Arsenic in the groundwater of the Upper Brahmaputra floodplain: Variability, health risks and potential impacts

The upper Brahmaputra floodplain (UBF) is highly enriched with geogenic contaminants, mostly the Arsenic (As), owing to its sensitive geomorphology, aquifer groundwater (GW) dynamics, huge sediment deposition along with natural and anthropogenic disturbance significantly accelerate the As leaching rate into the groundwater, leading to an increase the health risk. Concerning the above active processes in the Lakhimpur district of UBF, current work aims to investigate seasonal dynamics of As contamination and associated health hazard for local community. To carry out this study, 51 GW samples analyzed which reveal the seasonal variation in As concentrations with the minimum average concentration in the monsoon season (4.7 μg.L−1) and the maximum in the post-monsoon season (18.5 μg.L−1) with 50% of the samples exceeding permissible limits. The differences in the local geological conditions and the GW flow may contribute to the spatial variations in mean As concentration in the study area. Also, the active GW recharge process identified in post-monsoon season accelerates the As leaching in the area's aquifers. Further, results indicate higher As levels associated with a pH range of 6–7 favours As desorption from minerals under reducing conditions. The hazard index indicates that the children population has high carcinogenic risk compared to adult populations. Furthermore, the study highlights the social risk potential arising from public health crises due to As exposure. Overall, results indicate high As concentrations in region with moderate seasonal variability and demand a dire attention for long-term monitoring to provide sustainable water resources to safeguard the people at risk.

Recognition of Landslide Triggering Mechanisms and Dynamics Using GNSS, UAV Photogrammetry and In Situ Monitoring Data

Detecting the mechanism of landslides and evaluating their dynamics is challenging, especially concerning composite landslides. For this purpose, several investigation and monitoring techniques should be implemented to obtain reliable information on landslide characteristics (e.g., geological and hydrogeological conditions and type of landslide processes), kinematics (displacement rate), and potential triggering mechanisms (e.g., change in groundwater table and precipitation). The Urbas landslide in northwest Slovenia has been studied for decades through geological, geotechnical, geodetic, and remote sensing investigations. However, due to the complexity of the landslide and the short duration of continuous monitoring, no assessment of its dynamics has been made. To meet this need, this study analysed continuous and periodic monitoring of landslide displacements using data from the global navigation satellite system (GNSS), a wire extensometer, unmanned aerial vehicle (UAV) photogrammetry, and hydrometeorological sensing (groundwater table, precipitation). The results of this study show that the dynamics of the Urbas landslide differ along the landslide area, depending on local geological and hydrogeological conditions. Consequently, certain parts of the landslide are at different evolutionary states and respond differently to the same external triggers.

Stability Analysis on the Steeply-Inclined Small-Angle Layered Surrounding Rock Masses at the Upstream High Sidewall of a Large-Span Cavern

The underground powerhouse of China’s Wudongde hydropower station is one of the world’s underground powerhouses with the largest span and height. Because the underground powerhouse is all located in steeply-inclined layered rock masses, and the bedding plane strike of the rock mass has a small angle with the axis of the main caverns, there is a serious risk of high sidewall instability. According to the basic principles of the structurally-controlled concept, the mechanical properties of bedding planes and other discontinuities are largely attributed to this problem. A thorough investigation was conducted into the Wudongde underground powerhouse throughout the excavation process to clarify the possible mechanisms behind these failures and to realize the dynamic adjustment of construction. First, the geological conditions and mechanical properties of the rock masses in the study area were introduced in detail. The stability of the right bank underground powerhouse’s surrounding layered rock mass was then investigated using a discontinuum-based numerical method. Special attention was paid to the excavation-induced failure mechanisms of the steeply-inclined small-angle layered rock masses at the upstream high sidewall. The results show that the failure of steeply-inclined small-angle layered surrounding rock masses presents significant three-stage characteristics, i.e., 1) rock plate forms due to the unloading opening of the bedding plane; 2) rock plate cracks due to bending; and 3) rock plate buckles or slides due to crack penetration. Based on the understanding of the deformation and failure mechanisms of steeply-inclined small-angle layered rock masses, the excavation sequence needs to be optimized according to local geological conditions. In practice, it is vital to insist on the principles of excavation by thin layers and finish all the supports before the next-step excavation.

A Critical Review on the Use of Shallow Geothermal Energy Systems for Heating and Cooling Purposes

The reduction of CO2 emissions has become a global concern. In this regard, the EU intends to cut CO2 emissions by 55% by 2030 compared to those of 1990. The utilization of shallow geothermal energy (SGE) in EU countries is considered the most effective measure for decarbonizing heating and cooling. SGE systems utilize heat energy collected from the earth’s crust to provide secure, clean, and ubiquitous energy. This paper provides a literature review on the use of SGE for heating and cooling purposes. The latest advances in materials, new innovative structures, and techno-economic optimization approaches have been discussed in detail. Shallow geothermal energy’s potential is first introduced, and the innovative borehole structures to improve performance and reduce installation cost is outlined. This is followed by an extensive survey of different types of conventional and thermally enhanced collectors and grouts. Attention is mainly given to the techno-economic analysis and optimization approaches. In published case studies, the least economic break-even point against fossil fuel-based heating systems occurs within 2.5 to 17 years, depending on the local geological conditions, installation efficiency, energy prices, and subsidy. Ground source heat pumps’ cost-effectiveness could be improved through market maturity, increased efficiency, cheap electricity, and good subsidy programs.

A Preliminary Result of Seismic Hazard Analysis in Eastern Part of Bali Island, Indonesia

Bali Island is one of the main tourist destinations in Indonesia. However, Bali Island is also prone to earthquakes, as evidenced by several historical destructive earthquakes, especially in the eastern part of Bali. A probabilistic seismic hazard modeling is undertaken to analyse the earthquake hazard, as well as studying the contribution of local geological conditions to earthquake ground motion. We use seismic waveforms retrieved from 23 temporary seismic stations across the eastern part of Bali Island from December 2018 to June 2019 and 5 permanent seismic stations around Mount Agung and Batur. The recording data were processed using the Horizontal to Vertical Spectral Ratio (HVSR) method. Our preliminary result shows local geological conditions for each station, represented by the value of the average shear-wave velocity on rocks to a depth of 30 meters (Vs30) and the total thickness of sediments above the bedrock (basin depth). These initial results will then be developed as site parameter input for probabilistic seismic hazard analysis in the eastern part of Bali.

Seismic microzoning of the Delhi metropolitan area, India—II: Hazard computation and zoning maps

AbstractWe present seismic microzonation maps of New Delhi, India, using the probabilistic seismic hazard analysis (PSHA) method with input seismic activity parameters estimated in Part‐I of this two‐part paper. Our calculations required three different attenuation equations for amplitude scaling of strong ground motion from three principal contributing sources: the National Capital Region (NCR), Northwestern Himalaya (NWH), and the Hindu Kush subduction (HKS). We show that uniform hazard spectral (UHS) amplitudes are dominated only by the local seismicity in the NCR at high frequencies beyond about 2 Hz. For intermediate and long periods, UHS amplitudes are dominated by contributions from the NWH and HKS earthquakes. Our results show that specifying strong motion amplitudes for use in engineering design by means of peak ground acceleration can lead to serious errors for buildings higher than four to five stories and hence should not be used. Our results also show that the shape of design spectra must depend on the nature of contributing earthquake sources, their relative activity, potential to create large magnitudes, and geographical placement relative to the site of interest, and thus a standard design‐spectrum shape cannot satisfy all these requirements. We use local geological site condition parameters directly in all calculations and present hazard maps for three different soil site conditions (“rock,” stiff soil sites, and deep soil sites). Thus, the user can extract the UHS amplitudes of pseudo relative velocity spectra at any site in the National Capital Territory by experimentally determining the local soil site conditions and then applying the corresponding maps shown in this paper.

Східноєвропейський досвід застосування багатошарових залізобетонних елементів зовнішнього стінового огородження

The capital building field is constantly updating the tasks: to reduce material consumption, cost and complexity of building, the mass of buildings and structures; significantly improve thermal protection; to increase the level of industrialization of building and factory readiness of prefabricated constructions; to improve the architectural and operational qualities of buildings and structures. Practical realization of the set tasks entails the the necessity to expand the use effective kinds of building materials and constructions, improving their properties. The field of effective three-layer constructions in civil, industrial and agricultural building is wide and multifaceted, as it covers almost all constructive elements of buildings, the solution of which depends on the functional requirements imposed on buildings and structures, local climatic and geological conditions, availability of building materials, level of development industrial base, etc. Already behind the idea itself of layered reinforced concrete constructiones have significant advantages: 1) the ability to select the materials of the layers taking into account the effective use of their main functional qualities; 2) reducing the cost and outlay of cement; 3) weight reduction of separate constructions and buildings and/or structures as a whole; 4) reducing heat consumption and increasing heat transfer resistance without thickening the construction; 5) improving the temperature-humidity regime in the room, etc. The purpose of this article is to perform a brief overview of research, proposals for standardization of design developments conducted during the most active implementation in Eastern European building practice of three-layer reinforced concrete constructions for fencing by the heat, air and waterproofing properties, strength, deformations and crack resistance, as well as their manufacturing technology. The article takes into account the results of research, field observations, materials for the development of new proposals, accumulated in many research and design departments of Eastern Europe in the period from the late 60’s to mid-80’s of the 20th century (Research Institute of Building Constructions, Kyiv Zonal Research Institute of Experimental Design, Ukrainian Research and Design Institute of Civil Rural Construction (Ukraine); Central Research Institute of Building Constructions named after V.A. Kucherenko, All-Union Research Institute of Fire Safety, All-Union Scientific Research Institute of Reinforced Concrete, Central Research and Design Institute of Residential and Public Buildings, Central Research and Design and Experimental Institute of Industrial Buildings and Structures, Central Research Institute of Experimental Design of Commercial and Domestic Buildings and Tourist Complexes (Russia), etc.).

Smart control of HVAC based on measurements of indoor radon concentration

Sufficient ventilation is important for creating a healthy indoor environment in both households and larger buildings (schools, offices, shops, warehouses). As the cost of heating and ventilation in large buildings is very large, modern ventilation systems apply smart control for optimizing the energy consumption. The control is typically based on temperature and/or CO2 levels, whereas other pollutants such as particulate microparticles and radon are not accounted for. Exposure to indoor radon is the second most important reason for lung cancer, with more than 200 000 casesestimated worldwide every year. The indoor radon concentration depends on many factors, from local geological conditions and weather, to building materials and natural and mechanical ventilation. Together with the Norwegian company OBEO AS, NORCE has completed a study of the indoor radon concentration at a Norwegian primary school prone to high radon levels. The study includes continuous measurements of radon, CO2 and temperature for multiple rooms for different use as well as data for the ventilation system. The aim for the project was to build knowledge for a larger research project, where the goal is to develop a control algorithm for HVAC systems which also takes radon levels into account. An important challenge is to make accurate sensors for measuring radon continuously at an affordable price for implementation in complex buildings. Generally, sensors that can measure at high frequency with good accuracy is very expensive. Thus, developing algorithms and mathematical models to treat the data from low-cost sensors can be an adequate tool for large systems/buildings. One must also account for the positioning of the sensor. For instance, it is known that the radon concentration is better distributed in a room with mechanical ventilation than in a room without, making the position of the sensor important for better interpretation of measurement data. In the pre-project we have studied how the radon levels show large variations that are related to the ventilation operation and daily/weekly variations. The large variations show the need for a high sampling rate (minutes to hours) to capture the peaks in the concentration. We have also studied the rate of change in radon concentrations over time and have amongst discovered a noticeable delay from the start of ventilation until radon is effectively removed from the air. The rate of change is an important parameter for planning ahead and securing fresh air during the full period of presence whilst optimizing the energy cost.

The roles of emplacement depth, magma volume and local geologic conditions in the formation of the giant Yulong copper deposit, Eastern Tibet

The relative importance of the oxidation state, water content, and copper and sulfur content of the causative magma in the formation of porphyry Cu deposits is hotly debated. The giant Yulong Cu deposit in Eastern Tibet, with proven reserves of 6.5 Mt Cu at 0.62%, is an example of an economically important porphyry deposit. We investigate the relative roles of factors and different processes controlling the formation of the ores. Zircon U-Pb age data and whole rock, amphibole and apatite major and trace element geochemistry are reported together with previously published data. The results indicate a focused sub-alkaline magma event at 41 Ma in the North Yulong district and contemporaneous mineralization between 41.0 and 40.9 Ma at Yulong. Among the Yulong intrusive complex, the causative K-feldspar granite porphyry with high K2O (up to 7 wt%) and SiO2 (∼70 wt%) contents and elevated Sr/Y ratios (70–90), is interpreted to be a product of fractional crystallization of the evolved sub-alkaline magma. When the Yulong deposit is compared with the global porphyry Cu deposits with similar metal endowment and coeval sub-economic intrusions and barren igneous rocks in the belt, we find that high oxidation states (ΔFMQ + 1.0∼+2.5) and water contents (∼4–6 wt%) coupled with elevated background Cu contents (∼40–120 ppm) in the causative magma are essential in the formation of porphyry Cu deposits. However, the porphyry Cu deposits have magmatic S concentrations (∼10–100 ppm; estimated from apatite SO3 contents) comparable to that of the barren igneous rocks, independent of the relative timing of apatite crystallization to fluid exsolution. Overall, these conditions are necessary but not sufficient alone to form a porphyry deposit. The economic porphyries commonly have shallower emplacement depths (∼4–5 km) which favor extensive fluid exsolution and larger magma volume (∼50–250 km3 at Yulong) which provide enough storage of ore elements than the barren igneous rocks. In the North Yulong district, extensive fluid exsolution is absent from the two sub-economic intrusions indicated by their relatively high and fixed oxygen fugacity and H2O and Cl contents in the magma evolution. In contrast, at Yulong, a local anticlinal structure provided a trap in which exsolved fluid from the magma was concentrated, and carbonate wall rocks triggered the efficient precipitation of metals during intense fluid-rock interactions and skarn alteration. Both are also critical processes in the formation of the giant Yulong Cu deposit.

Rare earth mining and consumption global trends and mining perspectives for the Mushugay Khudug deposit in southern Mongolia

In this work the 3 ore body drill core samples. 6 host rock samples from the main ore body of the Mushugay Khudug REE deposit in southern Mongolia were selected as most representative samples and studied by XRD and ICP-MS. LA-ICP-MS method to evaluate elemental and structural composition data of the deposit. According to our determinations the main orebody of the Mushugay Khuduk deposit contain up to 130 kg/ton of REEs. Despite the moderate total mineable reserve the main ore body of the Mushugay Khuduk deposit might compete economically with world's biggest REE mining deposits such as Bayan-Obo (Inner Mongolia. China) or Mountain Pass (California. USA) if consider the deposit's higher REE grade and easier to mine local geological condition. The important advantage of the Mushugay Khuduk deposit is that the relative contents of most valuable HREEs Eu. Tb. Dy. and Lu are significantly higher than that of Mountain Pass or Rayan-Obo. The relative net content of these four elements is 0.1% for Mountain Pass and 0.4% for Bayan-Obo. while the ore samples of the Mushugay Khuduk deposit has 0.75% according to our determinations.