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Geology and geochemical characteristics of the Xiajinbao Au deposit in Hebei Province, China
Get PDF秋田大学博士（工学）The North China Craton is one of important regions for precious metal resources in China. Eastern Hebei Province in the craton has a long history regarding supply of gold for royal dynasties for thousands of years. The exploration of gold resource has been focused on the granite porphyry for a long time in the North China Craton. The Xiajinbao gold deposit is located in Yanshan district of the Craton. It is located in the northeast part of Beijing, and about 210 km away from the Beijing. Granite porphyry (Ilmenite-series) and diorite are present in the Xiajinbao deposit. The orebody predominantly is hosted in the granite porphyry. In the Xiajinbao deposit, previous researches also suggested that the granite porphyry is the source of the gold mineralization based on the similar ages between the granite porphyry and mineralization. However, the gold mineralization of the Xiajinbao deposit is thought to be formed by oxidized magmatism such as diorite based on the data in this study.
The orebodies of the Xiajinbao deposit, composed of aggregates of large number of veins and veinlets having width from 5cm to 1mm, occur mainly in the granite porphyry within an area of 800m by 300m. Base on cross-cutting relationships, the veins are classified into pyrite-quartz veins, pyrite-chalcopyrite quartz veins, and sphalerite-galena quartz veins from earlier to later. Pyrite quartz veins are composed of large amounts of quartz and pyrite with trace amounts of chalcopyrite and electrum. Pyrite-chalcopyrite quartz veins are composed of large amounts of quartz, pyrite, and chalcopyrite. Sphalerite-galena quartz veins are composed of large amounts of quartz, sphalerite and galena, small amounts of pyrite and chalcopyrite, and trace amounts of native bismuth, tetrahedrite and electrum. Quantity of electrum in sphalerite-galena quartz veins are larger than that of electrum in the pyrite quartz vein and pyrite-chalcopyrite quartz veins.
The granite porphyry consists of quartz, orthoclase, plagioclase and biotite as phenocrysts with trace amounts of ilmenite, zircon, rutile and apatite without magnetite. On the other hand, the diorite consists of plagioclase, amphibole and biotite with small amounts of apatite, magnetite, hematite, ilmenite and pyrite. The magnetic susceptibility of granite porphyry is generally Akita University lower than 0.1×10⁻³ SI unit while the diorite have much higher magnetic susceptibility from 30 to 60 ×10⁻³ SI unit in the Xiajinbao deposit. The igneous activity of Xiajinbao mining area is characterized by bimodal igneous activity. The distribution of diorite dike accords with the distribution in areas having high Au content. Au rich part (approx. 220ppm) is present near the diorite dike in the underground workings of the Xiajinbao deposit. These geological features indicate that mineralization has relationship with those diorite dikes in space.
The SiO₂ and TiO₂ contents of granite porphyry are around 70 wt% and 0.2 wt%, respectively. The Al₂O₃ contents of granite porphyry range from 13.9 to 14.3 wt%. The T-Fe₂O₃ contents of granite porphyry range from 1.9 to 2.5 wt%. The Na₂O and K₂O contents of granite porphyry range from 2.3 to 2.9 wt% and 4.6 to 6.1 wt%, respectively. The aluminum saturation index of granite porphyry ranges from 1.12 to 1.28. These features suggest that the granite porphyry belongs to the ilmenite-series granitic rocks. The granite porphyry was formed by reduced magma. On the other hand, the SiO₂ and Al₂O₃ contents of diorite dikes are 49.1 to 51.1 wt% and 13.7 to 16.3 wt%, respectively. The TiO₂ content of diorite dikes ranges from 1.0 to 3.1 wt%. The T-Fe₂O₃ content of diorite dikes is 7.3 to 11.5 wt%. The Na₂O and K₂O contents of diorite dikes are 3.3 to 4.1wt% and 2.4 to 2.9wt%, respectively. The Zr/TiO₂ ratios of granite porphyry and quartz porphyry dikes are both around 770 while the Zr/TiO₂ ratios of diorite dikes in the underground and outcrop are approximately 150 and 60. These ratios indicate that the characteristics of magma of granite porphyry and quartz porphyry dikes are similar. On the other hand, these are different from the characteristics of magma of diorite dikes.
The sulfur fugacity of sphalerite-galena quartz vein is estimated to be around 10⁻¹² atm. The formation environment of the sphalerite-galena quartz vein of the Xiajinbao deposit is similar to the environment of zoned base metal veins associated with oxidized magma. The δ³⁴S values of sulfide minerals of the Xiajinbao deposit range from -3 to +8 ‰ with a mode of +4 ‰. The distribution of sulfur isotopic ratios of the sulfide minerals of the Xiajinbao deposit are similar to the distribution of δ³⁴S of ores associated with oxidized magmas. The formation environment of gold-bearing sphalerite-galena-quartz veins of the Xiajinbao deposit is different from formation environment of hydrothermal activities associated with reduced granitic magma. The oxygen and hydrogen isotopic ratios of hydrothermal solution in equilibrium with quartz from the sphalerite-galena quartz vein range from +3.3 to +5.5 ‰ and -38 to -41‰, respectively. The oxygen and hydrogen isotopic ratios suggest hydrothermal solution of the pyrite quartz veins, pyrite-chalcopyrite quartz veins and sphalerite-galena quartz veins was magmatic origin.
Based on the geological, geochemical and isotopic data, Au mineralization of the Xiajinbao deposit is thought to have intimate relation with oxidized magma such as diorite
Neovasculature can be induced by patching an arterial graft into a vein:A novel in vivo model of spontaneous arteriovenous fistula formation.
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Clinicopathological and long-term prognostic features of membranous nephropathy with crescents: a Japanese single-center experience.
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Effects of combined therapy of alendronate and low-intensit pulsed ultrasound on metaphyseal bone repair after osteotomy in the pxoximal tibia of glucocorticoid-induced osteopenia rats
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A comparison of the therapeutic efficacy of transarterial chemoembolization and combination therapy with transarterial chemoembolization plus sorafenib for unresectable hepatocellular carcinoma
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Influence of CYP3A5 genetic differences in tacrolimus on quantitative interstitial fibrosis and long-term graft function in kidney transplant recipients
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Behavior of elements in river watar of Tamagawa-Omonogawa River System containing acidic thermal watar in Akita Prefecture: Roles of dam lakes along the River System
Get PDF秋田大学博士（工学）For understanding the element cycles under subaerial environment, knowledge of chemical forms and the variation of chemical forms of elements in river water is important. The aim of this study was to assess the relevance of dissolved (0.2 μm) forms for the transportation and accumulation of elements in the river water of Tamagawa-Omonogawa River System in Akita Prefecture, Japan. This river system contains acidic thermal water due to the discharge of the Obuki Cl-SO4 type thermal water to Tamagawa River and Kawarage Cl-SO4 type thermal water to Omonogawa River at the upstream of both rivers. Obuki Hot Spring discharges 9000 L/min of acidic thermal water (pH 1.2) to Tamagawa River while Kawarage discharges 7300 L/min thermal water of pH 1.4 to Omonogawa River. The environmental impact of thermal water of Obuki Hot Spring is larger than that of thermal water of Kawarage Hot Spring. Tamagawa River runs through the area mainly composed of Quaternary and Neogene volcanic rocks and has four lakes and dam lakes along the river, while Omonogawa River runs through the area mainly composed of Neogene strata and Quaternary strata covering Neogene sedimentary rocks and has no dam lakes.
The characteristics of major elements are similar in Tamagawa and Omonogawa Rivers. All of the major elements are present in the dissolved form in the river water. Inflow of acidic thermal water into Tamagawa and Omonogawa Rivers changes the pH of the river waters to acidic in upstream. Toward downstream, the river water of Tamagawa and Omonogawa River become more neutral due to the addition of neutral river water from tributaries. However, the change of pH value of river water of Tamagawa-Omonogawa River System would not give effect to the state of chemical forms of major elements.
According to acidic river water at upstream of Tamagawa River, concentrations of dissolved metals are also high except Fe and As. Dissolved Fe and As easily change into colloidal and/or particulate forms in river water in upstream of Tamagawa River. As a result of the process, Fe-rich layered sediment is present in Tamagawa Dam Lake. A large influence of hydrothermal activity from Obuki Hot Spring was recorded in the sediment at Tamagawa Dam Lake, resulting in high Pb content within sediment layers at 5 to 8 cm from bottom of the dam. At the downstream site, the influence of acidic thermal water becomes small due to addition of neutral river water from tributary and supply of particulate material from the erosion of Neogene and Quaternary sedimentary rocks. The pH of river water of Tamagawa River changes from 4.6 at Tamagawa Dam Lake in upstream to 7.1 in downstream at Ogamari in Daisen City. The particulate forms of Al, Fe and trace metals in river water contribute to the increase of concentration of these elements in lower Tamagawa River in Omagari. Based on observation and analyses by SEM-EDX and XRD, the particulate materials are thought to be clay minerals such as chlorite and illite/montmorillonite.
In Omonogawa River, sizable proportion of Al and Fe were found within the particulate form that is similar to Tamagawa River. The small proportions of Cu and As were observed as dissolved form and the proportion of these elements in colloidal form increases toward downstream, which is a different tendency with the distribution of these elements in Tamagawa River. The clay minerals derived from the sedimentary rocks along Omonogawa River could be the host of elements as particulate form and caused the increasing concentration of Al, Fe, Mn and trace metals in river water at downstream site. Concentrations of Al, Fe, Mn and trace metals in particulate form of river water of Omonogawa River are higher than those of Al, Fe, Mn and trace metals in particulate form of river water of Tamagawa River.
The amounts of Al, Fe, Cu and As that are transported by river water of Tamagawa River in winter season decreased from upstream to downstream (118 to 18 ton/month, 8 to 6 ton/month, 49 to 26 kg/month and 37 to 23 kg/month, respectively). On the other hand, the amounts of Fe, Cu, and As that are transported by river water of Omonogawa River in winter season increase from upstream to downstream (15-148 ton/month, 22-225 kg/month and 112-308 kg/month, respectively) while the amount of Al in river water of Omonogawa River is constant (27 ton/month). The amounts of Al, Fe, Cu, and As in river water of Omonogawa River, however, are 18, 5, 13 and 2 times larger than those are transported by river water of Tamagawa River to the Sea of Japan, respectively. In other seasons, the amounts of elements transported by Omonogawa River are also several times larger than the amounts of elements transported by Tamagawa River. These differences accord with (1) the presence or absence of dam lakes along Omonogawa (no dam lake) and Tamagawa Rivers (4 dam lakes) and (2) difference in dominance of Quaternary and Miocene sedimentary rocks between Omonogawa and Tamagawa Rivers. The dam lake could play an important role as a sink for particulate materials and reducing the environmental impact
Study on the Improvement of Interior Illumination Distribution by Using Lighting Equipment on Window in order to Use Daylight
Get PDF秋田大学博士（工学）Lighting is always necessary during the operation hours from morning to night in an office building and generally, the amount of electric power consumed by lighting is about 20% to 30% of the total electric power consumption. Therefore, the positive effect of using daylight for energy saving in office, and the development of a system that utilizes daylight positively is attracting attention. When developing a lighting device in practice, the season, weather and many other factors have to be considered. For example, when using daylight, direct sunlight entering the room is often dazzling and cannot be used directly. And, in the case of Akita City, the solar altitude angle (the angle between the sunbeam and the earth plane) depends on the season, it is about 75°at noon of the summer solstice where the sun is the highest, while it is about 30°on the winter solstice. Furthermore, solar azimuth angle moves from east in morning to west in the evening. Due to this, the angle of light entering rooms from the windows also changes, which may affect the indoor lighting environment as well. In order to solve these problems, it is necessary to develop a window system using daylight combined with seasonal strong light shielding.
In this research, I have aimed to reflect the direct sunlight incident on the ceiling by attaching angle-changeable reflecting plates (blind-reflectors) to the window, and use the reflected diffused light from rough material of the ceiling for room lighting. In order to avoid dazzling daylight from the window and create a comfortable indoor environment, reflector angle that can be adjusted accordingly with changes in the solar angle of all seasons is needed and it is necessary to obtain the illuminance distribution of the work surface when designing the actual lighting. However, the angle of incident light from the window and the amount of incident light flux change gradually. In order to find out the illuminance distribution in various situations, it is necessary to spend enormous amount of time and cost in designing by performing actual measurements and calculation manually.
Therefore, in order to reduce the time and cost to manually measure and calculate these illuminance distributions, a simulation of illuminance distribution using the Monte Carlo method was performed. In preparing the simulator, I made it possible such that lighting fixtures, rooms, windows and etc. can be freely set and installed. In addition, an illuminance distribution simulator was created that can display the illuminance distribution chart after calculating the reflector angle with sunlight. The function to simulate changes in solar angle depending on the season and time zone was also calculated. In this simulator, the Monte Carlo method was used because compared with other methods, it can reproduce the properties of light with higher precision on a computer, and calculate the illuminance distribution by simulating various conditions in the room desired for virtual space. However, in order to obtain excellent calculation results, enormous calculation time is required. On the other hand, in this study, by using a new Monte Carlo method for the photon flux generation method from lighting fixtures, fluorescent lamps of various shapes can be reproduced with a point light source, and the calculation speed of the illuminance distribution can be shortened with a simulator. First, the validity of the lighting fixture and the validity of the window by comparing the measured value and the simulation value was compared using this simulator. This method was used to investigate the illuminance distribution in the indoor space. From the simulation results, the indoor lighting environment when changing the solar angle and the reflector’s angle in the window was compared. And thus, the possibility of reducing the power consumption was testified.
A model space of a typical laboratory of Akita University was considered in this research work and calculation of illuminance distribution was performed. These simulation works meet the indoor lighting standards described in 「Lighting standard JIS Z 9110: 2010」of the Japanese Industrial Standard (JIS). The sun angle used in the simulation was based on the solar altitude angle and solar azimuth angle at Akita University and the solar flux amount was also calculated from the measured values. In order to avoid problems such as sunset, this research used daylight in the time zone from 9:00 to 15:00 throughout the whole year. The illuminance distribution on the work surface was compared for the cases of with and without any reflectors installed in the window. From the results, one can understand that the lighting in the room was comfortable when the reflectors were installed in the window. And the effectiveness of the blind reflectors was also confirmed.
In the window system whereby reflectors were installed, the design of the reflectors is important. For example, when designing a reflector, if the width is too long, the daylight that can be reflected on the ceiling will be blocked, and the amount of light taken into the room will reduce. On the other hand, when the width of the reflector is too short, daylight illuminating the workplace through the reflectors will be too dazzling. In order to improve the practicality and performance of the reflector system, I have performed several simulation works to understand the dimensions of the blind reflectors and their installation process in a manner so that the highest amount of light is reflected on the ceiling. As a result, parameters such as the number of blind reflecting plates, length, distance, etc. were determined for real environment in order to get a better lighting system. In actual simulation, since comfortable lighting environment can be obtained, it is installed so that incident light can be reflected to the center of the ceiling. In this research, the JIS illuminance reference values was set as the target values, and by applying the knowledge of the change in the indoor environment due to the change of the position of the sunlight, the horizontal and vertical angle of the slat of the blind reflector was adjusted and the angles which satisfy the comfortable lighting environment under each environment was measured.
From these results, the amount of energy saving which can be achieved by comparing power consumption when using daylight was examined. In the near future, by improving the window system with reflectors, better energy saving effect is expected which will contribute to a sustainable energy saving society
Comprehensive evaluation of geothermal, solar, and wind enegy potential considering the impact of geophysical and environmental factors
Get PDF秋田大学博士（工学）Nowadays, governments and energy decision makers have decided to increase the share of renewable energy resources in the country's energy mix as an alternative to meet the increasing demand of energy and to protect environment from the air pollutions. The resources like solar, wind and geothermal energy are environmental friendly with almost no air pollution (as they do not burn any fuel) and also freely abundant around the world. The increasing rate of electricity consumption in Iran as a developing country approves the necessity of using renewable energies to generate electricity in the future and also benefit the environmental advantages associated with these kinds of energies.
However, dependency of these resources on climate and weather arises some challenges in renewable resource assessment. Despite fossil fuel power plants are usually being installed in the vicinity of populated and energy demand areas, renewable energy resources such as geothermal reservoir or the terrains with higher annual wind speed which commonly are suitable for wind farms construction exist at special regions. Thus, the transferability of the energy is one of the scant advantages of fossil fuels in comparison renewable energies. In this regard, installing renewable energy power plants at the best appropriate locations that results maximum energy generation, is necessary to generate power in a reasonable price. Therefore, a wise site selection for renewable power plants can make them competitive with relatively cheap fossil fuels. Suitable areas for each energy resource heavily depend on the technical, environmental and economic issues. In this study the potential of various renewable energy resources in two different parts of Iran have been evaluated to investigate the influences of climate effect. The main goal of this study is to introduce a general and executive methodology to increase the share of renewable energies all around the world. In this research, the various geothermal technologies including flash (single and double flash) and ORC (five various configurations) cycles, different commercial solar power plants (including photovoltaic and concentrated solar power) and onshore wind turbines have been tested to estimate their electricity generation potential.
This thesis follows two main goals including the evaluation of renewable energy potential in North West of Iran and the study generalization for northern part to investigate the impact of geophysical and environmental factors. For the first goal, the total renewable energy potential in order to generate electricity has been estimated in the North West of Iran. This area that is a mountainous region comprises three populous provinces namely East Azerbaijan, West Azerbaijan and Ardabil.
After a brief explanation of the current energy status in the world and Iran in the Chapter 1, the electricity consumption trend has been modeled to predict the future consumption for this area, in the Chapter 2. Two different prediction methods, including simple regression and Grey system were employed to model the existing energy consumption data.
According to the results of the simple regression equation and also the Grey system, the electricity consumption in 2050 was estimated to reach to 30,001.1 GWh and 37,462.01 GWh, respectively. Thus, in the worst condition this area will see the energy consumption of around 37 TWh as of 2050.
In Chapter 3, a thermo-economic analysis was used for existing geothermal reservoir at this area to define the best arrangement of geothermal technologies (including flash cycle and bottoming ORC cycle) that results in the higher energy production with lower energy cost. A single flash cycle which coupled with for IHE-ORC (ORC with internal hear exchanger) delivers around 330 GWh was determined as the most appropriate arrangement for this field.
Afterwards, in Chapters 4 and 5, solar and wind energy potential has been estimated using a multi criteria decision making analysis and by applying various criteria. In this regard, the different criteria have been classified into two groups to study the effect and importance of each factor. The elevation and slope criteria have been applied as the first group to show the effect of natural characters and items of the nature like mountainous areas. Similarly, other environmental items such as roads, rivers or cities that mostly are human made or changeable in the future have been considered as the second group. The main goal and advantage of this method is to show the elimination share of each criteria group and its influence on removing unsuitable areas.
The results of the first part for the first case study showed that there is a promising renewable potential in this area that can cover the electricity consumption more than 48 times. The total predicted energy consumption of this region in 2050 (37 TWh) can be covered by using total potential of geothermal power (330 GWh), wind energy (20,443 GWh) and a small percentage of huge available solar power (1,763,100 GWh).
In the second part of this thesis in Chapter 6, as the main achievement of this study was to make comprehensive and adjustable models for each energy resources that includes their all required criteria. These models allow us to calculate and map the potential of other regions with different specifications easily and only by changing the input data and layers. For this part again three other provinces which are located in the northern part of the country were chosen. North part of the country is a coastal area with moderate climate that comprises three provinces namely: Gilan, Mazandaran and Golestan. The results indicated that in comparison with Northwestern area, higher percentage of the total area in the North part (higher than 40%) has been eliminated for both wind and solar energy by environmental items. Despite the environmental criteria, in the slope and elevation points of view, much percentage of areas in Northwest part has been placed as unsuitable areas due to higher elevation and steep areas. Additionally, even though the allowed bounds of slope for solar application was much more restricted than wind power plants (lower than 15 and 3 degrees for wind and solar power plants, respectively) but the sum of these two factors for wind is higher than solar applications. Therefore, it can be concluded that elevation criterion was dominating factor for these areas and had very effective influence on removing the areas.
In conclusion, the introduction of this approach is the comparative tool to increase the share of renewable energies in the world. This method assists the energy planners to obtain the most promising areas for renewable energies by estimating their potential roughly based on their climate and other land characters. The results of this method are useful in the early stages of energy assessment processes to focus and invest more on promising areas in the next steps