Relationship between alteration mineralogy and lithogeochemistry associated with the Backun epithermal Au-Ag deposit

이길재 충남대학교 대학원 2009 국내석사

Hydrothermal alteration records the effects of fluid-rock interaction, and these effects are expressed as compositional changes that can be recognized in the geochemistry of the rocks. Where compositional changes define gradients that can be related to processes that form ore deposits, they potentially provide vectors toward sites likely to contain precious metal mineralization. Alteration indices and pathfinder elements, are potentially effective for targeting of mineralized veins, involving geochemical dispersion and mineralogy. To sum up with the geochemical dispersion, consequently simplified of K and Si enrichments and Na and Ca depletion present a larger footprint than do anomalous concentrations of precious metals, base metals, and pathfinder elements. Although most of the alteration index has been applied on VHMS deposits, the Backun epithermal Au-Ag deposit shows great possibility of application. The threshold could be the value of wall rock's alteration index, depends on the composition of forming minerals. The alteration box are most likely to be useful when epithermal deposit exploration is conducted. Clear gain or loss elements with high score of coefficients of correlation likely to be a great pathfinder. For granite, K2O, Rb, Tm, Sm, Y, Fe2O3, Ni, Co, Cd, Tl, S, Zn, Total S have not only positive strong coefficients of correlation with gold and silver, but also largely gained value toward mineralized vein. For intermediate dyke, Ni and Co have strong negative coefficients of correlation with gold and silver as well as loss of those elements, U is opposite that positive coefficient of correlation as well as gain of that element. These elements are potential pathfinder as well. Petrographic study of the paragenetic relationships between hydrothermal and supergene minerals is required to maximize the usefulness of whole-rock geochemical data (Warren et al., 2007).

Micromechanical Controls on Brittle to Plastic Fault Zone Deformation

Kohli, Arjun H ProQuest Dissertations & Theses Stanford Universit 2015 해외박사(DDOD)

This thesis focuses on the applications of experimental rock mechanics and geophysical microanalysis to the study of the structure, physical properties, and deformation mechanisms of geologic fault zones. The motivation for this approach is to connect mechanical and microstructural (micromechanical) data to physical processes occurring on faults in-situ. I examine these relationships in three distinct geologic settings, emphasizing the general interdependence of microstructure, mechanics, and mineralogy. Section 1 (Chapters 1-3) examines the physical properties on and around faults during hydrocarbon production from shale reservoirs. Chapters 1 and 2 focus on the compositional and thermal controls on shale frictional strength and stability, which provide insights into the occurrence of induced fault slip during hydraulic stimulation. Chapter 3 presents multi-scale investigations of shale matrix microstructure, employing electron microscopy and micro-computed tomography to highlight variations in pore networks with composition and reservoir setting. Section 2 (Chapter 4) explores the mechanical behavior of fault gouge from San Andreas Fault Observatory at Depth (SAFOD), which motivates a constitutive law consistent with microstructural evidence of aseismic deformation along the San Andreas Fault creeping section. Section 3 (Chapter 5) presents rheological and textural investigations of peridotite mylonite samples dredged from an oceanic transform fault, which provide new evidence of the depth extent of fluid infiltration and brittle deformation in the mantle lithosphere. Although these sections focus on distinct geophysical applications, they are united in demonstrating the utility of micromechanical studies in furthering our understanding of physical processes in geologic fault zones.

Biogeochemical Cycling in Pristine and Mining-Impacted Upland Fluvial Sediments

Saup, Casey Morrisroe ProQuest Dissertations & Theses The Ohio State Uni 2020 해외박사(DDOD)

Upland catchments play an outsized role in the processing and export of water, sediments, nutrients, and organic matter, thus strongly influencing downstream water quality. In Chapter 1, an overview of biogeochemical cycling within upland fluvial sediments is presented, focusing on key regional biogeochemical cycling patterns and solute export processes. Additionally, anthropogenic influences on this environment, such as historical mining activities and climate change, are briefly reviewed in this chapter.Chapter 2 explores the relationship between spatial hydrologic heterogeneity and microbial community assembly and functional potential within the hyporheic zone. The region of groundwater and river water mixing, known as the hyporheic zone, is a hotspot of microbial activity that influences solute export and cycling in rivers. Hyporheic mixing patterns can vary over small spatial scales, leading to heterogeneity in fluid chemistry and microbial community composition and function. Here, we integrate new mass-spectrometry data, metagenomic insights, and ecological models with previous analyses of microbial community composition and dissolved organic matter (DOM) quality to understand spatial relationships between hyporheic flow and microbial community assembly, metabolism, and DOM processing at high-resolution (100 locations) along a 200 m meander of East River, Colorado (USA). Ecological modeling revealed a strong linkage between community assembly patterns and underlying hydrologic and geochemical drivers, including the impact of physical heterogeneity (riverbed grain size) on microbial community structure. Geochemical profiles associated with upwelling groundwater suggest the influence of underlying geology, specifically Mancos-derived solutes, in driving community assembly. Distinct microbial community profiles and functional potential in zones of upwelling groundwater suggest that groundwater chemistry may have a greater influence on biogeochemical cycling within the river channel as periods of baseflow increase in both frequency and duration under future climate change scenarios.Chapter 3 investigates the seasonal impacts of snowmelt-dominated hydrology on hyporheic microbial community dynamics and associated biogeochemistry. Terrestrial and aquatic elemental cycles are tightly linked in upland fluvial networks. Biotic and abiotic mineral weathering, microbially-mediated degradation of organic matter, and anthropogenic influences all result in the movement of solutes (e.g., carbon, metals, nutrients) through these catchments, with implications for downstream water quality. Within the river channel, the region of hyporheic mixing represents a hotspot of microbial activity, exerting significant control over solute cycling. To investigate how snowmelt-driven seasonal changes in river discharge affect microbial community assembly and carbon biogeochemistry, depth-resolved pore water samples were recovered from multiple locations around a representative meander on the East River near Crested Butte, CO, USA. Vertical temperature sensor arrays were also installed in the streambed to enable seepage flux estimates. Snowmelt-driven high river discharge led to an expanding zone of vertical hyporheic mixing and introduced dissolved oxygen into the streambed that stimulated aerobic microbial respiration. These physicochemical processes contributed to microbial communities undergoing homogenizing selection, in contrast to other ecosystems where lower permeability may limit the extent of mixing. Conversely, lower river discharge conditions led to a greater influence of upwelling groundwater within the streambed and a decrease in microbial respiration rates. Associated with these processes, microbial communities throughout the streambed exhibited increasing dissimilarity between each other, suggesting that the earlier onset of snowmelt and longer periods of base flow may lead to changes in the composition (and associated function) of streambed microbiomes, with consequent implications for the processing and export of solutes from upland catchments.Chapter 4 explores the metal mobilization patterns that occurred as a result of a mine waste spill. The Gold King Mine spill in August 2015 released 11 million liters of metal-rich mine waste to the Animas River watershed, an area that has been previously exposed to historical mining activity spanning more than a century. Although adsorption onto fluvial sediments was responsible for rapid immobilization of a significant fraction of the spill-associated metals, patterns of longer-term mobility are poorly constrained. Metals associated with river sediments collected downstream of the Gold King Mine in August 2015 exhibited distinct presence and abundance patterns linked to location and mineralogy. Simulating riverbed burial and development of anoxic conditions, sediment microcosm experiments amended with Animas River dissolved organic carbon revealed the release of specific metal pools coupled to microbial Fe- and SO42--reduction. Results suggest that future sedimentation and burial of riverbed materials may drive longer-term changes in patterns of metal remobilization linked to anaerobic microbial metabolism, potentially driving decreases in downstream water quality. Such patterns emphasize the need for long-term water monitoring efforts in metal-impacted watersheds.Finally, Chapter 5 summarizes key findings and conclusions as well as outlines remaining questions that may be addressed in future work. The results presented in this study highlight the importance of seasonal and spatial hydrologic heterogeneity in upland watershed biogeochemistry. In collecting this information, I have expanded current knowledge of hyporheic hydrobiogeochemistry in upland fluvial systems. Particularly, I conclude that seasonally-driven dynamic water mixing patterns within the hyporheic zone create unique geochemical profiles that drive differences in microbial community composition, assembly, and functional potential. Our results provide insights into the relationship between hydrology and microbial community and metabolisms within river corridors, information which is critical to understanding water resources, particularly in our rapidly changing climate.

The mineralogy of tin slags

Farthing, Dori Jean The Johns Hopkins University 2002 해외박사(DDOD)

Slag is the waste formed when ore is smelted to extract a metal. This research investigated the mineralogy, chemistry, and alteration of slag and has forged new pathways in the world of slag research by using multiple geological and analytical tools. These tools include simple hand sample observations, traditional light microscopy, X-ray diffraction, X-ray fluorescence, and electron microscopy (electron microprobe and transmission electron microscopy). Knowledge of slag mineralogy, chemistry, and alteration is necessary to predict if a slag will release hazardous elements into groundwater, surface water, or soil. This is especially a concern when slags contain radioactive elements or heavy metals. This research concentrated upon the mineralogy, chemistry, and alteration of tin slag from southwest Great Britain and from sites in Pennsylvania monitored by the United States Nuclear Regulatory Commission (NRC). The mineralogy of these slags was not uniform, and there were few similarities between the British and the American samples. British tin slags formed from two different smelting processes (blast furnace or reverberatory furnace) are distinct mineralogically and chemically. Also, many of the slags from Cornwall are radioactive. In all of the British slag fragments, glass and iron prills are the most susceptible to alteration. Studies of the slag from the NRC sites yielded different information. Samples of hibonite from one of the slags were studied with transmission electron microscopy in order to investigate their atomic structure. The hibonite crystals were practically defect-free, although one crystal featured a second nanoscale phase within its structure. The interface between this phase and the hibonite was coherent. Another NRC slag contained Cr-rich spinel. Further studies of this slag indicated that dendritic periclase and metallic iron prills were highly susceptible to alteration and were replaced by Fe-oxyhydroxides at the sample's edges. An estimated weathering rate for this slag is 7 μm of slag per year. An estimate of the maximum release rate for U and Th from the slag is 2.4 ng/cm<super> 2</super>year. A complete understanding of the mineralogy, composition, and alteration features of all slags is essential for determining their long-term safety and stability.

중금속 존재형태 및 광물학적 특성을 고려한 중금속오염 토양정화의 새로운 접근

유종찬 전북대학교 일반대학원 2017 국내박사

In this study, soil washing process based on the fractionation and mineralogy characteristics of heavy metals was developed in order to enhance the technical, economic, and environmental efficiencies. This study was composed as follows: (1) literature investigation in soil washing process provided with the information of site and metal characteristics as well as the process efficiency, (2) determination of metal extraction characteristics based on fractionation and mineralogy of metals, (3) applicability assessment of those extraction mechanisms using field soils, (4) proposal of screening matrix using parameters influencing on chemical extraction efficiency. As a results of literature investigation related to chemical extraction in washing process for metal-contaminated soils with Cu, Pb, Zn, and As, it was found that soil texture, soil organic matter, contamination source, fractionation and mineralogy of metals, and washing conditions include type/concentration of washing agents highly influenced to the process efficiency in technical. However, it was difficult to confirm determining the parameters influenced on the chemical extraction efficiency because most of the literatures did not provide the same information of soil and contaminants. Among them, the type/concentration of washing agents as well as the fractionation/mineralogy of heavy metals as the contamination sources and site characteristics highly influenced to efficiency of the process. Therefore, the selection of the process conditions as well as the understand of site/metal characteristics are important to enhance the efficiency of the process. Furthermore, two types of washing processes were carried out to determine metal extraction characteristics, which was representatively conducted for Pb. In the washing process to evaluate extraction characteristics of Pb presented in labile forms and Pb minerals from Pb-contaminated artificial and field soil samples, at first ferric iron based extractants include FeCl3 and Fe(NO3)3 did significantly enhance the Pb extraction from soils. These extractants could be used as an extracting agent for labile Pb in soils and PbO, PbCO3, Pb3(CO3)2(OH)2, and Pb5(PO4)3(OH) having a high solubility through ion exchange between Pb and hydrogen ions produced by dissociation of water molecule. In particular, ferric iron ions remained in solution during the washing process repeatedly produced the hydrogen ions which continuously extracted Pb into solution from soils. Futhermore, they could be used as an oxidizing agent for PbS through redox reaction between ferric iron and sulfide. FeCl3 was the most an applicable extractant to remediate contaminated marine sediment with Cu and Zn because of the unique characteristics include a high proportion of carbonates, organic matter and sulfides of marine sediment compared with inland soil. Cu was associated with organic matter and sulfides, which could be extracted by FeCl3 through redox reaction between ferric iron and sulfide and the complexation between organic matter and Fe instead of Cu. The labile Zn presented in the sediment was extracted by repeatedly ion exchange with hydrogen ions during the washing process. Actually, the excessive use of inorganic acids was effective to extract Cu and Zn. However, they induced a severe solution and sediment acidification, which contributed in a significant increase of agent costs in neutralizing wastewater and sediment. Finally, we proposed a chemical extraction screening matrix on washing process to provide washing guideline as the characteristics of soil and contaminant through literature investigation for influencing parameters in chemical extraction. Based on the screening matrix, in addition chemical extraction process using twelve types of metal-contaminated soils with Cu, Pb, Zn, and As formed in various contamination sources was conducted and evaluated the applicability of screening matrix. There were a significant positive tendency between the extraction efficiency and metal/site characteristics which are matched with literatures. However, the characteristics of the soils and heavy metals investigated in the literature were inconsistent with most soil samples used in this study. Therefore, it will be necessary to continuously conduct literature investigations related to the characteristics of soils and heavy metals as well as the process efficiency, and to obtain as much data as possible.

Mineralogy of Hypermineralized Bone

Li, Zhen Washington University in St. Louis 2013 해외박사(DDOD)

In the present study, a rostrum bone from a Mesoplodon densirostris whale (~96 wt.% mineral) and bullae (ear bones) from Tursiops truncates dolphins (~85 wt.%) are analyzed by several techniques, e.g., Raman spectroscopy, electron microprobe, and scanning electron microscopy, to investigate the mineralogy, to compare hypermineralized bone to enamel, and to distinguish age-related changes of the bioapatite in bone. Firstly, it is necessary to confirm that these hypermineralized materials are true bone, rather than hypermineralized enamel or other dense bio-tissues. The Raman spectra of the rostrum and bullae show similar peak occurrence as in other normal bones, except for the low intensity of peaks for organics. Raman spectra also confirm that the mineral in the rostrum and bulla is carbonated hydroxylapatite, just as in other normal bones. A set of bone features, e.g., collagen fibrils, lacunae, osteons, vascular holes, and blood vessels, are identified in the rostrum. The dolphin's bulla has long been recognized as true bone because it is actually the ear bone. However, these two types of hypermineralized bone show distinct processes of mineralization. The high density of the bulla results from complete filling of the inter-trabecular spaces with hypermineralized tissue, whereas the rostrum undergoes hypermineralization during extensive remodeling and development of secondary osteons. Secondly, the hypermineralized rostrum, as a bone exemplar, was used to investigate the chemistry of bioapatite. Electron microprobe analyses of the rostrum's bioapatite show an average carbonate content of ~8 wt% and an average Ca/P atomic ratio of 1.7. Electron microprobe and Raman analyses show a homogenous distribution of the mineral content, except around a few vascular holes and vessels. Hydroxyl depletion in the bioapatite is coupled with carbonate substitution and Ca can be substituted by Na and Mg in mineralization. In addition, the rostrum has some minor elements (K and Cl) and extremely low-concentration trace elements (Al, Si, Fe, Ti and Sr), as in typical bone materials. Thirdly, the rostrum was compared to the tooth enamel. At the micrometer scale, the lengths and widths of mineral prisms in enamel are four times larger than those in the rostrum. However, platelets that constitute the prisms are wider in the rostrum (~200 nm) than those in enamel (~70 nm). The bioapatite crystals in the rostrum also show a lower degree of crystallinity compared to those in enamel based on the widths of the nu1 P-O stretch at about 960 Deltacm-1 in Raman spectra. The hypermineralized bone therefore has a greater heterogeneity in almost every aspect of its mineralogy compared to enamel. The tooth enamel is much closer to the standard hydroxylapatite in its chemistry. Finally, the mineralogical changes in bioapatite were investigated using dolphins' bullae. The bullae from dolphins at ages of < 3 months, 2.5 years, and 20 years were studied. Transverse sections show that the bullae have (previously undescribed) organic-enriched edge areas and mineral-enriched central areas. Additionally, the central areas have a ~2 wt.% more carbonate in their bioapatite than the edge areas. During aging, the abundant pores in the edge areas become filled with densely mineralized tissue whereas organic matter is reduced. These changes yield greater homogeneity in mineral content throughout the adult bullae. Ca/P atomic ratios and the concentrations of Mg, S, and other minor/trace elements, otherwise, are almost constant in the central areas over time. Enhancement of the coupled substitutions of CO3 2- for PO43- and Na for Ca during aging yield a carbonate content up to ~10 wt.% in the adult bulla, making its carbonate content at the high end of all bones. Remarkably, the degree of crystallinity of the bioapatite remains approximately constant with age despite the increase in carbonate contents. (Abstract shortened by UMI.).

Effect of Mineralogic Heterogeneity on Acid Fracturing Efficiency

Jin, Xiao Texas A&M University ProQuest Dissertations & Thes 2020 해외박사(DDOD)

Creating sufficient and sustained fracture conductivity contributes directly to the success of acid fracturing treatments. The permeability and mineralogy distributions of formation rocks play significant roles in creating non-uniformly etched surfaces that can withstand high closure stress. Previous studies showed that depending on the properties of formation rock and acidizing conditions (acid selection, formation temperature, injection rate, and contact time), a wide range of etching patterns (roughness, uniform, channeling) could be created. Different etching patterns can dictate the resultant fracture conductivity. Insoluble minerals and their distribution can completely change the outcomes of acid fracturing treatments. However large portion of acid fracturing studies is based on experimental investigation and uses homogeneous rock samples such as Indiana limestones that do not represent the highly heterogeneous features of carbonate rocks. This work studies the effect of heterogeneity, and more importantly, the distribution of insoluble rock on acid fracture conductivity.In this research, acid fracturing experiments were conducted using both outcrop homogeneous Indiana limestone samples and heterogeneous downhole carbonate rock samples. The Indiana limestone tests served as a baseline. The highly heterogeneous carbonate rock samples contain several types of insoluble minerals, such as quartz, anhydrite, pyrite, and various kinds of clays, along with sealed natural fractures. These minerals are distributed in the form of streaks correlated against the flow direction, or as smaller nodules. After acidizing the rock samples, these minerals act as pillars that significantly reduce fracture conductivity decline at higher closure stresses. Both x-ray diffraction (XRD) and x-ray fluorescence (XRF) test results help pinpoint the type and location of different minerals on the fracture surfaces. Surface scans showing surface topography after acidizing injection is captured by a surface profilometer. The surface scan results were used to correlate fracture conductivity as a function of mineralogy distribution. Theoretical models considering geostatistical correlation parameters were used to match and understand the experimental results.The observations of the experimental study showed that insoluble minerals with higher mechanical properties were less crushed at higher closure stresses, resulting in a less steep conductivity decline with increased closure stress. If the acid-etching creates enough conductivity, the rock sample can sustain higher closure stress with a much lower fracture conductivity decline rate compared with Indiana limestone samples. Fracture surfaces with insoluble mineral streaks correlated against the flow direction offer the benefit of being able to maintain conductivity at high closure stress, but not necessarily high initial conductivity. Using a fracture conductivity model with correlation length, the fracture conductivity behavior for the homogenous rock samples were matched. To match the downhole samples fracture conductivity behavior, the fracture conductivity model was modified with both x-ray diffraction tests for mineralogy distribution and triaxial tests for the rock’s Young’s Modulus. Parametric study with the geostatistical parameters was conducted to show that the fracture surfaces with mineral streaks correlated with the flow direction could increase initial acid fracturing conductivity significantly as compared to the case when the streak is correlated against the flow direction. The modified fracture conductivity mineralogy model was used in an acid fracturing model to calculate the overall fracture conductivity after the acid etched-width has been determined and the model is validated with the production data from a vertical deep carbonate well. The study used an inverse workflow to match the treatment pressure, determine fracture geometry, and match experimental fracture conductivity results with that simulated by the acid fracturing model. This study shows that fracture conductivity can be optimized by taking advantage of the distribution of insoluble minerals along the fracture surface, and discusses the critical considerations to make the acid fracturing treatment successful. If the surface minerals are not properly accounted for as pillars, fracture conductivity at higher closure stresses might be severely under-predicted, leading to acid fracturing not being used even though it is a cost-effective simulation method.

Comprehensive Study on Mineralogical and Geochemical Applications in Geosciences and Archaeometry

Bongsu Chang 고려대학교 대학원 2024 국내박사

본 연구는 유리 및 암석을 포함하는 지질물질을 대상으로 광물학적, 지구화학적 또는 암석학적 특성에 대한 포괄적인 분석과 해석을 수행하고, 그 자료가 지니는 지질학적 의미를 지구과학과 고고과학 분야에 적용함으로써 지질학 지식의 효용성과 확장성을 넓히는데 그 목적이 있다. 이를 위한 첫 번째 연구에서는, 화학조성의 차이에 따라 네 타입으로 분류되는 고대 유리 유물의 지리적 기원지를 확인하고, 타입별로 나타나는 독특한 지구화학적 특성이 기원지역의 기후와 지질 특성이 반영된 원료 물질의 사용에 기인한 결과라는 점을 규명하였다. 이는 향후 고대 동서 교역 네트워크 복원 연구에서 주요한 과학적 근거로 사용될 수 있다. 두 번째 연구에서는 응회암을 구성하는 광물상 조합과 화학조성 자료를 기반으로 응회암에 나타난 독특한 층상 조직이 형성된 과정을 화산 활동과 강우가 연계된 지질모델로 설명하였으며, 대상 응회암이 형성된 과정과 환경에 대한 시각화 된 통찰을 제공함으로써 향후 원료 암석을 확보하기 위한 전략 수립 과정에서 기원지 특정을 위한 지질학 및 지리학적 근거로 사용될 수 있다. 세 번째 연구는 휴대가 가능하고 현장 적용이 가능한 비파괴 분석법을 이용하여 암석의 광물학적, 지구화학적 특성을 정량적으로 파악함으로써, 조립질 화성암의 기원지를 노두 단위에서 명확하게 규명하였다. 특히, 정량 지구화학 자료를 기반으로 수십 km 범위에 걸쳐 존재하는 심성암체의 화학조성이 공간적으로 변화하는 경향성을 발견하고, 이에 근거하여 원료 암석 예상 분포지역의 범위를 제한시키는 방법론을 제시했다는 점에 의미가 있다. 마지막으로는 석탄 채굴 및 선별 과정에서 발생되는 폐기물인 석탄 맥석을 대상으로 광물학적, 이화학적 특성을 파악하고 마그네슘을 이용한 표면 개질을 통해 수용액 내 3가 비소 저감을 목적으로 하는 지질 물질의 환경 소재로의 적용성 연구를 수행하였으며, 지질학적 천연소재 물질을 환경 정화에 재활용한다는 관점에서 의의가 있다. 본 연구를 통해서, 연구 수행의 근간이 된 광물학과 지구화학에 기반한 지질학적 사고방식과 방법론이 가까운 지구과학 분야는 물론이고 환경학, 넓게는 고고학 분야에 필요로 하며, 특히 기존의 정형화된 사고체계를 변화시키거나 문제를 해결하는 새로운 관점을 제시할 수 있다는 가능성을 보였다. 앞으로, 보다 다양한 학문분야에서 지질학의 확장된 역할을 기대한다. This study investigates the mineralogical and geochemical properties of archaeological and geological materials, specifically ancient glass, stone artifacts, and coal gangue. It examines their applications in geosciences and archaeometry across four chapters. The first chapter establishes a comprehensive method for identifying the geographical origins of ancient glass by analyzing geochemical signatures and examining the impact of climatic variations on geological processes that impart unique markers on glass artifacts. The second chapter explores the mineralogy and geochemistry of stones used in arhat statuettes, offering an in-depth analysis of their provenance and the geological processes involved in their formation. The third chapter introduces a novel, non-destructive approach to trace the origins of coarse-grained igneous stone in Bodhisattva sculptures, showing how geochemical variations in plutonic rock suites can identify source materials. The final chapter investigates the mineralogical and geochemical characteristics of modified coal gangue for arsenite sequestration, providing insights into the repurposing of waste materials for environmental remediation. Collectively, this thesis significantly enhances provenance strategies in archaeology, deepens our understanding of cultural artifacts through geochemical and mineralogical analyses, and offers new perspectives on using geological waste for environmental remediation.

The EaRTH Disk Model: Analysis and Integration of Protoplanetary Disk Mineralogy and Structure

Grimble, William Allen Richard Rochester Institute of Technology ProQuest Dissert 2022 해외박사(DDOD)

Our understanding of how exoplanets form and evolve relies on analyses of both the mineralogy of protoplanetary disks and their detailed structures; however, these key complementary aspects of disks are usually studied separately. We present initial results from a hybrid model that combines the empirical characterization of the mineralogy of a disk, as determined from its mid-infrared spectral features, with the well-tested MCFOST radiative transfer disk model that takes into account realistic disk density and temperature structures, a combination we call the EaRTH Disk Model. With the results of the mineralogy detection serving as input to the radiative transfer model, we generate mid-infrared spectral energy distributions that reflect both the mineralogical and structural parameters of the corresponding disk. Initial fits of the SED output by the resulting integrated model to Spitzer Space Telescope mid-infrared (IRS) spectra of the protoplanetary disk orbiting the nearby T Tauri star MP Mus demonstrates the potential advantages of this approach by revealing details like the dominance of warm small olivine and cool small pyroxene in the dusty disk of MP Mus. The methodology proposed here provides insight into disk composition and structure, but requires fine-tuning in the radiative transfer stage to reproduce specific spectral features. However, it should be directly applicable to the interpretation of mid-infrared spectra of protoplanetary disks that will be produced by the James Webb Space Telescope. Additionally, while the model can successfully match known observations assuming a typical fiducial protoplanetary disk, it is necessary to alter the model to match data when structural differences are observed, such as a gap or rings; adjusting the model to match infrared observations while remaining consistent with millimeter observations demonstrates the model’s adaptability to different disk structures, which we do using the Spitzer IRS spectra and Atacama Large Millimeter/sub-Millimeter Array (ALMA) observations of MP Mus, as well as the transition disks of GM Aur and LkCa 15. The results illustrate the large differences that occur in protoplanetary disk development despite similar ages, likely the result of planetary formation.

William Buckland(1784-1856)의 『Geology and Mineralogy 』 : 자연신학과 지사학적 배경을 중심으로

박영욱 서울大學校 大學院 1990 국내석사