Mineral identification using data-mining in hyperspectral infrared imagery

Les applications de l’imagerie infrarouge dans le domaine de la géologie sont principalement des applications hyperspectrales. Elles permettent entre autre l’identification minérale, la cartographie, ainsi que l’estimation de la portée. Le plus souvent, ces acquisitions sont réalisées in-situ soit à l’aide de capteurs aéroportés, soit à l’aide de dispositifs portatifs. La découverte de minéraux indicateurs a permis d’améliorer grandement l’exploration minérale. Ceci est en partie dû à l’utilisation d’instruments portatifs. Dans ce contexte le développement de systèmes automatisés permettrait d’augmenter à la fois la qualité de l’exploration et la précision de la détection des indicateurs. C’est dans ce cadre que s’inscrit le travail mené dans ce doctorat. Le sujet consistait en l’utilisation de méthodes d’apprentissage automatique appliquées à l’analyse (au traitement) d’images hyperspectrales prises dans les longueurs d’onde infrarouge. L’objectif recherché étant l’identification de grains minéraux de petites tailles utilisés comme indicateurs minéral -ogiques. Une application potentielle de cette recherche serait le développement d’un outil logiciel d’assistance pour l’analyse des échantillons lors de l’exploration minérale. Les expériences ont été menées en laboratoire dans la gamme relative à l’infrarouge thermique (Long Wave InfraRed, LWIR) de 7.7m à 11.8 m. Ces essais ont permis de proposer une méthode pour calculer l’annulation du continuum. La méthode utilisée lors de ces essais utilise la factorisation matricielle non négative (NMF). En utlisant une factorisation du premier ordre on peut déduire le rayonnement de pénétration, lequel peut ensuite être comparé et analysé par rapport à d’autres méthodes plus communes. L’analyse des résultats spectraux en comparaison avec plusieurs bibliothèques existantes de données a permis de mettre en évidence la suppression du continuum. Les expérience ayant menés à ce résultat ont été conduites en utilisant une plaque Infragold ainsi qu’un objectif macro LWIR. L’identification automatique de grains de différents matériaux tels que la pyrope, l’olivine et le quartz a commencé. Lors d’une phase de comparaison entre des approches supervisées et non supervisées, cette dernière s’est montrée plus approprié en raison du comportement indépendant par rapport à l’étape d’entraînement. Afin de confirmer la qualité de ces résultats quatre expériences ont été menées. Lors d’une première expérience deux algorithmes ont été évalués pour application de regroupements en utilisant l’approche FCC (False Colour Composite). Cet essai a permis d’observer une vitesse de convergence, jusqu’a vingt fois plus rapide, ainsi qu’une efficacité significativement accrue concernant l’identification en comparaison des résultats de la littérature. Cependant des essais effectués sur des données LWIR ont montré un manque de prédiction de la surface du grain lorsque les grains étaient irréguliers avec présence d’agrégats minéraux. La seconde expérience a consisté, en une analyse quantitaive comparative entre deux bases de données de Ground Truth (GT), nommée rigid-GT et observed-GT (rigide-GT: étiquet manuel de la région, observée-GT:étiquetage manuel les pixels). La précision des résultats était 1.5 fois meilleur lorsque l’on a utlisé la base de données observed-GT que rigid-GT. Pour les deux dernières epxérience, des données venant d’un MEB (Microscope Électronique à Balayage) ainsi que d’un microscopie à fluorescence (XRF) ont été ajoutées. Ces données ont permis d’introduire des informations relatives tant aux agrégats minéraux qu’à la surface des grains. Les résultats ont été comparés par des techniques d’identification automatique des minéraux, utilisant ArcGIS. Cette dernière a montré une performance prometteuse quand à l’identification automatique et à aussi été utilisée pour la GT de validation. Dans l’ensemble, les quatre méthodes de cette thèse représentent des méthodologies bénéfiques pour l’identification des minéraux. Ces méthodes présentent l’avantage d’être non-destructives, relativement précises et d’avoir un faible coût en temps calcul ce qui pourrait les qualifier pour être utilisée dans des conditions de laboratoire ou sur le terrain.The geological applications of hyperspectral infrared imagery mainly consist in mineral identification, mapping, airborne or portable instruments, and core logging. Finding the mineral indicators offer considerable benefits in terms of mineralogy and mineral exploration which usually involves application of portable instrument and core logging. Moreover, faster and more mechanized systems development increases the precision of identifying mineral indicators and avoid any possible mis-classification. Therefore, the objective of this thesis was to create a tool to using hyperspectral infrared imagery and process the data through image analysis and machine learning methods to identify small size mineral grains used as mineral indicators. This system would be applied for different circumstances to provide an assistant for geological analysis and mineralogy exploration. The experiments were conducted in laboratory conditions in the long-wave infrared (7.7μm to 11.8μm - LWIR), with a LWIR-macro lens (to improve spatial resolution), an Infragold plate, and a heating source. The process began with a method to calculate the continuum removal. The approach is the application of Non-negative Matrix Factorization (NMF) to extract Rank-1 NMF and estimate the down-welling radiance and then compare it with other conventional methods. The results indicate successful suppression of the continuum from the spectra and enable the spectra to be compared with spectral libraries. Afterwards, to have an automated system, supervised and unsupervised approaches have been tested for identification of pyrope, olivine and quartz grains. The results indicated that the unsupervised approach was more suitable due to independent behavior against training stage. Once these results obtained, two algorithms were tested to create False Color Composites (FCC) applying a clustering approach. The results of this comparison indicate significant computational efficiency (more than 20 times faster) and promising performance for mineral identification. Finally, the reliability of the automated LWIR hyperspectral infrared mineral identification has been tested and the difficulty for identification of the irregular grain’s surface along with the mineral aggregates has been verified. The results were compared to two different Ground Truth(GT) (i.e. rigid-GT and observed-GT) for quantitative calculation. Observed-GT increased the accuracy up to 1.5 times than rigid-GT. The samples were also examined by Micro X-ray Fluorescence (XRF) and Scanning Electron Microscope (SEM) in order to retrieve information for the mineral aggregates and the grain’s surface (biotite, epidote, goethite, diopside, smithsonite, tourmaline, kyanite, scheelite, pyrope, olivine, and quartz). The results of XRF imagery compared with automatic mineral identification techniques, using ArcGIS, and represented a promising performance for automatic identification and have been used for GT validation. In overall, the four methods (i.e. 1.Continuum removal methods; 2. Classification or clustering methods for mineral identification; 3. Two algorithms for clustering of mineral spectra; 4. Reliability verification) in this thesis represent beneficial methodologies to identify minerals. These methods have the advantages to be a non-destructive, relatively accurate and have low computational complexity that might be used to identify and assess mineral grains in the laboratory conditions or in the field

Site specific calibration of laser induced breakdown spectroscopy for rapid elemental analysis of gold ore drill core samples

Site-specific calibration of laser induced breakdown spectroscopy (LIBS) analysis can be achieved by presenting known geological sample data to update algorithms, therefore improving analysis of unknown samples post-calibration. The goal of this project is to optimise drill core analysis by LIBS for samples from Kittilä gold mine. In total 227 samples have been produced and analysed with a range of analytical techniques to build a comprehensive, site-specific reference library. The data from these analyses has been input into the reference library and utilised by algorithms for spectral peak identification during LIBS analysis of bulk drill core material. The semi-quantitative and quantitative data of 40 Kittilä samples has been used as a comparison to ICP-AES data used by the mine. The Kittilä powders were used to produce 39 pellets, each representative of a section of drill core of which the ICP-AES and TXRF data was known. The pellets were scanned by LIBS and the data then compared to the known data. LIBS showed strong correlations (>0.75) with ICP-AES data for As, Cr, Cu, Fe, Mn and S, poor correlations were seen for Pb and Co, however these can be explained by issues related to ICP-AES. LIBS pellet data proved strongly competitive as 5/9 elements displayed stronger correlations between LIBS and ICP-AES than TXRF. Subsequently, the successful scanning of drill core boxes directly has proven that calibration can increase the speed with which the bulk material can be effectively analysed

Prospeg project - pegmatite remote sensing and mapping. Final report

365870/13 (depósito legal)No âmbito das actividades de I&DT da empresa Sinergeo, Lda., o projecto PROSPEG (nº 11480), dedicado à investigação em prospecção e pesquisa e pegmatitos graníticos, co-financiado pelo “ON.2 – O Novo Norte e QREN através do fundo Europeu de Desenvolvimento Regional (FEDER), resultou de uma co-promocão com a Universidade do Minho. É objectivo geral do projecto o desenvolvimento de programas de prospeccão e pesquisa de pegmatitos no território português, utilizando como via fundamental para a primeira aproximação a áreas de pesquisa, metodologias de análise distanciada e deteccão remota. Justifica-se a investigação neste domínio pelas dificuldades de implementação de outros métodos geofísicos e geoquímicos, dado o deficiente contraste entre pegmatito e encaixante. Por outro lado, a inscrição da análise distanciada e deteccão remota em programas de prospecção estratégica de pegmatitos, também se afigura vantajosa em termos da relação custo/beneficio e da extensão e densidade da cobertura que permite. Em estádio estratégico as acções de prospecção incidiram sobre um conjunto de áreas, reconhecida ou hipoteticamente férteis no que respeita a ocorrência de pegmatitos com interesse económico. Essas áreas podem ser encaradas como compartimentos da Província Pegmatítica Varisca do Norte e Centro de Portugal onde ocorrem pegmatitos com uma grande diversidade intrínseca, estrutural, morfométrica, mineralógica e económica, representando simultaneamente diferentes níveis estruturais de colocação e de exumação dos conjuntos e corpos pegmatíticos individuais. Os suportes escolhidos para a análise distanciada foram imagens multiespectrais dos sensores LANDSAT e SPOT e ainda imagens disponibilizadas pelo Google Earth Pro. Estas foram submetidas a tratamento, através de processamentos digitais que incluíram a ampliação de contraste, a combinação RGB de bandas espectrais, a análise em componentes principais e a classificação Maxver de imagens. A conjugação destas técnicas permitiu tornar mais evidentes padrões geométricos, cromáticos, texturais e espectrais da expressão superficial de pegmatitos e seus indicadores de prospecção. Combinando aqueles procedimentos de processamento com indicações relativas a faixas e maciços produtivos, provenientes da análise sobre a distribuição regional de corpos nas áreas consideradas e aproveitando critérios empíricos geológico-estruturais e geomorfológicos, foi possível seleccionar um conjunto de áreas mais restritas sobre as quais se desenvolveram trabalhos de investigação geológica. Estes compreenderam numa primeira fase cartografia geológica a escalas 1:5000, como via para a identificação de sectores com índices pegmatíticos em situação potencialmente económica, a investigar mediante sondagens. A partir destes levantamentos, alguns guias estruturais e litológicos condicionantes da presença de pegmatitos em contexto intra-granítico, também puderam ser discriminados. A direccão N30E, tardi-Varisca, parece condicionar de forma estrita a instalação dos corpos com maior volume no Norte e Centro de Portugal. Por outro lado também se nota que a distribuição dos pegmatitos revela um caracter coincidente com sectores de maior diversificação e heterogeneidade litológica, reconhecendo-se as seguintes fácies tendentes para pegmatitos: leucogranitos com grão fino com biotites nodulares, amarelecidos por lixiviação com influência supergénica; fácies com tendência leucocrata com diferenciações difusas pegmatíticas; fácies microporfiróides com evidências de fluxo; fácies miarolíticas pontuadas por bolhas pegmatíticas; leucogranitos portadores de cordierite e granada; biotititos estabelecidos na superfície de contacto entre fácies graníticas e granitos porfiróides enrubescidos por hematitizacão hidrotermal a supergénica. O programa de prospeccão pontual com sondagens levado a cabo foi em alguns casos bem-sucedido, tendo--se chegado a intersectar em profundidade uma bolsada pegmatítica com dimensão apreciável. Noutros casos foi possível delimitar em profundidade o desenvolvimento de corpos conhecidos, sujeitos a exploração no passado, e aí aumentar o quantitativo de reservas potenciais. Nos casos em que se recorreu a métodos destrutivos de furação, adoptou-se de forma inovadora, como forma de obter correspondentes colunas de sondagem, a filmagem de furos combinada com a análise mineralométrica de cuttings. Como subsídios do programa de sondagens também se refere a optimizacão de modelos geométricos e conceptuais de pegmatitos, os quais podem representar conjecturas paradigmáticas passíveis de extrapolação aos campos portugueses e desta forma apoiar subsequentes programas de prospecção pontual. Também a partir dos logs de sondagem, aqui encarados como colunas graníticas produtivas em pegmatitos, foi possível inferir sobre tendências de fraccionação, segregação e fluxo, capazes de fomentar o aparecimento de magmas leucograníticos transicionais e pegmatíticos, que podem posteriormente evoluir in situ ou ser mobilizados e libertados para corredores estruturais. As tendências parecem ser em alguns casos oscilatórias com ritmos bem definidos na organização das cúpulas, e do ponto de vista da detecção remota as fácies resultantes são à partida perceptíveis, na medida em que representam tipos cromáticos extremos e contrastantes, com expressão cartográfica mais extensiva do que os corpos pegmatíticos. Como linha de investigação inovadora, capaz de apoiar a prospecção de pegmatitos através de detecção remota, ainda se obtiveram medidas de reflectância de produtos litológicos pegmatíticos e seus encaixantes produtivos. O correspondente levantamento realizou-se com recurso a um espectroradiómetro tendo os espectros obtidos sido organizados numa base de dados específica. Estes podem ser correlacionados com determinadas oscilações espectrais nas imagens de satélite constituindo assim um acervo útil a utilizar no processamento de imagens, designadamente multi- e hiperespectrais. Da análise efectuada aos espectros, verificou-se que os respeitantes a massas de quartzo se revelaram mais distintos. Também foi possível separar do ponto de vista espectral encaixantes leucograníticos e testar a influência da cobertura dos substractos exumados por líquenes. Verificou- se que a partir de percentagens de recobrimento de 35%, o sinal espectral e efectivamente homogeneizado, impossibilitando a discriminação litológica. Considerando o crescente valor estratégico, económico e tecnológico atribuído aos recursos pegmatíticos e atendendo à inadequação de muitos outros métodos de prospecção, vislumbra-se aplicabilidade efectiva para as metodologias aqui exploradas.Within the framework of the R & D activities of the company Sinergeo Ltd., the project PROSPEG (no 11480), dedicated to the investigation through prospecting and research of granitic pegmatites, co-funded by “ON.2 – O Novo Norte” and QREN, through the European Regional Development Fund (ERDF), resulted from a co-promotion with the University of Minho. The overall objective of this project is the development of pegmatites prospecting programs in the Portuguese territory, using as main via for the primary approach to research areas, remote mapping analysis and remote sensing methodologies. The investigation in this domain is justified by the difficult implementation of other geophysical and geochemical methods, given the lack of strong contrast between pegmatite and enclosing rocks. On the other hand, the remote mapping analysis and remote sensing inscription in strategic prospecting programs is also advantageous in cost/benefit terms and in terms of extension and density of coverage allowed. In a strategic phase the prospecting actions focused on areas, known as/or hypothetically fertile for pegmatites with economic interest. These areas are compartments of the Variscan Pegmatitic Province in North and Center Portugal. Here, pegmatites with high intrinsic, structural, morphological, mineralogical and economic diversity can be found, simultaneously representing different structural levels of emplacement and exhumation of individual pegmatitic sets and bodies. The supports chosen for remote mapping analysis were multispectral images from LANDSAT and SPOT sensors and images from Google Earth Pro. These were treated through digital processes like contrast broadening, RGB combination of spectral bands, principal components analysis and Maxver classification. The conjunction of these techniques turned more evident geometric, chromatic, textural and spectral patterns of the superficial expression of pegmatites and its prospecting indicators. By combining those processing procedures with indications of productive stripes and massifs, obtained from the analysis on the regional distribution of bodies in the considered areas, and using empiric geological-structural and morphological criteria, it was possible to select a set of more restricted areas on which was done geological investigation. In a first phase, the geological investigation comprised geological mapping at 1:5000 scale, as a way for identifying sectors with pegmatitic bodies in potentially economic situation to be investigated through drillings. From these surveys were also discriminated some structural and lithological guides conditioning the presence of pegmatites in an innergranite context. The late-Variscan direction N30E seems to strictly condition the emplacement of bodies with higher volumes in the North and Center of Portugal. On the other hand, it is also noticeable that the pegmatites distribution reveals a coincident character with sectors of higher lithological diversification and heterogeneity, with the following facies tending to pegmatites: fine grained leucogranites with biotite nodules, yellowed by supergene leaching influence; facies with leucocratic tendency with diffuse pegmatitic differentiations; microporphyroid facies with flow evidences; miarolitic facies punctuated by pegmatitic bubbles; leucogranites with cordierite and garnet; biotitites established on the contact surface between granitic facies, and porphyroid granites reddened by hydrothermal and supergene hematization. The drilling program was, in some cases, well succeeded, having been intersected a pegmatitic body in depth, with considerable dimension. In other cases it was possible to delimit the development of known bodies in depth, subjected to exploitation in the past, and increase the amount of potential reserves. In the cases where destructive drilling methods were used, it was adopted, in an innovative way, the filming of boreholes combined with mineralometric cutting analysis, as a way to obtain correspondent drilling columns. As a result of the drilling program is also referred the optimization of geometric and conceptual pegmatite models which can represent paradigmatic conjectures amenable to be extrapolated to the Portuguese fields and, in this way, support subsequent prospecting programs. Also from the logs, here perceived as granitic columns productive in pegmatites, it was possible to infer fractionation, segregation and flow tendencies, capable of fomenting the appearance of transitional leucogranitic and pegmatitic magmas that may then evolve in situ or be mobilized and released to structural corridors. The trends seem oscillatory in some cases, with well-defined rhythms in the domes organization. From the remote sensing viewpoint the resulting facies are perceptible as they represent extreme and contrasting chromatic types with more extensive cartographic expression than the pegmatitic bodies. As a line of innovative research, capable of supporting pegmatites prospection through remote sensing, were also obtained reflectance measures of lithologic pegmatitic products and their productive enclosings. The correspondent survey was done through the use of a spectroradiometer and the spectra obtained were organized in a specific database. These can be correlated with some spectral oscillations in the satellite images, and thus represent a useful collection, to multi- and hyperspectral images processing. From the spectra analysis it was found that quartz masses spectra are more distinct. It was also possible to separate from a spectral viewpoint leucogranitic enclosings and test the influence of lichens cover. It was found that with percentages of coating as of 35% the spectral signal is effectively homogenized, turning impossible the lithological discrimination. Considering the increasing strategic, economic and technological value attributed to pegmatitic resources and considering the inadequacy of many other prospecting methods, the methodologies here explored are effectively applicable."ON.2 – O Novo Norte" e QRE

Imaging spectrometry and the Ronda peridotites

In Chapter 2, the results of detailed geologic mapping of sedimentary strata of the Subbeticum of Ronda are presented including a stratigraphic description of several sections near Ronda, El Burgo, Ardales, Teba, and Arriate in the Ronda-Málaga area. These are used to develop time-facies profiles on basis of which the paleogeography is reconstructed with emphasis on Miocene turning points. Timing of rift-related Mesozoic tectonic events, Early Miocene compressional tectonic events, and Late Miocene strike-slip tectonic events are derived from the result of a backstripping analysis using a synthetic composite stratigraphic section as input data. The final results are presented within the framework of Western Mediterranean plate tectonics yielding a number of deformation events characterizing the tectono-sedimentary evolution of the area.A review of recent work on field and microstructures within the Ronda peridotite body is given in Chapter 3. Paleostress analysis of fault-slip data from the peridotites are discussed. These lead to three stress tensors: an extensional, a compressional, and a strike-slip related tensor. Similar work conducted on Cretaceous and Tertiary carbonates of the Subbeticum give identical stress tensors. For the carbonates, tectonic stylolites and extension veins allow to relatively date these stress tensors. This dating together with the timing of tectonic phases from the backstripping analysis is used to derive an alternative model for the emplacement of the Ronda peridotites.Visible and near-infrared reflectance spectra of carbonate minerals, carbonate mineral mixtures, and un-weathered rock samples are discussed in Chapter 4. First, bidirectional reflectance theory is addressed forming the basis for a semi-empirical model to simulate reflectance of mineral mixtures from their single-component reflectance spectra. The following topics are discussed in the remainder of this Chapter: carbonate absorption band position, effects of particle size, effects of sorting, calcite-dolomite mixtures and the shifting 2.3μm absorption band, and the effects of impurities such as aqueous fluid inclusions, transition metal ions, organic matter. Finally, spectra of rock samples are discussed in relation to the mineral spectra.Reflectance spectra of ultrarnafic rocks and minerals forming these rocks are discussed in Chapter 5. After a review of some earlier work, mineral spectra of olivines, orthopyroxenes, and clinopyroxenes are presented. Un-weathered rock spectra of several samples of dunites, lherzolites, harzburgites, and pyroxenites are discussed. The remainder of the Chapter is devoted to the effect of serpentinization on the reflectance spectra of ultrarnafic rocks. Its is demonstrated that the degree of serpentinization can be quantified by using the depth of OH -features occurring near 1.4μm and 2.3μm and the brightness of a sample measured as the reflectivity at 1.6μm. From a study of synthetic mixtures of olivine, serpentine, and magnetite prepared in the laboratory it is derived that the spectral quenching effect of magnetite affects the spectral properties of serpentines with 55 % serpentine minerals or less. Thus highly serpentinized areas can be mapped using the above mentioned characteristics regardless the amount of magnetite.In Chapter 6, reflectance spectra of weathered peridotite and carbonate rock samples, soils, and vegetation, derived from the Ronda-Málaga area, are discussed. Part of this Chapter is based on a case study developed for the Los Pedroches batholith near Almadén (southCentral Spain). A total of 13 soil samples were taken over the contact aureole of the granitic intrusion and analyzed spectrally as well as chemically. The reflectance spectra of relevant minerals are discussed and subsequently the soil spectra. From these spectra, the change of albedo, Fe, AlOH absorption, H 2 O, and OH -absorption over the contact zone are quantified using the spectra. Field spectra using a TM simulator spectrometer are used to link the laboratory spectra and the TM image. Finally, image processing techniques using ratio images are used to map changes in iron content etc of soils over the area. This case study demonstrates the possibility of linking laboratory and pixel spectra when calibrating the data carefully using field spectrometry.In Chapter 7, the preprocessing of the raw imaging spectrometer data is discussed. First, a technical description of the sensors used is given. These are the Airborne Visible and Infrared Imaging spectrometer (AVIRIS) and the GER imaging spectrometer. Next quantification of signal-to- noise ratios is discussed using two alternative methods. The main topic is the atmospheric calibration of imaging spectrometer data. Several methods are used: Flat-field calibration, Internal Average Reflectance method, Empirical line method, Logresidual method, and a atmospheric simulation model. The performance of these methods is compared using a number well-characterized standard field targets in the Cuprite mining district AVIRIS data set and the GERIS data set from southern Spain. Comparison of the results directly reflects the difference between atmospheric calibration in presence or absence of heavy vegetation.If the imaging spectrometer data are properly calibrated, the next logical step would be to use the data to map surface mineralogy. Mineral mapping techniques are treated in Chapter 8. Some techniques have been proposed for this purpose which are not always very successful, many studies use conventional classification techniques. Specific imaging spectrometer techniques are introduced: inverse mixing modelling, spectral angle mapping, and band-depth analysis. The main body of the text deals with a new mineral mapping technique based on indicator kriging. This technique uses automatic zonation techniques to identify absorption features and non-parametric geostatistics to calculate the probability that a pixel belongs to a certain mineralogy. The performance of this technique is discussed in the framework of conventional image classification techniques.In last final Chapter 9, several techniques and methodologies discussed in previous Chapters are applied to the GER 63-channel imaging spectrometer data set flown over the Ronda peridotites and adjacent carbonates which was calibrated using techniques discussed in Chapter 7. Two Case Studies are presented to emphasize the use of imaging spectrometry for geologic mineral exploration purposes. The first Case Study deals with the problem of dolomitization which is an important parameter in oil exploration. Calcite-dolomite mixtures and dolomitization patterns are mapped using the semi-linear model for the position of the carbonate absorption band derived in Chapter 4. Conditional simulation techniques and indicator kriging are used to estimate the calcite content of pixels. The second Case Study addresses the degree of serpentinization in the peridotites; an indication for possible asbestos deposits. The approach is based on the theoretical results derived in Chapter 5. Results of mineral mapping using techniques discussed in Chapter 8, show that several minerals could be mapped using the GER data set which give information on metamorphic facies. These metamorphic minerals bear important conclusions on the conditions of metamorphism related to the emplacement of the peridotites discussed in Chapters 2 and 3

Faculty Publications and Creative Works 2002

Introduction One of the ways in which we recognize our faculty at the University of New Mexico is through Faculty Publications & Creative Works. An annual publication, it highlights our faculty\u27s scholarly and creative activities and achievements and serves as a compendium of UNM faculty efforts during the 2001 calendar year. Faculty Publications & Creative Works strives to illustrate the depth and breadth of research activities performed throughout our University\u27s laboratories, studios and classrooms. We believe that the communication of individual research is a significant method of sharing concepts and thoughts and ultimately inspiring the birth of new ideas. In support of this, UNM faculty during 2002 produced over 2,278 works, including 1,735 scholarly papers and articles, 64 books, 195 book chapters, 174 reviews, 84 creative works and 26 patented works. We are proud of the accomplishments of our faculty which are in part reflected in this book, which illustrates the diversity of intellectual pursuits in support of research and education at the University of New Mexico. Terry Yates Vice Provost for Researc

A review of archean orogenic gold deposits in greenstone belts and the Slave Province : exploration in the Yellowknife domain, NWT, Canada

A review of Archean granite-greenstone terranes, orogenic gold deposits, the Slave Province and modern exploration tools, techniques and methods was conducted to identify prospective areas in the Yellowknife domain for hosting orogenic gold deposits and illustrate the best exploration methods for delineating this deposit type. This study identifies Archean granite-greenstone terranes as economically important hosts to quartz-carbonate vein-hosted orogenic gold deposits. These deposits occur at convergent plate margins, but can also be related to local extensional tectonics within a convergent setting. Heat generated from tectonic processes can trigger hydrothermal fluid movement along first-order faults and shear zones. Precipitation of gold-bearing quartz-carbonate veins from the hydrothermal fluids occurs in second- and third-order faults and shear zones related to the first-order structures. This study also identifies the Archean Slave Province in northern Canada as a well-endowed craton with numerous orogenic gold deposits, diamondiferous kimberlites, VMS deposits and several other mineralization styles. In particular, three greenstone belts (Yellowknife, Cameron River and Beaulieu River) associated with likely first-order structures are comprised of prospective rocks for hosting orogenic gold and VMS mineralization. The Yellowknife greenstone belt hosts the past-producing and former world-class Con and Giant orogenic gold deposits, but has been little explored with modern exploration techniques. The Cameron River and Beaulieu River greenstone belts host numerous base and precious metal VMS and BIF-hosted orogenic gold prospects and deposits, indicating mineralization is present. There is considerable potential for significant discoveries to be made using modern exploration techniques in the greenstone belts; however, exploration in the region has been hindered over the past decade by ongoing political negotiations. Once the political negotiations are finalized, application of modern exploration methods and techniques in the prospective greenstone belts should be carried out. Regional scale methodologies should be applied to generate targets using predictive modelling, implicit 3D modelling, 3D geochemistry and exploration targeting so decisions defining a businesses strategy for ground acquisition of high priority targets are made using quantitative analysis. Once ground is acquired, field-based exploration for orogenic gold and VMS deposits should include geological mapping with a focus on structural geology, geochemical sampling and airborne magnetic, radiometric and EM geophysical surveys. Prior to reconnaissance drilling, integration of all data layers and interpretation within a common 3D earth model should be conducted. Following successful reconnaissance drilling, definition drilling along strike and down dip of intersected mineralization, combined with borehole geophysics, should be carried out to delineate the extent of mineralization