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1
Yao, Yufeng. "Anhydrite precipitation and evolution of permeability in ocean ridge crest hydrothemal systems." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/25793.
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Becker, Stephen Paul. "Fluid Inclusion Characteristics in Magmatic-Hydrothermal Ore Deposits." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/28318.
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Magmatic-hydrothermal ore deposits are formed in association with aqueous fluids that exsolve from hydrous silicate melts during ascent and crystallization. These fluids are invariably trapped as inclusions in vein-filling minerals associated with hydrothermal fluid flow, and their composition may be modeled based on the H₂O-NaCl system. Thus, if we know the pressure-volume-temperature-composition (PVTX) properties of H₂O-NaCl solutions, it is possible to interpret the PTX trapping conditions, which is important for understanding the processes leading to the generation of the hydrothermal system and ore mineralization.
High salinity (> 26 wt. % NaCl) fluid inclusions contain liquid, vapor, and halite at room temperature, and are common in magmatic-hydrothermal ore deposits. These inclusions homogenize in one of three ways: A) halite disappearance (Tmhalite) followed by liquid-vapor homogenization (ThL-V), B) simultaneous ThL-V and Tmhalite, or C) ThL-V followed by Tmhalite. The PVTX properties of H₂O-NaCl solutions three phase (L+V+H) and liquid-vapor (L+V) phase boundaries are well constrained, allowing researchers to interpret the minimum trapping pressure of inclusion types A and B. However, data that describe the pressure at Tmhalite for inclusion type C are limited to a composition of 40 wt. % NaCl. To resolve this problem, the synthetic fluid inclusion technique was used to determine the relationship between homogenization temperature and minimum trapping pressure for inclusions that homogenize by mode C. These results allow researchers to interpret the minimum trapping pressure of these inclusions, and by extension the depth at which the inclusions formed.
The temporal and spatial distribution of fluid inclusions formed in associated with porphyry copper mineralization has been predicted using a computer model. A simple geologic model of an epizonal intrusion was developed based on a Burnham-style model for porphyry systems and thermal models of the evolution of epizonal intrusions. The phase stability fields and fluid inclusion characteristics at any location and time were predicted based on PVTX properties of H₂O-NaCl solutions. These results provide vectors towards the center of a magmatic-hydrothermal system that allow explorationists to use fluid inclusion petrography to predict position with the overall porphyry environment when other indicators of position are absent.Ph. D.
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Severmann, Silke. "The geochemistry and geomicrobiology of relict hydrothermal sulphide deposits." Thesis, University of Southampton, 2000. https://eprints.soton.ac.uk/42169/.
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The diagenetic re-mineralisation of seafloor-sulphide deposits and the role of microbes in the metal-exchange processes were investigated in metalliferous sediments from the Alvin relict hydrothermal zone in the TAG area at 2608'N (Mid- Atlantic Ridge). The solid-phase and concomitant pore water concentrations of AI, Si, Ca, Clot, Corg, S, Fe, Mn, Cu, Zn, P, V, Co, U, Mo, Au, Ag and REE's were measured in a 230 cm long gravity core from the southern periphery of the relict vent field. These measurements were complemented by detailed analysis of bacterial abundance and specific activity. The altered sulphidic sediments are capped with a ~30cm thick layer of carbonate-rich (~60% CaCO3), Fe-stained sediments. Two distinct sulphide layers, interbedded with Fe-oxysilicates, and overlain by a thin layer of Fe/Mn oxyhydroxides, were found in this core. The dominant mineral-phase in both sulphide layers, which originate from mass-wasting of mound sediments, is pyrite with some goethite. Reaction of the exposed metal-sulphides in the upper sulphide layer with seawater has produced a thin layer of secondary atacamite, which is enriched in Au. Primary sphalerite is dissolved in the upper sulphide layer and re-precipitation as secondary sphalerite directly above and below. U continues to be scavenged from the porewater, producing marked enrichments on oxidised sulphide rims. The re-mineralisation processes identified in this core are in close analogy to the large-scale zone-refining that has been described for the active TAG mound and ancient ore-deposits. REE/Fe ratios clearly distinguish between plume derived sediments in the carbonate cap and slumped material from the hydrothermal mound. The REE signature of bulk sediments and clay phases imply multiple stages of alteration by diffuse fluids in the upper sulphide layer and intermediate layer, whereas the lower sulphide layer is not affected. Alteration by reactive low-temperature hydrothermal fluids is also inferred to be responsible for the observed diagenetic overprinting of trace-metal distributions in the upper sulphide layer. The intermediate layer is rich in nontronite, which has been precipitated in situ from diffuse fluids. The presence of Mn- and Fe-reducing bacteria coincide with elevated porewater concentrations of Mn and Fe, indicating direct involvement of bacteria in the cycling of these metals. Total counts of viable cells and general activity measurements show that although bacterial populations are relatively small, they are healthy and well adapted to this potentially toxic environment. The existence of active microbial communities in metalliferous sediments may therefore provide a continuum of bacterial populations between high and low temperature hydrothermal systems, thus representing an important transitional stage in the hydrothermal ecosystem. Microbial reduction and oxidation of S was observed throughout the core, indicating that microorganisms are particularly active in terms of S-cycling. For deep-sea sediments extremely high sulphate reduction rates (67 nmol/cm3/d) were measured in the ironstained carbonate cap. In the absence of significant organic carbon (~0.2 %) this strongly suggests the synthesis of alternative electron-donors by chemolithotrophic bacteria to support the observed high rates of heterothrophic activity in these sediments.
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Martin, Jeffrey T. "The influence of silica precipitation and thermoelastic stresses on the evolution of a ridge crest seafloor hydrothermal system." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/28026.
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Lecumberri, Sanchez Pilar. "Spatial and temporal evolution of fluids in hydrothermal ore deposits." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/50960.
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Magmatic-hydrothermal systems typically have vertical extents of several hundredmeters and their geochemical characteristics (e.g. mineral assemblages) vary considerably
over that vertical extent. As a consequence the expression in outcrop varies depending on
the level of erosion. Therefore understanding the geochemical zonation of magmatic-hydrothermal
ore deposits opens the possibility to detect deep magmatic-hydrothermal
systems, and to assess qualitatively the degree of erosion that has taken place in the area
and at which level the mineralization may occur. This dissertation presents the
characterization of two shallow hydrothermal systems and their potential relations with
deeper magmatic-hydrothermal systems. In addition, this dissertation develops the
equations to directly interpret thermometric data from the fluid inclusion type dominant in
one of those deposits (fluid inclusions that homogenize by halite disappearance).
Red Mountain, AZ is a porphyry copper system with a well-preserved lithocap
providing an ideal candidate to characterize the shallow expression of porphyry copper
systems in the southwestern US. The distribution of fluid inclusions, alteration mineralogy
and grade indicate that the intrusive responsible for the mineralization was only partially
intercepted during the exploration program and that one single magmatic event was likely
responsible for the mineralization detected. Fluid inclusion types and clay minerals are
systematically distributed within the deposit. The fluid responsible for the shallow
hypogene mineralization was a low pH-intermediate temperature-low density fluid while a
high salinity fluid was responsible for deep mineralization.
Wutong is a Pb-Zn-Ag deposit in the Nanling belt (southeast China). The combination
of fluid inclusion and mineral thermometry indicates that the Wutong deposit formed at
relatively low pressures. The age and isotopic composition of the mineralization indicates
that the deposit formed during the Cretaceous from crustal derived fluids. The occurrence
of a shallow magmatic-hydrothermal system of Cretaceous age in this region suggests that
Cretaceous intrusions, despite not outcropping very commonly in this particular region may
occur at deeper levels.
Ph. D.
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Veselinović, Milica. "Genetic models for epithermal gold deposits and applications to exploration." Thesis, Rhodes University, 1992. http://hdl.handle.net/10962/d1005562.
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Epithermal gold deposits are the product of large-scale hydrothermal systems in tectonically active regions. They form at shallow crustal levels where the physico-chemical conditions change abruptly. Two major groups of epithermal gold deposits can be distinguished based on their genetic connection with: A) Copper-molybdenum porphyry systems and B) Geothermal systems related to volcanic centres and calderas. Epithermal gold deposits connected with geothermal systems encompass three major types: adularia-sericite, acid-sulphate and disseminated replacement (the Carlin-type). Their essential ingredients are: high heat source which leads to convection of groundwater in the upper crust; source of hydrothermal fluid, metals and reduced sulphur; and high-permeability structures which allow fluid convection and metal deposition. Mixing of these ingredients leads to the formation of epithermal gold deposits throughout crustal history, without any restriction on age. The ores were deposited from near-neutral (adularia-sericite type and some of the Carlin-type) to acidic (acid-sulphate type and porphyry-related epithermal gold deposits), low-salinity, high C0₂ and high H₂S fluids, which were predominantly meteoritic in origin. The transport capability of deep fluids in epithermal hydrothermal systems may be shown to be dependent largely on their H₂S content and, through a series of fluid mineral equilibria, on temperature and on C0₂ content. The most common mechanisms of ore deposition are boiling (phase separation), mixing of fluids of different temperatures and salinities, reaction between them and wall rocks, dilution and cooling. An understanding of genetic models for epithermal gold deposits provides the basis for the selection of favourable areas for regional to prospect-scale exploration.
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Webber, Alexander Patrick. "Hydrothermal mineral deposits and the behaviour of Au within the Earth." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/359115/.
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Jamieson, John William. "Size, Age, Distribution and Mass Accumulation Rates of Seafloor Hydrothermal Sulfide Deposits." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/24056.
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Hydrothermal discharge on the seafloor results in significant accumulation of base- and precious-metal-rich sulfide material. Technological advances as well as elevated metal prices have led to a growing interest in the direct mining of these deposits from the modern ocean floor. The research presented in this thesis details an investigation of the size, grades, distribution, and accumulation rates of these deposits on the seafloor. A three-part resource assessment, originally designed for land-based ore deposits, was used to generate a predictive framework for the global seafloor sulfide resource. Using detailed descriptions of sizes, grades and locations for 92 known deposits, a resource estimate was generated that predicts a total of ~1,000 deposits and a total global abundance of 600 Mt of sulfide within the neovolcanic zones of the modern ocean floor. A detailed study of the hydrothermal sulfide deposits along the Endeavour Segment of the Juan de Fuca Ridge was carried out to investigate the processes of sulfide accumulation at the ridge-segment scale. Results of 226Ra/Ba dating of barite within the deposits indicate that hydrothermal activity has been ongoing for ~6,000 years and venting has been continuous at the Main Endeavour and High Rise vent fields for ~2,300 and 850 years, respectively. Abundant older sulfide samples from inactive sites outside of the main vent fields indicate a complex history of venting along the ridge segment. Analysis of high-resolution bathymetry of the Endeavour Segment, generated from eight autonomous underwater vehicle surveys, revealed the location of 581 individual hydrothermal sulfide edifices along 15 km of ridge length. Using GIS-based software, the volume of each edifice was calculated, and the total amount of sulfide at Endeavour is estimated to be 1.2 Mt. This estimate is the first comprehensive resource evaluation on the seafloor at this scale. Sulfide has been accumulating within the Endeavour axial valley at a rate of ~400 tonnes per year, which is similar to estimates for the TAG deposit on the Mid-Atlantic Ridge. Using endmember hydrothermal fluid chemistry data and estimates of fluid discharge rates, the mass accumulation rate calculated for Endeavour corresponds to a sulfide depositional efficiency of 6%.
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Knight, Cheryl L. Erickson. "Critical properties of NaCI-H₂O Solutions." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/40937.
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Critical properties of the NaCI-H20 fluid system are of fundamental interest to a variety of geochemical applications including fluid inclusion studies, numerical modeling of hydrothermal systems, and development of theoretical models for two·component fluid systems. Although many workers have expressed interest in NaCl·H20 fluid critical properties, most studies have been limited to small compositional ranges with little agreement among data sets at higher salinities. Critical densities are recorded in only one of these reports, and no studies have determined the locations of NaCl-H20 critical isochores (PT projections of critical densities). Furthermore, no studies to date have determined critical properties of NaCl·H20 solutions in excess of room temperature saturation (26.4 wt.% NaCl).
Master of Science
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Santaguida, Frank Carleton University Dissertation Earth Sciences. "The Paragenetic relationships of epidote-quartz hydrothermal alteration within the Noranda Volcanic Complex, Quebec." Ottawa, 1999.
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Reardon, Nancy Catherine. "Magmatic-hydrothermal systems and associated magnetite-apatite-actinolite deposits, Echo Bay, Northwest Territories." Thesis, University of Ottawa (Canada), 1992. http://hdl.handle.net/10393/7543.
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Magnetite-apatite-actinolite deposits occur as pervasive replacement, veins, pods and breccias within wall rocks to the plutons of the Mystery Island intrusive suite at Echo Bay, Northwest Territories. The plutons and their altered wall rocks host previously-mined pitchblende, native Ag, Ni-Co arsenide veins. Although numerous studies were carried out on the pitchblende, native Ag, Ni-Co arsenide veins, the origin of the altered rocks which host them remains uncertain. Overall, this study reveals that the formation of magnetite-apatite-actinolite veins, pervasive replacement of rocks by albite and magnetite-apatite-actinolite, and hydrothermal brecciation by magmatic fluids is consistent with geologic and isotopic data. Thus, it is inferred that these deposits formed by replacement in a hydrothermal system dominated by magmatic fluids exsolved by cooling epizonal plutons of the Mystery Island intrusive suite. (Abstract shortened by UMI.)
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Ahmed, Ayesha Doris. "Beyond the confines of the ore deposit : mapping low temperature hydrothermal alteration above, within, and beneath Carlin-type Gold deposits." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/29423.
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Multiple analytical techniques were employed to investigate distal patterns in low temperature hydrothermal fluid flow into and out of Carlin-type gold deposits in two study areas: the Leeville deposit and the Shoshone range including the Pipeline, Gold Acres and Elder Creek deposits. Previous studies indicate that gold is hosted in lower Paleozoic carbonate rocks overlain by thick sequences of similarly aged siliciclastic rocks. Patterns in δ¹⁸O depletion (<20‰VSMOW), and Au, As, Sb, Hg, Tl, and Te concentrations in lower Paleozoic carbonate rock identified three disconnected lateral fluid pathways into the Pipeline deposit: a main conduit providing gold-bearing fluid to the main ore body, the Abyss fault located ~300m below the main ore zone, and the RMT located underneath the Abyss fault. Following gold precipitation in the Pipeline deposit, gold-depleted fluids were likely exhausted laterally, at least initially, along the same structures as those that allowed fluid to enter the deposit. Upon intersecting the RMT fault, fluid either exploited the fault to reach surface, or transgressed overlying siliciclastic rocks via small scale faults and fractures. δ¹⁸O and δD values of H₂O in equilibrium clay minerals, and the concentration and crystallinity of illite outlined multiple zones of hydrothermal alteration in surface rocks from both the Shoshone Range and Leeville study areas, however no genetic link was established to Carlin-type gold mineralization at depth. Similarities in trace element geochemistry, ore assemblage, and alteration assemblages however, suggest that the Elder Creek deposit may represent low temperature (200°C) gold mineralization resulting from the exhaust of Carlin-type ore forming fluid. The region above the surface projection of the Leeville deposit exhibits multiple zones of hydrothermal fluid upflow resulting in pervasive illitization of surface siliciclastic rocks. The Pipeline/ Gold Acres also contain abundant crystalline illite. The presence of highly crystalline illite highlights zones of focused fluid upflow, typically along faults and other secondary permeability structures such as breccias.
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Schmidt, Katja [Verfasser]. "Temporal and Spatial Variability in the Geochemistry of Hydrothermal Fluids and Hydrothermal Ferromanganese Deposits at the Mid-Atlantic Ridge / Katja Schmidt." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2012. http://d-nb.info/1035032112/34.
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Kaiser, Rohrmeier Majka. "Age and geodynamic evolution of hydrothermal vein deposits in the Madan extensional complex (Bulgaria) /." Zürich, 2005. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=15878.
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Knorsch, Manuel. "The mechanisms and implications of hydrothermal mineral replacement reactions in carbonate-hosted ore deposits." Thesis, Knorsch, Manuel (2021) The mechanisms and implications of hydrothermal mineral replacement reactions in carbonate-hosted ore deposits. PhD thesis, Murdoch University, 2021. https://researchrepository.murdoch.edu.au/id/eprint/64693/.
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Mineral replacement reactions commonly occur during the formation and alteration of ore deposits. In such settings, primary minerals are often dissolved, with new phases forming as products in the presence of a fluid phase. Particularly within carbonate-hosted epigenetic ore deposits, mineral replacement reactions represent a fundamental ore-forming mechanism whereby primary carbonates are replaced by secondary minerals. These replacement processes generate porosity and facilitate ore mineral precipitation. This study compares observations of natural, ore-forming mineral replacement reactions with laboratory-derived hydrothermal replacement experiments to decipher the metasomatic processes of ore formation from the deposit scale to the nanoscale. This thesis presents insights on (i) the ore-forming mechanisms and post-ore alteration of the Artemis Zn-Cu-Au prospect (Chapters 2 and 3), (ii) the pseudomorphic replacement of calcite by siderite (Chapter 4), and (iii) the replacement of bastnaesite by rhabdophane and monazite (Chapter 5). These chapters focus on the mechanisms, porosity formation, and element redistribution of mineral replacement reactions, typically observed in carbonate-hosted mineral deposits.
Chapter 2 details the importance of mineral replacement reactions during the formation and post-depositional alteration of a carbonate replacement deposit. The study was carried out on the Artemis Zn-Cu-Au prospect, which is located in the Cloncurry district, NW Queensland, Australia. The high-grade polymetallic mineralization displays a complex association of massive sulfides and carbonates hosted in a vertical marble lens. Petrographic analyses suggested three major stages: (i) pre-ore stage marble; (ii) ore stage mineralization involving the dissolution of calcite from the marble and precipitation of sulfides and secondary carbonates; and (iii) a post-ore alteration stage involving the replacement of sulfides by calcite and garnet. The replacement of Co-rich arsenopyrite (Fe0.75Co0.26As1.13S0.83) by relatively Co-poor arsenopyrite (Fe0.86Co0.15As0.99S0.99) revealed formation temperatures of 650 ± 50 and 450 ± 70 °C, respectively. In the post-ore stage, pyrrhotite Fe(1-x)S, (x = 0.091–0.119) was pervasively replaced by an almandine-spessartine-rich garnet. The microscale investigations of the mineralization processes in the Artemis orebody document the impact of hydrothermal mineral replacement reactions on metal sequestration. Mineral replacement reactions facilitate the formation of ore deposits and subsequent alteration processes, which may lead to the late-stage loss of economic value of the deposit.
Chapter 3 discusses the importance of conducting nanoscale investigations of mineral replacement reactions to constrain their physicochemical conditions, exemplified by the suggested replacement of pyrrhotite by garnet at the Zn-Cu-Au Artemis prospect. Nanoscale examinations by transmission electron microscopy (TEM) of the grain boundary between pyrrhotite and garnet reveal textural and compositional complexity at the reaction front. The single crystal of pyrrhotite has a <100 nm thick Bi-rich rim (~2.7 at.% of Bi). The pyrrhotite rim is bounded by a 5–20 nm wide hematite layer, while pores (<10 nm thick) are present between the two phases. The garnet single crystal and the hematite layer are separated by a gap (10–30 nm). These observations indicate that the replacement of pyrrhotite by hematite proceeded via the coupled dissolution reprecipitation (CDR) mechanism, while Bi precipitated from the hydrothermal solution. The newly formed porosity was occupied by subsequent precipitation of garnet. This study highlights the importance of nanoscale characterization for revealing detailed mechanisms of sulfide alteration.
Chapter 4 details experiments on the replacement of calcite by siderite in Fe-rich hydrothermal fluids, investigating the effects of temperature (60–200 °C), solution pH (1.8–10), time (2–1680 h), and calcite precursor (marble and Iceland spar). Two contrasting replacement processes were identified: At 60 °C, the replacement was slow at a transformation of 89% after 1680 h for Iceland spar experiments. Siderite precipitated preferentially along the twin boundaries of calcite, and porosity developed in-between the twins. At 200 °C, the reaction was much quicker at a transformation of 94 % after 8 h. Several concentric 5–15 μm thick epitaxial siderite layers, separated by gaps (<15 μm) that were partly occupied by akaganeite [Fe3+O(OH,Cl)], replaced the calcite grains. Two siderite populations were identified: (i) metastable, pristine and Ca-rich siderite-1 and (ii) microporous, Ca-poor siderite-2. With time, siderite-1 equilibrated with the Fe-rich bulk fluid and transformed into siderite-2, marking the second replacement step. The formation of microporosity created permeability as a result of molar volume change between siderite-1 and -2 (-4.8%). The concentric layer formation is interpreted as an “oscillatory” CDR mechanism, which forms due to the interplay of passivation, fluid with nonequilibrium composition at the reaction front, and secondary porosity formation. Both textures may be used to interpret reaction conditions in natural mineral replacement reactions, especially within carbonate-replacement deposits.
Chapter 5 focuses on the replacement of the rare earth element (REE) fluorocarbonate mineral bastnaesite (REECO3F), which is frequently affected by fluid-induced alteration processes throughout all crustal levels. The experiments studied the effect of epithermal phosphate-bearing solutions on bastnaesite, which led to its replacement by monazite (REEPO4) and rhabdophane (REEPO4∙nH2O). At 90 °C, fibrous metastable rhabdophane replaced bastnaesite, which was then gradually replaced by monazite. At 220 °C, only monazite formed, and the reaction initiation was much quicker. Spot analyses showed that REE patterns were similar between bastnaesite and monazite. However, rhabdophane preferentially scavenged Nd to Ho. The presented results provide new insights into the formation conditions of rhabdophane and monazite and detail contrasting REE fractionation processes in the epithermal environment, which are critical to our understanding of the genesis of REE deposits.
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Patterson, Lucia Maria. "Hydrothermal footprint of Carlin-type gold deposits at the district scale : Jerritt Canyon Mining District, Elko County, Nevada /." abstract and full text PDF (UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1464422.
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Thesis (M.S.)--University of Nevada, Reno, 2009."May, 2009." Includes bibliographical references (leaves 202-215). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2009]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.
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Collings, Matthew David. "Complexation of Ba and Cu in hydrothermal NaCl brines : insights from EXAFS spectroscopy and molecular dynamics." Thesis, University of Bristol, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326719.
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Zhang, Xingchun. "The geology and hydrothermal evolution of sediment-hosted gold deposits in Southwestern Guzhou Province, PRC." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301310.
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Simmons, Adam Thomas. "Magmatic and hydrothermal stratigraphy of Paleocene and Eocene porphyry Cu-Mo deposits in southern Peru." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/45533.
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A geological investigation of the of the Paleocene-Eocene Cu-Mo porphyry belt of southern Peru was undertaken at the Quellaveco Cu-Mo porphyry system with complimentary work completed at the Cuajone and Toquepala mines. This work adds to the understanding of the formation and evolution of igneous systems associated with Cu-Mo porphyry formation in an understudied but economically significant copper source globally.
The Quellaveco Igneous Complex is composed of at least five phases of porphyritic intrusions which were emplaced into a slightly older equigranular granodiorite batholith and Late Cretaceous Toquepala Group volcanic rocks. These intrusions were emplaced from approximately 58Ma to 53Ma. The intrusions with the closest temporal and spatial association to copper may have been emplaced in as short a timespan as approximately 1.5m.y. These time periods and time spans are almost identical to those for the emplacement of the igneous systems at Cuajone and Toquepala. At Quellaveco, zircon mineral chemistry indicates that the igneous systems associated with porphyry copper formation are different to those not associated with porphyry copper formation. Geochemical disruptions, flat to cup shaped Eu/Eu* anomalies and rapid changes in temperature of formation of the zircons with their growth are indicative of zircons from the porphyry intrusions from Quellaveco. It is postulated that these geochemical signatures may indicate that intrusions associated with the formation of the hydrothermal systems are derived from fractionating and cooling magmatic systems which remained relatively oxidized and were subject to periodic geochemical disturbance. The geochemical disturbances may reflect a dynamic deeper magmatic system where magma mixing, replenishment and scouring of wall rock took place. At Quellaveco, each of the porphyritic intrusions are temporally related with a hydrothermal system. Each hydrothermal system is an evolution of mineral assemblages in veins from biotite-magnetite-chalcopyrite rich veins to quartz-sulphide rich veins to quartz vein with quartz-sericite selvages. This sequence of vein evolution repeats itself at Quellaveco at least four times. Each hydrothermal system occurs immediately after the emplacement of at least five porphyry intrusion suites.
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Burisch, Mathias [Verfasser], and Gregor [Akademischer Betreuer] Markl. "Ore-forming processes of hydrothermal vein-type deposits, SW Germany / Mathias Burisch ; Betreuer: Gregor Markl." Tübingen : Universitätsbibliothek Tübingen, 2016. http://d-nb.info/1165235234/34.
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Vitor, Ribeiro De Sá. "3D geostatistical modeling and integration of lithology, physical properties and element contents for characterizing metal deposit in a seafloor hydrothermal vent area." Kyoto University, 2020. http://hdl.handle.net/2433/254523.
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Flores, Gilberto Eugene. "Microbial Ecology of Active Marine Hydrothermal Vent Deposits: The Influence of Geologic Setting on Microbial Communities." PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/250.
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The discovery of deep-sea hydrothermal vents in 1977 revealed an ecosystem supported by chemosynthesis with a rich diversity of invertebrates, Archaea and Bacteria. While the invertebrate vent communities are largely composed of endemic species and exist in different biogeographical provinces, the possible factors influencing the distribution patterns of free-living Archaea and Bacteria are still being explored. In particular, how differences in the geologic setting of vent fields influence microbial communities and populations associated with active vent deposits remains largely unknown. The overall goal of the studies presented in this dissertation was to examine the links between the geologic setting of hydrothermal vent fields and microorganisms associated with actively venting mineral deposits at two levels of biological organization. At the community level, bar-coded pyrosequencing of a segment of the archaeal and bacterial 16S rRNA gene was employed to characterize and compare the microbial communities associated with numerous deposits from several geochemically different vent fields. Results from these studies suggest that factors influencing end-member fluid chemistry, such as host-rock composition and degassing of magmatic volatiles, help to structure the microbial communities at the vent field scale. At the population level, targeted cultivation-dependent and -independent studies were conducted in order to expand our understanding of thermoacidophily in diverse hydrothermal environments. Results of these studies expanded the phylogenetic and physiological diversity of thermoacidophiles in deep-sea vent environments and provided clues to factors that are influencing the biogeography of an important thermoacidophilic archaeal lineage. Overall, these studies have increased our understanding of the interplay between geologic processes and microorganisms in deep-sea hydrothermal environments.
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Preston, Louisa Jane. "A Multidisciplinary Study of Biomarkers in Hydrothermal Deposits : Applications to the Search for Life on Mars." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/4276.
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Hydrothermal systems have been suggested as suitable environments for the appearance of life on the Early Earth and may provide habitats for microorganisms on Mars. The deposits created by these systems are preserved in the geological record. This research investigates the key mineralogical, textural and biological markers found in terrestrial hydrothermal deposits that can be used as analogues in the search for evidence of life on Mars. Samples of silica sinter from Iceland and New Zealand, the Rhynie Chert 396 Ma old deposit from Aberdeenshire and hydrothermally altered impactites from the Chicxulub impact crater have been analysed to understand the mineralogical properties unique to the different hydrothermal conditions and the evidence of extant or extinct microorganisms within them. Re-colonisation of basaltic substrates by hot spring-derived cultures was also carried out. This research was conducted using a multidisciplinary approach with the analytical techniques and instruments involved currently used for in-situ and orbital observations of planetary bodies. The principal techniques, Fourier Transform Infrared (FTIR) spectroscopy and Gas Chromatography Mass Spectrometry (GCMS), were used due to their combined capabilities in the identification of a variety of rocks and minerals, and a wide range of organic compounds. This PhD research has shown that FTIR in particular is an exceptional analytical technique for use in astrobiological investigations. This research has characterised hydrothermal deposits of different ages and created by different processes on Earth to ascertain their potential for preserving organic compounds in similar deposits on Mars. Results indicate that siliceous hydrothermal deposits of recent and ancient formation yield biomolecular evidence for past and present microbial colonisation as do hydrothermally altered impact deposits and re-colonised basaltic substrates. The identification of mineralogical and biological information using FTIR reflectance spectroscopy has wide implications in the search for life on Mars and other planetary bodies.
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Mercer, Celestine Nicole. "Mineralogical indicators of magmatic and hydrothermal processes in continental arc crust /." Connect to title online (Scholars' Bank) Connect to title online (ProQuest), 2009. http://hdl.handle.net/1794/10250.
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Wilt, Jan Carol. "Geochemical patterns of hydrothermal mineral deposits associated with calc-alkalic and alkali-calcic igneous rocks as evaluated with neural networks." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186500.
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Six alkalinity and oxidation classes of fresh igneous rocks were correlated with trace elements in rock chip samples from temporally and spatially associated ore deposits. Learning vector quantization and back-propagation artificial neural networks correctly classified 100 percent of whole rock oxides and 99 percent of mineralized samples; discriminant analysis correctly classified 96 and 83 percent, respectively. The high degree of correlation between chemistries of igneous rocks and related mineralization implies genetic links between magmatic processes or sources and the ore deposits studied. The petrochemical classification was evaluated by assigning 43 deposits to classes defined on eight variation diagrams, training neural networks to classify analyses of 569 igneous and 887 mineralized samples, and testing the networks on their ability to classify new data. Whole rock analyses were obtained from mining districts in which trace element geochemistry was also available. Half the data was eliminated using five alteration filter graphs. The K₂O and Fe₂O₃/FeO versus SiO₂ diagrams and iron mineralogy best defined alkalinity and oxidation classes. Neural networks trained with 90, 80, 70, or 50 percent of the samples correctly classified 81 to 100 percent of randomly withheld data. SiO₂/K₂O ratios of alkali-calcic igneous rocks are 14-20 and of calc-alkalic 20-30. Fe₂O₃/FeO ratios are >0.8 with abundant magnetite and sphene for oxidized, 0.5-1.2 with magnetite, sphene, and rare ilmenite for weakly oxidized, and <0.6 with ilmenite only in reduced subclasses. Lead-zinc-silver deposits as at Tombstone and Tintic are related to oxidized alkali-calcic igneous rocks. Polymetallic lead-zinc-copper-tin-silver deposits, such as Santa Eulalia and Tempiute, Nevada, are associated with weakly oxidized alkali-calcic rocks. Tin-silver deposits of Llallagua and Potosi are correlated with reduced alkali-calcic intrusives. Porphyry copper deposits as at Ray and Sierrita are connected with oxidized calc-alkalic plutons. Gold-rich porphyry copper deposits, such as Copper Canyon and Morenci are linked to weakly oxidized calc-alkalic plutons. Disseminated gold deposits, such as Chimney Creek, Nevada, are temporally and chemically correlated with reduced calc-alkalic igneous rocks, although physical connections between plutons and Carlin-type deposits remain unconfirmed. Magma series classification and neural networks have profound applications and implications to exploration, alteration and zoning studies, and metallogenesis.
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Murphy, Daniel M. K. "Regolith expression of hydrothermal alteration : a study of the Groundrush and Vera Nancy gold deposits of Northern Australia." University of Western Australia. School of Earth and Environment, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0186.
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[Truncated abstract] Mineralogical and geochemical characteristics were identified for regolith overlying two Australian Au deposits that discriminate mineralized and associated hydrothermally-altered rock from weathered rock that was not hydrothermally-altered. Mineralization was lithologically controlled within a previously unrecognized diorite dyke at the lower Proterozoic mesozonal Groundrush deposit, Tanami region, Northern Territory. Although hydrothermal alteration effects within the dyke were subtle and obliterated by weathering, Ti/Zr ratios clearly discriminated the diorite dyke from visually indistinguishable but generally unmineralized dolerite. In contrast, the Carboniferous Vera Nancy low-sulphidation epithermal Au deposit, located in the Drummond Basin, northeast Queensland, comprises structurally-controlled quartz veins within a relatively chemically homogenous suite of andesitic lavas and subvolcanic intrusions. A zoned hydrothermal alteration system in the hangingwall of the main vein grades from a proximal silica-pyrite alteration zone through an argillic zone into regionally extensive propylitic 'background'. Deep chemical weathering has destroyed the minerals diagnostic of the different alteration zones in bedrock to leave a kaolinitic regolith overlying all alteration zones. However, the silica-pyrite alteration zone is identified in regolith by retention of the anomalous concentrations of Au, As, Sb and Mo present in bedrock, and mineralogical characteristics, determined from X-ray diffraction investigations, discriminated weathered argillic from propylitic alteration zones. ... Metasomatic reactions, including weathering reactions, are typically difficult to specify, as some reactants and products may be removed by fluids, and thus evidence for their involvement is absent from the observed assemblages. In addition, the range of possible reactions even for relatively simple systems is such that identifying the real reaction may be intractable without additional information. Linear algebra provides an approach to this problem. If minerals and aqueous phases are represented as columns in a matrix with elements as rows, any vectors in the null space of this matrix (if it is greater than 0-dimensional) provide coefficients to balance reactions between the phases. The 'Gale' vectors for a set of phase are the row vectors of any basis for this null space. The relationships between phases are clarified through examination of these vectors in d-dimensional Gale vector space, where d is the dimension of the null space. The hyperplane normal to any vector in Gale vector space separates the space into reactant and product half-spaces. The geometric relationships between the Gale phase vectors describe all the possible reactions. Because changes to parameters (e.g. volume, mass, density) can be determined for each possible reaction, Gale analysis can be used to identify reactions consistent with these constraints. Gale analysis of weathering at the Vera deposit indicated that all the possible weathering reactions producing kaolinite, goethite and quartz from illite, pyrite and siderite resulted in minor reductions in volume and mass only, whereas acid-neutral weathering of propylitic rocks exhibited greater mass losses, consistent with observation and geochemical interpretation.
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Gagnon, Joel Edward. "Genesis of hydrothermal high field strength element mineral deposits : evidence from laser ablation--inductively coupled plasma mass spectrometry." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100367.
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High field strength elements (HFSE) are geologically and economically important. These elements were once thought to be immobile during metasomatic processes, however, a growing body of empirical evidence indicates that HFSE can be mobilized under certain conditions. Despite this evidence, little is known about the factors controlling solubility, transport and deposition of HFSE by aqueous fluids, apart from some theoretical estimates and rare experimental studies. Therefore, the study of natural systems (e.g., HFSE ore deposits) provides an excellent opportunity to evaluate HFSE mobility by aqueous fluids. Five localities where evidence of hydrothermal transport of HFSE has been previously documented were included in this study: Gallinas Mountains, New Mexico; South Platte, Colorado; Rock Canyon Creek, British Columbia; St. Lawrence, Newfoundland; and Strange Lake, Quebec/Labrador. Minerals and, in the case of South Platte, fluid inclusions from these localities were analyzed using petrography and laser ablation inductively-coupled plasma mass spectrometry (LA-ICPMS) to evaluate the source of the HFSE and the hydrothermal fluids responsible for HFSE transport, and factors controlling HFSE and gangue mineral (e.g., fluorite, quartz) precipitation. Analysis of some of the important gangue minerals, which are also the primary host of fluid inclusions in many of these deposits (e.g., fluorite), is difficult using 266 nm Nd:YAG-based LA-ICPMS. Furthermore, complex mineral intergrowths and the desire to quantify the chemical composition of unknown minerals required the development of analytical and data reduction protocols for LA-ICPMS. Methods for conducting traversed opening of fluid inclusions, removing the host mineral contribution to fluid inclusion signals by calculating count rate ratios, and quantifying the composition of minerals without using an internal standard are presented. In general, hydrothermal enrichment of HFSE in these deposits appears to have resulted from interaction of an HFSE- and F-bearing magmatic fluid with another, Ca-bearing fluid or with Ca-bearing wall rocks or preexisting minerals. In most cases, HFSE appear to be derived locally, within the associated igneous intrusion.
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Taner, Havva. "The nature, origin and physicochemical controls of hydrothermal Mo-Bi mineralization in the cadillac and preissac deposits, Quebec /." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=55640.
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Ishizu, Keiichi. "Clarifying detailed resistivity structures in seafloor hydrothermal fields by inversion of electric and electromagnetic data." Kyoto University, 2020. http://hdl.handle.net/2433/253259.
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Scott, John G., and n/a. "Structural controls on gold - quartz vein mineralisation in the Otago schist, New Zealand." University of Otago. Department of Geology, 2006. http://adt.otago.ac.nz./public/adt-NZDU20070412.160816.
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Hydrothermal fluid flow is spatially and genetically associated with deformation in the earth�s crust. In the Otago Schist, New Zealand, the circulation of hydrothermal fluids in the Cretaceous formed numerous mesothermal gold-quartz vein deposits. Otago schist rocks are largely L-S tectonites in which the penetrative fabric is the product of more than one deformation phase/transposition cycle. Regional correlation of deformation events allowed mineralised deposits to be related to the structural evolution of the Otago Schist. Compilation of a detailed tectonostratigraphy of New Zealand basement rocks reveals that extensional mineralisation correlates with the onset of localised terrestrial fanglomerate deposition, thermal perturbation and granitic intrusion that mark the beginning of New Zealand rifting from the Antarctic portion of Gondwana.
Laminated and breccia textures in mineralised veins suggest that host structures have experienced repeated episodes of incremental slip and hydrothermal fluid flow. However, analysis of vein orientation data in terms of fault reactivation theory (Amontons Law) shows that most deposits contain veins that are unfavourably oriented for frictional reactivation. Repeated movement on unfavourably oriented structures may involve dynamic processes of strain refraction due to competency contrasts, the effect of anisotropy in the schist, or localised stress field rotation.
Deposits have been classified on the basis of host structure kinematics at the time of mineralisation into low angle thrust faults, and high angle extensional fault - fracture arrays. Low angle deposits have a mapped internal geometry that is very different from conventional imbricate thrust systems. This study applied ⁴⁰Ar/�⁹Ar geochronology to selected deposits and has identified at least three distinct mineralisation events have occurred within the central axial belt during the Cretaceous. Relationships between radiometric apparent age and inferred crustal depth reveal that after metamorphism, the onset of cooling and rapid exhumation of the schist belt coincides temporally and spatially with the age of mineralisation and structural position of a regional scale low angle shear zone in Otago.
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Bennett, Andrew John. "Relationship between gold and arsenic in hydrothermal pyrite : experimental results and applications to submicroscopic gold in massive sulphide deposits." Thesis, University of Leeds, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421978.
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Craddock, Paul R. "Geochemical tracers of processes affecting the formation of seafloor hydrothermal fluids and deposits in the Manus back-arc basin." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/55328.
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Thesis (Ph. D.)--Joint Program in Chemical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2009.Includes bibliographical references.
Systematic differences in trace element compositions (rare earth element (REE), heavy metal, metalloid concentrations) of seafloor vent fluids and related deposits from hydrothermal systems in the Manus back-arc basin (Eastern Manus Basin, EMB and Manus Spreading Center, MSC) are used to investigate processes that affect their formation. Processes responsible for observed differences in fluids and deposits from distinct geologic settings include (a) fluid-rock interaction (with temperature, pressure and crustal composition as variables), (b) magmatic acid volatile input and, (c) local seawater entrainment and mixing with hydrothermal fluids, coupled with sulfide precipitation and metal remobilization. REE distributions in vent fluids in the Manus Basin exhibit a wide range of chondrite-normalized patterns that contrast with the relatively uniform distributions observed in mid-ocean ridge vent fluids. This heterogeneity is attributed to marked differences in fluid pH and fluoride and sulfate concentrations that significantly affect REE solubility. The data indicate that REEs can be used as indicators of the styles of magmatic acid volatile input in back-arc hydrothermal systems. Anhydrite in deposits record the same range of REE patterns, suggesting that REE distributions preserved in anhydrite can be used as indicators of past magmatic acid volatile input. Vent fluid heavy metal and metalloid concentrations also exhibit considerable differences. High metal concentrations in EMB versus MSC vent fluids reflect low pH, largely from input of magmatic acid volatiles (indicated by fluoride concentrations greater than seawater). In EMB, metal concentrations are locally affected by dissolution of previously deposited sulfide owing to low pH conditions affected by magmatic acid volatile input or seawater entrainment and mixing with hydrothermal fluid that leads to sulfide precipitation and secondary acidity generation.
(cont.) Massive sulfide deposits in the Manus Basin exhibit a wide range of mineral compositions and heavy metal enrichments. The formation of Zn-rich (sphalerite/wurtzite) deposits in the MSC and of Cu-Fe and Cu-As-rich (chalcopyrite, tennantite) deposits in the EMB reflects differences in the conditions of sulfide precipitation (temperature, pH) and in metal concentrations. The data suggest that heavy metal and metalloid distributions in massive sulfide deposits can be used as indicators of the conditions of vent deposit formation.
by Paul R. Craddock.
Ph.D.
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Perold, Jacques. "Ceramic parameters in the financial evaluation of brick clay deposits, with reference to two South African examples." Diss., Pretoria : [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-08212007-121848.
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Törmänen, T. (Tuomo). "Ore mineralogy, geochemistry, and formation of the sediment-hosted sea floor massive sulfide deposits at Escanaba Trough, NE Pacific, with emphasis on the transport and deposition of gold." Doctoral thesis, University of Oulu, 2004. http://urn.fi/urn:isbn:9514276264.
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Abstract
Recent sea floor sulfide deposits form when seawater, heated within the oceanic crust, discharges to the sea floor. Upon mixing with cold seawater, sulfide-forming elements such as sulfur, iron, copper, and zinc are precipitated from the fluid.
Actively forming sea floor massive sulfide deposits are found from different lithologic and tectonic environments varying from mid-ocean ridges to back-arc spreading centers. At a few localities, sulfide deposits are associated with turbiditic sediments that cover the axial valley of the spreading center. The southern part (Escanaba Trough) of the Gorda Ridge (NE Pacific) is one such example. At Escanaba Trough, massive sulfide deposits are associated with small sediment hills, which were uplifted by the intrusion of sills and laccoliths within the sediments. Hydrothermal deposits are dominated by pyrrhotite-rich massive sulfides, with subordinate amounts of sulfate-rich precipitates and polymetallic sulfides. Compared to deposits hosted by volcanites, Escanaba Trough sulfides contain relatively low amounts of copper and zinc. However, the average gold concentration is relatively high for a sediment-hosted deposit, and is comparable with other, Au-enriched, sea floor sulfide deposits.
Despite the relatively high Au concentration in many volcanic-hosted sea floor sulfide deposits, discrete Au grains are rare. They occur mostly with sphalerite, pyrite, chalcopyrite and tetrahedrite-tennantite. Sixteen of the pyrrhotite-rich samples from Escanaba Trough were found to contain visible Au grains. They occur mostly with native Bi and various BiTe phases, and to lesser degree, with Fe-Co sulfarsenides.
Transport of Au in sea floor hydrothermal systems is attributed to the presence of Au(HS)2- complex, which is destabilized when the fluid mixes with seawater. Hydrothermal fluids are generally undersaturated with respect to Au complexes and additional mechanisms, such as remobilizing earlier precipitated Au is required to explain the high Au concentrations encountered in many deposits. At Escanaba Trough the mechanism is attributed to early precipitation of Bi as melt droplets, at temperatures greater its melting temperature, as liquid Bi is capable of collecting Au even from an undersaturated fluid. Upon cooling Au is exsolved from the Bi host as native Au or maldonite (Au2Bi).
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Dolansky, Lila. "Controls on the genesis of hydrothermal cobalt mineralization: insights from the mineralogy and geochemistry of the Bou Azzer deposits, Morocco." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18693.
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The cobalt deposits at Bou Azzer, Morocco, represent an unusual type of mineralization and an important source of cobalt to the global economy. The orebodies are distributed along the borders of Neoproterozoic serpentinite massifs and consist predominantly of (Co,Ni,Fe) arsenides and sulpharsenides, with accessory sulphides and gold in a quartz-carbonate gangue. The ore minerals were deposited from acidic (pH<5), highly saline brines (~36-51 wt. % NaCl + CaCl2 eq.) under moderately reducing conditions, at temperatures of ~200-400C and pressures of more than 880 bars. The metals were leached from the serpentinites by As-bearing, Na-dominated magmatic brines and transported in solution as chloride complexes. Ore mineral deposition occurred mainly in response to increasing pH and decreasing oxygen fugacity of the fluids, which resulted from increased interaction with the serpentinites, and mixing between the magmatic brines and Ca- and sulphate-enriched meteoric waters. The mineralization is Late Devonian in age and related to pre-collisional tectonics of the Hercynian orogeny.Les gisements de cobalt de Bou Azzer (Maroc) représentent un type peu commun de minéralisation ainsi qu'une source importante de cobalt pour l'économie mondiale. Les gisements sont distribués sur les périphéries des massifs de serpentinite néo- protérozoïques, et sont composés majoritairement d'arséniures et de sulpharséniures de Co-Ni-Fe, avec des quantités mineures de sulphures et de l'or dans une gangue de quartz-carbonate. Les minerais de cette masse ont été déposés a partir des saumures acides (pH<5) et fortement salines (~36-51 wt.% NaCl + CaCl2 éq.), sous des conditions reduites, à des températures variant entre 200 et 400C et des pressions plus de 880 bars. Les métaux ont été lixiviés des serpentinites par des saumures magmatiques riches en sodium et contenant de l'arsenic, pour ensuite être transportés en solution, sous la forme de complexes de chlorure. La déposition des minerais s'est produite principalement en réponse à l'augmentation du pH et de la diminution de la fugacité de l'oxygen des fluides, causés par une interaction accrue avec les serpentinites, ainsi que par le mélange entre les saumures magmatiques et les eaux météoriques enrichies de Ca et sulfate. Les minéralisations datent de la Dévonienne supérieure et sont liées à la convergence pré-collisionnelle de l'orogenèse hercynienne.
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Mosser, Kevin Lynn. "Mineralogy, paragenesis, and fluid inclusion relationships of the hydrothermal ore deposits at Florida Mountain, Carson mining district, Owyhee County, Idaho." Thesis, The University of Arizona, 1991. http://hdl.handle.net/10150/144647.
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Exploration on Florida Mountain in southwestern Owyhee County, Idaho has defined four separate Au-Ag-Se orebodies. These deposits differ greatly in size, shape, grade, and metal ratios. However, all four are related to the same episode of epithermal vein mineralization. Ore deposition was associated with an active geothermal field related to a series of Mid-Miocene (15.2 to 16.6 m.y.a.) silicic domes and flows. Hydrothermal fluids of meteoric origin were localized along NW-trending faults and leached their constituents from the surrounding rocks. Metals were transported as complexes of sulfur and selenium in a 1% NaCl equivalent solution at 260$\sp\circ$C. Ore deposition occurred some 400m below the paleo-surface as the result of boiling and fluid mixing. The major ore minerals are aguilarite, acanthite, and electrum. The gangue is predominantly quartz and adularia. Hydrothermal alteration includes propylitic, sericitic, kaolinitic, and potassic assemblages. Supergene effects in the deposits are minimal.
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Lerchbaumer, Linda [Verfasser], and Hans [Akademischer Betreuer] Keppler. "The Nature of Fluids in Hydrothermal Copper and Molybdenum Ore Deposits - An experimental and analytical study / Linda Lerchbaumer. Betreuer: Hans Keppler." Bayreuth : Universität Bayreuth, 2012. http://d-nb.info/1059412896/34.
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Rosset, Sandra. "Evolution of hydrothermal alteration and mineralization at the deformed Kerr and Deep Kerr Cu-Au porphyry deposits, northwestern British Columbia, Canada." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/64240.
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The calc-alkalic Kerr and Deep Kerr Cu-Au porphyry deposits are located in northwestern British Columbia, and are part of the Kerr-Sulphurets-Mitchell (KSM) property. The deposits comprise a steeply dipping tabular intrusive complex extending N-S ~2.4 km, with a vertical extent >2 km. Ore is primarily hosted within syn-mineral intrusions of monzonite (~197 Ma: Bridge, 1993) which intruded volcanosedimentary rocks of the Hazelton group. The Kerr deposit contains probable reserves of 276 million tonnes at 0.43% Cu, and 0.22g/t Au, for a contained total of 2.6 billion lb’s Cu, and 2.0 million oz’s Au (Seabridge Gold, 2016). The Deep Kerr deposit has an inferred resource estimate of 1.92 billion tonnes grading 0.41% Cu and 0.31 g/t Au for a contained total of 17.3 billion lb’s Cu, and 19.1 million oz’s Au (Seabridge Gold, 2017).
Hydrothermal alteration assemblages are zoned, from early high-temperature potassic alteration located centrally at depth, outwards into subsequent dark chlorite-sericite and sericite-chlorite alteration assemblages. The upper ~1.5 km of the deposit is largely overprinted by late phyllic alteration. Potassic alteration was initially more extensive, and has been largely overprinted. The vein paragenesis comprises ten main vein types subdivided into syn-mineral and late- to post-mineral veins. Copper and gold mineralization are primarily associated with A and B type quartz-sulphide veins contemporaneous with potassic alteration. High-grade copper and gold mineralization is correlated with quartz vein abundance above 500 m elevation within the deposit, and is of a more disseminated style below this elevation. Phyllic alteration introduces molybdenum.
A hydrothermal zonation in both white micas and chlorites was indicated with short-wave infrared spectroscopy. White mica composition becomes more Fe+Mg rich (phengitic) distally from the hydrothermal centre, and is also more phengitic at depth within potassic and dark chlorite-sericite altered rocks. The Mg content of chlorites relative to Fe increases with increasing proximity to the centre of the hydrothermal plume. A zonation in sulphides and suphates was indicated by sulphur isotope analysis. Sulphides are isotopically lighter (lower δ³⁴S values) proximal to the high-grade core of the deposit, and sulphates become isotopically heavier (increasing δ³⁴S values) with decreasing depth in the hydrothermal system.Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate
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Fußwinkel, Tobias [Verfasser], and Thomas [Akademischer Betreuer] Wenzel. "Direct evidence for fluid mixing processes during formation of post-Variscan, unconformity-related hydrothermal vein deposits / Tobias Fußwinkel ; Betreuer: Thomas Wenzel." Tübingen : Universitätsbibliothek Tübingen, 2014. http://d-nb.info/116289721X/34.
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Payne, Caldwell Robert. "Alteration, Mineralization, and Stable Isotope Geochemistry of the Wind Mountain and Willard-Colado Epithermal Deposits, Nevada: Implications for Amagmatic Hydrothermal Activity." OpenSIUC, 2014. https://opensiuc.lib.siu.edu/theses/1396.
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The Wind Mountain (WM) and Willard-Colado (WC) deposits, respectively of Washoe and Pershing Counties, Nevada, represent recent episodes of low-sulfidation, epithermal gold-silver mineralization. They have the principal features of amagmatic epithermal deposits including 1) young ages (<7 Ma), with Willard-Colado at 6.03 ± 0.04 Ma and Wind Mountain at a Pliocene or younger age, 2) absence of associated coeval igneous rocks, 3) development along range-front fault zones, and 4) proximity to modern geothermal systems. Such deposits in the Great Basin are generated by deeply convecting meteoric hydrothermal fluids that derive their thermal energy from the region's high heat flow and metals and volatiles from the traversed rock packages or shallow mantle. Hydrothermal alteration assemblages at both WM and WC are zoned outward from controlling structures along stratigraphic horizons and subsidiary structures, grading through silica, silica-kaolinite, kaolinite, and hematite-rich zones. Silicic and argillic alteration represents main stage hydrothermal activity; significant steam-heated alteration lithocaps are absent. Weathering-related, acid-sulfate fluids overprinted mineralized rocks at both deposits, oxidizing pyrite, remobilizing Au, and producing widespread hematite-goethite-kaolinite-alunite alteration. Gold mineralization is unique at each deposit but formed in several general paragenetic stages. Element maps generated by laser ablation-inductively coupled plasma-mass spectrometry demonstrate that primary Au is in solid solution with pyrite or arsenian pyrite forming patchy concentrations and enriched rims. Secondary and possibly remobilized Au occurs as disseminated electrum and native gold along fractures in silicified rocks. Elevated concentrations of Ag, As and Sb spatially correlate with primary and secondary Au. A final stage is represented by gold in Fe-oxide/hydroxide rims on pyrite crystals or aggregates. The hydrothermal fluids at WM and WC dominantly consisted of meteoric water, based on their low δ18OH2O and δDH2O values calculated from quartz δ18O, kaolinite δ18O and δD, and calcite δ18O data and assumed temperatures characteristic of the epithermal environment. Black calcite prominently fills the range-front faults where at WM it displays a banded texture and contains acicular Mn-oxide inclusions and at Colado is part of a vein sequence grading from centrally distributed quartz, through quartz-calcite and calcite to distal gypsum. Calcite δ13C values are similar to those of igneous and some sedimentary carbon but distinct from values for tufas along the WM range-front fault and at Pyramid Lake. Alunite and gypsum have negative δ34S values indistinguishable from those of pyrite, as well as from H2S in the San Emidio geothermal fluids near WM. This isotopic correspondence results from kinetically inhibited, nonequilibrium isotopic exchange during the low temperature oxidation of reduced sulfur species. It is consistent with the surficial and near surface formation of gypsum, particularly at WM where lenticular gypsum beds are in stratigraphic proximity to sinter containing reed casts. Alunite δ34S values, combined with a psuedocubic habit and association with quartz, support an origin by weathering rather than steam-heated processes. The absence of steam-heated alteration at both deposits is likely related to a high water table during hydrothermal activity, which at WM was expressed by springs depositing sinter or gypsum. Collectively, the data for Wind Mountain and Willard-Colado are consistent with the amagmatic genetic model. Meteoric hydrothermal fluids circulating along range front faults assimilated C, S and potentially Au and other metals from organic bearing sedimentary±volcaniclastic and metasedimentary host rock packages and (or) sediments in adjoining Cenozoic basins. Although they lack a steam-heated alteration lithocap, such as those prominently displayed at the Hycroft and Florida Canyon amagmatic deposits, weathering pervasively altered the tops of the deposits following a substantial drop in the water table due to a change to a drier climate or uplift of the ranges due to local tectonism.
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Pollock, J. Michael. "Geology and geochemistry of hydrothermal alteration, eastern portion of the North Santiam mining area." PDXScholar, 1985. https://pdxscholar.library.pdx.edu/open_access_etds/3582.
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The Ruth Mine is a base-metal vein deposit near the eastern margin of a reported porphyry copper deposit in the Western Cascade Range in Oregon. Uplift of the Western Cascade Range has resulted in a deeply dissected terrain in which more than a kilometer of the stratigraphy overlying the porphyry-style mineralization is preserved and exposed. The stratigraphic units, which are middle Tertiary in age, have been given arbitrary letter designations beginning with the lowest unit (Unit A) through the uppermost unit (Unit D).
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Wilson, Ryan. "Hydrothermal Fe-Carbonate Alteration Associated with Volcanogenic Massive Sulfide (VMS) Deposits in Cycle IV of the Noranda Mining Camp, Rouyn-Noranda, Quebec." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/22838.
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Massive sulfide deposits in the Noranda mining camp, northwestern Québec, are mainly associated with extensive footwall alteration defined by intense chloritization and sericitization. However, Fe-carbonate alteration also occurs in proximity to some deposits. To test the exploration significance of carbonate alteration in the camp, two areas of intense carbonate alteration were examined, around the small Delbridge deposit and near the new Pinkos occurrence in the Cyprus Rhyolite. Between 1969 and 1971, the Delbridge deposit produced 370,000 t of ore grading 9.6% Zn, 0.61% Cu, 110 g/t Ag, and 2.1 g/t Au. Recent drilling at the new Pinkos occurrence intersected 2.64 m of massive to semi-massive sulfides grading 8.1% Zn and 18.2 g/t Ag. Alteration mapping has shown that the distribution of Fe-carbonates can be used to identify vertically extensive zones of hydrothermal upflow at both properties. At Delbridge, intense Fe-carbonate alteration in brecciated rhyolite defines a pipe-like upflow zone that extends vertically for up to 300 m within the stratigraphic footwall of the massive sulfides and 100 m into the hanging wall. The location of known massive sulfide mineralization coincides with the intersection of the alteration pipe and a favorable horizon marked by the occurrence of fine-grained volcaniclastic rocks. At Pinkos, a similar zone of Fe-carbonate alteration occurs in outcrops of coherent rhyolite. Fe-carbonate alteration is most intensely developed along polygonal cooling fractures in massive rhyolite and decreases in intensity towards the centers of the columns. Fe-carbonate stringers and locally abundant matrix carbonate occur in fragmental rocks at the stratigraphic top of the coherent rhyolite flows and are most intense at the location of sulfide-bearing outcrops that mark the known mineralized horizon. Whereas Fe-carbonate alteration defines the central part of the hydrothermal upflow zones at both properties, disseminated pyrite occurs at the margins and is widespread outside the main upflow zones. This may indicate that Fe-carbonate in the main upflow zones formed at the expense of earlier disseminated sulfides. Replacement of pyrite by synvolcanic Fe-carbonate alteration at Delbridge and Pinkos can probably be attributed to a relatively high concentration of dissolved CO2, possibly of magmatic origin, in the main-stage ore-forming fluids.
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Wilkening, Richard Matthew. "The geology and hydrothermal alteration of the Bear Creek Butte area, Crook County, central Oregon." PDXScholar, 1986. https://pdxscholar.library.pdx.edu/open_access_etds/3656.
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The Eocene Clarno Formation, the Oligocene John Day Formation and basalts of the High Lava Plains are exposed in the Bear Creek Butte area in Central Oregon. In this area the Clarno Formation can be divided into a lower sequence composed of intermediate lava flows with intercalated mudflows and volcaniclastic sediments and an upper sequence of rhyolite and basalt flows and felsic ruffs. Separating the two units is a well developed saprolite. The change from intermediate to rhyolite-basalt volcanism reflects a change in the tectonic environment of the Cascade volcanic arc from compression to relaxation as subduction of the Farallon plate by the North American plate slowed, allowing extension of the continental plate margin to occur.
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Rodríguez, Madrid Alfonso Luis. "Geology, alteration, mineralization and hydrothermal evolution of the La Bodega-La Mascota deposits, California-Vetas Mining District, Eastern Cordillera of Colombia, Northern Andes." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/46070.
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La Bodega (LB) and La Mascota (LM) deposits (inferred resources in 2010 of 3.47 Moz Au, 19.2 Moz Ag and 84.4 Mlbs Cu at 2 g/t Au cut off) are located in the California-Vetas Mining District, 35 km NE of Bucaramanga, in the Eastern Cordillera of Colombia within the Santander Massif.
Mineralization exhibits NE-trending, NW-dipping structural control associated with the right lateral strike-slip La Baja fault. Mineralization at LB is composed of veins networks and tectonic-hydrothermal breccias while LM mineralization is largely contained in hydrothermal breccias with adjacent narrow veining zones. Mineralization is hosted in Proterozoic Bucaramanga (gneiss) Complex and Triassic-Jurassic leucogranites.
Hydrothermal alteration and mineralization occur in six stages. An early porphyry-style phase comprises stages 1 and 2. Stage 1 is characterized by propylitic alteration with epidote, chlorite, calcite, specularite veins, minor pyrite and chalcopyrite, probably associated in time with Mo-Cu mineralization (Re/Os on molybdenite ~10 Ma) and porphyritic granodiorites (U/Pb in zircon ~10-8.4 Ma) cropping out in the district. Stage 2 (⁴⁰Ar/³⁹Ar on muscovite ~3.4 Ma) is characterized by phyllic alteration (muscovite/sericite – illite, quartz, pyrite) associated with quartz+pyrite veins. Epithermal phase (stages 3-6) is related to multi-phase hydrothermal breccia development and advanced argillic (quartz-alunite) alteration which based on alunite ⁴⁰Ar/³⁹Ar geochronology took place between ~2.6 and ~1.3 Ma. Stage 3 is characterized by copper sulfide deposition. Stage 4 is characterized by wolframite deposition in veins/breccias. Stage 5 is characterized by enargite deposition. Stage 6 is characterized by minor porous quartz deposition followed by sphalerite with alunite+quartz. Pyrite is common to all these stages. Gold-silver mineralization took place in stages 2-5 associated with sulfides, sulfosalts, tellurides, as electrum and native gold. Hydrothermal events were by followed by near surface supergene alteration and fault reactivation that created intensely fractured/gouge-rich fault zones.
At LM, stages 4-5 quartz primary fluid inclusions assemblages indicate boiling and they have homogenization temperatures of ~143-238°C and salinities of 0.5-5.6 wt% NaCl equiv. LM and LB pyrite exhibit light δ³⁴S signatures: -16.9‰ to –11.3‰ at LM and -8.3‰ and –6.1‰ at LB. Alunite δ¹⁸O and δD data indicate that it was precipitated largely from magmatic fluids.
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Wade, Lowell. "The mineralogy and major element geochemistry of ferromanganese crusts and nodules from the northeastern equatorial Pacific Ocean." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30427.
Full textAbstract:
A study of the mineralogy and major element geochemistry of ferromanganese crusts and nodules from the northeastern equatorial Pacific Ocean involved three inter-related projects: ft) the major element geochemistry of crusts and nodules from two study areas, (2) the development of a selective sequential extraction scheme (SSES) and a differential X-ray diffraction technique (DXRD) for the study of the mineralogy of the deposits, and (3) the application of the SSES and DXRD to a small population of crusts and nodules from the two study areas. The objectives of the first project were to relate the composition of the crust and nodule samples to the environment of formation as well as to the mineralogy which could be identified from a bulk powdered sample. The SSES was developed to determine the partitioning of Cu, Ni, and Co concentrations between the Mn and Fe oxides present in crusts and nodules. In developing a SSES, two goals had to be attained: (1) since crust and nodule samples are finite in size and numerous different analyses are to be preformed on a single sample, a SSES should be developed which uses as small amount of sample as feasible, and (2) develop a SSES which is as time efficient as possible. The development of the DXRD in conjuction with the SSES identified which Mn and Fe oxide mineral phase was responsible for hosting Cu, Ni, and Co. In developing the DXRD procedure two other goals had to be attained: (1) use of small leached samples, and (2) recovery of the sample aafter XRD analysis. The purpose of the third project was to test the two analytical procedures on a group of crust and nodule samples which have a wide range in compositions and oxide phase mineralogies.
One group of hydrothermal nodules, from Survey Region B, was found to be enriched in Mn and depleted in Fe and Si. The Mn-rich mineral phases were identified as todorokite and birnessite. The second group of hydrothermal nodules, from Survey Region B, was found to be enriched in Fe and Si and depleted in Mn. The Fe-Si rich mineral phase was identified as iron-rich nontronite. Both groups of hydrothermal nodules were depleted in Co, Cu, and Ni. Dymond et al. (1984) and Chen & Owen (1989) identified one group of hydrothermal nodules located close to the East Pacific Rise (EPR) as being enriched in Fe but depleted in Mn, Cu, Ni, and Co. This composition agrees with the Fe-Si rich hydrothermal nodules identified in Survey Region B. Both Dymond et al. (1984) and Chen & Owen (1989), however, interpreted a second group of nodules, close to the EPR, which were enriched in Mn but depleted in Cu, Ni, and Co as suboxic diagenetic deposits. This group of nodules is the Mn-rich end-member composition of hydrothermal nodules identifed in this study.
The composition of nodules from Survey Region B indicates there is a correlation between Co abundance and the proximity of the nodules to the hydrothermal discharge from the JEPR. Nodules that are Co-enriched are found farthest away from hydrothermal activity. In contrast, cobalt-depleted nodules coincide with known areas of hydrothermal activity.
The SSES and DXRD was applied to a small population of crusts and nodules from the two Survey Regions. The DXRD patterns from the second stage of leaching on the crusts and nodules showed that the iron phase mineralogy in marine crusts and nodules is either akaganeite or ferrihydrite. The DXRD patterns from the second stage of leaching on the Mn-rich hydrothermal crusts and nodules, from Survey Region B, identified the Mn-bearing mineral hausmannite.Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate
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Mhangara, Paidamwoyo. "Testing the ability of ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) to map hydrothermal alteration zones : a case study of the Haib Porphyry Copper-Molybdenum Deposit, Namibia." Thesis, Stellenbosch : Stellenbosch University, 2005. http://hdl.handle.net/10019.1/50462.
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Thesis (MSc)--Stellenbosch University, 2005.ENGLISH ABSTRACT: The availability of multispectral data from the satellite-borne ASTER (Advanced Space borne Thermal Emission Reflection Radiometer) sensor with 14 spectral bands, launched on 18 December 1999, ushers in a new dimension in large-scale mineral exploration. The ASTER bands are strategically positioned to map distinctive absorptive features for mapping alteration mineralogy, which has increased the potential to map hydrothermal alteration zones as compared to the conventional Landsat TM satellite and aerial photographs. This research tests the ability of ASTER to map hydrothermal alteration zones by applying various image enhancement techniques and comparing them. The study area is the Haib copper prospect in Namibia. The Crosta technique, standard colour composites, spectral band ratioing, the software defoliant technique, log residuals and spectral linear unmixing were applied and compared against results from the previous detailed geophysical and geochemical exploration. The results from all the techniques corresponded with published geological maps from previous work and indicated ASTER's ability to detect alteration zonations. Comparison of the methods applied showed that choice of technique is usually dependent of the level of detail which one seeks to achieve. Standard colour composite and log residuals are more useful for a generalized overview of the alteration mineralogy, whilst uniquely defining mineral end members is achieved by application of the Crosta technique, ratioing and spectral linear unmixing. Application of the software defoliant techniques involved ratioing results, which are affected by spectral interferences from other minerals. The presence of a highly fractured system has been established by application of Sobel filtering. A spatial association of the extracted fracture system with alteration areas suggest mineralization at the Haib is fracture controlled. The results support the presence of argillicphyllic and prophylitic alteration zones on a regional scale, a scenario which can be equated to the Lowell-Guilbert model. The potassic-phyllic zone boundary could not be spectrally detected which also supports previous studies which suggest the potassic zone is nondefinitive and is over-printed by the phyllic zone. The results demonstrate that ASTER is an effective tool to map hydrothermal alteration systems in arid areas.
AFRIKAANSE OPSOMMING: Multispektrale data van die ASTER (' Advanced Space Borne Thermal Emmission Reflection Radiometer') sensors bestaande uit 14 spektrale bande, afkomstig van 'n satelliet gelanseer op 18 Desember 1999 lui 'n nuwe era in vir grootskaalse minerale eksplorasie. Die ASTER bande is strategies sodanig op die spektrum geposisioneer om onderskeidende absorberende verskynsels van veranderde mineralisasie te identifiseer. Hierdie data het die potensiaal verhoog om hidrotermale veranderingstelsels meer suksesvol te karteer as met konvensionele Landsat TM beelde en lugfotos. Hierdie navorsing toets die vermoeëns van ASTER om hidrotermale veranderingstelsels te karteer deur 'n wye reeks beeldverrykings tegnieke toe te pas en te vergelyk. Die studiegebied IS die Haib koperafsetting in Namibië. Die Crosta tegniek, standaard kleursamestellings ('colour composites'), ratio-tegnieke, plantegroeistroping ('software defoiliant'), log residuele ('log residual '), en spektrale lineêre ontmenging ('spectral linear unmixing') is toegepas en die resultate met vorige gedetailleerde geofisiese en geo-chemiese veldopnames te vergelyk. Die verkreë resultate van al die verskillende tegnieke het grootliks met gepubliseerde geologiese kaarte van die gebied ooreengestem en bevestig dat ASTER data geskik is om sulke mineralogies veranderde gebiede te karteer. Vergelykings tussen die tegnieke het getoon dat die keuse van tegniek bepaal word deur die vlak en tipe detail wat verlang word. Standaard kleursamestellings en die log residuele tegnieke lewer goeie resultate om veralgemeende oorsigte van mineralogies veranderde sones te verskaf, terwyl die Crosta-, ratio- en spektrale lineêre ontmengingstegnieke meer suksesvol is om spesifieke minerale te identifiseer. Die plantegroei stropingtegniek is nodig in gevalle waar spektrale ratios deur plantegroeiresponse geaffekeer word. Die aanwesigheid van 'n intensief gefraktuurde sisteem is bepaal deur 'n Sobel filter toe te pas. Ruimtelike assosiasies tussen die voorkoms van die gefraktuurde sone met en die minealogies gewysigde sones dui aan dat mineralogiese wysiging in die Haib gebied deur frakturering beheer is. Die resultate steun die aanwesigheid van argillities-fillitiese enpropolities gewysigde sones op 'n streekskaal, 'n scenario wat deur die Lowell-Guilbertmodel voorgehou word. Die grense van die kalium-fillitiese sone kon nie spektraal waargeneem word nie. Dit steun ook vorige studies wat suggereer dat die kaliumsone nieafbakenbaar is en waarskynlik deur die fillitiese sone oorlê word. Die resultate bevestig onomwonde dat ASTER data benut kan word om hidrotermaal veranderde sones in semiariede gebiede effektief te karteer.
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Jensen, Collin G. "Multi-Stage Construction of the Little Cottonwood Stock, Utah: Origin, Intrusion, Venting,Mineralization, and Mass Movement." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7552.
Full textAbstract:
The Little Cottonwood stock in central Utah, USA, is a composite granitic pluton that hosts the White Pine porphyry Mo-W deposit towards its northeast margin. The deposit is centered on the smaller White Pine intrusion, and associated igneous units include the Red Pine porphyry, phreatomagmatic pebble dikes, and rhyolite dikes. Twelve new U-Pb zircon LA-ICP-MS ages, for samples from this deposit and in pebble dikes from the nearby East Traverse Mountains, give peak ages of about 30 Ma and 27 Ma for the Little Cottonwood stock and White Pine intrusion, respectively, which correlate well with ages from previous studies. Ages of about 26 Ma were obtained for the previously undated Red Pine porphyry.The ages of the Little Cottonwood stock, White Pine intrusion, and Red Pine porphyry, as well as disparities in whole rock elemental differentiation trends, suggest that these units are magmatically distinct, and are not simply derivatives of one another with varying degrees of differentiation. Quench textures and resorbed quartz in the Red Pine porphyry are evidence that the magma system vented, which probably produced volcanic eruptions and emplacement of pebble dikes nearly synchronously with quartz-sericite-pyrite alteration and Mo-W mineralization. The mineralogy and geochemistry of these units imply that the magmas formed in a subduction-related magmatic arc setting rather than in an extensional basin related to orogenic collapse.Pebble dikes in the East Traverse Mountains 17 km away contain igneous clasts that resemble the units in the White Pine deposit in texture, mineralogy, and in U-Pb zircon ages. This supports other recent studies that suggest that the East Traverse Mountains rested atop the White Pine deposit prior to being displaced in a mega-landslide, and the pebble dikes in both locations are the top and bottom of the same mineralized phreatomagmatic system.The construction of the pluton began with intrusion of the Little Cottonwood stock, then the White Pine and Red Pine magmas. Fluid exsolution from the Red Pine magma accompanied venting, inception of the mineralizing hydrothermal system, and quenching to a porphyritic stock. Pebble dikes intruded into the overlying East Traverse Mountain block, which catastrophically failed millions of years later and was emplaced in its current location.
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Steele-MacInnis, Matthew. "Thermodynamics of geologic fluids." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/22026.
Full textAbstract:
Fluids play a vital role in essentially all geologic environments and processes, and are the principal media of heat and mass transfer in the Earth. The properties of geologic fluids can be diverse, as fluids occur at conditions ranging from ambient temperatures and pressures at Earth's surface, to extreme temperatures and pressures in Earth's deep interior. Regardless the wide ranges of conditions at which geologic fluids occur, fluid properties are described and governed by the same fundamental thermodynamic relationships. Thus, application of thermodynamic principles and methods allows us to decipher the properties and roles of geologic fluids, to help understand geologic processes.
Fluid inclusions in minerals provide one of the best available tools to study the compositions of geological fluids. Compositions of fluid inclusions can be determined from microthermometric measurements, based on the vapor-saturated liquidus conditions of model chemical systems, or by various microanalytical techniques. The vaporsaturated liquidus relations of the system H2O-NaCl-CaCl2 have been modeled to allow estimation of fluid inclusion compositions by either microthermometric or microanalytical methods.
Carbon capture and storage (CCS) in deep saline formations represents one option for reducing anthropogenic CO2 emissions into Earth's atmosphere. Availability of storage volume in deep saline formations is a significant component of injection and storage planning. Investigation of the volumetric properties of CO2, brine and CO2-saturated brine reveals that storage volume requirements are minimized when CO2 dissolves into brine. These results suggest that a protocol involving brine extraction, CO2 dissolution and re-injection may optimize CCS in deep saline formations.
Numerical modeling of quartz dissolution and precipitation in a sub-seafloor hydrothermal system was used to understand the role of fluid-phase immiscibility ("boiling") on quartz-fluid interactions, and to predict where in the system quartz could deposit and trap fluid inclusions. The spatial distribution of zones of quartz dissolution and precipitation is complex, owing to the many inter-related factors controlling quartz solubility. Immiscibility exerts a strong control over the occurrence of quartz precipitation in the deeper regions of fluid circulation.Ph. D.
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Keith, Manuel [Verfasser], and Karsten [Akademischer Betreuer] Haase. "From active submarine vent systems to fossil volcanic-hosted massive sulphide deposits: an in-situ analytical study of hydrothermal sulphides / Manuel Keith. Gutachter: Karsten Haase." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2015. http://d-nb.info/1080362703/34.
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Korkalo, T. (Tuomo). "Gold and copper deposits in Central Lapland, Northern Finland, with special reference to their exploration and exploitation." Doctoral thesis, University of Oulu, 2006. http://urn.fi/urn:isbn:951428108X.
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Abstract
At least 30 gold deposits verified by means of one or more notable diamond drill hole results have been discovered in Central Lapland in the last 20 years, and these can be divided spatially into groups, between which the metal composition varies. The deposits contain varying amounts of sulphides and sulpharsenides as well as gold. Pyrite is the most common sulphide mineral in the gold deposits associated with volcanic rocks, and usually pyrrhotite in those associated with sedimentary rocks. The principal sulphide minerals in those connected with banded iron formations are pyrite and arsenopyrite. A separate group of formations consists of the palaeoplacer gold deposits associated with the molasse-like quartzites and conglomerates of Central Lapland.
The iron oxide-copper-gold deposits of Central Lapland, which are a significant potential source of copper and gold, are mostly associated with skarn rocks at the eastern contact of the acidic intrusive rocks of Western Lapland and with skarn rocks occurring as interlayers in metavolcanic and metasedimentary rocks.
The gold deposits that have led to actual mining activities in Central Lapland are Saattopora in Kittilä and Pahtavaara in Sodankylä. Apart from the Laurinoja iron oxide-copper-gold ore body in Kolari, copper concentrate has been produced from the Saattopora gold ore deposit and the Pahtavuoma copper ore deposit. Only one gold ore in Central Lapland is being actively exploited at present, that of the Pahtavaara mine, which was worked in 1995–2000 and reopened in 2003.
The best starting point for successful gold ore exploration in Central Lapland can be achieved through a thorough knowledge of the deformation zones and their structures and alteration processes and the application of geochemical methods. Magnetic surveys can be of help in identifying and locating deformation zones of interest for exploration purposes and the majority of the associated shear zones and faults. Ore-critical zones usually feature graphite-bearing schists and iron sulphide-bearing sequences that can be traced by electrical methods and used as marker zones to verify the results of geological mapping. Geological, geophysical and geochemical techniques have been used in great diversity, and in particular till geochemistry and bedrock drilling have been methods by which the gold and copper deposits in Central Lapland have been discovered.
A total of 7.6 million tonnes of gold and copper ores, including the Laurinoja iron oxide-copper-gold ore, were extracted in Central Lapland over the period 1982–2000. The resulting production of gold during this period was 10 800 kg, together with 21 000 tonnes of copper in concentrates and 4500 kg of silver.
The gold and copper ores have been concentrated by gravity separation and/or flotation, since the ores so far taken into production has been of the free milling type. However, a substantial proportion of the deposits in the area contain copper, nickel, cobalt and arsenic as well, in the form of sulphides or sulpharsenides, so that the achievement of commercially saleable products calls for the use of different leaching processes. Deposits have also been found in Central Lapland that have consisted partly or entirely of refractory gold ore in which gold is lying in the crystal lattice of pyrite and/or arsenopyrite, the processing of which by the above-mentioned methods is not economic, as it requires pre-treatment by bio-oxidation or pressure oxidation in order to convert the gold to a cyanide-soluble form.