Academic literature on the topic 'Ultramafics'
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Journal articles on the topic "Ultramafics"
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Gathania, C. R., A. K. Chattopadhyay, B. Sharma, S. S. Ameta, and A. K. Ghosal. "Occurrence of Ultramafics of Komatiitic Affinity in the Rikhabdev-Dungarpur Belt, Udaipur and Dungarpur Districts, Rajasthan." Journal Geological Society of India 46, no. 6 (1995): 585–94. http://dx.doi.org/10.17491/jgsi/1995/460602.
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Abstract Preliminary study of the ultramafic suite of rocks emplaced concordantly in the Proterozoic supracrustals of the southern Rajasthan (Aravalli Supergroup) indicates their komatiitic nature. Though the diagnostic spinifex texture is not observed in the highly serpentinised and metamorphosed ultramafics, the amygdaloidal structure and the previously reported igneous joints provide textural evidences for the extrusion of the ultramafic lava. The altered ultramafics still retain certain chemical signatures (high MgO and Mg-No., low Ti02, Al2O3and alkalis) of standard komatiites.
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Kutty, T. R. N., S. R. N. Murthy, and G. V. Anantha Iyer. "REE Geochemistry and Petrogenesis of Ultramafic Rocks of Chalk Hills, Salem." Journal Geological Society of India 28, no. 6 (1986): 449–66. http://dx.doi.org/10.17491/jgsi/1986/280603.
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Abstract REE geochemistry of plagioclase-free, plagioclase-bearing and titanoclinohumite-bearing ultramafic suite of Chalk Hills is presented. The rare earth elements are determined by spark source mass-spectrography combined with a preanalytical chemical concentration reaching ± 4 accuracy and 0.01 ppm detection limit. Plagioclase-free ultramafics are 10 times LREE depleted. while HREE abundance is 1-2 times those of chondrite. Since the samples are not serpentinised, these REE patterns are considered to be primary and compare well with those of high temperature peridotites, particularly on CeN-YbN diagram. The plagioclase-bearing ultramafics and the gabbros have LREE contents 4-22 times chondritic, while the HREE varies from 2-12. The REE patterns of ultramafics from the smaller body show uniform increase in (La/Yb)N ratios from 7 to 15. Higher abundance levels of incompatible alkali elements which do not correlate with the MgO contents, may suggest metasomatic introduction of these elements into the smaller body. Petrogenetic modeling, based on partial melting of spinel peridotites as the source rocks with 2 times chondritic abundance, points towards the residual nature of the plagioclase-free ultramafics after extracting 8-10% of the melt. On the other band, the observed REE patterns of the plagioclase-bearing ultramafics and the gabbros not only indicate the absence of rocks more siliceous than syenogabbros but also suggest that they represent compositions of a depleted parent melt from which they originated. Thus the ultramafic association of Chalk Hills is distinctly different from the igneous suites associated with ophiolites and alpine peridotites.
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van der Ent, Antony, Tanguy Jaffré, Laurent L'Huillier, Neil Gibson, and Roger D. Reeves. "The flora of ultramafic soils in the Australia–Pacific Region: state of knowledge and research priorities." Australian Journal of Botany 63, no. 4 (2015): 173. http://dx.doi.org/10.1071/bt15038.
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In the Australia–Pacific Region ultramafic outcrops are both widespread and extensive, covering thousands of km2. Soils derived from ultramafic bedrock impose edaphic challenges and are widely known to host highly distinctive floras with high levels of endemism. In the Australia–Pacific Region, the ultramafics of the island of New Caledonia are famed for harbouring 2150 species of vascular plants of which 83% are endemic. Although the ultramafic outcrops in Western Australia are also extensive and harbour 1355 taxa, only 14 species are known to be endemic or have distributions centred on ultramafics. The ultramafic outcrops in New Zealand and Tasmania are small and relatively species-poor. The ultramafic outcrops in Queensland are much larger and host 553 species of which 18 (or possibly 21) species are endemic. Although New Caledonia has a high concentration of Ni hyperaccumulator species (65), only one species from Western Australia and two species from Queensland have so far been found. No Ni hyperaccumulator species are known from Tasmania and New Zealand. Habitat destruction due to forest clearing, uncontrolled fires and nickel mining in New Caledonia impacts on the plant species restricted to ultramafic soils there. In comparison with the nearby floras of New Guinea and South-east Asia, the flora of the Australia–Pacific Region is relatively well studied through the collection of a large number of herbarium specimens. However, there is a need for studies on the evolution of plant lineages on ultramafic soils especially regarding their distinctive morphological characteristics and in relation to hyperaccumulation.
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Guice, George L., Michael R. Ackerson, Robert M. Holder, et al. "Suprasubduction zone ophiolite fragments in the central Appalachian orogen: Evidence for mantle and Moho in the Baltimore Mafic Complex (Maryland, USA)." Geosphere 17, no. 2 (2021): 561–81. http://dx.doi.org/10.1130/ges02289.1.
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Abstract Suprasubduction zone (SSZ) ophiolites of the northern Appalachians (eastern North America) have provided key constraints on the fundamental tectonic processes responsible for the evolution of the Appalachian orogen. The central and southern Appalachians, which extend from southern New York to Alabama (USA), also contain numerous ultramafic-mafic bodies that have been interpreted as ophiolite fragments; however, this interpretation is a matter of debate, with the origin(s) of such occurrences also attributed to layered intrusions. These disparate proposed origins, alongside the range of possible magmatic affinities, have varied potential implications for the magmatic and tectonic evolution of the central and southern Appalachian orogen and its relationship with the northern Appalachian orogen. We present the results of field observations, petrography, bulk-rock geochemistry, and spinel mineral chemistry for ultramafic portions of the Baltimore Mafic Complex, which refers to a series of ultramafic-mafic bodies that are discontinuously exposed in Maryland and southern Pennsylvania (USA). Our data indicate that the Baltimore Mafic Complex comprises SSZ ophiolite fragments. The Soldiers Delight Ultramafite displays geochemical characteristics—including highly depleted bulk-rock trace element patterns and high Cr# of spinel—characteristic of subduction-related mantle peridotites and serpentinites. The Hollofield Ultramafite likely represents the “layered ultramafics” that form the Moho. Interpretation of the Baltimore Mafic Complex as an Iapetus Ocean–derived SSZ ophiolite in the central Appalachian orogen raises the possibility that a broadly coeval suite of ophiolites is preserved along thousands of kilometers of orogenic strike.
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Singh, M. M., and Vinod K. Singh. "Geochemistry and tectonic setting of the supracrustal rocks from the central part of the Bundelkhand craton, India." Journal of Geoscience, Engineering, Environment, and Technology 4, no. 2-2 (2019): 3. http://dx.doi.org/10.25299/jgeet.2019.4.2-2.2175.
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Supracrustal rocks (mafics and ultramafics) occurs along with banded iron formation, and felsic volcanics around Babina, Dhaura, and Mauranipur linear east-west trends in central part of the Bundelkhand craton represent Archean crust. The mafic and ultramafic rocks geochemically classified into Komatiite and Basaltic Komatiite and have high-Fe Tholeiitic in composition which may relate with the primitive mantle. The major and trace element geochemistry of mafic and ultramafic rocks correspond to hydrated mantle with wedge tectonic sources and ocean ridge geological characteristics.
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Sreckovic-Batocanin, Danica, Dragan Milovanovic, and Kadosa Balogh. "Petrology of the Garnet Amphibolites from the Tejici Village - Povlen Mt., Western Serbia." Annales g?ologiques de la Peninsule balkanique, no. 64 (2002): 187–98. http://dx.doi.org/10.2298/gabp0264187s.
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Different metamorphic rocks discovered near the village of Tejici (Povlen Mt., Western Serbia) represent members of the olistostrome m?lange metamorphosed during the obduction/emplacement of some still hot ultramafic body. They occupy the area of about 2 km2. The garnet amphibolites are of highest metamorphic grade in the area of Tejici and were chosen as the most convenient rocks for determination the pressure-temperature conditions of metamorphism and of ultramafics during their emplacement.
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Nayak, Debajyoti, Pranab Das, and Sagar Misra. "Petrology and Geochemistry of Mesoarchean Sukinda Ultramafics, Southern Singhbhum Odisha Craton, India: Implications for Mantle Resources and the Geodynamic Setting." Minerals 13, no. 11 (2023): 1440. http://dx.doi.org/10.3390/min13111440.
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The Sukinda ultramafic complex in India comprises precisely two areas: Kaliapani (KLPN) and Katpal (KTPL). These areas consist of a sequence of lithotypes, including orthopyroxenite, dunite, serpentinite, and chromitite, displaying a rhythmic layering of rocks. These rocks exhibit a cumulate texture and stand out due to their elevated Mg# (78.43–93.20), Cr (905.40–58,799 ppm), Ni (193.81–2790 ppm), Al2O3/TiO2 (27.01–74.06), and Zr/Hf (39.81–55.24) ratios, while possessing lower TiO2 contents (0.01–0.12 wt%). These ultramafics, characterized by low Ti/V (0.83–19.23) and Ti/Sc (7.14–83.72) ratios, negative anomalies of Zr, Hf, Nb, and Ti in a primitive mantle-normalized spider diagram, indicate that the ultramafics originate from a depleted mantle source. Furthermore, the presence of enriched LREE compared to HREE, a negative Eu anomaly, and enrichment of Th, U, and negative Nb anomalies suggest a subduction setting. The whole-rock geochemical data reveal high levels of MgO, Cr, and Ni, as well as low TiO2 and CaO/Al2O3 ratios and high Al2O3/TiO2 ratios. Moreover, the mineral chemistry data of the ultramafic rocks show high-Mg olivine (Fo 90.9−94.1) in dunite, high-Mg orthopyroxene (En 90.4–90.7) in orthopyroxenite, and high Cr# (0.68–0.82) and low Mg# (0.40–0.54) in chromite, alongside significant Al2O3 (9.93–12.86 wt%) and TiO2 (0.20–0.44 wt%) contents in the melt. Such geochemical characteristics strongly suggest that the Sukinda ultramafic originates from the fractional crystallization of a boninitic parental magma, which is derived from the second-stage melting in a depleted metasomatized mantle source within a supra-subduction zone tectonic setting.
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Firstova, Anna, Georgy Cherkashov, Tamara Stepanova, Anna Sukhanova, Irina Poroshina, and Victor Bel’tenev. "New Data for the Internal Structure of Ultramafic Hosted Seafloor Massive Sulfides (SMS) Deposits: Case Study of the Semenov-5 Hydrothermal Field (13°31′ N, MAR)." Minerals 12, no. 12 (2022): 1593. http://dx.doi.org/10.3390/min12121593.
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The internal structure of Seafloor Massive Sulfides (SMS) deposits is one of the most important and complex issues facing the study of modern hydrothermal ore systems. The Semenov-5 hydrothermal field is a unique area where mass wasting on the slope of the oceanic core complex (OCC) structure exposes the subsurface portion of the deposit and offers an exceptional opportunity to observe massive sulfides that have formed not only on the seafloor but in sub-seafloor zones as well. This paper examines the internal structure of the OCC-related Semenov-5 hydrothermal field along with analysis of the mineralogy and chemistry of different parts of sulfide deposit. The seafloor deposit is comprised of pyrite, marcasite, hematite, goethite, lepidocrocite, rare pyrrhotite, isocubanite and Co-rich pyrite. Sulfide chemistry indicates the prevailing influence of ultramafics on their composition irrespective of the spatial relation with basalt lavas. Sub-seafloor mineralization is associated with ultramafic rocks and is represented by massive and disseminated sulfides. Pyrrhotite, isocubanite, pyrite, chalcopyrite, Co-rich pyrite, quartz with rutile, quarts with hematite and Cr-spinels are fixed in massive subseafloor mineralization. The presence of Cr-spinels as well as a very high Cr content are regarded as indicators of the metasomatic nature of this part of the deposit that had formed as a result of ultramafic replacement. As a result, three zones of a hydrothermal ore-forming system have been described: massive sulfides precipitated from hot vents on the surface of the seafloor, massive sulfides formed due to replacement of ultramafics below the seafloor and disseminated sulfide mineralization-filled cracks in hosted rocks which have formed stockwork around metasomatic massive sulfides. Despite differences in the mineral and geochemical composition of sub-seafloor and seafloor mineralization, all minerals subject to the sample formed as a consequence of fluid circulation in ultramafic rocks and were linked by a common ore-forming process.
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Çina, A. "MINERALOGY OF CHROMITITE, BULQIZA ULTRAMAFIC MASSIF, ALBANIAN OPHIOLITIC COMPLEX." Bulletin of the Geological Society of Greece 43, no. 5 (2017): 2577. http://dx.doi.org/10.12681/bgsg.11665.
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Ultramafic massif of Bulqiza belongs to Eastern Jurassic Albanian ophiolite belt of IAT-BSV- type. This massif is the most important chromite-bearing ore. The mantle ultramafics have extremely refractory nature. This is due to the high partial fusion of upper mantle which is depleted in CaO and Al2 O3 . The chromitite is situated to different parts of ultramafic pile, from bottom Cpx harzburgites up to massive dunites and cumulate ultramafic but the mainly chromite potential belongs to mantle harzburgite –dunite level and to transition dunites partly. The chromite is chiefly of Cr-rich metallurgical type. The atomic ratios of chromite , Fo of olivine and some physical properties of them vary according to the chromitite setting and reflects the evolution of Ol-Sp equilibrium process depended of the chromite concentration, from baren dunitic lenses towards dunite envelops of the ore bodies and the interstitial and inclusions of olivine within chromite grains. Two particular chromite deposits are the Bulqiza- Batra tabular folded ore body and Shkalla, pencil –like ore body.
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Ivanov, K. S., N. V. Vakhrusheva, V. N. Puchkov, P. B. Shiryaev, N. N. Farrakhova, and A. E. Bogomolova. "Unserpentinized harzburgites of the Voikaro-Synyinsky massif of the Polar Urals as the initial source of chromium for the formation of deposits." Doklady Rossijskoj akademii nauk. Nauki o Zemle 516, no. 1 (2024): 382–90. https://doi.org/10.31857/s2686739724050086.
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The composition and age of unserpentinized harzburgites, which are found in the Voikaro-Synyinsky massif in the form of budins and relict bodies in the fields of olivine-antigorite rocks development, have been studied. The structure, compositions of rocks and minerals, as well as the distribution of rare-earth elements and Sm-Nd absolute dating (≈2330 million years) allow us to consider these unserpentinized harzburgites as fragments of the mantle and the earliest formations among the ultramafic Voikaro-Synyinsky massif. The silicates of these harzburgites are characterized by increased chromium content, which in subsequent different processes turns into chromium spinelide. Based on the data obtained, the resources of chromium mobilized during the transformation of primary ultramafics were evaluated.
Dissertations / Theses on the topic "Ultramafics"
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Ramos, Rodrigo Chaves. "Complexo ofiolítico Arroio Grande, sudeste do Escudo Sul-Rio-Grandense: caracterização e discussões das unidades ortoderivadas." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/94680.
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O presente trabalho é a continuação das pesquisas anteriores relacionadas às rochas metamáficas e metaultramáficas da região de Arroio Grande, sudeste do Escudo Sul-rio-grandense. A partir de estudos de campo, microscopia óptica, microscopia eletrônica de varredura e difratometria de raios X, essa associação de rochas (anfibolitos, serpentinitos cromíferos, xistos magnesianos, micaxistos, quartzitos e mármores) foi interpretada como possíveis fragmentos de crosta oceânica relacionados ao encerramento de um paleo-oceano durante o ciclo orogênico Brasiliano/Pan-Africano no Neoproterozoico e denominada de Complexo Ofiolítico Arroio Grande. Nesta dissertação é apresentada uma breve descrição deste complexo ofiolítico e o seu contexto geológico, além de breves considerações sobre sua importância do ponto de vista da evolução do paleocontinente Gondwana Ocidental durante o Neoproterozoico. Em seguida, é apresentado o artigo denominado “Geologia da associação metamáfica-ultramáfica da região de Arroio Grande, sudeste do Escudo Sul-rio-grandense”, aceito para publicação no periódico Pesquisas em Geociências da Universidade Federal do Rio Grande do Sul, no qual são caracterizadas as unidades metamáficas e metaultramáficas do referido complexo. Tais pesquisas têm como principal objetivo adicionar novos dados aos já existentes na literatura, aquecendo as discussões acerca da existência ou não de possíveis ofiolitos na porção oriental do Escudo Uruguaio-Sul-rio-grandense relacionados à ocorrência do paleo-oceano Adamastor, e dos modelos evolutivos para a reconstrução do paleocontinente Gondwana Ocidental.<br>The present work is the continuation of previous researches related to the metamafic and meta-ultramafic rocks located near the town of Arroio Grande, southeastern Sul-rio-grandense Shield. Through fieldwork, optical microscopy, scanning electron microscopy and X-ray diffraction, this rock association (amphibolites, chromian serpentinites, magnesian schists, mica schists, quartzites and marbles) was interpreted as possible slices of an oceanic crust related to the closure of a paleo-ocean during the Brasiliano/Pan-African orogenic cycle and called Arroio Grande Ophiolitic Complex. A brief description of this ophiolitic complex and his geological setting is presented in this dissertation, with brief considerations on their importance, from the point of view of the Western Gondwana paleocontinent evolution during the Neoproterozoic Era. Subsequently, the article entitled "Geology of the Arroio Grande meta-mafic-ultramafic association, southeastern Sul-riograndense Shield”, accepted for publication in the Pesquisas em Geociências Journal of the Rio Grande do Sul Federal University is presented, where the metamafic and meta-ultramafic units of the aforesaid complex are characterized. Such researches have as main objective to add new data to existing literature, promoting discussions about the possible existence of ophiolites related to the occurrence of the Adamastor paleo-ocean in the eastern portion of the Uruguaio-Sul-rio-grandense Shield and about geologic evolution models for the reconstruction of Western Gondwana paleocontinent.
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Bettarini, Isabella. "The nickel hyperaccumulating plants of genus Odontarrhena (Brassicaceae): novel insights from molecular, physiological and biochemical analyses." Doctoral thesis, Università di Siena, 2021. http://hdl.handle.net/11365/1128453.
Full textAbstract:
Due to the high nickel concentrations, serpentine soils provide a very restrictive and selective environment for
plant life. Some plants, termed “Ni-hyperaccumulators”, are adapted to live on these heavy-metal-enriched
soils without toxicity symptoms. Ni-hyperaccumulators are increasingly important for research on metal
tolerance, homeostasis and biotechnological applications.
This project aims to investigate nickel accumulation in taxa and populations of Odontarrhena, a genus of tribe
Alysseae (Brassicaceae) that includes over 85 species many of which are Ni-hyperaccumulators.
Based on a previous systematic study conducted on poorly-known populations of Odontarrhena native to
Albania we performed a molecular study to characterize taxa and populations of this genus. To this purpose
we used DNA sequencing and the AFLP-fingerprint technique to reconstruct the species phylogenetic
relationships and the population differentiation patterns in relation to their distribution, ploidy level, intensity
of anthropic site disturbance, altitude, soil type and metal concentration population (Ni, Cr, Co, Ca, Mg). We
found significant population differentiation, dominance of within-population variation, no isolation by
geographic distance and existence of six genetic groups variously represented across the six taxa possibly due
to hybridization especially in disturbed sites.
Next, we compared metal concentrations in native Odontarrhena populations from Albania in relation to their
soil of origin. We determined the concentration of the most important trace metals (Ni, Co, Cr, Mg, Ca, K, Fe
and Mn) in soil, plant roots and shoots of five taxa from 20 different outcrops. We found large differences in
mineral element concentrations in soils and also between the plants; shoot Ni concentrations in Albanian
Odontarrhena taxa depend on soil Ni concentrations but not on species identity. For O. chalcidica, the most
widely distributed species, this “environmental fingerprint” was found not only for Ni, but also for Ca and Mg.
After these investigations on native populations from the natural environment, we designed an experimental
study in controlled conditions. Plant seedlings of seven taxa and 11 populations of Odontarrhena from
serpentine and non-serpentine sites of the Balkan peninsula and Italy were cultivated in hydroponics with
increasing NiSO4 concentrations to determine plant growth and Ni accumulation. These plantlets were
analyzed to test inter- and intra-specific differences in nickel tolerance and accumulation, in relation to Ni
levels in the soils and in wild plants. We found a metal stimulatory effect on growth that was present in the
low-dose zone and significantly fitted the Brain-Cousens hormetic model. Taxa showed broad variation in
tolerance, with the most tolerant plants requiring the highest Ni concentration for optimal growth. Our data
suggested that tolerance is associated with hyperaccumulation ability.
Among the obligate and facultative serpentinophytic species of Odontarrhena that have been investigated we
found a notable exception, O. sibirica, a facultative serpentinophyte in which accumulation ability was
enigmatic from previous studies. We addressed this issue using observational and experimental methods as in
our previous researches. We found that Ni-concentrations in the native populations sampled on serpentine soils
in Greece were always much lower than the hyperaccumulation threshold. When cultivated together with other
Ni-accumulating Odontarrhena species on the same natural ultramafic soil, O. sibirica was the only one unable
to accumulate the metal. When grown in hydroponics at different NiSO4 levels Ni-accumulation occurred only at higher concentrations which, however, had a toxic effect. This peculiar combination of Ni-response traits
could be the result of a partial evolutionary loss of ability with respect to all other Ni-accumulating congeneric
species. For its unique characteristics, O. sibirica could therefore represent a unique model system for further
studies on the evolutionary dynamics, physiological mechanisms and genetic control of metal accumulation
and homeostasis.
In a parallel study, we investigated photosynthesis responses of the same plants using an experimental
approach. In non-hyperaccumulator plants, toxicity symptoms to above 10 μg g-1 DW nickel concentrations in
soils can include inhibition of photosynthesis, impaired nitrogen assimilation and disturbed enzyme activity.
However, there is a complete lack of information about how Ni-hyperaccumulators reconcile that extraordinary
amount of metal in their shoots with an efficient photosynthetic activity, or at least on which photosynthetic
parameters the excess of Ni impacts less in these plants. We measured Ni effects on growth, root and shoot
metal accumulation and several photosynthetic parameters, such as gas exchange, chlorophyll fluorescence
analyses and pigments content in three Odontarrhena taxa (two hyperaccumulators, one not) grown in
hydroponics and exposed to three NiSO4 treatments. We found that Ni-hyperaccumulators species are
photosynthetically more efficient under Ni excess in respect to the non-accumulating species. In fact, Ni
treatment in O. chalcidica increased not only the photochemical efficiency of PSII and the CO2 assimilation
rate, but also the stomatal conductance.
Finally, this project focused on the determination of the activity of the enzyme urease, the only Nimetalloenzyme
known so far in plants, in selected Odontarrhena taxa. The hypothesis to test was whether the
high basal requirement for this micronutrient in these plants could be linked to a depletion of the Ni cytosolic
pool at low external metal concentration, due to hyperaccumulation mechanism and impairing urease activity.
To this purpose, enzyme activity and Ni shoot concentration were determined in plants of accumulating and
non-accumulating taxa of Odontarrhena cultivated on Ni-rich serpentine soil and on garden soil, as well as in
samples of O. bertolonii cultivated in hydroponics at increasing Ni concentrations. Odontarrhena
hyperaccumulators showed similar urease activity when grown on both kinds of soils, with no relation between
the enzyme activity and the leaf Ni accumulation. Contrarily, clear indications came from the experiment in
controlled conditions, where the presence of Ni determined a progressive stimulation, in respect to control
samples, of the activity of the enzyme, associated with an increase in shoot metal concentration. A significant
relationship was found between the levels of urease activity and the amount of Ni accumulated in the leaves.
Therefore, the already known Ni-stimulated growth of O. bertolonii at increasing metal concentrations in the
low-dose zone could be explained by a Ni-induced activity of urease, associable to an enhanced nitrogen
metabolism, unless other still unknown physiological functions of Ni in hyperaccumulating plants.
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Souza, Thamy Lara. "Controles mineralógicos e geoquímicos do níquel não sulfetado em rochas ultramáficas no Escudo Sul-Riograndense." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/94678.
Full textAbstract:
Este trabalho tem como objetivo investigar os processos controladores da mobilidade e concentração de níquel (Ni) em rochas ultramáficas serpentinizadas no Escudo Sul-Riograndense (ESrg), Rio Grande do Sul (RS), Brasil. A composição primária das rochas ultramáficas hospedeiras de Ni constitui um parâmetro relevante, mas os processos secundários são os controladores mais importantes dessas mineralizações, principalmente a serpentinização, pressupondo-se que o Ni possa migrar da olivina ou metamórfica para os minerais do grupo das serpentinas. Para a caracterização mineralógica e textural das rochas ultramáficas serpentinizadas da porção oeste do ESrg, foram aplicadas técnicas de petrografia e Microscopia Eletrônica de Varredura. Para a análise química dos elementos em rocha total foi realizada fluorescência de Raios-X, ICP e ICP-MS. Estas técnicas permitiram classificar quimicamente as rochas e relacionar a variação da intensidade dos eventos metassomáticos, metamórficos e hidrotermais que modificaram a mineralogia dos protólitos. No entanto, foram necessárias estudos de detalhe dos minerais individuais, notadamente olivinas e serpentinas com o uso da microssonda eletrônica para determinar as concentrações de Ni e suas variações nos diferentes corpos ultramáficos investigados. Dessa forma, foi possível quantificar e identificar os minerais concentradores de Ni e a relação dos eventos com a mobilidade e concentração dos elementos. Os resultados de microssonda indicam que as olivinas dos peridotitos do Maciço Pedras Pretas possuem baixos teores de níquel que variam de 0,13% a 0,21% e a média é 0,17%, enquanto que as olivinas dos harzburgitos da Sequência Cerro Mantiqueiras possuem teores mais elevados na média de 0,31%. As olivinas do Pedras Pretas possuem composição homogênea enquanto que aquelas do Cerro Mantiqueiras mostram variações composicionais importantes com conteúdo de Fo 92-98 e teores de níquel entre 0,3% e 0,4%. Tais variações no Cerro Mantiqueiras podem estar relacionadas a diferenças na composição do protólito ou a outro fator desconhecido que necessita futuras investigações. As olivinas e serpentinas no Cambaizinho e Serrinha mostram valores de níquel entre 0,19% a 0,3%, comparáveis ao Cerro Mantiqueiras, porém bem mais elevados que o Pedras Pretas. Este estudo mostra que os corpos ultramáficos do Cambaizinho- Serrinha e Cerro Mantiqueiras possuem potencial para desenvolver depósitos de Ni não sulfetado devido as concentrações relativamente elevadas de Ni nas olivinas. Entretanto, tais depósitos não se desenvolveram devido a dois fatores principais: o primeiro está ligado à superposição de eventos de metamorfismo e deformação recorrentes no tempo e no espaço que propiciaram a mobilização do Ni; o segundo fator é atribuído a ausência de agentes supergênicos favoráveis para a formação de depósitos lateríticos como os observados na região norte do Brasil.<br>This paper investigates the processes controlling the mobility and concentration of nickel (Ni) in serpentinized ultramafic rocks in the Sul- Riograndense Shield (ESrg), Rio Grande do Sul (RS), Brazil. The primary composition of the ultramafic Ni host is a relevant parameter, but the secondary processes are the almost important controllers of these mineralizations, mainly serpentinization, assuming that Ni may migrate from igneous or metamorphic olivine minerals to the group of serpentine this phase. For the mineralogical and textural characterization of the serpentinized ultramafic rocks of the western portion of ESrg, were applied techniques of petrographic and scanning electron microscopy. For chemical analysis of elements in rock whole was performed X-ray fluorescence, ICP and ICP-MS. Although these techniques allow chemically classification of rocks and relate the variation of intensity in which metasomatics, metamorphic and hydrothermal events, changed the that mineralogy of the rock, however analysis of individual mineral detail, notably olivine and serpentine minerals using the electron microprobe detail, were necessary to determine the concentrations of Ni and variations in different ultramafic bodies investigated. Thus, it was possible to quantify and identify the Ni concentrators minerals and the relationship of events with the mobility and concentration of the elements. The microprobe results indicate that the olivine of peridotite Pedras Pretas have low contents of NiO ranging from 0.13% to 0.21% and averaged 0.17%, while the olivine harzburgites Cerro Mantiqueiras have higher levels of NiO averaging 0.31%. The olivine of Pedras Pretas have a homogeneous composition as those of Cerro Mantiqueiras show important compositional variations with a content of forsterite the Fo 92-98 and NiO contents of between 0.20% and 0.40%. Such variations in Cerro Mantiqueiras may be related to differences in the composition of the protolith or another unknown factor that needs further investigation. The olivine and serpentine in Cambaizinho and Serrinha, show NiO values between 0.19 % to 0.3 %, values comparable to the Cerro Mantiqueiras, but higher than the Pedras Pretas. This study shows that the Cambaizinho, Serrinha and Cerro Mantiqueiras have the potential to develop non- sulphide Ni deposits, due high Ni concentrations in olivine. However, these deposits are not developed due two main factors: the first is linked to the superposition of events the metamorphism and deformation applicants in time and space, that enabled the Ni mobilization; the second factor is attributed to lack preservation of profiles suitable for the Ni concentration, due to uplift and erosion lateritic subsequent.
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Scoon, Roger N. "Discordant bodies of postcumulis, ultramafic rock in the upper critical zone of the Bushveld complex : iron-rich ultramafic pegmatite bodies at Amandelbult and the Driekop platiniferous ultramafic pipe." Thesis, Rhodes University, 1986. http://hdl.handle.net/10962/d1004912.
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From the abstract: In the layered sequence of the Bushveld Complex a number of distinct, but possibly genetically related groups of transgressive, postcumulus, ultramafic and mafic rock are recognised. The main part of this thesis investigates a suite of postcumulus rocks for which the name iron-rich ultramafic pegmatite is proposed. The majority of iron-rich ultramafic pegmatite bodies examined are from the upper critical zone of the layered sequence at Rustenburg Platinum Mines Amandelbult Section, in the northern sector of the western Bushveld Complex. Field relationships imply that the iron-rich ultramafic pegmatites should be considered as an integral feature of the layered sequence, even though they transgress the cumulates. Consequently, this thesis also includes a study of the cumulate sequence at Amandelbult. A second group of postcumulus, ultramafic rocks which is investigated comprises latiniferous ultramafic pipes; the Driekop pipe has been selected as a case study. This thesis is presented in four sections, namely, an introduction and verview, and studies on the Driekop pipe, the cumulate sequence at mandelbult and the iron-rich ultramafic pegmatite suite. A new classification scheme of discordant bodies of postcumulus, ultramafic rock in he Bushveld Complex is proposed (see also Viljoen & Scoon, in press). In he scheme presented here, two main varieties of postcumulus, ultramafic rock re recognised, namely, non-platiniferous magnesian dunites and iron-rich ltramafic pegmatites.
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Remus, Marcus Vinicius Dorneles. "Geologia e geoquimica do complexo cambaizinho, sao gabriel - RS." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 1990. http://hdl.handle.net/10183/5238.
Full textAbstract:
Mapeamentos geológicos feitos pelo autor na região do Arroio Cambaizinho - são Gabriel/RS, resultaram na definição do Complexo Cambaizinho, representado pelas seqüências meta-sedimentar e máfica-ultramáfica, intimamente associadas ao longo de toda a extensão da associação supracrustal. A seqüência meta-se dimentar é constitu1da por gnaisses quartzo-feldspáticos dominan tes, anfibolitos bandados e quartzitos subordinados, derivados de sedimentos areno-pelítico-carbonatados estruturados, de forma ritmica em ambiente subaquoso. Niveis composicionais de ocorrência restrita contendo estaurolita, definem o grau metamórfico (médio) para esta região. Intercalações de serpentinitos, xistos magnesianos variados e anfibolitos a granulação fina, na forma de camadas e/ou lentes interestratificadas nos meta-sedimentos indicam suas derivações a partir de derrames e/ou intrusões , ígneas de pequena profundidade de composição básica-ultrabásica. Este juntamente com níveis de sedimentos qu1micos intercalados e corpos de gabros, constituem a seqüência máfica-ultramáfica. O complexo, representa o segmento norte de um cintu rão supracrustal polideformado de forma geométrica aproximadamente linear, com orientação NNE, que se extende desde a localidade de Passo do Ivo, situado mais a sul, até a região objeto deste trabalho. Quatro fases de deformação dúcteis foram das para a área, estando as duas primeiras (Dl e D2) identifica associadas xx aos eventos metamórficos regionais Ml e M2. O metamorfismo mais antigo (Ml), assinalado por paragêneses diagnósticas em metapelitos alcançou o fácies anfibolito (zona da estaurolita), estando representado em outras litologias pela ocorrência de olivina metamórfica em paragênese com tremolita e/ou talco (meta-serpentinitos) e hornblenda mais oligoclásio/andesina em meta-básicas. O M2, mais jovem, atingiu o fácies xistos verdes, cujas assembléias mineralógicas se associam à foliação S2, de distribuição ir regular ao longo do cinturão. As condições fisicas de Ml foram de média P/T, similares às do metamorfismo Dalradiano. Intrusões graniticas na forma de lâminas (corpos ta bulares) durante a segunda fase de deformação D2, datados pelo mé todo Rb/Sr em 661 :: 29 Ma e agrupados sob a denominação de Granatóides Sanga do Jobim, fornecem idades mínimas para o complexo. Os vários grupos composiciconais da seqüência máfic~ -ultramáfica, individualizados com base em critérios petrográf~ cos e conteúdo de elementos maiores correspondem a: serpentinitos e olivina-talco ultramafitos (cumulados komatilticos); xis tos magnesianos à talco e clorita e anfibólio xistos (komatiitos); clorita-hornblenda xistos (basaltos komatiiticos), litos e metagabros (basaltos e gabros tolelticos). anfibo Estes vários tipos litológicos foram originados através de diferentes graus de fusão parcial do manto como indicado pelo hiato composicional de MgO (11 à 17%) e os diferentes padrões de ETR existentes entre os anfibolitos/metagabros (toleitos) e os serpentinitos/xistos magnesianos (komatiltos).As variações composicionais no interior de cada grupo, foram controladas pelo fracionamento (acumulação ou extração) de olivina e pouco ortopiroxênio (serpentinitos e olivina-talco ultramafitos)clinopiroxênios (clorita e anfibólios xistos, clorita hornblenda xistos), clinopiroxênio e plagioclásio (anfibolitos e metagabros). As abundâncias e os padrões de ERTL (elementos terras raras leves) enriquecidos, juntamente com os baixos valores das razões A1203/Ti02 e CaO/Ti02 das amostras de xistos magnesiinos das camadas A e B sugerem derivações deste material a partir de baixas percentagens de fusão de um manto enriquecido em mentos incompatíveis. As anomalias negativas de Ce e Eu na ele maio ria das rochas da seqüência máfica-ultramáfica indicam que protólitos ígneossofreram alterações em ambiente submarino.<br>Geologic mapping performed by the author on the Camb~ izinho area resulted in the separation of the Cambaizinho Complexo This includes sedimentary and mafic-ultramafic metamorphosed se quences which area closely intertongued all over the supracrustal association. Meta sedimentary sequence is built up mainly by quartz- feldspáthic gneisses and less abundant banded amphibolites with minor amounts of quartzites. These supposedely represent metamorphosed subaqueous rithmically banded arenaceous marly sediments. At some levels of restrict occurrence, representing an iron rich composition, staurolite bearing metamorphic assemblages suggests medium grade of metamorphism for this region. Interfingered serpentinites, some varieties of magnesian schists and fine grained amphibolites enclosed in the meta sedimentary rocks suggests lava flows and low depth intrusions of basics/ultrabasic composition. These volcanic magmatic rocks altogether with gabro bodies and interlayered chemical sediments built up the mafic-ultramafic sequence. Cambaizinho Complex represents the northern segment of a supracrustal, multideformed, linear belt trending NNE which stretches from this area till Passo do Ivo to the south. Four deformation phases were recognized for this area being first and second(Dl and D2) associated to regional metamorphic events, Ml and M2. The oldest metamorphic episode (Ml) signaled by diagnostic paragenesis in metapelites reached amphibolite facies (staurolite zone) being represented in magnesian rocks by olivine-tremoliteItalc (meta-serpentinites) and hornblende-oligoclase/ andesine in metabasites. M2 metamorphic event, younger is represented by greenschist facies whose mineralogic assemblages are associated to S2 foliation irregularly distributed along the belt. Physical conditions for Ml metamorphism of intermediate values for P/T are comparable to those of Dalradian metamorphism. Granitic intrusions form sheaf-like bodies belong to the second phase of deformation (D2) give the minimum Rb/Sr age of 661 z29 Ma for the whole complex and were named Sanga do Jobim Gra nitoids. The whole compositional range of the mafic-ultramafic sequence separated on the petrographic cri teria and major elements contents are named serpentinites and olivine-talc ultramaphites (komatiitic cumulates), magnesian talc schists and chlorite-amphibole schists (komatiites), chlorite-hornblende schists (basaltic komatiites) and amphibolites and meta-gabros (tholeitic and gabros). The lithologic types above are thought to have originated by different degrees of partial mantle fusion as suggested by MgO hiatus (11-17%) and various ETR patterns found for amphibQ lites and meta-gabros(tholeites) and serpentinites/magnesian sch! sts (komatiites). Compositional variations in each group were cog troled by fractionation (accumulation/extraction) of olivine and minor orthopyroxene (serpentinites and olivine-talc ultramaphites) pyroxenes and lesser amounts of olivine (talc magnesian schists), clinopyroxenes (chlorite and amphibole schists and chlorite-hornblende schists), clinopyroxene and plagioclase (amphibolites and meta-gabros) . Abundancies and enriched patterns of LREE with low values of Al2Oa/Ti02 and CaO/Ti02 rates of altogether magnesian schists of A & B layers suggests derivations of this material from feeble percentages of fusion of the mantle enriched in incompatible elements. Negative Ce and Eu anomalies in most rocks of th~ mafic-ultramafic sequence point to protolites submited to altera tion in submarine environment.
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Georgiou, Elena. "Geologie, petrologie et petrochimie du complexe plutonique de la foret d'akapnou, chypre, et des gites de chromite associes." Orléans, 1987. http://www.theses.fr/1987ORLE2033.
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L'etude cartographique en depit d'un tectonique complexe, a permis d'observer de bas en haut: sequence mantelique (harzburgites a enclaves dunitiques); sequence cumulative (dunite principale, plastiquement deformee, wchrlites, pyroxenites, gabbros et plangiogranites)
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Moffat, David Thomas. "The serpentinized ultramafites of the Shetland Caledonides." Thesis, University of Liverpool, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328460.
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Boulet, Frederic. "Mycorrhizal symbiosis as a strategy for survival in ultramafic soils." University of Western Australia. Soil Science and Plant Nutrition Discipline Group, 2003. http://theses.library.uwa.edu.au/adt-WU2004.0051.
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Ultramafic soils enriched in nickel, such as found in Australia and New Caledonia, are associated with unique, diverse and poorly known vegetation communities. Re-establishment of these highly specific ecosystems is still a challenge for Ni mining companies. Ultramafic vegetation communities are the outcome of a long evolution process resulting in their adaptation to the extreme soil conditions found on ultramafic outcrops. Mycorrhizal fungi, a very common plant symbiont, are generally thought to be beneficial to plants in other ecosystems, providing plants with phosphorus and even promoting metal tolerance in plants in some cases. We examined the hypothesis that mycorrhizal fungi may contribute to the survival of plants in ultramafic soil conditions. Bandalup Hill, an ultramafic outcrop enriched in Ni (South West of Western Australia) was selected to assess the contribution of mycorrhizal fungi to ultramafic plants. Soil constraints, in particular the degree of Ni toxicity, were assessed at two sites with ultramafic soils within the outcrop. Total metal, nutrient, DTPA extractable Ni and available P were measured in soil while Ni, Ca and Mg were tested in the soil solution. In addition, nutrients and metals were analyzed in shoots of some plant species occurring at each site: Eucalyptus flocktoniae, Melaleuca pomphostoma, Melaleuca coronicarpa and Hakea verucosa. Topsoils in Bandalup Hill and plant shoots had high levels of Ni, and very low levels of P, K and N. Variation in DTPA extractable Ni between sites reflected the variation in shoot Ni level of E. flocktoniae and M. pomphostoma. Variations in soil solution Ni levels reflected variations in shoot Ni levels of M. coronicarpa and H. verucosa between sites. The germination requirements of the plant species used to assess the soil constraints was assessed. Species selected included Eucalyptus flocktoniae, Melaleuca coronicarpa, and Hakea verucosa. Seeds of E. flocktoniae and M. coronicarpa had a higher germination rate if pre-treated with smoke water, while no pre-treatment was required to germinate H. verucosa seeds. The unusual germination requirement of E. flocktoniae and M. coronicarpa involve complex chemical signals that may be present in the soil when the conditions are more favorable for plant establishment. Such unusual germination requirement may represent an adaptation to the hostile conditions of the ultramafic soils of Bandalup Hill. The mycorrhizal association and root characteristics of the selected plant species was also assessed after 8 weeks of growth in undisturbed ultramafic topsoil cores from Bandalup Hill. Roots of these species (including H. verucosa from a previously designated non-mycorrhizal family, Proteaceae) were associated with mycorrhizal fungi. Roots of E. flocktoniae and M. coronicarpa were colonized by both arbuscular mycorrhizal fungi (AMF) and ectomycorrhizal fungi (ECM), while roots of H. verucosa only contained some AM fungal structures. All species had high shoot to root ratios and their root characteristics reflected their association with mycorrhizal fungi. Based on the previous observations, uninoculated and inoculated E. flocktoniae seedlings were grown for 10 to 16 weeks in sand amended with Ni at 0, 0.2, 1 and 2.3 mg/kg. Mycorrhizal inoculum consisted of spores of Pisolithus sp. (ECM) or a mix of AMF spores and colonized root fragments, both originating from Bandalup Hill. Another inoculum consisted in Pisolithus sp. spores from a site with ultramafic soils in New Caledonia. Inoculation with AM and ECM fungi from Bandalup Hill was beneficial to E. flocktoniae. Benefits consisted mainly of a reduction of Ni shoot translocation at the highest Ni soil level. At 1 mg/kg soil Ni, E. flocktoniae exhibited a certain degree of tolerance to Ni. A substantial increase in growth and nutrient uptake with Pisolithus sp. from Western Australia was also observed. The contribution of AM fungi from Bandalup Hill to E. flocktoniae, M. coronicarpa, H. verucosa, and Trifolium subterraneum (clover) was then examined in ultramafic soil from Bandalup Hill.Steaming of ultramafic soil increased the availability and plant uptake of P. Consequently, uninoculated seedlings grew better, and inoculation with AM fungi decreased the growth of native plant species but did not affect their shoot Ni concentration. The presence of AM fungi increased the concentration of P in shoots of native plants species. Inoculation had no effect on the growth and nutrient content of subterranean clover. As mining activities have the potential to reduce the infectivity of AM fungi in topsoils, the effect of disturbance and storage practices on the AM infectivity of ultramafic topsoils collected in summer or winter from Bandalup Hill was investigated. Disturbance consisted in passing topsoil through a 2mm seive and cutting roots into 1cm fragments. Disturbed topsoil was then stored at room temperature in pots that were either sealed from the atmosphere or left open, and pots were maintained at field capacity. E. flocktoniae seedlings were planted in undisturbed and disturbed topsoil just after topsoil collect and then after 3, 6 and 9 months of topsoil storage. AM fungi present in the topsoil collected in summer was less susceptible to initial disturbance than AM fungi present in topsoil collected during winter. Also, storage of topsoil in sealed pots watered to field capacity was more detrimental to its infectivity than storage of topsoil in dry conditions. Mycorrhizal fungi can contribute to the survival of some native plant species in the ultramafic soils of Bandalup Hill and they may represent another strategy to improve the success of Ni mine revegetation. However, such contribution may not be the unique avenue for native plants to survive in ultramafic soils of Bandalup Hill.
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Uddin, Salah. "Surface charge characterization and flotation of an ultramafic nickel ore." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=107688.
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AbstractAbout 300 million tonnes of inferred Ni resource in ultramafic hosted rocks is present in 'Thompson Nickel Belt' in north central Manitoba. The processing challenges result from electrostatic interaction between pentlandite (the main Ni-mineral) and serpentine (the main gangue and one of the MgO minerals). As a contribution to meeting the challenge, the thesis examines the role of particle and bubble surface charge and the effect of fibre disintegration on flotation behavior of an ultramafic Ni ore sample. For surface charge characterization the sedimentation potential technique was used. A novel integrated device was developed to measure sedimentation potential, conductivity and pH simultaneously. Maxwell's model was used to calculate volume fraction of dispersed phase from conductivity, and zeta potential, when appropriate, was calculated from the Smoluchowski equation. The technique was validated by showing good agreement with iso-electric point for alumina, silica and bubble suspensions with electrophoresis measurements. The technique was extended to characterize mixed minerals including ultramafic ore, and bubbles in the presence of particles. The results provided some evidence of metal ion adsorption on particles and the possibility of non-hydrophobic particle attachment to bubbles. The latter was reinforced by visualization studies of a pendant bubble exposed to particle suspensions.A novel fibre disintegration strategy was devised combining both chemical (acid) and physical (grinding) treatment based on work to enhance carbon dioxide uptake by serpentine. Using HCl, subsequent conventional flotation (amyl xanthate, soda ash and MIBC) gave significantly improved results over the untreated ore. Using H2SO4, arguably the practical option led to flotation without collector due to elemental sulphur formation on pentlandite, and without frother due to high ionic strength solutions. Improved Ni grade-recovery with higher MgO mineral rejection was achieved. Structural changes in the fibres were followed using various spectroscopic techniques and a mechanism of fibre disintegration suggested.<br>Environ 300 millions de tonnes de ressources inférées de Ni ultramafiques hébergé est présent dans 'ceinture nickélifère de Thompson' dans le centre-nord du Manitoba. Le traitement des défis résultant de l'interaction électrostatique entre pentlandite (le principal Ni-minéraux) et la serpentine. En tant que contribution à relever le défi, la thèse examine le rôle des particules et la charge de surface des bulles et l'effet de la désintégration des fibres sur le comportement de flottaison d'un échantillon de minerai de nickel ultramafiques. Pour la caractérisation de charge de surface de la technique de sédimentation potentielle a été utilisée. Un nouveau dispositif intégré a été développé pour mesurer le potentiel de sédimentation, la conductivité et le pH simultanément. Le modèle de Maxwell a été utilisée pour calculer la fraction volumique de phase dispersée de la conductivité, et le potentiel zêta, le cas échéant, a été calculée à partir de l'équation de Smoluchowski. La technique a été validée en montrant un bon accord avec l'iso-électrique de point pour les suspensions d'alumine, de silice et de bulles avec des mesures d'électrophorèse. La technique a été étendue afin de caractériser les minéraux mélangés, y compris de minerai ultramafiques, et des bulles dans la présence de particules. Les résultats ont fourni des preuves de ion métallique adsorption sur les particules et la possibilité de l'attachement des particules non-hydrophobe à bulles. Ce dernier a été renforcée par des études de la visualisation d'une bulle Pendentif exposés à des suspensions de particules.Une stratégie nouvelle fibre de désintégration a été conçu combinant à la fois chimique (acide) et physiques (broyage) un traitement basé sur le travail pour améliorer l'absorption du dioxyde de carbone par la serpentine. En utilisant HCl, à la suite de flottation conventionnelle (amyl xanthate, la cendre de soude et de MIBC) a donné des résultats nettement améliorés au cours des minerais non traités. Utiliser H2SO4, sans doute l'option la pratique conduit à de flottaison sans collecteur due à la formation du soufre élémentaire sur la pentlandite, et sans buse due à des solutions à haute force ionique. Amélioration de qualité Ni-reprise avec le rejet supérieur de MgO de a été atteint. Les changements structurels dans les fibres ont été suivis en utilisant diverses techniques de spectroscopie et d'un mécanisme de désintégration de fibre suggéré.
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Phillips, David. "Mineralogy and petrology of the Townlands iron-rich ultramafic pegmatite." Thesis, Rhodes University, 1985. http://hdl.handle.net/10962/d1007617.
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The Townlands iron-rich ultramafic pegmatite is a relatively large pipelike body situated in the western corner of Rustenburg Section, Rustenburg Platinum Mines. It is characterised by a strong negative magnetic signature and transgresses the noritic layered sequence of the upper critical zone of the Bushveld Complex. The layered rocks are downwarped in the vicinity of the pipe and are in sharp contact with the pegmatitic material. The pegmatite varies in composition between dunite and wehrlite, with the marginal zones being more wehrlitic in composition. Olivine (Fo₃₀ - Fo₅₂) and clinopyroxene (Wo₄₅En₃₀Fs₂₅ - Wo₄₅En₃₇Fs₁₈) are the dominant constituents and accessory phases include ilmenite, Ti -magnetite, apatite, amphiboles, chlorite-group minerals, biotite, ilvaite and a host of unusual ore minerals. The Fe-Ti oxides exhibit exsolution textures typically found in slowly cooled igneous rocks and temperatures of formati on are consi dered to be in excess of 800°C. The UG2 chromitite leader layers intersected by borehole TLP.l are enriched in Fe and Ti and exhibit compositions intermediate between chromite and Ti-magnetite. The ore mineral assemblage includes a primary sulphide assemblage consisting of troilite, chalcopyrite, cubanite and pentlandite, and an array of unusual phases formed by late-stage secondary processes. The unusual sulphides mooihoekite and haycockite, that occur in certain parts of the pegmatite, are considered to have formed by partial replacement of the primary assemblage and a possible paragenetic sequence is discussed. Mineral compositions and whole rock geochemical data are consistent with an origin for the pegmatite by crystallization from a fractionated melt. It is suggested that intercumulus fluids, trapped during the crystallization of the noritic layered sequence, accumulated in an area of structural weakness, in response to an increasing overburden pressure and/or tectonic activity. Evidence is also presented that indicates that the Townlands pegmatite may consist of at least two separate, but adjoining pegmatite bodies.<br>KMBT_363<br>Adobe Acrobat 9.54 Paper Capture Plug-in
Books on the topic "Ultramafics"
1
Mies, Jonathan W. Ultramafic rocks of the Alabama Piedmont. Geological Survey of Alabama, Economic Geology Division, 1994.
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1959-, Mittwede Steven K., Stoddard Edward F. 1949-, and Geological Society of America. Southeastern Section. Meeting, eds. Ultramafic rocks of the Appalachian Piedmont. Geological Society of America, 1989.
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Hancock, Kirk D. Olivine potential of the Tulameen ultramafic complex. Province of British Columbia, Ministry of Energy, Mines and Petroleum Resources, Mineral Resources Division, Geological Survey Branch, 1991.
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Theyer, P. Ultramafic rocks of the Island Lake area. Manitoba Energy and Mines, Geological Services, 1985.
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Hancock, Kirk D. Ultramafic associated chromite and nickel occurrences in British Columbia. Province of British Columbia, Ministry of Energy, Mines, and Petroleum Resources, Mineral Resources Division, Geological Survey Branch, 1991.
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Obeso, Juan Carlos de. Tracing alteration of ultramafic rocks in the Samail ophiolite. [publisher not identified], 2019.
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J, Patchett P., and United States. National Aeronautics and Space Administration., eds. Stored mafic/ultramafic crust and early Archean mantle depletion. Dept. of Geosciences, University of Arizona, 1990.
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Mowatt, Thomas C. Platinum and palladium in mafic-ultramafic igneous rocks, northwestern Alaska. Bureau of Land Management, Alaska State Office, 1991.
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Moreva-Perekalina, T. V. Ultramafic xenoliths from alkaline basalts of Finkenberg (Siebengebirge, West Germany). Rijksmuseum van Geologie en Mineralogie, 1985.
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Drake, Avery Ala. The Soldiers Delight ultramafite in the Maryland Piedmont. U.S. G.P.O., 1994.
Find full textBook chapters on the topic "Ultramafics"
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Lee, W. G. "New Zealand Ultramafics." In The Ecology of Areas with Serpentinized Rocks. Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-3722-5_15.
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Kruckeberg, A. R. "Plant life of western North American ultramafics." In The Ecology of Areas with Serpentinized Rocks. Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-3722-5_3.
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Sequeira, Eugénio, Calos Aguiar, and Carlos Meireles. "Ultramafics of Bragança Massif: Soils, Flora and Vegetation." In Natural Heritage from East to West. Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-01577-9_17.
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Bockheim, James G. "Ultramafic Soils." In Soil Geography of the USA. Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-06668-4_23.
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Pinti, Daniele L. "Ultramafic Rocks." In Encyclopedia of Astrobiology. Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-44185-5_5099.
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Pinti, Daniele L. "Ultramafic Rocks." In Encyclopedia of Astrobiology. Springer Berlin Heidelberg, 2023. http://dx.doi.org/10.1007/978-3-662-65093-6_5099.
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Pinti, Daniele L. "Ultramafic Rocks." In Encyclopedia of Astrobiology. Springer Berlin Heidelberg, 2021. http://dx.doi.org/10.1007/978-3-642-27833-4_5099-3.
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Pinti, Daniele L. "Ultramafic Rocks." In Encyclopedia of Astrobiology. Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-27833-4_5099-2.
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Wyllie, Peter J. "The Ultramafic Belts." In The Earth's Crust and Upper Mantle. American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm013p0480.
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Bucher, Kurt. "Metamorphism of Ultramafic Rocks." In Springer Textbooks in Earth Sciences, Geography and Environment. Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-12595-9_5.
Full textConference papers on the topic "Ultramafics"
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Videla, Héctor A., Patricia S. Guiamet, Sandra Gómez de Saravia, Liz Karen Herrera, Carlos Arroyave, and Daniel G. Poire. "Assessment of Microbiological and Atmospheric Effects on Rock Decay." In CORROSION 2003. NACE International, 2003. https://doi.org/10.5006/c2003-03571.
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Abstract The case history chosen for this study is the church of Veracruz, the most representative church of the cultural heritage of the city of Medellin, Colombia. The church construction was started in 1682 and its front was built with peridotite, an ultramafic rock containing more than 90% of iron and magnesium minerals, such as olivine and pyroxene. The possible causes of biodeterioration are studied by using microbiological techniques of isolation and culture, complemented with optical and electron scanning microscopy (SEM) observations. The impact of atmospheric factors on the structural material are studied by assessing the characteristics and amount of atmospheric pollutants. Three different surface analysis techniques were used: energy dispersion X-ray analysis (EDAX), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR spectroscopy).
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Kirkham, Samuel, Marian E. Buzon, and Robert Reid. "CHARACTERIZING METAMORPHOSED ULTRAMAFICS IN CARROLLTON, GEORGIA." In Joint 69th Annual Southeastern / 55th Annual Northeastern GSA Section Meeting - 2020. Geological Society of America, 2020. http://dx.doi.org/10.1130/abs/2020se-344931.
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Conklin, Jonathan, Veronica Ferry, Madi Hall, et al. "A STORY OF BLANTON BRANCH ULTRAMAFICS: HOW AN OUTCROP EXPOSES THE HISTORY OF THE MANTLE." In Joint 69th Annual Southeastern / 55th Annual Northeastern GSA Section Meeting - 2020. Geological Society of America, 2020. http://dx.doi.org/10.1130/abs/2020se-344687.
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Babu, M. M., A. Kumar, Mangeesh, A. P. Kumar, and M. N. Divya. "Delineation of PGE mineralization occurring with in the ultramafics in Jayachamarajapura schist belt, Tumkur district, Karnataka." In 1st Indian Near Surface Geophysics Conference & Exhibition. European Association of Geoscientists & Engineers, 2019. http://dx.doi.org/10.3997/2214-4609.201979026.
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Ilyina, Vera. "THE STUDY OF SERPENTINIZED ULTRAMAFICS FROM THE KARELIAN-KOLA REGION AND THE PRODUCTION OF A MG-RICH-SILICATE REAGENT ON THEIR BASIS FOR THE REMOVAL OF HEAVY METALS FROM SOLUTIONS." In 18th International Multidisciplinary Scientific GeoConference SGEM2018. Stef92 Technology, 2018. http://dx.doi.org/10.5593/sgem2018/4.2/s18.027.
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Sekar, Lokesh Kumar, and Esuru Rita Okoroafor. "Thermohydrochemical Modeling of Hydrogen Generation from Stimulated Ultramafic Rocks." In SPE Reservoir Simulation Conference. SPE, 2025. https://doi.org/10.2118/223864-ms.
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Abstract This study is a preliminary model of hydrogen generation from stimulated ultramafic rocks. A coupled thermohydrochemical model simulates the multifaceted processes of heat transfer, fluid flow, and chemical reactions, accounting for hydrogen generation, phase changes, thermal energy release, and new material formation during induced serpentinization. Some of the model inputs were from experimental data, and others were taken from works in literature. The hydrogen generation from the stimulated ultramafic rock was compared to the base model of unstimulated ultramafic rock. The model was also used to explore various well configurations. The model was run for two months with 15 days of injection, 15 days of shut-in, and 30 days of production. The simulations of stimulated rocks revealed a larger hydrogen generation yield than the unstimulated case. For vertical wells, the stimulated case gave a two-fold increase in produced hydrogen compared to the unstimulated case. Also, the cumulative production from the vertical wells in the ultramafic rock layer was nearly equivalent to that of horizontal wells. While an increase in lateral length initially resulted in larger gas production rates, the increase in lateral length allowed for more water production, leading to a rapid decline in the gas production rate and leveling of the cumulative gas production for the different lateral lengths. Catalysis was identified as a significant factor in improving hydrogen generation from ultramafic rocks. The increase in reaction rates and lowering of activation energy resulted in a huge increase in hydrogen generation within the ultramafic rock layer. In the presence of a seal/caprock, as was modeled in this study, the stimulated ultramafic rock layer can act as a temporary hydrogen accumulation site. Sensitivity analysis was conducted to evaluate the effects of fault thickness on hydrogen migration and accumulation. In the vertical well scenarios, fault thickness exhibited minimal influence on hydrogen production. Conversely, the sensitivity analysis on fault thickness in the horizontal well scenarios revealed that increasing fault thickness negatively impacted cumulative hydrogen production from the well in the ultramafic layer. However, for the well in the porous medium layer, increased fault thickness led to an enhancement in cumulative hydrogen production, with an observed increase of up to a thousand-fold. These findings were used to deduce the optimal conditions for hydrogen generation, migration, and accumulation. The findings from this preliminary study indicate that a horizontal well in the ultramafic rock layer with catalysis to speed up reactions, a thick fault to allow for migration of the generated hydrogen, and a porous medium in the vicinity of the source rock make an effective configuration for maximizing hydrogen generation, migration, and accumulation. The study suggests that there are opportunities to optimize operational parameters to improve hydrogen generation. There is also a need for a lot of data to finetune the model, grid refinement studies, and codes that can model the complex coupled processes associated with hydrogen generation from stimulated ultramafic rocks. This study provides critical insights for engineering optimized ultramafic hydrogen generation systems, and pioneers a significant advancement in modeling this potential low-carbon energy technology.
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Zhang, Tiansheng, and Haiying Huang. "Physical Properties and Fracture Network Characteristics of Mafic and Ultramafic Rocks." In 57th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2023. http://dx.doi.org/10.56952/arma-2023-0951.
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ABSTRACT Mineral carbon storage in mafic and ultramafic rocks is a novel concept for CO2 sequestration. In contrast to carbon sequestration in sedimentary formations, where structural and residual trappings are the primary mechanisms of storage, solubility and mineral trappings are expected to be the dominant storage mechanisms in mafic and ultramafic rocks. Mafic and ultramafic rocks are rich in calcium, magnesium and iron. Mineral carbonation occurs when these rocks are exposed to an environment with CO2 and water. Feasibility of mineral carbon storage has been demonstrated in field trials in Iceland and eastern Washington state. In this work, we conduct a comprehensive literature review on the properties of mafic and ultramafic rocks such as basalt, gabbro and peridotite. We examine the ranges of material properties and their correlations as well as rock mass characteristics and their implications in terms of carbon sequestration. Comprehensive knowledge of intact rocks and rock mass properties will be essential for research and development of carbon storage in these rocks. INTRODUCTION Mineral carbon storage in mafic and ultramafic rocks is a novel concept for CO2 sequestration. In contrast to carbon sequestration in sandstone formations, where structural and residual trappings are the primary mechanisms of storage, solubility and mineral trappings are expected to be the dominant storage mechanisms in mafic and ultramafic rocks. Mafic and ultramafic rocks are rich in calcium, magnesium and iron. Mineral carbonation occurs when these rocks are exposed to an environment with CO2 and water. Pilot field studies have been previously conducted - the Wallula Project in eastern Washington state (McGrail et al., 2017) and the CarbFix and CarbFix2 Project in southwest Iceland (Matter et al., 2016; Clark et al., 2020; Ratouis et al., 2022). These projects aimed at capturing CO2 permanently through mineral carbonation in basalt. Nearly 1,000 tons of supercritical CO2 were injected over a three-week period in summer 2013 in the Wallula Project. Two permeable basalt interflow reservoir zones with a combined thickness about 20 m within a layered basalt sequence at a depth of 830 − 890 m below the surface were chosen as the target zone. Field monitoring and characterization were carried out over a two-year period post injection. Isotope analysis of carbonate minerals from side-wall cores sampled post injection showed isotopic signatures of injected CO2. Presence of free-phase CO2 was detected from wireline logging at the top of the two injection interflow zones, likely due to buoyancy driven flow. But no vertical migration of CO2 above the injection zones was observed. These evidences suggest that storage and rapid mineralization of CO2 in a suitable basalt formation are feasible.
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Kremer, Christopher Henry, John F. Mustard, and Michael S. Bramble. "A WIDESPREAD ULTRAMAFIC SANDSTONE ON MARS." In GSA Annual Meeting in Indianapolis, Indiana, USA - 2018. Geological Society of America, 2018. http://dx.doi.org/10.1130/abs/2018am-320588.
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Yousufi, Atal. "DISTRIBUTION OF ULTRAMAFIC COMPLEXES IN AFGHANISTAN." In 19th SGEM International Multidisciplinary Scientific GeoConference EXPO Proceedings. STEF92 Technology, 2019. http://dx.doi.org/10.5593/sgem2019/1.1/s01.020.
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Sonnenberg, Emily A., Connor J. Harris, Meridith A. Miska, and Paul A. Mueller. "GEOCHEMISTRY OF DADEVILLE COMPLEX MAFIC-ULTRAMAFIC ROCKS." In GSA Annual Meeting in Phoenix, Arizona, USA - 2019. Geological Society of America, 2019. http://dx.doi.org/10.1130/abs/2019am-335143.
Full textReports on the topic "Ultramafics"
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Duke, J. M. Ultramafic-hosted asbestos. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1995. http://dx.doi.org/10.4095/207990.
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Duke, J. M. Mafic/ultramafic-hosted chromite. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1995. http://dx.doi.org/10.4095/208046.
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Milidragovic, D., and N. Cleven. Field relationships indicating cumulate intermingling at the Wrede Creek and Lunar Creek Alaskan-type ultramafic-mafic intrusions, north-central British Columbia. Natural Resources Canada/CMSS/Information Management, 2023. http://dx.doi.org/10.4095/331430.
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Convergent margin-related magmatic deposits hosted by ultramafic-mafic intrusions are becoming an increasingly important global resource of Ni-Cu-PGE. In the northern Canadian Cordillera, a sub-class of ultramafic-mafic intrusions, known as the Alaskan-type intrusions, are hosted within the accreted arc terranes of the North American continental margin. These intrusions have long been recognized for their chromite-associated PGE mineralization potential. However, their potential to host significant Ni-Cu-PGE sulfide mineralization and to be used in efforts to reduce greenhouse gas emissions through permanent carbon mineralization is becoming increasingly studied. This report describes the main lithologies and field relationships observed at the Wrede Creek and Lunar Creek Alaskan-type intrusions in British Columbia during recent fieldwork.
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LeCheminant, A. N., and J. H. Bedard. Diamonds associated with ultramafic complexes and derived placers. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1996. http://dx.doi.org/10.4095/211743.
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Fox, D., and J. T. van Berkel. Mafic-ultramafic occurrences in metasedimentary rocks of southwestern Newfoundland. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1988. http://dx.doi.org/10.4095/122420.
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Baragar, W. R. A., U. Mader, and G. M. Lecheminant. Lac Leclair carbonatitic ultramafic volcanic centre, Cape Smith Belt, Québec. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1992. http://dx.doi.org/10.4095/132853.
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Bailey, D. G., G. S. Langdon, J. Malpas, and P. T. Robinson. Ultramafic and Related Lavas From the Margi area, Troodos Ophiolite. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1992. http://dx.doi.org/10.4095/133539.
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Peterson, T. D., M. Sanborn-Barrie, and J. Chakungal. Petrological investigation of ultramafic-mafic plutonic rocks, Southampton Island, Nunavut. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2011. http://dx.doi.org/10.4095/289244.
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Newberry, R. J., L. E. Burns, and G. H. Pessel. Preliminary report - geology of the Red Mountain ultramafic complex, Seldovia, Alaska. Alaska Division of Geological & Geophysical Surveys, 1985. http://dx.doi.org/10.14509/1132.
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Paktunc, A. D. St. Stephen Mafic-Ultramafic Intrusion and Related Nickel-Copper Deposits, New Brunswick. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1986. http://dx.doi.org/10.4095/120381.
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