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Littérature scientifique sur le sujet « Ultramafic rock »

Auteur : Grafiati

Publié le 9 mars 2023

Mis à jour le 10 mars 2023

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Articles de revues sur le sujet "Ultramafic rock"

Jahidin, LO Ngkoimani, LM Iradat Salihin, Hasria, Erzam S. Hasan, Irfan Ido et Suryawan Asfar. « Analysis of Ultramafic Rocks Weathering Level in Konawe Regency, Southeast Sulawesi, Indonesia Using the Magnetic Susceptibility Parameter ». Journal of Geoscience, Engineering, Environment, and Technology 5, n^o 2 (24 juin 2020) : 73–81. http://dx.doi.org/10.25299/jgeet.2020.5.2.4247.

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The Konawe region is part of the Sulawesi Southeast Arm ophiolite belt where ultramafic rocks are exposed in the form of dunite and peridotite. The formation of nickel deposits is closely related to the weathering process of ultramafic rocks as a source rock. Ultramafic rocks exposed to the surface will experience weathering which is influenced by many factors, including in the form of climate change, topography, and existing geological structures. The weathering process in the source rock can influence variations in chemical elements and magnetic properties in laterite soil profiles. For example, the chemical weathering might affect magnetic mineralogy and the physical weathering could affect granulometry as well as the quantity of magnetic minerals in the soil. Condition of weathering of ultramafic rocks (initial, moderate and advanced) can affect nickel content in laterite sediments. The weathering profile study of serpentine mineral is an indication of the lateralization process that occurs in ultramafic rocks and is carried out through petrographic analysis of thin cuts and polish cuts. Determination of weathering level like this is based on the level of weathering of the mineral serpentine. In this study, the determination of the weathering level of ultramafic rocks (initial, moderate, and continued) uses magnetic susceptibility parameter. A total of 232 ultramafic rock core samples obtained from 34 hand samples were taken from different places and weathered levels were analyzed. The results of the research have shown that the magnetic susceptibility of ultramafic rocks in the study area varies, from 580 x 10-6 SI to 4.724 x 10-6 SI. Based on the value of magnetic susceptibility, magnetic minerals contained in ultramafic rock samples are hematite and geotite minerals. This means that the weathering level of ultramafic rock samples is the continued weathering level. The level of continued weathering that occurs in ultramafic rocks in the study area produces nickel laterite deposits with a nickel content of 1.65 - 2.40% in the saprolite zone, 0.42% in the saprock zone, and 0.20 - 0.51% in the basic rock zone (bedrock).

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Guice, George L., Michael R. Ackerson, Robert M. Holder, Freya R. George, Joseph F. Browning-Hanson, Jerry L. Burgess, Dionysis I. Foustoukos, Naomi A. Becker, Wendy R. Nelson et Daniel R. Viete. « Suprasubduction zone ophiolite fragments in the central Appalachian orogen : Evidence for mantle and Moho in the Baltimore Mafic Complex (Maryland, USA) ». Geosphere 17, n^o 2 (5 février 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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Hasria, Erzam S. Hasan, Deniyatno, L. M. Iradat Salihin et Asdiwan. « Characteristics of Ultramafic Igneous Rock Ofiolite Complex in Asera District, North Konawe Regency Southeast Sulawesi Province ». Journal of Geoscience, Engineering, Environment, and Technology 5, n^o 3 (18 août 2020) : 121–26. http://dx.doi.org/10.25299/jgeet.2020.5.3.4113.

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The research area is located in Asera District, North Konawe Regency, Southeast Sulawesi Province which has ultramafic rock lithology. The purpose of this study is to determine the characteristics of ultramafic igneous rocks using petrographic and geochemical analysis. Petrographic analysis aims to determine the types and abundance of minerals present so that rock types can be determined based on the classification of Travis (1955) and Streckeisen (1976). The geochemical analysis aims to determine the oxide/major element so that it can determine the type of magma based on the AFM classification according to Irvine and Baragar (1971) and the origin of the magma / original rock formation environment based on Pearce (1977). Petrographic analysis results showed that ultramafic rocks in the study area consisted of 2 types of rocks namely peridotite consisting of wherlit and lherzoite and serpentinite. The results of geochemical analysis indicate that the type of magma in the study area is thoellitic series and the origin of the magma/rock formation environment comes from the expansion of the oceanic floor or mid oceanig ridge (MOR) which is ultramafic.

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Edgar, A. D., L. A. Pizzolato et G. M. Butler. « Petrology of the ultramafic lamprophyre and associated rocks at Coral Rapids, Abitibi River, Ontario ». Canadian Journal of Earth Sciences 31, n^o 8 (1 août 1994) : 1325–34. http://dx.doi.org/10.1139/e94-115.

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An ultramafic lamprophyre sill and dikes, and an olivine–melilite-rich dike rock intrude Lower to Middle Devonian sediments and low- to high-grade Archean metamorphic rocks on the west bank of the Abitibi River, Coral Rapids, Ontario. Although previously considered to be kimberlitic, all these rocks contain olivine + clinopyroxene + phlogopite ± melilite, and hence are ultramafic alkaline rocks. The ultramafic lamprophyre can be distinguished from the dike by its lower SiO2, Na2O, Al2O3, and higher MgO and FeO. In contrast the olivine–melilite dike rock has a more uniform composition, characteristically contains melilite, and has higher Cr and Ni contents. Enriched light rare earth element (LREE) chondrite-normalized patterns are similar for all rocks.Olivine, clinopyroxene, and phlogopite have Mg# (Mg# = 100 Mg/(Mg + Fe) mol) typical of minerals in primitive alkaline rocks. Melilite composition is similar to that of igneous melilites. Phlogopites in all rock types are enriched in Ba and F and the degree of enrichment is distinct for each rock type. Accessory minerals include apatite, carbonates, chlorite, sericite, and sodalite (only in the olivine–melilite-bearing rock).The mineralogy and chemistry of the Coral Rapids rocks suggest that they are derived from a primitive olivine melilitite magma that may have evolved by fractionation of small amounts of olivine and clinopyroxene to form these alkaline ultramafic magmas.Xenoliths in the ultramafic lamprophyre sill and in lesser abundance in the olivine–melilite dike rock include olivine, phlogopite, and clinopyroxene-rich mantle-derived assemblages. The similarity between these xenoliths and their host rocks at Coral Rapids and those from southwest Uganda and West Eifel, Germany, suggests that the Coral Rapids rocks may be derived from magmas that originated from metasomatized mantle sources.

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ZINCHUK, NIKOLAY. « Specific features of petrographic study of kimberlite ». Domestic geology, n^o 6 (10 janvier 2023) : 34–49. http://dx.doi.org/10.47765/0869-7175-2022-10033.

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Based on the analysis of specific actual and analytical material capabilities and perspectives of petrographic and petrological investigations of kimberlite rocks are indicated. Kimberlite is a volcanic igneous rock, undersaturated by silica, enriched in volatiles of peralkaline ultramafic hybrid formations, containing mantle and crust material in varying quantities and ratios. Mantle material in kimberlite is represented by xenoliths of ultramafic, alkali-rich mafic-ultramafic rocks and xeno-minerals from them.

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Hasria, Febiyanti, Masri, Ali Okto, Erzam S. Hasan, La Hamimu, Sawaludin, La Ode Muhammad Iradat Salihin et Wahab. « Serpentinization Study On Ultramafic Rock at Morombo Area, Lasolo Islands District, North Konawe Regency, Southeast Sulawesi, Indonesia ». Journal of Geoscience, Engineering, Environment, and Technology 7, n^o 1 (30 mars 2022) : 15–20. http://dx.doi.org/10.25299/jgeet.2022.7.1.6643.

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The research is in Morombo area, North Konawe Regency, Southeast Sulawesi. The purpose of this study was to determine the characteristics of serpentinized ultramafic rock and serpentine paragenesis. Research was conducted using field observations and laboratory analysis consisting of petrographic and geochemical analysis in the form of X-Ray Fluorosence (XRF). Petrographic analysis was carried out to identify the mineral content and textures in the rock and to determine the percentage of serpentine mineral presence. Both of these rocks are petrographically dominated by primary minerals olivine and clinopyroxine and secondary minerals namely lizardite, chrysotile, antiorite and opaque minerals. The XRF analysis was to determine the elements of Ni, Fe, Co, MgO, SiO2, CaO, Al2O3 and P in ultramafic rocks. The results of petrographic analysis show that serpentinized ultramafic rocks in the study area consist of serpentinized dunite and serpentinized peridotite. The formation of clay minerals in rocks does not occur because of the low serpentinization process in the rock. The results of XRF analysis showed that all samples in the bedrock showed Ni content above 0.2%. This is caused by the enrichment of Ni which is interpreted as a result of the serpentinization process along with the formation of lizardite in the rock. The serpentinization sub-processes in the study area comprised by hydration, serpentine recrystallization, and deserpentinization. Serpentine paragenesis is formed from the mid-oceanic ridge ocean floor, the orogenic phase to weathering. Substitution of Mg by Ni in ultramafic rocks will produce Ni-Serpentin. It is estimated that in the research area lizardite and chrysotile lizardite and chrysotile are the causes of Ni enrichment in bedrocks. The serpentinization characteristics of ultramafic rocks in the study area show a low to moderate level of serpentinization.

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Erskine, Bradley G. « Geologic Investigations for Compliance with the CARB Asbestos ATCM ». Environmental and Engineering Geoscience 26, n^o 1 (20 février 2020) : 99–106. http://dx.doi.org/10.2113/eeg-2290.

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ABSTRACT The California Air Resources Board Airborne Toxic Control Measure for Construction, Grading, Quarrying, and Surface Mining Operations (ATCM) provides requirements for the evaluation for naturally occurring asbestos (NOA) on a construction site. There are two compliance triggers: (1) a determination that the site is located within a geographic ultramafic rock unit, defined as a geographic area designated as an ultramafic rock on referenced maps, and (2) the presence of NOA, serpentinite, or ultramafic rock. The California Geological Survey requires that NOA evaluations be conducted by a licensed professional geologist. However, under the ATCM, a professional geologist is required only when a property owner wishes to demonstrate that a geographic ultramafic rock unit is not actually represented by ultramafic rocks. The professional geologist who must advise whether the ATCM applies at a construction site is therefore placed in a precarious position. Does a limited desktop review of geologic maps meet any standard of practice? If the ATCM is triggered by the presence of asbestos, is the geologist negligent if no evaluation is recommended or conducted? Could geologic units be pre-screened for asbestos potential? Using case studies and geologic data in the city of San Francisco and East Bay, this presentation reviews these issues and provides a context for the geologist to conduct the appropriate level of investigation for compliance with the ATCM.

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RAJAKARUNA, Nishanta, Kerry KNUDSEN, Alan M. FRYDAY, Ryan E. O'DELL, Nathaniel POPE, Fred C. OLDAY et Suzie WOOLHOUSE. « Investigation of the importance of rock chemistry for saxicolous lichen communities of the New Idria serpentinite mass, San Benito County, California, USA ». Lichenologist 44, n^o 5 (24 août 2012) : 695–714. http://dx.doi.org/10.1017/s0024282912000205.

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AbstractAlthough several lichen inventories exist for European ultramafic sites, only four surveys of serpentine lichens for North America have been published to date. Of those, only one has been conducted in California. We conducted a survey of saxicolous lichens from ultramafic rocks (including nephrite, partially serpentinized peridotite, and serpentinite) and non-ultramafic rocks (including silica-carbonate, shale, and sandstone) at the New Idria serpentinite mass, San Benito County, California. X-ray Fluorescence Analysis of the rocks from which the lichens were collected revealed significant elemental differences between the ultramafic and non-ultramafic rocks for 26 of the 32 major and trace elements analyzed. We identified a total of 119 species of lichenized and lichenicolous fungi; 60 species were restricted to ultramafic substrata, 19 to silica-carbonate, and 15 to shale and sandstone. Only 4 species were shared in common. A permutational multivariate analysis of variance (perMANOVA) test revealed significant differences in lichen assemblages between ultramafic and non-ultramafic rocks at the species level but not at the generic level, with species richness (alpha-diversity) significantly greater at the ultramafic sites. We suggest that, although differences in geochemistry clearly influence the lichen community composition, other factors, especially substratum age and the physical characteristics of the rock, are of equal, if not greater, importance. Of all the species collected, six, Buellia aethalea, B. ocellata, Caloplaca oblongula, Rhizocarpon saurinum, Thelocarpon laureri, and Trapelia obtegens, are reported new to California, along with an apparently previously undescribed Solenopsora sp. The rest of the species encountered are relatively frequent in the lichen flora of southern and central California, except Aspicilia praecrenata, a rare California endemic that we collected on both ultramafic and non-ultramafic rocks.

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Martins, Vanessa, Douglas Ramos Guelfi Silva, Giuliano Marchi, Maurício Cunha Almeida Leite, Éder de Souza Martins, Ana Stella Freire Gonçalves et Luiz Roberto Guimarães Guilherme. « EFFECT OF ALTERNATIVE MULTINUTRIENT SOURCES ON SOIL CHEMICAL PROPERTIES ». Revista Brasileira de Ciência do Solo 39, n^o 1 (février 2015) : 194–204. http://dx.doi.org/10.1590/01000683rbcs20150587.

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The current high price of potassium chloride and the dependence of Brazil on imported materials to supply the domestic demand call for studies evaluating the efficiency of alternative sources of nutrients. The aim of this work was to evaluate the effect of silicate rock powder and a manganese mining by-product, and secondary materials originated from these two materials, on soil chemical properties and on brachiaria production. This greenhouse experiment was conducted in pots with 5 kg of soil (Latossolo Vermelho-Amarelo distrófico - Oxisol). The alternative nutrient sources were: verdete, verdete treated with NH4OH, phonolite, ultramafic rock, mining waste and the proportion of 75 % of these K fertilizers and 25 % lime. Mixtures containing 25 % of lime were heated at 800 ºC for 1 h. These sources were applied at rates of 0, 150, 300, 450 and 600 kg ha-1 K2O, and incubated for 45 days. The mixtures of heated silicate rocks with lime promoted higher increases in soil pH in decreasing order: ultramafic rock>verdete>phonolite>mining waste. Applying the mining waste-lime mixture increased soil exchangeable K, and available P when ultramafic rock was incorporated. When ultramafic rock was applied, the release of Ca2+ increased significantly. Mining subproduct released the highest amount of Zn2+ and Mn2+ to the soil. The application of alternative sources of K, with variable chemical composition, altered the nutrient availability and soil chemical properties, improving mainly plant development and K plant uptake, and are important nutrient sources.

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Σερέλης, Κ., Ε. Γκάρτζος et Π. Τσαουσίδου. « STUDY OF THE WALL ROCK ALTERATION OCCURRING IN ULTRAM A F I C ROCKS HOSTING MAGNESITE DEPOSITS, EVIA, GREECE »,. Bulletin of the Geological Society of Greece 36, n^o 1 (1 janvier 2004) : 377. http://dx.doi.org/10.12681/bgsg.16688.

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Three different kinds of alteration processes occur in the studied ultramafic host rocks of the magnesite deposits of N. Evia. In chronological order: Pre-magnesite event (serpentinization), syngenetic brown alteration and weathering. This paper concerns the syngenetic wall rock alteration of the ultramafic host rocks. Two types of wall rock alteration were distinguished. The first one named type (B-i) concerns cases of brown alteration accompanying thin to medium size veins of magnesite. Alteration is restricted in thin (a few cm to 20 cm) vein-parallel bands occurring on both sides of the vein. Alteration increases gradually towards the edges of the vein. The altered band consists mainly of abundant dolomite and/or quartz. The second type (B2) concerns argillic alteration of large ultramafic masses in areas with intense magnesite mineralization and can be observed along the walls of the open pit mines. Secondary vermiculite has been formed in this case. Both types are related to the genesis of the magnesite deposits

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Thèses sur le sujet "Ultramafic rock"

SCARSI, MARCO. « Faulting, fluid-rock interaction and hydrothermal mineralisation in ultramafic rocks (Voltri Massif, Ligurian Alps) ». Doctoral thesis, Università degli studi di Genova, 2018. http://hdl.handle.net/11567/929962.

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This study deals with reverse faults within intensely carbonated metalherzolites, with related gold mineralisations, from the Voltri Massif, and in particular within the Lavagnina Lakes area, in the Gorzente Valley. This area is located in northwest Italy among the municipalities of Casaleggio Boiro, Lerma, Mornese, and Bosio (Alessandria, Italy; GPS coordinates WGS84, 44.600685° N, 8.784286° E). The Voltri Massif is a metaophiolitic complex, which occurs within the Eastern edges of the Ligurian Alps. It is made up of of metaophiolitic rocks associated with metasediments and slices of subcontinental lithospheric mantle. These rocks underwent a complex Alpine tectono-metamorphic evolution, with blueschist- to eclogite- facies peak metamorphism with variable retrogressive overprints. For this study the analysed structures are the upper crustal deformational events (UDC), from late- to post-orogenic linked to the collisional events. These deformational events are linked to different structural regimes, and developed during the late-Alpine to early-Appenine events. The Lavagnina Lakes area is mainly characterised by outcrops of serpentinites, lherzolites, metabasites, metagabbros, lenses of metasediments, and listvenites (in decreasing order of volumetric extension). From a structural point of view, this area is characterised by brittle to brittle-ductile systems of shear zones, with associated carbonates and chalcedony-quartz veins associated with local gold mineralisations. Hydrothermal, carbon-rich fluids permeated the rocks and sustained these deformation stages producing widespread and intense carbonate-rich alteration zones, exclusive meso- and microstructures within carbonates fault zones, called fault pearls, chalcedony shear veins along fault surfaces, widespread quartzchalcedony and carbonates veining, and leading to local gold mineralisation. The geological survey allowed identifying four main structures (Chapter 5) that I studied in detail. In particular I studied the Bisciarelle Creek thrust fault for the occurrence of meso- and microstructures never reported in literature, called fault pearls. Their compositional and textural characteristics, described in chapter 5.3.4, make the fault core of the Bisciarelle fault a peculiar geological object. 2 The data shown in chapter 7 provide constraints on the chemical properties of the fluid that generate the intense carbonation along the Bisciarelle fault. Through the mass transfer profiles was possible to identify and quantify those elements transferred from the fluid to the rock and vice versa. The morphometric image analysis results (Described in chapter 5.3.5) show that the fault pearls have circular shape irrespective to the direction of observation (parallel and orthogonal to the slickenlines), with values that indicate a nearly perfect circular shape. These values are in line with the roundness values, hence the fault pearls in three-dimensions can be considered as nearly perfect spheres or as very spherical textures. Single-spot SEM-EDS (Chapter 8) analyses show that ferroan dolomite makes the pearl bands (CaO: 29.13±2.33 wt%; MgO: 19.03±4.86 wt%; FeO: 1.77±0.87 wt%) and that minor compositional variations across large and thin bands exist, and that silica makes most of the chalcedony veins (SiO2: 97.97±3.23 wt%). Elemental imaging by LA-ICPTOFMS (Chapter 8) provides a detailed account of the distribution of chemical elements within pearls, matrix, and chalcedony shear veins. Mineral paragenesis and elemental imaging by LA-ICP-TOFMS confirm the hypothesis of hydrothermal derivation of the fault rock. This is best evaluated by comparing the concentration ranges of the key trace elements As, Sb, In, Ga, Ag, Zn, and Cu of fault pearls levels and chalcedony with those of the same elements in the average upper crust. Such comparison clearly shows that the peak concentrations of these elements are 5 (Cu, Zn) to 50 (Sb, In) times higher than those of the upper crust, demonstrating that the Bisciarelle fault fluid was capable to transport and deposit a suite of ore elements. These evidences are fundamental to discuss the possible origin of the fluids that developed the carbonation and the fluid-rock interactions along the Bisciarelle thrust fault and along the main fault of the Lavagnina Lakes area. On the basis of all the constraints described, the fault pearl features are compatible with a genesis from a process called “transient” boiling in microfluidics. This process occurs within cavities when a liquid is instantaneously overheated and a vapour phase nucleates and expands up to explosive boiling, and so generates a myriad of vapour bubbles. Such process, which occurred during mixed mode fracturing in the fault, implies that pearls might reflect the liquid-vapour 3 fractionation of chemical elements in a boiling hydrothermal fluid during seismic failure. The close association of fault pearls with seismic-related structures such as submicron carbonates coating of slip surfaces, quartz microtexture related to silica gel deposition, syn-kinematic filamentous phase, injection veins with similar characteristics and overpressure with respect to seismic pseudotachylites along slip zone supports the hypothesis that fault pearls developed during shear events at seismic rates, and hence are considerable as paleo-seismic events indicators. Moreover I discuss the tectonic evolution of the Lavagnina Lakes area linked to the syn-kynematic fluid rock interaction, the origin of the fluids and the gold mineralisations of the area. The occurrence of syn-tectonic fluid flow and consequent fluid-rock interaction (e.g. carbonation) along the two systems of Reverse Shear Zones (RSZ1-RSZ2), is testified by: metasomatic alteration (ALT-1, ALT-2, and ALT-3), at least three main systems of veins (V1, V2, and V3), and hydraulic and cockade breccias. The evidence that the carbonation took place along these structures, in particular along the RSZs systems, and within their damage zones, highlights how these structures acted as important fluid pathways and played a major control in the distribution of the ore deposits. Finally, I stress out further consideration about the comparison between the gold mineralisations of the area with the gold mineralisations of the whole Voltri Massif.

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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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Berly, Thomas. « Ultramafic and mafic rock types from Choiseul, Santa Isabel and santa Jorge (Northeastern Solomon Islands) : origins and significance ». Grenoble 1, 2005. http://www.theses.fr/2005GRE10223.

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Les Iles Salomon forment une double chaîne d'îles située au nord-est de l'Australie entre la Papousie Nouvelle Guinée et les Iles Vanuatu (Océan Pacifique), résultant de la récente collision (<10 Ma) du plus grand plateau océanique au monde - Ontong Java (OJP) avec l'arc volcanique des Iles Salomon, issu de la subduction de la plaque Pacifique sous la plaque indo-australienne (depuis 43 Ma). Résultant de cette collision, des écailles de roches ultramafiques (péridotites et pyroxénites) et mafiques (basaltes et gabbros) ont été obductées et affleurent au nord-est des Iles Salomon. L'objectif de cette thèse est d'étudier ces roches en utilisant une approche pluri-disciplinaire (pétrologie, minéralogie et géochimie) afin de déterminer leur origine et leur formation. Les harzburgites de Choiseul et les pyroxénites de Santa Isabel et San Jorge ne sont pas liées à OJP mais résultent d'un mécanisme complexe du métasomatisme du manteau d'arc par des fluides issus de la plaque subductée. Ces fluides, riches en éléments lithophiles (Cs, Ba, Rb, Sr et Pb) sont des magmas hydratés résultant de la fusion des sédiments subductés. Les roches mafiques (incluant les basaltes et les gabbros) représentent un complexe ohiolitique complet de bassin d'arc. En conclusion, la formation et l'exhumation de ces roches ultramafiques et mafiques des Iles Salomon sont étroitement liées à la collision OJP-arc
The Solomon Islands are a double chain of islands in the Pacific Ocean (Noth-east of Australia) resulting from the recent collision (<10 Ma) of the world's largest oceanic plateau Ontong Java (OJP) with the Solomon arc. In response of this collision, thin fault slices of peridotites, pyroxenites, gabbros and basalts are now exposed on the islands of Santa Isabel, san Jorge and Choiseul (Northeastern Solomons). Although some pillow basalts are OJP-related, the origins of the most of the mafic and ultramafic rocks remain uncertain. The Choiseul peridotites are interpreted to have two stage origins: 1-residual harzburgites formed beneath an ocean ridge; 2) infiltration of a reactive metasomatic agent released from the slab. Similar but more complex metasomatic process results in the formation of the pyroxenites from San Jorge and Santa Isabel. This metasomatic agent released from the slab is likely to represent an hydrous granitic melt derived from the subducted sediments. The mafic rocks (including the basalts and gabbros) are interpreted as portions of an arc-backarc crust. As a result, the formation and the exhumation of the ultramafic and mafic rocks from the Solomon Islands are directly related to the OJP-arc collision

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Clark, David 1979. « Petrogenetic and economic significance of the whole-rock chemistry of ultramafic cumulates in the Cape Smith foldbelt, northern Quebec ». Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112390.

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The ultramafic cumulate rocks of the Raglan horizon in the Proterozoic Cape Smith fold belt of northern Quebec have a common parental liquid in equilibrium with olivine of Fo89 composition. Cumulate olivines have experienced a trapped liquid shift to lower forsterite composition proportionally to the fraction of trapped liquid in the cumulate. Anomalously low nickel contents in analyses of both olivine and whole-rock chemistries are observed only in cumulates with the most modal olivine and which are proximal to known Ni-Cu-(PGE) deposits. The calculated compositions of the trapped liquid fraction indicate that most of the Raglan cumulates formed from Fe-rich high-MgO basalts, which are restricted to the base of the Chukotat volcanic stratigraphy. We propose that a lower degree of adiabatic partial melting of a mantle source accounts for the Fe-rich nature of these parental liquids and may provide an explanation for the presence of numerous Ni-Cu-(PGE) deposits in the sills of the Raglan horizon.

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Sterritt, Victoria Athena. « Understanding physical property : mineralogy relationships in the context of geologic processes in the ultramafic rock-hosted mineral deposit environment : aiding interpretation of geophysical data ». Thesis, University of British Columbia, 2006. http://hdl.handle.net/2429/32686.

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Inversion of potential field geophysical data to generate physical property models is becoming increasingly common in the exploration industry. This study aimed to develop relationships between physical properties and mineralogy in ultramafic rock-hosted mineral deposits, based on an analysis of the crater facies-dominated Anuri kimberlite (Canada) and the intrusive magmatic sulfide deposit at Kabanga (Tanzania). Physical property distributions for rock types and minerals that contribute to density and magnetic susceptibility were characterized in both deposits. Magnetic susceptibility is directly related to magnetite abundance, which is an igneous phase and is produced by serpentinization of ultramafic rocks of both deposits. Magnetite in kimberlite also occurs in crustal xenoliths, which dilute the diamond content. Consequently, susceptibility in the Anuri kimberlite is inversely related to diamond grade. In the Kabanga magmatic sulfide deposit, susceptibility is unrelated to ore content, but does indicate the degree of serpentinization. Density is a function of dense minerals concentrated with ore during primary sorting and settling processes in both deposits. As such, density is directly correlated with ore in both volcaniclastic kimberlite breccia of the Anuri kimberlite and ultramafic rocks at Kabanga. However, serpentinization decreases the density of ultramafic rocks significantly, masking any density anomalies associated with sulfide minerals. Modeling demonstrates that a pervasively serpentinized rock with up to 50% sulfide minerals can have a density equal to that of a barren ultramafic rock. A combination of susceptibility and density can be used to identify high-grade rocks in both deposits. In the Anuri kimberlite, rocks with high diamond contents have susceptibilities less than 10 x 10⁻³ SI and densities of 2.42 - 2.51 g/cm³. In magmatic sulfide deposits, susceptibility and density can be used to accurately calculate ore mineral abundances. Relationships developed between physical properties and mineralogy for these deposits can not only be applied to other crater facies-dominated kimberlites and both intrusive and extrusive magmatic sulfide deposits, but also to other ultramafic rock-hosted mineral deposits with comparable geologic processes. Consequently, both magnetic and gravity surveys can be interpreted in combination to give a powerful remote tool in predicting grade.
Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
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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.

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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.
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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GUERINI, SARA SIBIL GIUSEPPINA. « STRUCTURE, GEOCHEMISTRY AND PETROLOGY OF SERPENTINITES AND LISTVENITES IN THE WESTERN ALPS : CONSTRAINTS ON CARBONATION AND ELEMENT MOBILIZATION FROM SUBDUCTION TO OPHIOLITE EMPLACEMENT ». Doctoral thesis, Università degli Studi di Milano, 2022. http://hdl.handle.net/2434/927547.

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This Ph.D. Thesis is intended as a multidisciplinary research work on the Zermatt-Saas (Western Alps) serpentinites and associated carbonated rocks. The main goal of this thesis is to decipher the carbonation processes involving serpentinites and the concomitant element mobilization, while also attempting at defining the serpentinites’ subduction-to emplacement- evolution. To address these aims, field work activities, spanning from acquisition of macro-structural data to sampling of representative lithologies, and detailed petrography were carried out on a sequence of serpentinites, carbonated serpentinites and listvenites from the Mount Avic Massif (Zermatt-Saas Zone, Aosta Valley, Western Alps) and neighbouring area of Vercoche. On the selected data set a wide range of geochemical analyses were carried out not only to define the bulk rock compositions but also to trace, by means of EMPA, LA-ICP-MS, µ-Raman applied to microstructurally selected sites, variations and chemical gradients of elements relevant for this study (i.e., redox sensitive elements such as C and S, but also major and trace elements). In order to decipher the subduction-to emplacement evolution of serpentinites, detailed petrology and geochemical investigations were applied to unravel the signature of fluid-rock interaction during subduction. Moreover, by integrating structural, petrological and geochemical results with thermodynamic modelling, the P-T-(t)-d paths representative of the evolution of serpentinites were obtained. Serpentinites from the Mount Avic massif retain structural and geochemical fingerprints of a long-lived evolution. Mantle (and oceanic) relics can be easily distinguished from the prograde metamorphic recrystallized phases: clinopyroxene, olivine and Cr-cores within magnetite preserve their mantle texture and, in part, their original composition. These features suggest that the serpentinites derived from mantle peridotites, mainly represented by harzburgite, that were exhumed and exposed at the Mesozoic Tethyan Ocean floor prior to alpine subduction. In this context, mantle peridotites likely interacted with seawater that enhanced the pervasive serpentinization and caused the progressive replacement of olivine and pyroxene by serpentine-lizardite with “mesh” and “bastite” textures, respectively. Bulk rock trace and REE patterns obtained on serpentinites as well as in situ concentrations of trace and rare Earth elements on serpentinite forming minerals suggest that the Mount Avic serpentinite still largely retains its oceanic geochemical signature despite intense Alpine subduction metamorphism. At the onset of the Tethyan ocean closure due to convergence between the Paleo-Europe and Paleo-Adria continental plates, the serpentinites underwent prograde metamorphism during Alpine subduction. Different mineral assemblages marking superposed fabrics are variably retained within the serpentinites. In foliated serpentinites, despite the pervasive overprinting provided by S2 foliation, relics of pre-D2 structures are preserved. In particular, Ti-chondrodite, clinopyroxene, olivine, antigorite and magnetite-bearing assemblage, marking pre-to early D1 metamorphic stage, attest for peak UHP conditions attained at Pmin = 2.8-2.85 GPa for T = 600-645°C. The crystallization of Ti-clinohumite along Ti-Chondrodite rims during D1 deformation stage, suggest that serpentinites, after reaching the peak metamorphic conditions, experienced a quasi-isothermal decompression from pre-to early D1 conditions, still within typical Alpine subduction geothermal gradient of 6.5-8.0°C/km. Detailed LA-ICP-MS analyses carried out on clinopyroxene, humite, olivine and serpentine minerals showed that Zr, Ti, Hf and Sr elements were mobilized during the transition from the mantle to the subduction environment. The lizardite-antigorite transition phase was accompanied by Sr, Cl and alkalis release in an open system which likely occurred in early oceanic stage and was complete at T>390°C. Differently, the partitioning of Ti, Hf, Zr between clinopyroxenes and Ti-clinohumite supports the idea that mantle clinopyroxene breakdown and successive high-pressure clinopyroxene and Ti-clinohumite crystallization took place in a closed space environment. During the retrograde path, the serpentinites re-equilibrated at Pmin = 2.4-1.7 GPa and T = 510-610°C; at these conditions, D2 deformation stage caused the crystallization of Ti-clinohumite and Ti-chondrodite in textural equilibrium along S2 foliation planes together with olivine, clinopyroxene, antigorite and magnetite. Locally, veins and shear zones marked by clinopyroxene, olivine and Ti-clinohumite postdating S2 foliation, attest that during syn-to-post-D2 exhumation hot geothermal gradients (20°C/km), indicative of greenschist facies re-equilibration, were reached. These new results provide unprecedented insights on the geochemistry, petrology and P-T peak conditions at which the Mount Avic serpentinites (Zermatt-Saas Zone) re-equilibrated during the alpine subduction and exhumation and allow for a comparison with the UHP serpentinite slices belonging to the Cignana Lake and Valtournanche (Créton) units of the Zermatt-Saas Zone north of the Aosta-Ranzola fault. Serpentinites of the Mount Avic massif underwent carbonation likely during their retrograde evolution, which caused the formation of carbonate-bearing lithologies comprising carbonated serpentinites and listvenites. These metasomatized rocks represent valuable records of CO2 sequestration enhanced by fluid-rock interaction mainly focused along serpentinite shear zones. Fluid-rock interaction, responsible for the genesis and evolution of carbonated serpentinites and listvenites, is attested not only by macro-scale, but also by micro-scale structural features. Petrographic observations suggest that the Mount Avic serpentinites, after having experienced D2 and post-D2 stages at high-pressure and greenschist facies conditions, respectively, likely reached lower T and P conditions while being progressively infiltrated by CO2-rich fluids. Ti-clinohumite relics within partially carbonated serpentinite, presently pseudomorphically replaced by olivine and ilmenite and the presence of Ti-clinohumite not yet replaced by olivine and ilmenite, but still in equilibrium with olivine and clinopyroxene, constrain the P-T conditions attained by serpentinites prior to carbonation and supports the hypothesis that the initiation of carbonation of serpentinites took place just before, or even simultaneously with, Ti-Chu breakdown, likely during the early retrograde greenschist facies re-equilibration of serpentinites. Based on thermodynamic modelling, the equilibrium P-T conditions for listvenitization are constrained at 0.3GPa and 300°C and the minimum amount of CO2, required for the infiltrating fluid to produce the listvenite mineral assemblage is XCO2 (min) = 0.02. Upon fluxing of CO2-bearing fluids, carbonated serpentinites are progressively transformed into listvenites as evidenced by the crystallization of quartz as a product of talc breakdown, making-up matrices together with aggregates of magnesite and fuchsite fibres, attesting for the presence of K in the infiltrating fluid. The presence of Cr-spinel, magnetite and mesh texture relics in listvenites is regarded as a clear petrogenetic relationship with serpentinites. Electrolytic fluid infiltration modelling suggests that the Mount Avic listvenites attained low T and very high fluid/rock (F/R) ratios: prolonged fluid infiltration at low temperatures causes the solubility of quartz to increases to the point that part of the SiO2 present in the listvenite matrix is dissolved in the fluid and then precipitated in veins which diffusively characterize listvenites. Furthermore, with progressive fluid infiltration, MgO/SiO2 ratio increases up to a point (at F/R between 6 and 7 and ca. 38-42% CO2), where the infiltrating fluid removes CO2 from the system. The dissolution of carbonate and concurrent silicification of the altered rock, once all the talc has reacted with CO2,aq to form magnesite and quartz, is thermodynamically predicted at T ≤ 200°C under prolonged fluid influx. The petrographic investigation on sulfides allowed to depict a chemical gradient: from serpentinites to listvenites the sulfide abundance decreases in accordance with the decrease in S (wt%) abundance observed by measured bulk rock values as well as predicted by thermodynamic models. In serpentinites the sulfur-poor heazlewoodite and pentlandite are associated with awaruite Ni-Fe alloy, in accordance with the observations that Fe-Ni alloys tend to be preferentially found in peridotites that have been only partially serpentinized. Passing to carbonated serpentinites the sulfide abundances progressively decreases and their composition changes. In particular, in carbonated serpentinites, neither Ni-Fe alloys nor pentlandite are identified while sulfur-poor heazlewoodite forms aggregates with sulfur-rich Co-bearing NiS. Finally, the transition from carbonated serpentinites to listvenites is marked by the limited presence of small-grained pentlandite and haezlewoodite, and absence of alloys while magnetite is progressively replaced by hematite displaying martite texture. The pseudomorphic martitic replacement of magnetite by hematite due to magnetite oxidation, observed exclusively within listvenites, and not in carbonated serpentinites where sulfides are still present, suggests that once the sulfides are completely dissolved, the fluid continues to evolve towards high oxygen fugacity (fO2) conditions. Prior to fluid infiltration, serpentinites attained very low fO2 and fS2 as constrained by the presence of Ni-Fe alloys (i.e., awaruite) and sulfur-poor assemblage (heazlewoodite and pentlandite) in magnetite-bearing antigorite-serpentinites. Within the successive steps of fluid infiltration, the redox conditions of the system changed: the passage from serpentinites to carbonated serpentinites is marked by more oxidising conditions, by a marked increase in Fe3+/Fetotal ratios and by the stability of heazlewoodite with sulfur-rich Co-bearing NiS (millerite). The transition from carbonated serpentinites to listvenites is marked by the consumption of sulfides and the concomitant constant increase in fO2. It is likely that sulfides in the Mount Avic carbonated serpentinites and listvenites were dissolved by sulfate-dominant fluids in oxidising rocks. Listvenites are predicted to be stable at high-fO2, above the MH (magnetite-hematite) buffer where hematite is expected to be stable, consistently with petrographic observations of pseudomorphic replacement of magnetite by martite-textured hematite. Interestingly, nickel shows high mobility during the carbonation process, passing from being retained in sulfides and alloys in serpentinites (awaruite, pentlandite and heazlewoodite) to form rare millerite in carbonated serpentinite and listvenites and to be concentrated in trevoritic cores within spinels in listvenites. The comparison between serpentinites and listvenites by means of trace elements allows to evaluate that the compatible elements (V, Sc, Zn, Cr, Ni and Cu) were redistributed between the two rock types suggesting a mainly closed-system behaviour during listvenitization and internal cycling of such components from the host minerals in the serpentinite. Differently, higher incompatible (K, Rb, Sr, Ba Nb) and fluid mobile elements concentrations in listvenites suggest that these elements were sourced externally from the serpentinites. Moreover, Co zoning within sulfides in carbonated serpentinites may reflect the interaction of the host rock with saline fluids, whose provenance could be attributed to dehydration reactions affecting serpentinites or to fluids released upon metasediments devolatilization. Based on stable carbon and oxygen isotope compositions of magnesite, it is proposed that the CO2-rich fluids promoting serpentinite carbonation derived from devolatilization of metasedimentary rocks in the subduction zone while metaperidotites were already facing early exhumation conditions during their early retrograde evolution. During syn-to-post D2 early retrograde path serpentinites experienced strain conditions favourable for the formation of shear zones; such structures served as preferred pathways for CO2-rich fluid circulation and enhanced the carbonation of serpentinites and the formation of listvenites. Only in Oligocene times, when the post-emplacement tectonics was active, the rheological contrast between serpentinites and listvenites worked as weakness surface that facilitated the nucleation of the normal fault along which listvenites and carbonated serpentinite crop out. The combination of field, macro and micro-structural, petrological and geochemical data with thermodynamic modelling, provide new and unprecedented insights 1) on the P-T-(t)-d history of the serpentinites from the Mount Avic: this represents the first attempt at defining a P-T stability field for the Zermatt-Saas serpentinites south of the Aosta-Ranzola fault in the Western Alps; 2) on the interaction of CO2-bearing fluids with serpentinites to form carbonated serpentinites and listvenites and how this process controls element mobilization, variations of redox sensitive elements and carbonation.

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de, Oliveira Elson Paiva. « Petrogenesis of mafic-ultramafic rocks from the Precambrian Curaca terrane, Brazil ». Thesis, University of Leicester, 1990. http://hdl.handle.net/2381/35079.

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The Caraiba copper-rich hypersthenite-norite complex in the Early Proterozoic Curaca terrane of northern Bahia, Brazil, is not a tholeiitic layered sill as has been previously suggested. It is re-interpreted as a series of multiple dyke-like intrusions, possibly derived through partial melting of an incompatible element enriched harzburgitic to orthopyroxenitic lithospheric mantle source region. It contains peridotitic and gabbroic xenoliths. Copper-rich gabbroic xenoliths may represent volcanic rocks taken to upper mantle depths by a process of subduction. The chemistry of some of the regional mafic rocks and of three granitoid generations suggest for the Curaca terrane a tectonic evolution similar to Phanerozoic continent-continent collision belts, which was possibly initiated at an Andean-type margin. A Middle Proterozoic mafic dyke swarm that post-dates the main period of crustal growth is interpreted as having originated from a heterogeneous garnet-bearing source in the asthenospheric mantle, and is likely to be related to a mantle plume or hotspot during the development of the coeval Espinhaco aulacogen. The parental magma of these dykes is thought to have resided in small zoned magma chambers. Comparison with other mafic dykes from the Brazilian shield suggests derivation of the Early Proterozoic dykes from more depleted, more refractory, lithospheric mantle sources than those of the younger dykes, which are believed to have had a significant asthenospheric contribution in their petrogenesis. The chemistry of these dykes reflects the evolution of the sub-continental mantle with time.

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Kieser, Nigel Bernard John. « Platinum-group element dispersion associated with mafic and ultramafic rocks in Alaska ». Thesis, Imperial College London, 1996. http://hdl.handle.net/10044/1/8235.

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Power, Matthew R. « Models for the genesis of industrial minerals in mafic and ultramafic rocks ». Thesis, University of Exeter, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245925.

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Livres sur le sujet "Ultramafic rock"

Pell, Jennifer. Alkaline ultrabasic rocks in British Columbia : Carbonatites, nepheline syenites, kimberlites, ultramafic lamprophyres, and related rocks. Victoria, B.C., Canada : Province of British Columbia, Ministry of Energy, Mines and Petroleum Resources, Mineral Resources Division, Geological Survey Branch, 1987.

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Rare earth elements in ultramafic and mafic rocks and their minerals : Main types of rocks : rock-forming minerals. London : CRC Press/Balkema, 2010.

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Mies, Jonathan W. Ultramafic rocks of the Alabama Piedmont. Tuscaloosa, Ala : Geological Survey of Alabama, Economic Geology Division, 1994.

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1959-, Mittwede Steven K., Stoddard Edward F. 1949- et Geological Society of America. Southeastern Section. Meeting, dir. Ultramafic rocks of the Appalachian Piedmont. Boulder, Colo : Geological Society of America, 1989.

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Theyer, P. Ultramafic rocks of the Island Lake area. Winnipeg : Manitoba Energy and Mines, Geological Services, 1985.

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Hancock, Kirk D. Olivine potential of the Tulameen ultramafic complex. Victoria, B.C., Canada : Province of British Columbia, Ministry of Energy, Mines and Petroleum Resources, Mineral Resources Division, Geological Survey Branch, 1991.

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Vincent, Harold R. Geology of selected mafic and ultramafic rocks of Georgia : A review. Atlanta : Georgia Department of Natural Resources, Environmental Protection Division, Georgia Geologic Survey, 1990.

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Moreva-Perekalina, T. V. Ultramafic xenoliths from alkaline basalts of Finkenberg (Siebengebirge, West Germany). Leiden : Rijksmuseum van Geologie en Mineralogie, 1985.

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Obeso, Juan Carlos de. Tracing alteration of ultramafic rocks in the Samail ophiolite. [New York, N.Y.?] : [publisher not identified], 2019.

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Himmelberg, Glen R. Petrogenesis of the ultramafic complex at the Blashke Islands, southeastern Alaska. [Reston, Va.?] : Dept. of the Interior, U.S. Geological Survey, 1986.

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Chapitres de livres sur le sujet "Ultramafic rock"

Yushun, Min. « Hydrogen and oxygen isotopic studies of selected ultramafic-type serpentine-asbestos deposits in western China ». Dans Water-Rock Interaction, 211–14. London : Routledge, 2021. http://dx.doi.org/10.1201/9780203734049-52.

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Plyusnina, L. P., et G. G. Likhoidov. « Experimental study of granite-ultramafic interaction and its effect on gold solubility in aqueous-chloride solutions ». Dans Water-Rock Interaction, 825–28. London : Routledge, 2021. http://dx.doi.org/10.1201/9780203734049-205.

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Chu, Xuelei, Weiguo Huo, Qicheng Fan et Ruoxin Liu. « Stable isotopic investigation on CO2 fluid inclusions in ultramafic xenoliths of the Cenozoic basalts in eastern China ». Dans Water-Rock Interaction, 179–81. London : Routledge, 2021. http://dx.doi.org/10.1201/9780203734049-44.

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Pryadunenko, Anna, et Kåre Kullerud. « Economical Potential of an Ultramafic Rock at the Kvaløya Island, North Norway ». Dans Springer Geochemistry/Mineralogy, 19–27. Cham : Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-13948-7_3.

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Vladykin, N. V., I. A. Sotnikova et N. V. Alymova. « Zhidoy Alkali-Ultramafic Rock and Carbonatite Massif : Geochemical Features, Its Sources Aednd Ore-Bearing ». Dans Springer Proceedings in Earth and Environmental Sciences, 49–62. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-69670-2_3.

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Pinti, Daniele L. « Ultramafic Rocks ». Dans Encyclopedia of Astrobiology, 2564. Berlin, Heidelberg : 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 ». Dans Encyclopedia of Astrobiology, 1. Berlin, Heidelberg : 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 ». Dans Encyclopedia of Astrobiology, 1. Berlin, Heidelberg : Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-27833-4_5099-2.

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Taylor, Hugh P., Robert T. Gregory et Bruno Turi. « 18O/16O Evidence for Fluid-Rock Interaction in the Upper Mantle : Data from Ultramafic Nodules and K-Rich Volcanic Rocks in Italy ». Dans Chemical Transport in Metasomatic Processes, 1–37. Dordrecht : Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-4013-0_1.

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Bucher, Kurt, et Martin Frey. « Metamorphism of Ultramafic Rocks ». Dans Petrogenesis of Metamorphic Rocks, 171–95. Berlin, Heidelberg : Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/978-3-662-04914-3_5.

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Actes de conférences sur le sujet "Ultramafic rock"

Oskierski, Hans Christoph, Tobias Kluge, Andreas Beinlich et Paul M. Ashley. « Ultramafic Rock Carbonation between 40° and 255° C ». Dans Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.2001.

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Cardace, Dawn. « TRACKING SHIFTS IN BIOGEOCHEMICAL INTERACTIONS IN ULTRAMAFIC ROCK SYSTEMS ». Dans Joint 52nd Northeastern Annual Section and 51st North-Central Annual GSA Section Meeting - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017ne-291141.

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Kargin, Alexey, et Vadim Kamenetsky. « Links between Ultramafic Lamprophyres and Kimberlites in the Anabar Shield, Yakutia, Russia : Evidence from Multiphase Inclusions in Rock-Forming Minerals ». Dans Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.1251.

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Ma, Qian, Yue-Heng Yang et Zhidan Zhao. « Precise Determination of Lu, Hf Concentrations and Hf Isotopic Compositions in Mafic to Ultramafic Rock Reference Materials by MC-ICP-MS ». Dans Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.1684.

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Dilek, Yildirim. « ORIGIN AND EMPLACEMENT OF MAFIC–ULTRAMAFIC ROCK ASSEMBLAGES FROM DOWNGOING SLABS AT SUBDUCTION–ACCRETION COMPLEXES : PACIFIC RIM EXAMPLES AND ANCIENT ANALOGUES IN COLLISION ZONES ». Dans GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-300625.

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Wimer, Michael, Katharine Johanesen et Adam J. Ianno. « AMPHIBOLITE FACIES METAMORPHISM OF TREMOLITE/ACTINOLITE-BEARING ULTRAMAFIC ROCKS FROM ROCKY RIDGE AND PEDEN ULTRAMAFIC BODIES OF THE ASHE METAMORPHIC SUITE, NC ». Dans Joint 69th Annual Southeastern / 55th Annual Northeastern GSA Section Meeting - 2020. Geological Society of America, 2020. http://dx.doi.org/10.1130/abs/2020se-344835.

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Sonnenberg, Emily A., Connor J. Harris, Meridith A. Miska et Paul A. Mueller. « GEOCHEMISTRY OF DADEVILLE COMPLEX MAFIC-ULTRAMAFIC ROCKS ». Dans GSA Annual Meeting in Phoenix, Arizona, USA - 2019. Geological Society of America, 2019. http://dx.doi.org/10.1130/abs/2019am-335143.

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Ilyina, V. P., et P. V. Frolov. « Ultramafic rocks of the Aganozero chromium ore deposit (South Karelia) as a non-conventional magnesium-silicate raw material for the production of new ceramic materials ». Dans Mineralogical and technological appraisal of new types of mineral products. Petrozavodsk : Karelian Research Center of RAS, 2019. http://dx.doi.org/10.17076/tm13_11.

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Ultramafic rocks of the Aganozero chromium ore deposit located in South Karelia are of practical interest as a high-Mg raw material for industrial application. The preliminary results of the study of high-Mg rocks and minerals from the Aganozero deposit for the production of new materials are reported. The high technological level and economic efficiency of the ceramic materials produced, based on Karelia’s high-Mg rocks and industrial minerals, were achieved by reducing energy consumption and simplifying the technological process. The practical application of local types of mineral products will increase the raw materials potential for the production of various types of refractories and industrial ceramics.

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Feldman, Anthony, Elisabeth Hausrath, Elizabeth Rampe, Oliver Tschauner et Tanya S. Peretyazhko. « ULTRAMAFIC SOILS : ANALOGUES FOR INCIPIENT WEATHERING ON MARS ». Dans Joint 118th Annual Cordilleran/72nd Annual Rocky Mountain Section Meeting - 2022. Geological Society of America, 2022. http://dx.doi.org/10.1130/abs/2022cd-373783.

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Curtis, Sabrina, Melissa S. Rice, Michael D. Kraft, Sean R. Mulcahy et Kristiana Lapo. « SPECTRAL VARIABILITY IN WEATHERED ULTRAMAFIC TERRESTRIAL ANALOGS FOR MARTIAN ROCKS ». Dans GSA Connects 2021 in Portland, Oregon. Geological Society of America, 2021. http://dx.doi.org/10.1130/abs/2021am-370626.

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Rapports d'organisations sur le sujet "Ultramafic rock"

Goff, F., G. Guthrie, D. Counce, E. Kluk, D. Bergfeld et M. Snow. Preliminary investigations on the carbon dioxide sequestering potential of the ultramafic rock. Office of Scientific and Technical Information (OSTI), août 1997. http://dx.doi.org/10.2172/563233.

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Zagorevski, A., J. Ryan, C. Roots et N. Hayward. Ultramafic rock occurrences in the Dawson Range and their implications for the crustal structure of Yukon-Tanana terrane, Yukon (parts of NTS 115I, J and K). Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2012. http://dx.doi.org/10.4095/290992.

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Fox, D., et 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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Peterson, T. D., M. Sanborn-Barrie et 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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Covello, L., S. M. Roscoe, J. A. Donaldson, D. Roach et W K Fyson. Archean quartz arenite and ultramafic rocks at Beniah Lake, Slave Structural Province, N.W.T. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1988. http://dx.doi.org/10.4095/122635.

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Laurent, R., et R. Hebert. Petrological features of gabbroic and ultramafic rocks from deep drill CY-4, Cyprus. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1989. http://dx.doi.org/10.4095/127328.

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Ayers, L. D., et J. Young. Characterization of Mafic - Ultramafic Intrusive Rocks in the Flin Flon - Snow Lake area, Manitoba. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1989. http://dx.doi.org/10.4095/127282.

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Ryan, J. J., A. Zagorevski, N. R. Cleven, A J Parsons et N. L. Joyce. Architecture of pericratonic Yukon-Tanana terrane in the northern Cordillera. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/326062.

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West-central Yukon and eastern Alaska are characterized by widespread metamorphic rocks that form part of the allochthonous, composite Yukon-Tanana terrane and parautochthonous North American margin. Structural windows through the Yukon-Tanana terrane expose parautochthonous North American margin in that broad region, particularly as mid-Cretaceous extensional core complexes. Both the Yukon-Tanana terrane and parautochthonous North American margin share the same Late Devonian history, making their discrimination difficult; however, distinct post-Late Devonian magmatic and metamorphic histories assist in discriminating Yukon-Tanana terrane from parautochthonous North American margin rocks. The suture between Yukon-Tanana terrane and parautochthonous North American margin is obscured by many episodes of high-strain deformation. Their main bounding structure is probably a Jurassic to Cretaceous thrust, which has been locally reactivated as a mid-Cretaceous extensional shear zone. Crustal-scale structures within composite Yukon-Tanana terrane (e.g. the Yukon River shear zone) are commonly marked by discontinuous mafic-ultramafic complexes. Some of these complexes represent orogenic peridotites that were structurally exhumed into the Yukon-Tanana terrane in the Middle Permian.

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Hulbert, L. J. Metallogeny of Mafic and Ultramafic Rocks of the Trans - Hudson Orogen of northern Saskatchewan and Manitoba. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1989. http://dx.doi.org/10.4095/127281.

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Barthelmes, Michael. Kennesaw Mountain National Battlefield Park : Geologic resources inventory report. National Park Service, novembre 2021. http://dx.doi.org/10.36967/nrr-2288173.

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Geologic Resources Inventory reports provide information and resources to help park managers make decisions for visitor safety, planning and protection of infrastructure, and preservation of natural and cultural resources. Information in GRI reports may also be useful for interpretation. This report synthesizes discussions from a scoping meeting held in 2012 and a follow-up conference call in 2020. Chapters of this report discuss the geologic setting and significance, geologic features and processes, and geologic resource management issues within Kennesaw Mountain National Battlefield Park. Information about the previously completed GRI map data is also provided. A GRI map poster (separate product) illustrate the GRI map data. Geologic features, processes, and resource management issues identified include erosion and mass wasting, fluvial features and processes, monadnocks, earthworks, stone quarry, building stone, ultramafic rocks, seismic activity, caves and karst, and eolian features and processes.

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