Orientador: Ticiano Jose Saraiva dos Santos / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-17T05:05:21Z (GMT). No. of bitstreams: 1 Amaral_WagnerdaSilva_D.pdf: 21391816 bytes, checksum: 86ac3a60986656ddccb8ef31c72ee455 (MD5) Previous issue date: 2010 / Doutorado / Geologia e Recursos Naturais / Doutor em Geociências

M.Sc. / Please refer to full text to view abstract

English Abstract The Dunkelsteiner Wald granulite massif in Lower Austria belongs to the Gföhl unit of the Moldanubian zone of the Bohemian Massif. Predominant rocks are felsic granulites which in some places contain garnet pyroxenites and peridotites. There are positions of mafic and intermediate granulites on their intersection. Primary mineral association of mafic granulites is garnet, clinopyroxene rich on Jd and Ca-Tschermack component and kyanite. These rocks probably represent Ca-richer variant of pyroxenites. Contemporary mineral association is make by garnet, clinopyroxene, plagioclase and orthopyroxene. Accessory there is amphibole, spinel, rutile and Ilmenite in the rocks. Sapphire inclusion in garnet cores close to kyanite inclusions has been observed in several cases. Decompression of these rocks creates specific symplectite textures in mafic granulites characterized by plagioclase inclusions. These inclusions are partly or fully surrounded by garnet porphyroblasts on their edges and coarse grain symplectics of plagioclase and pyroxene in matrix. A possible explanation of emergence of this specific texture in rocks on intersection with felsic granulite is an infiltration of melt from felsic lithology. Proof can be the enrichment of K component on edges of plagioclase grains. On the other hand,...

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When these fluids interact with the surrounding rocks, small aliquots of these fluids are trapped as imperfections in the crystal lattice and fractures of minerals. These microscopic features are called fluid and melt inclusions, and are one of the best tools available to probe, measure and determine the chemical and physical properties of crustal fluids. In the present study we examine new developments into our understanding of fluid-rock interactions using fluid and melt inclusion as tools to provide insights into the evolution of the Earth's crust from the deep continental crust to the surface. Chapter II "Raman spectroscopic characterization of H2O in CO2-rich fluid inclusions in granulite facies metamorphic rocks", is a brief review of the current understanding of granulite rocks and their formation, and a new development into our ability to characterize the composition of the fluids trapped as fluid inclusions in minerals in granulite facies rocks. Chapter III "Reassessment of the Raman CO2 densimeter", details new developments in the use of the Raman spectroscopy to characterize the density of CO2. In this chapter we describe briefly the Raman effect of CO2 and the density dependence of the Fermi diad using different Raman instruments, laser sources and gratings to understand the differences in the published data. Chapter IV "Serpentinization reaction rates measured in olivine micro-batch reactors" describes new insights into the serpentinization process by using olivine micro-reactors. The micro-reactor technique is a new experimental development that allows researchers to monitor the fluid chemistry as well as the mineral composition changes inside synthetic fluid inclusion. / Ph. D.

Travel times from a refraction and wide-angle reflection seismic survey across the Coast Plutonic Complex and Stikine terrane of British Columbia were inverted to derive two dimensional P and S-wave seismic velocity models of the crust and uppermost mantle. A felsic upper crust and a felsic to intermediate middle crust are observed in both the batholith complex and the accreted Stikine island arc terrane. The P and S wave models demonstrate a high-velocity (P 7.0 km/s, S 3.8 km/s) layer in the lower crust beneath the youngest (late Cretaceous to Eocene) portion of the continental arc complex. In contrast, the lower crust under the Stikine terrane has lower velocities consistent with amphibolite or other hydrated mafic rocks. The Moho is at ~35 km depth under the Stikine terrane, deepens to ~38 km beneath the youngest portion of the arc, then shallows towards the coast. The high velocity zone under the younger portion of the Coast Plutonic Complex has a 1.81 Vp/Vs ratio and is interpreted to have a bulk composition of mafic garnet granulite. This garnet granulite and large volumes of granodiorite-dominated melt were created by arc dehydration melting of amphibolite (or hydrated gabbro) in the pre-existing lower crust Reverse time migration method was applied to image aftershocks recorded by a dense array deployed after the 2011 Virginia earthquake. Events as tiny as magnitude -2 were successfully imaged as point sources. The propagation of energy release as a function of time and space was observed for events larger than magnitude 2.5. Spatial resolution of the images was ~200 m, which synthetic data tests show was primarily limited by the temporal sampling rate. Improved temporal and spatial sampling could produce images with sharper resolution. / Ph. D.

Pour la première fois, une étude par spectroscopie infrarouge à transformée de Fourrier et par microsonde ionique des minéraux majeurs de la croûte inférieure et des péridotites mantelliques a été entreprise afin de mieux caractériser les mécanismes d’incorporation et les teneurs en eau de ces minéraux nominalement anhydres, et de déterminer leurs compostions isotopiques en H, O, et Li pour retracer les échanges latéraux et horizontaux de l’eau dans la lithosphère continentale profonde. Les résultats montrent que: (1) Les minéraux nominalement anhydres, comme les pyroxènes et plagioclase, dans les granulites de la croûte inférieure contiennent de l’eau en trace essentiellement sous forme hydroxyles et accessoirement sous forme moléculaire, avec des concentrations (exprimées en poids H2O) allant de 200 à 2330 ppm pour les clinopyroxènes, de 60 à 1875 ppm pour les orthopyroxènes, de 65 à 900 ppm pour les plagioclases. Les teneurs calculées pour chaque roche totale d’après sa composition minéralogique et la teneur en eau des minéraux varient de 155 à 1100 ppm. (2) Les teneurs en H2O des minéraux majeurs et en roche totale de la croûte continentale inférieure sont manifestement plus élevées que celles du manteau lithosphérique sous-jacent, suggérant des variations verticales de la quantité d’H2O dans la lithosphère continentale profonde. Un tel contraste peut affecter de façon notable le comportement rhéologique de la lithosphère continentale. (3) Les rapports isotopiques de l’oxygène des pyroxènes étudiés, et probablement les roches totales, exprimés en [delta]18OSMOW , vont de ~ 4,5 à 12,5‰. Ceci indique la contribution de matériaux recyclés de la croûte continentale durant la pétrogenèse des échantillons ayant un TM18O élevé. (4) Les minéraux de la granulites sont caractérisés par des valeurs de élevées TMD, avec des valeurs de -80~-10‰ exprimées en [delta]DSMOW; les minéraux sont le plus souvent en équilibre les uns avec les autres lorsque l’on considère leurs compositions isotopiques moyennes. (5) Les compositions isotopiques du Lithium mesurée dans les minéraux de nos échantillons de granulites, exprimées en [delta]7Li par rapport à Lsvec, varient de -13 à +4.7 ‰. Ces valeurs sont donc pour la plus part inférieures à celles mesurées sur les MORB (2 – 6‰). La dispersion des valeurs reflètent l’hétérogénéité de la source des granulites, et les valeurs bassent resultent probablement de la perte par diffusion de Li pendant la mise en place des liquides silicatées provenant du manteau dans la croûte inférieure. (6) La grande hétérogénéité des teneurs en eau et en Lithium, et des compositions isotopiques de H-O-Li indique l’absence de circulation de fluide pervasive au travers de la croûte inférieure, qui aurait pour effet de supprimer les hétérogénéités à petite échelle et de les diminuer fortement à grande échelle / For the first time, systematic investigations of water content and H-O-Li isotopic compositions of minerals in lower crustal granulites, as well as water content of minerals in mantle peridotites, from eastern China have been carried out by Fourier transform infrared spectrometer and ion microprobe. The results show that: (1) Nominally anhydrous minerals, such as pyroxenes and plagioclase, in the lower crust generally contain trace amounts of structural water, with their content (H2O by wt.) varying from 200 to 2330 ppm for clinopyroxene, 60 to 1875 ppm for orthopyroxene, 65 to 900 ppm for plagioclase and 155 to 1100 ppm for the estimated bulk compositions. (2) Water contents of minerals in lower crustal granulites from eastern China, and their bulk values, are significantly higher than those in the underlying upper mantle, implying vertical heterogeneities of water distribution in the deep continental lithosphere; the contrast in water content even affect the rheological strength of the lithosphere. (3) The O-isotopic compositions of pyroxenes in the lower crustal granulites from eastern China are highly variable between different localities (~ 4.5 to 12.5‰, expressed in [delta]18OSMOW values), indicating variable influences from recycled crustal materials on their protoliths. (4) The H-isotopic compositions of granulite minerals from eastern China, are mostly in the range of -80 to -10‰ expressed in [delta]DSMOW values, and these minerals are usually in equilibrium with their [delta]D values. The relatively high [delta]D of granulite minerals may be related with degassing loss of H during the genesis of granulites. (5) The Li-isotopic compositions of granulite minerals from eastern China are usually in the range of -13 to 4.7‰, mostly lower than those of MORB (2-6‰). They reflect the source heterogeneity and are probably results of high-T Li diffusion during the intrusion of their original melts into the preexisting lower crust. (6) The large dispersion of Li and water contents and of H-O-Li isotopic results indicate the absence of any pervasive fluids in the lower crust

Thesis (DSc)--Stellenbosch University, 2012 / ENGLISH ABSTRACT: This study is an investigation of the anatectic history of high-grade paragneisses from the Ancient Gneiss Complex (AGC) in Swaziland. The work involved an integrated field, metamorphic, geochemical, geochronological and structural study of metasedimentary granulites from three separate, but spatially related areas of outcrop in south-central Swaziland, which were subjected to multiple high-grade partial melting events throughout the Meso- to Neoarchaean. The project has aimed to constrain the age(s) and conditions of metamorphism, so as to contribute to the understanding of geodynamic processes in the Barberton and AGC granite-greenstone terranes, as well as to investigate certain physical and chemical aspects of anatexis in the migmatites. The metamorphic record retained in these rocks, constrained by phase equilibria modelling as well as zircon and monazite SHRIMP and LA-ICP-MS geochronology, informs on the state of the mid- to lower-crust of the southeastern Kaapvaal Craton during key events associated with early lithosphere assembly and crustal differentiation. It also suggests that the region is comprised of more than one high-grade terrane. Two of the areas investigated experienced high-temperature metamorphism at ca. 3.23-3.21 Ga, in addition to a major 830-875º C, 6.5-7.6 kbar anatectic event at ca. 3.11-3.07 Ga. Intermediate and younger high-temperature events are recorded at ca. 3.18 Ga, ca. 3.16 Ga and 2.99 Ga. The timing of these metamorphic events coincided with the amalgamation of the eastern domain of the proto-Craton via subduction and accretion of micro-continental fragments at ca. 3.23 Ga, including the Barberton Greenstone Belt (BGB) and AGC terranes, as well as discrete episodes of crustal differentiation and potassic granitic magmatism between ca. 3.23 and 3.10 Ga. The third area investigated holds no record of Mesoarchaean metamorphism, but instead experienced a 830- 855 ºC, 4.4-6.4 kbar partial melting episode at ca. 2.73 Ga. This broadly coincided with the formation of a large continental flood basalt province, the ca. 2.71 Ga Ventersdorp LIP, and widespread intracratonic granitic magmatism on the Craton towards the end of the Neoarchaean. An explanation for the contrast in metamorphic record in the two terranes may be that the 2.71 Ga granulites represent a much younger sedimentary succession, and that granulites from the older terrane were left too restitic, after substantial partial melting during the Mesoarchaean, to record subsequent high-grade events. Finally, this study documents the details of S-type granitic magma production and extraction from a typical metapelitic source. Using the 2.73 Ga granulites from the AGC as a natural field laboratory, a case is made for the selective entrainment of peritectic garnet to the magma as a mechanism for generating relatively mafic, peraluminous S-type granite compositions. The work demonstrates the evolution of entrained peritectic garnet in such magmas, and is in strong support of a ‘peritectic phase entrainment’ process by which relatively mafic granite magmas are produced from melts which, in theory, should be highly leucocratic. / AFRIKAANSE OPSOMMING: Hierdie studie ondersoek die anatektiese geskiedenis van hoëgraadse metasedimentêre gneise uit die Ancient Gneiss Complex (AGC) in Swaziland. Die werk behels 'n geïntegreerde veld, metamorfiese, geochemiese, geochronologiese en strukturele studie van metasedimentêre granuliete van drie afsonderlike, maar ruimtelik verwante gebiede in suid-sentraal Swaziland, wat aan verskeie hoëgraadse anatektiese gebeure onderworpe was gedurende die Meso-tot Neoargeïese tydsperiode. Die studie is daarop gemik om die ouderdomme en die kondisies van metamorfose vas te stel, om sodoende by te dra tot die begrip van die geodinamiese prosesse in die Barberton en AGC granietgroensteen terrein, asook om sekere fisiese en chemiese aspekte van die anatektiese proses te ondersoek. Die metamorfe rekord, bepaal deur mineraal ewewigsmodellering sowel as sirkoon en monasiet SHRIMP en LA-ICP-MS geochronologie, belig die toestand van die middel-tot laer-kors van die suidoostelike Kaapvaal Kraton tydens vroeë litosfeer samesmelting en differensiasie. Dit stel ook voor dat die streek uit meer as een hoëgraadse terrein bestaan. Twee van die gebiede het hoë-temperatuur metamorfose by 3.23-3.21 Ga ervaar, asook 'n hoof 830-875 ° C, 6.5-7.6 kbar anatektiese gebeurtenis by 3.11-3.07 Ga. Intermediêre en jonger hoë-temperatuur gebeure was ook by 3.18 Ga, 3.16 Ga en 2.99 Ga geregistreer. Die metamorfose van die gebied stem ooreen met die samesmelting van die oos Kaapvaal Kraton domein deur subduksie en aanwas van mikro-kontinente by 3.23 Ga, insluitend die Barberton en AGC terreine, asook diskrete episodes van kors differensiasie en kalium-ryke graniet magmatisme tussen 3.23 en 3.10 Ga. Die derde gebied hou geen rekord van Mesoargeïkum metamorfose nie. In plaas daarvan het dit 'n 830-855 ° C, 4.4-6.4 kbar anatektiese episode by 2.73 Ga ervaar, wat ooreenstem met die vorming van 'n groot kontinentale vloedbasalt provinsie, die 2.71 Ga Ventersdorp Supergroep, en wydverspreide intrakratoniese graniet magmatisme teen die einde van die Neoargeïkum. 'n Moontlike verduideliking vir die kontras in metamorfe rekord in die twee terreine mag wees dat die 2.71 Ga granuliete 'n jonger sedimentêre afsetting verteenwoordig, en dat granuliete van die ouer terrein te restieties gelaat was na aansienlike anateksis in die Mesoargeïkum, om daaropvolgende hoëgraadse gebeure te registreer. Ten slotte, hierdie studie dokumenteer die besonderhede van S-tipe graniet magma produksie en ontginning van 'n tipiese metasedimentêre bron. Die 2.73 Ga granuliete word gebruik as 'n natuurlike veld laboratorium om die selektiewe optel-en-meevoering van peritektiese granaat tot die magma te ondersoek. Die werk toon die evolusie van peritektiese granate in sulke magmas aan, en ondersteun lewering van relatiewe mafiese graniet magmas deur 'n ‘peritektiese fase optel-en-meevoerings’ proses.

The Saxonian Granulite Massif in the Saxothuringian Domain of the Bohemian Massif, is represented by a single granulite body consisting of felsic and mafic granulites formed during Variscan tectono-metamorphic event. The granulites with peak metamorphic P-T conditions of ~2.3 GPa and 970-1060 řC (Fuhrman and Lindsley, 1988; Rötzler and Romer, 2001) were exhumed and emplaced into the palaeozic sedimentary cover sequence, which resulted into contact metamorphism affecting these metasedimentary rocks and development of a contact metamorphic aureole. In the map view, the granulite body has elongated shape with the long axis oriented in NE- SW direction and it is surrounded by the so called schist mantle reflecting the extent of the contact metamorphic aureole. Within two kilometers distance away from the contact with granulite body, the metamorphic grade in metasediments decreases from cordierite gneiss, andalusite bearing micaschist to phyllite. Detailed field structural analysis in the studied area revealed a deformation record associated with four main deformation phases. In granulites the oldest deformation fabric contains kyanite and sillimanite. This fabric is locally overprinted by the subhorizontal green schist facies fabric, mainly along the margins of the granulite body. In metasediments, the...