Дисертації з теми "U-Pb monazite geochronology"
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Laurent, Antonin. "Etude pétrologique et chronométrique (U-Th-Pb) de la monazite et du zircon dans les granulites de ultra-haute température du Rogaland, Norvège." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30290/document.
Повний текст джерелаUnderstanding mountain building processes requires a better integration of petrological and peochronological data in order to link pressure-temperature paths to absolute ages. This work focuses on the behaviour of monazite and zircon, which are used as geochronometers, in ultra-high temperature granulites of Rogaland (South Norway). We show that linking in-situ U-Th-Pb dating of monazite with its major- and trace-element composition lead to the recognition of two ultra-high temperature (UHT) metamorphic events in Rogaland at c.1030-1005 Ma and c. 940-930 Ma. Indeed, the examination of monazite-xenotime-huttonite phase relationships suggests that monazite may record crystallization age at or near ultra-high temperature. Besides, the chemical and U-Th-Pb-O isotopic characterization of zircon neo-crystallization or overgrowths indicates that the Rogaland crust remains molten (> 800 °C at 0.7-0.4 GPa) at least during 60 My between the two identified UHT excursions. This manuscript also highlights the various factors responsible for U-Th-Pb (partial) resetting in the course of granulite facies metamorphism. Zircon behaviour is mostly controlled its level of amorphization, enhancing Pb loss during annealing, whereas monazite resetting is dominated by dissolution-precipitation processes in the presence of a melt or fluid phase. More specifically, we point out that monazite may be used to monitor the redox conditions of its crystallizing medium since monazite may incorporate the redox-sensitive element S in its lattice as sulphate. Finally, we demonstrate a spatial and temporal correlation between magmatism and UHT metamorphism in Rogaland. The timescale, P-T path and tectono-magmatic history however cannot be explained by currently accepted models for UHT. We suggest that physical and thermal specificities of Proterozoic mantle may explain the observed ultra-hot orogen style and the occurrence of gravity driven processes during orogeny
Fielding, Imogen Olivia Heather. "In Situ U–Pb Geochronology of Hydrothermal Xenotime and Monazite to Date Gold Mineralization in the Northern Capricorn Orogen, Western Australia." Thesis, Curtin University, 2018. http://hdl.handle.net/20.500.11937/75055.
Повний текст джерелаJones, Carson L. "U-Pb geochronology of monazite and zircon in Precambrian metamorphic rocks from the Ruby Range, SW Montana deciphering geological events that shaped the NW Wyoming province /." [Kent, Ohio] : Kent State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=kent1214308001.
Повний текст джерелаTitle from PDF t.p. (viewed Oct. 5, 2009). Advisor: Peter Dahl. Keywords: Geochronology; Radiometric Dating; Plate Tectonics. Includes bibliographical references (p. 106-109).
Ghosh, Amiya Kumar. "Reconnaissance U-Pb geochronology of Precambrian crystalline rocks from the northern Black Hills, South Dakota: Implications for regional thermotectonic history." [Kent, Ohio] : Kent State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=kent1240007954.
Повний текст джерелаTitle from PDF t.p. (viewed Feb. 12, 2010). Advisor: Peter Dahl. Keywords: Black Hills; Crook Mountain granite; Homestake gold mine; gold mineralization; magmatism; metamorphism; metapelite; g monazite; zircon; titanite; geochronology; thermotectonism Includes bibliographical references (p. 97-106).
Caquineau, Tom. "Etude géochronologique U-Pb et isotopique Lu-Hf sur zircon du groupe de Turee Creek : implications sur l’événement de grande oxygénation et les glaciations paléoprotérozoïques." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC236/document.
Повний текст джерелаThe Archean – Proterozoic transition at 2.45 Ga is marked by major environmental changes in Earth’s history (atmosphere oxygenation and global glaciations). The origin and the relationships between these events are debated. Sedimentary sequences that record these events have been widely studied in North America (Huronian sequence) and South Africa (Transvaal). An analog sequence in the Pilbara craton in Western Australia (Turee Creek Group, TCG) contains 3 glacial horizons. 3 continental drill cores (Turee Creek Drilling Project, TCDP) were performed in order to investigate the sequence. U-Pb geochronology of monazite and zircon from drill core and surface samples allows to date the first paleoproterozoic glaciation at 2.45 Ga and a second glacial event at ~2.34 Ga. Re-Os analyses of pyrites from the second diamictite yielded an isochron at 2.31 Ga. These results enable to propose a correlation scenario of the paleoproterozoic glacial events recorded on different continents. A ‘Snowball Earth’ would have occured at 2.45 Ga at least on 5 cratons. A second glaciation could have occured at ~2.31 Ga on 4 cratons. Detrital zircons age spectrum highlights age peaks at 2.45, 2.54, 2.68, 2.82, 2.95 and 3.2 Ga. A crystal of Hadean zircon was discovered and indicate the existence of a probable differentiated crust within the Pilbara craton at 4.0 Ga. 70% of the analyzed zircons have juvenile Hf isotope composition, suggesting that the TCG incorporated volcanic material from continental large igneous provinces through the erosion of the underlying Hamersley and Fortescue groups
Séjourné, Brianna L. "Behaviour of Accessory Monazite and Age Significance During Metamorphism and Partial Melting During Grenville Orogeny: An Example from Otter Lake Area, Central Metasedimentary Belt, QC." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31574.
Повний текст джерелаKuiper, Yvette Dominique. "Isotopic constraints on timing of deformation and metamorphism in the Thor–Odin dome, Monashee Complex, southeastern British Columbia." Thesis, Department of Geology, University of New Brunswick, 2003. http://hdl.handle.net/1882/46.
Повний текст джерелаMonazite crystals in pelitic schist, quartzite and orthogneiss, which have U–Pb ages younger than 40Ar/39Ar hornblende ages in amphibolite in northwest Thor–Odin, may have grown during tension in the presence of fluids. Titanite, xenotime and zircon dates may be interpreted in the same way. Thus, the U–Pb dates that were previously interpreted as representing peak of metamorphism and the hornblende 40Ar/39Ar dates that were previously interpreted as representing cooling ages, may be interpreted as reflecting meteoric fluid penetration of the crust during regional extension. This implies that the age of the thermal peak of metamorphism is older than ~75–70 Ma. Migmatisation in a basement orthogneiss in Thor–Odin occurred at ~1.8 Ga. Dissolution rims are preserved in zircon between ~1.8 Ga domains and 52 Ma overgrowths. Because growth of new zircon (and possibly other U–Pb accessory phases) did not take place, any geological event that occurred during the ~1.8 Ga to 52 Ma time interval is not recorded. Cordilleran deformation and metamorphism may have taken place within that time interval, e.g. in the Middle Jurassic and/or mid- to Late Cretaceous, the time of Cordilleran deformation and metamorphism in the rocks overlying the Monashee Complex.
The Joss Mountain orthogneiss, west of the Monashee Complex in the Selkirk Allochthon, is dated at 362 +/– 13 Ma. F3 folding in pelitic schist at Joss Mountain is constrained between ~73 and ~70 Ma. Existing structural, metamorphic and geochronological data in, and close to, the Shuswap Metamorphic Complex in the southern Canadian Cordillera are shown to be consistent with a channel flow model.
Weller, Owen M. "An integrated metamorphic and geochronological study of the south-eastern Tibetan plateau." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:f4104b43-389a-4d54-bd7b-ba3fc0e8ab95.
Повний текст джерелаSeydoux-Guillaume, Anne-Magali. "LES EFFETS DE L'IRRADIATION DANS LES MINERAUX ET LEURS CONSEQUENCES EN GEOCHRONOLOGIE." Habilitation à diriger des recherches, Université Paul Sabatier - Toulouse III, 2011. http://tel.archives-ouvertes.fr/tel-00606544.
Повний текст джерелаGoncalves, Philippe. "PÉTROLOGIE ET GÉOCHRONOLOGIE DES GRANULITES DE ULTRA-HAUTES TEMPÉRATURES DE L'UNITÉ BASIQUE D'ANDRIAMENA (CENTRE-NORD MADAGASCAR). Apport de la géochronologie in-situ U-Th-Pb à l'interprétation des trajets P-T." Phd thesis, Clermont-Ferrand 2, 2002. http://www.theses.fr/2002CLF21375.
Повний текст джерелаFields, C. E. "Liebig-aged (c. 1640 Ma) magmatism and metamorphism in c. 1760 Ma crust in the Warumpi and southern Aileron Province, central Australia: a case for revising the tectonic framework of Proterozoic Australia." Thesis, 2012. http://hdl.handle.net/2440/92217.
Повний текст джерелаThe southern margin of the North Australian Craton (NAC) has been suggested to represent a long-lived (c. 1860 to 1600 Ma) active margin that preserves a cryptic record of the growth and assembly of the Australian continent. The Warumpi Province is juxtaposed against the southern Aileron Province, and has been interpreted as exotic to the NAC, though the timing of collision between the Warumpi Province and the southern Aileron Province is contentious. U-Pb zircon and monazite LA-ICP-MS geochronology from granulite facies metapelites and granitic gneisses along the southern margin of the Aileron Province and northern margin of the Warumpi Province, has shown it is characterised by c. 1780-1740 Ma magmatic rocks and c. 1640-1615 Ma magmatic and metamorphic rocks. The evidence for these events is preserved in kilometre-scale migmatitic boudins and low-strain zones enveloped by pervasive E-W trending higher strain belts. The overprinting high strain fabrics are Grenvillian age and constrained to c. 1175-1070 Ma. Phase equilibria modelling on a garnet-sillimanite-cordierite metapelite dated at c.1616 Ma, from a low-strain domain within the southern Aileron Province, indicates that peak metamorphic conditions were ~7-8 kbar and between 740-900 °C, and were associated with a down-pressure or decompressional P-T history. A metamorphic monazite age of c.1620 Ma was also preserved in a granitic gneiss located in an older, low-strain domain. The presence of the c. 1760 Ma and c. 1640 Ma timelines in both the Warumpi and Aileron Provinces calls into question the proposed exotic nature of the Warumpi Province. A speculative interpretation is that the Liebig-aged metamorphism and magmatism, seemingly associated with relatively shallow orientated, low strain fabrics, represents a period of extension rather than collision.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 2012
Lawson-Wyatt, M. A. "Regional Inkamulla-aged (ca. 1740–1755 Ma) tectonism along strike of the Mt Hay-Redbank Hill region, southern Aileron Province, central Australia." Thesis, 2012. http://hdl.handle.net/2440/92908.
Повний текст джерелаLA-ICP-MS U-Pb monazite and zircon geochronology from granulite facies metapelites and granites indicate Inkamulla-aged metamorphism has occurred in the southern Aileron province, immediately east of the Mt Hay and Mt Chapple massifs. Gneissic metasediments and a granitic gneiss from an EW-striking structural belt in the southern Aileron Province yield ages reflective of the Inkamulla Igneous Event (1754-1741 Ma) and the Chewings Event (1593-1545 Ma), along with magmatic ages of 1627 and 1641 Ma. The Chewings age is interpreted to represent structural reworking associated with discrete shear zones along the northern margin of the EW belt. Magmatic ages of ca. 1640 Ma typically associated with Warumpi Province magmatism and deformation are found within the study area, which weakens the argument that the Warumpi terrane is exotic from the Aileron Province. The metamorphic conditions of 780-920°C and 5-10 kbars indicate an elevated geothermal gradient.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 2012
Morphett, W. J. "Geochronological and structural insights into the evolution of the Lower Burra and Callana Groups near Arkaroola: structural mapping and U-Pb metamorphic monazite dating." Thesis, 2013. http://hdl.handle.net/2440/106291.
Повний текст джерелаThe lowermost sediments of the Adelaide Supergroup near Arkaroola display pronounced structural complexity and anomalously high metamorphic grade. The timing of the structures, fabrics and metamorphism in the region remain unconstrained, although all are currently interpreted to have occurred during the Delamerian Orogeny. Monazite U/Pb geochronology provides a useful technique for dating amphibolites facies rocks and, combined with map scale and micro structural observations, suggests the peak metamorphism and at least one deformation event occurred significantly earlier than the Delamerian Orogeny. Monazite derived 206Pb/238U age estimates place the timing of peak metamorphism at 705.2±7.4 Ma with observations from thin section revealing a bedding parallel fabric pre-dating peak metamorphism. U/Pb analysis also reveals a second monazite growth event at 644.2±8 Ma the cause of which is hypothesised to be fluid related. Regional folding and axial planar fabric generation post-dates this metamorphism and can be seen to overprint the earlier fabric and wrap the cordierite porphyroblasts. This final deformation event remains largely unconstrained as in situ dating of monazite was not possible in this study. The inferred parasitic relationship between the folds within the studied region and the Arkaroola Syncline which folds the youngest sediments in the Adelaidian Sequence allows for the deposition to be constrained subsequent to the conclusion of the Adelaide Rift Complex.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2013
Kimpton, B. J. "The geological relationship between Kanmantoo Cu-Au deposit mineralisation, hydrothermal metasomatism and igneous intrusives." Thesis, 2018. http://hdl.handle.net/2440/130628.
Повний текст джерелаThe Kanmantoo Cu-Au deposit has been in episodic operation since 1846, one decade after the capital city of Adelaide was established some 40 kilometres to the NW. Regionally and within the host stratigraphy there exists archetypal evidence of the Cambrian Delamerian Orogeny through a complex structural, metamorphic and intrusive history. Consequently, numerous theories exist within the literature regarding a syngenetic or epigenetic style of mineralisation and the debated contribution, if any, of magmatic hydrothermal fluids. This study has documented numerous felsic intrusive vein sets within the Kanmantoo Cu-Au deposit which have been utilised to constrain the role of igneous activity on mineralisation within a wider Delamerian context. Monazite U–Pb ages of felsic veins show that intrusion first occurred at syn-peak metamorphic, syn-orogenic conditions (495.11 ± 2.79 Ma), continuing periodically until post-peak metamorphic, extensional conditions (483.43 ± 2.52 Ma). Intrusions are coeval with mineralisation and are temporally and geochemically analogous to magmatic activity in the adjacent Monarto and Murray Bridge provinces. Analysis of trace elements in monazites identifies the Kanmantoo Cu-Au deposit as a syn- to post-peak metamorphic hydrothermal anomaly which, combined with the presence of felsic veins, indicates that mineralisation resulted partly from fluids generated by a pluton at depth. These findings broadly confirm the prospectivity of Delamerian-affected terranes throughout large parts of South Eastern Australia where pervasive intrusive geology exists.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2018
Greenslade, M. M. "Ultrahigh temperature metamorphism: testing models for collision vs extension." Thesis, 2015. http://hdl.handle.net/2440/118029.
Повний текст джерелаThe Warumpi Province has been interpreted to be exotic and accreted to the Northern Australian Craton (NAC) during the Liebig Orogeny at c.1640Ma. However, phase equilibria modelling of melt-deficient, Mg-Al rich granulite facies rocks at Hill 830, in the Mount Liebig area show contradictory evidence of a decompressional pressure-temperature path and a high metamorphic gradient of 90°Ckbar. This interpretation in conjunction with abundant c.1780- 1740Ma and c.1640Ma magmatism in the southern Aileron and Warumpi Provinces, indicate that the tectonic regime at c.1640Ma may instead be a south-migrating, extensional scenario, compared to the previously accepted collisonal regime; speculating that the Warumpi Province is not ‘exotic’ to the NAC.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2015