High-Temperature Metamorphism and the Role of Magmatic Heat Sources at the Rogaland Anorthosite Complex in Southwestern Norway

Westphal, M.

doi:10.1093/petrology/44.6.1145

Cited by 78 publications

(49 citation statements)

References 46 publications

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“…The alumina content of orthopyroxene commonly displays a continuous range from 2 to 8 wt.% Al 2 O 3 , supporting continuous polybaric crystallization during diapiric rise of the anorthositic mush (Charlier et al, 2010a). Final pressures of emplacement estimated from mineral assemblages in the contact metamorphic aureoles range from 3 to 6 kbar (Berg, 1977;Jansen et al, 1985;Westphal et al, 2003).…”

Section: Crystallization Conditions Of Anorthositesmentioning

confidence: 87%

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Fe–Ti–V–P ore deposits associated with Proterozoic massif-type anorthosites and related rocks

Charlier

Namur

Bolle

et al. 2015

Earth-Science Reviews

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a b s t r a c t a r t i c l e i n f oMagmatic rocks containing economic concentrations of iron, titanium, vanadium and phosphorous are commonly associated with massif-type anorthosites and related rocks. This rock association is part of the anorthositemangerite-charnockite-(rapakivi-)granite suites that are restricted to the Proterozoic. Understanding the geochemistry and emplacement mechanisms of ilmenite, magnetite and apatite ore deposits is crucial for exploration, efficient mining operations and ore processing. This review discusses the controlling factors on the grade of an ore, its mineralogy, and its major and trace element distribution. We present petrogenetic models of currently mined deposits (Lac Tio, Tellnes, Damiao) and discuss the characteristics of minor ore bodies from anorthosite provinces worldwide (Grenville, North China Craton, East European Craton, Rogaland, Laramie). Models of formation of anorthosite and related rocks are presented, as well as the nature of the possible parental magmas of the suite. A mineralogical classification of Fe-Ti ores is proposed: (1) Gabbro-noritic ilmenite ore ± apatite ± magnetite; (2) Ti-magnetite-dominated ore; (3) Nelsonite (Fe-Ti oxides + apatite); and (4) Rutile-ilmenite ore. The stability of ilmenite and magnetite is then critically reviewed and the influence of various factors, particularly oxygen fugacity and crystallization pressure, is examined. We discuss liquidus compositions of Fe-Ti oxides and the behavior of important trace elements such as Cr and V, both of which are sensitive to fO 2 variations. Postcumulus evolution of both oxides can occur due to re-equilibration with trapped liquid, re-equilibration with ferromagnesian silicates, exsolution, oxidation, reaction between ilmenite and magnetite, and metamorphic overprinting. These various processes are described and their effects on the oxide geochemistry are emphasized. Several potential ore-forming processes have been invoked and can explain the formation of huge concentration of ilmenite, ±magnetite, ±apatite. Fractional crystallization can be combined with crystal sorting and plagioclase buoyancy to produce relative enrichment of dense ore minerals. Silicate liquid immiscibility can segregate conjugate Si-rich and Fe-rich melts, the latter being enriched in Fe-Ti-P. Magma mixing can produce hybrid magmas located in a single-phase field of the phase diagram and precipitate a pure ilmenite cumulate. Alternative processes are also described, such as ejection of Fe-Ti-enriched residual melts by filter-pressing and compaction, solidstate remobilization of ilmenite in veins, and hydrothermal transport of Fe and Ti from the host anorthosite followed by concentration in veins and lenticular ore bodies. The magnetic properties of Fe-Ti ore deposits present contrasting signatures, depending on whether the natural remanent magnetization is dominated by hemo-ilmenite or multi-domain magnetite. Micro-and macro-scale deformation features of ore rocks are intimately correlated with magma emplacement, and...

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Section: Crystallization Conditions Of Anorthositesmentioning

confidence: 87%

“…Anorthosite complexes are emplaced into high-grade metamorphic rocks and are surrounded by an aureole of contact metamorphism (Berg, 1977) up to 20 km thick (Westphal et al, 2003;Drüppel et al, 2013). Granulite-facies assemblages with orthopyroxene, pigeonite or osumilite are common (Möller et al, 2003).…”

Section: Crystallization Conditions Of Anorthositesmentioning

confidence: 99%

Fe–Ti–V–P ore deposits associated with Proterozoic massif-type anorthosites and related rocks

Charlier

Namur

Bolle

et al. 2015

Earth-Science Reviews

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“…One of the most significant advances to occur in recent years has been the developmentdalready with numerous iterationsdof a thermodynamic mixing ('aex') model for sapphirine that incorporates ferric iron (Taylor-Jones and Wheller and Powell, 2014). It has been recognised for many years that natural sapphirine commonly contains appreciable ferric iron (e.g.…”

Section: Thermodynamic Model For Ferric Sapphirinementioning

confidence: 99%

“…Hensen, 1986;Hensen and Harley, 1990;Harley, 2004;Harley, 2008). Expansion of the FMAS (Hensen, 1971(Hensen, , 1987, FMASH (Bertrand et al, 1991) and KFMASH (Audibert et al, 1995;Carrington and Harley, 1995a,b;Kelsey et al, 2004Kelsey et al, , 2005 chemical systems historically used to interrogate the metamorphic evolution of UHT granulites to include Fe 3þ (as 'O' or Fe 2 O 3 ) and Ti (as TiO 2 ) allows for Fe-Ti oxides magnetite, ilmenite-haematite and rutile to be included as an integral part of the phase assemblage analysis (Hensen, 1986;Sandiford et al, 1987;Powell and Sandiford, 1988;Taylor-Jones and Powell, 2010;Korhonen et al, 2012b;Wheller and Powell, 2014), as well as the incorporation of Fe 3þ and Ti into the aex models of major silicate phases (White et al, 2000;White et al, 2007;White et al, 2014a).…”

Section: Thermodynamic Model For Ferric Sapphirinementioning

confidence: 99%

“…Sandiford et al, 1987;Harley and Fitzsimons, 1991;Gnos and Kurz, 1994), including adjacent to anorthositic/mafic intrusions (e.g. Berg and Wheeler, 1976;Berg, 1977;Caporuscio and Morse, 1978;Kars et al, 1980;Arima and Gower, 1991;Dasgupta et al, 1997;Westphal et al, 2003;Peng et al, 2010;Kooijman et al, 2011;Guo et al, 2012;Mitchell et al, 2014), as well as on a regional scale (e.g. Ellis et al, 1980;Grew, 1980;Sheraton et al, 1980;Grew, 1982b;Lal et al, 1987;Dasgupta et al, 1994;Brown and Raith, 1996;Ouzegane and Boumaza, 1996;Sengupta et al, 1999;Hollis and Harley, 2002;Sarkar et al, 2003a;Schmitz and Bowring, 2003;Bose and Das, 2007;Braun et al, 2007;Harley and Kelly, 2007a;Brandt et al, 2011;Das et al, 2011;Smithies et al, 2011;Adjerid et al, 2013;Korhonen et al, 2013a;Collins et al, 2014;Walsh et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

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On ultrahigh temperature crustal metamorphism: Phase equilibria, trace element thermometry, bulk composition, heat sources, timescales and tectonic settings

Kelsey

Hand

2015

Geoscience Frontiers

349

285

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a b s t r a c tUltrahigh temperature (UHT) metamorphism is the most thermally extreme form of regional crustal metamorphism, with temperatures exceeding 900 C. UHT crustal metamorphism is recognised in more than 50 localities globally in the metamorphic rock record and is accepted as 'normal' in the spectrum of regional crustal processes. UHT metamorphism is typically identified on the basis of diagnostic mineral assemblages such as sapphirine þ quartz, orthopyroxene þ sillimanite AE quartz and osumilite in MgeAlrich rock compositions, now usually coupled with pseudosection-based thermobarometry using internally-consistent thermodynamic data sets and/or Al-in-Orthopyroxene and ternary feldspar thermobarometry. Significant progress in the understanding of regional UHT metamorphism in recent years includes: (1) development of a ferric iron activityecomposition thermodynamic model for sapphirine, allowing phase diagram calculations for oxidised rock compositions; (2) quantification of UHT conditions via trace element thermometry, with Zr-in-rutile more commonly recording higher temperatures than Ti-in-zircon. Rutile is likely to be stable at peak UHT conditions whereas zircon may only grow as UHT rocks are cooling. In addition, the extent to which Zr diffuses out of rutile is controlled by chemical communication with zircon; (3) more fully recognising and utilising temperature-dependent thermal properties of the crust, and the possible range of heat sources causing metamorphism in geodynamic modelling studies; (4) recognising that crust partially melted either in a previous event or earlier in a long-duration event has greater capacity than fertile, unmelted crust to achieve UHT conditions due to the heat energy consumed by partial melting reactions; (5) more strongly linking UePb geochronological data from zircon and monazite to PeT points or path segments through using Y þ REE partitioning between accessory and major phases, as well as phase diagrams incorporating Zr and REE; and (6) improved insight into the settings and factors responsible for UHT metamorphism via geodynamic forward models. These models suggest that regional UHT metamorphism is, principally, geodynamically related to subduction, coupled with elevated crustal radiogenic heat generation rates.Ó 2014, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

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Mullite-corundum-spinel-cordierite-plagioclase xenoliths in the Skaergaard Marginal Border Group: multi-stage interaction between metasediments and basaltic magma

Markl

2005

Contrib Mineral Petrol

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High-Temperature Metamorphism and the Role of Magmatic Heat Sources at the Rogaland Anorthosite Complex in Southwestern Norway

Cited by 78 publications

References 46 publications

Fe–Ti–V–P ore deposits associated with Proterozoic massif-type anorthosites and related rocks

Fe–Ti–V–P ore deposits associated with Proterozoic massif-type anorthosites and related rocks

On ultrahigh temperature crustal metamorphism: Phase equilibria, trace element thermometry, bulk composition, heat sources, timescales and tectonic settings

Mullite-corundum-spinel-cordierite-plagioclase xenoliths in the Skaergaard Marginal Border Group: multi-stage interaction between metasediments and basaltic magma

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