Petrology of nepheline syenite pegmatites in the Oslo Rift, Norway: Zr and Ti mineral assemblages in miaskitic and agpaitic pegmatites in the Larvik Plutonic Complex

Andersen, Tom; Erambert, Muriel; Larsen, Alf Olav; Selbekk, Rune S.

doi:10.2478/mipo-2013-0007

Cited by 23 publications

(13 citation statements)

References 18 publications

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“…Table 8) and, consequently, they plot below the line joining the other phases, suggesting cationic vacancies with respect to the formula normalized to eight Si. These low totals have already been observed by Andersen et al (2013). The compositional characteristics of these phases are best exemplified in the diagrams of Fig.…”

Section: F-disilicatessupporting

confidence: 54%

“…More generally, there is need of a more stringent chemical classification of these phases, in the absence (and usefulness) of crystallographic determinations made crystalby-crystal, composition-by-composition (e.g. Atencio et al, 1999;Christiansen et al, 2003a,b;Chakhmouradian et al, 2008;Andersen et al, 2013;Melluso et al, 2014b). (Fig.…”

Section: F-disilicatesmentioning

confidence: 99%

“…The F-disilicates of Itatiaia are commonly found in other syenites and peralkaline silicaundersaturated rocks worldwide (e.g. Platt, 1986, 1988;Moreau et al, 1996;Atencio et al, 1999;Carbonin et al, 2005;Ridolfi et al, 2006;Andersen et al, 2010Andersen et al, , 2013Lustrino et al, 2012;Melluso et al, 2012a;2014b;Rønsbo et al, 2014). They are the result of the concentration of the remaining fluorine (after fluorite crystallization and/ or fluorite resorption) and other elements in the interstitial liquids after the dominant crystallization of felsic phases, but the (apparently random) combination of different disilicates in a given rock, their widely changing Ca/Na, Mn/Fe, Ti/Zr and Zr/ Nb ratios, and the concentration of REE are still poorly understood from a thermodynamic point of view (Andersen et al, 2010).…”

Section: Significance Of Accessory Phases In Strongly Evolved Meltsmentioning

confidence: 99%

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TheREE-and HFSE-bearing phases in the Itatiaia alkaline complex (Brazil) and geochemical evolution of feldspar-rich felsic melts

et al. 2017

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The Late Cretaceous Itatiaia complex is made up of nepheline syenite grading to peralkaline varieties, quartz syenite and granite, emplaced in the metamorphic rocks of the Serra do Mar, SE Brazil. The nepheline syenites are characterized by assemblages with alkali feldspar, nepheline, Fe-Ti oxides, clinopyroxene, amphibole, apatite and titanite, while the peralkaline nepheline syenites have F-disilicates (rinkite, wöhlerite, hiortdahlite, låvenite), britholite and pyrophanite as the accessory phases. The silica-oversaturated rocks have alkali feldspar, plagioclase, quartz, amphibole, clinopyroxene and Fe-Ti oxides; the chevkinite-group minerals are the featured accessory phases and are found with allanite, fluorapatite, fluorite, zircon, thorite, yttrialite, zirconolite, pyrochlore and yttrocolumbite. The major- A nd trace-element composition of the Itatiaia rocks have variations linked to the amount of accessory phases, have smooth, enriched chondritenormalized rare-earth element (REE) distribution patterns in the least-evolved nepheline syenites and convex patterns in the most-evolved nepheline syenites. The REE distribution patterns of the quartz syenites and granites show a typical pattern caused by fractional crystallization of feldspar and amphibole, in an environment characterized by relatively high oxygen fugacity (>NiNiO buffer) and high concentrations of H2O and F, supporting the crystallization of hydrous phases, fluorite and F-disilicates. The removal of small amounts of titanite in the transition from the least-evolved to the most-evolved nepheline syenites stems from petrogenetic models involving REE, and is shown to be a common feature of the magmatic evolution of many other syenitic/trachytic/phonolitic complexes of the Serra do Mar and elsewhere

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Section: F-disilicatessupporting

confidence: 54%

Section: F-disilicatesmentioning

confidence: 99%

Section: Significance Of Accessory Phases In Strongly Evolved Meltsmentioning

confidence: 99%

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TheREE-and HFSE-bearing phases in the Itatiaia alkaline complex (Brazil) and geochemical evolution of feldspar-rich felsic melts

et al. 2017

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“…The results of WDS-EMP analyses on eudialytes have been processed in accordance with Johnsen and Grice [23] and Pfaff et al [52] along with common crystal-chemical principles, as applied by Andersen et al [53,54] Naming end-members is less important than understanding the crystal chemistry of the eudialyte-group minerals, however, an attempt was made to determine the dominant end-members in Norra Kärr eudialyte by following the hierarchical guidelines set up by Johnsen et al [19] as far as possible and by distinguishing end-members by the cation occupancy in the M(1), M (2), and M(3) sites. We have only included the major end-members in this study (Tables 2 and 3).…”

Section: Crystal Chemistry Of the Eudialyte-group Mineralsmentioning

confidence: 99%

Three Compositional Varieties of Rare-Earth Element Ore: Eudialyte-Group Minerals from the Norra Kärr Alkaline Complex, Southern Sweden

et al. 2013

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Agpaitic nepheline syenites at the Norra Kärr Alkaline Complex, southern Sweden, are rich in zirconium and rare-earth elements (REE), which are mainly accommodated in eudialyte-group minerals (EGM). Norra Kärr hosts three compositionally distinct groups of EGM, which are complex zirconosilicates. Analyses of EGM by electron beam energy-dispersive (SEM-EDS) and wavelength-dispersive (WDS-EMP) X-ray microanalysis are presented and compared, complemented by whole-rock analyses. The SEM-EDS and WDS-EMP methods produce comparable results for most elements. Considering that most SEM instruments have a user-friendly EDS system, it is a useful tool for reconnaissance work in research and especially in exploration-related studies. The EGM evolved markedly from an initial Fe-rich and REE-poor, but HREE-dominated variety, to an intermediate Fe-Mn and HREE-rich one, and to a final Mn-and LREE-rich variety, which occur in rocks classified as lakarpite and grennaite. Based on the Mn/(Fe+Mn) ratios of the EGM, this trend is interpreted as a result of magmatic evolution. The threefold diversity of EGM presented in this work is much broader than has previously been documented.

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“…5B). Wöhlerite may also be altered around the rim with the association of fluorite and hiortdahlite (Andersen et al, 2013).…”

Section: Pegmatite Mineral Assemblagesmentioning

confidence: 99%

Pegmatites of the Larvik Plutonic Complex, Oslo Rift, Norway: field relations and characterisation

Sunde¹,

Friis²,

Andersen³

2019

NJG

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The Larvik Plutonic Complex (LPC) contains pegmatites with a wide array of mineral assemblages and morphological features. The pegmatites have traditionally been described as nepheline syenite and syenite pegmatites which carry agpaitic or miaskitic mineral assemblages, respectively. However, several pegmatites fall outside this simple characterisation due to 'agpaitic-like' late magmatic mineral assemblages such as hiortdahlite and eudialyte group minerals. Morphological and mineralogical differences between pegmatites are not unique to, or related with, specific areas of the LPC. Compositional variation and deformation features of the host pluton are the main mechanisms for differing morphology and mineral assemblages between LPC pegmatites. Natrolite replacement of feldspathoid is the most common alteration feature in the nepheline syenite pegmatites. The extent of alteration is closely associated with crystallisation of saccharoidal albite and aegirine. Detailed description of a nepheline syenite pegmatite situated in the Sagåsen quarry provides new insights into the internal evolution and mineral distribution of a large representative pegmatite body. The most important mechanism driving hydrous alteration is the crystallisation of anhydrous primary minerals which leads to an immiscible hydrous fluid driving in situ alterations of primary mineral assemblages.

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Petrology of nepheline syenite pegmatites in the Oslo Rift, Norway: Zr and Ti mineral assemblages in miaskitic and agpaitic pegmatites in the Larvik Plutonic Complex

Cited by 23 publications

References 18 publications

TheREE-and HFSE-bearing phases in the Itatiaia alkaline complex (Brazil) and geochemical evolution of feldspar-rich felsic melts

TheREE-and HFSE-bearing phases in the Itatiaia alkaline complex (Brazil) and geochemical evolution of feldspar-rich felsic melts

Three Compositional Varieties of Rare-Earth Element Ore: Eudialyte-Group Minerals from the Norra Kärr Alkaline Complex, Southern Sweden

Pegmatites of the Larvik Plutonic Complex, Oslo Rift, Norway: field relations and characterisation

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