Trace element partitioning in plagioclase feldspar

Bédard, Jean H.

doi:10.1016/j.gca.2006.05.003

Cited by 201 publications

(110 citation statements)

References 120 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…These differences are also found in the bulk composition of the EGM-bearing nepheline microsyenite dyke (Table 1), which suggests that EGMs crystallized in an environment where Eu, Sr, and Ba were already depleted. This depletion could be assigned to previous extensive fractionation of plagioclase and/or alkali feldspar (e.g., Blundy & Wood 1991, Bédard 2006, Brotzu et al 2007, Henderson & Pierozynski 2012, Carvalho & Janasi 2012) from the parental melt, similar to the interpretation by Schilling et al (2011b) regarding the same features observed in the EGMs from Ilímaussaq and Mont Saint-Hilaire.…”

Section: Petrologic Implicationssupporting

confidence: 63%

Eudialyte-group minerals from the Monte de Trigo alkaline suite, Brazil: composition and petrological implications

et al. 2016

View full text Add to dashboard Cite

ABSTRACT:The Monte de Trigo alkaline suite is a SiO 2 -undersaturated syenite-gabbroid association from the Serra do Mar alkaline province. Eudialyte-group minerals (EGMs) occur in one nepheline microsyenite dyke, associated with aegirine-augite, wöhlerite, låvenite, magnetite, zircon, titanite, britholite, and pyrochlore. Major compositional variations include Si (25.09-25.57 apfu), Nb (0.31-0.76 apfu), Fe (1.40-2.13 apfu), and Mn (1.36-2.08 apfu). The EGMs also contain relatively high contents of Ca (6.13-7.10 apfu), moderate enrichment of rare earth elements (0.38-0.67 apfu), and a relatively low Na content (11.02-12.28 apfu), which can be correlated with their transitional agpaitic assemblage. EGM compositions indicate a complex solid solution that includes eudialyte, kentbrooksite, feklichevite, zirsilite-(Ce), georgbarsanovite, and manganoeudialyte components. EGM trace element analyses show low Sr and Ba contents and a negative Eu/Eu* anomaly, which are interpreted as characteristic of the parental magma due to the previous fractionation of plagioclase and/or alkali feldspar. The EGMs from the dyke border have higher contents of Fe, Sr (2,161-2,699 ppm), Mg (1,179-3,582 ppm), and Zn (732-852 ppm) than those at the dyke center. These differences are related to the incorporation of xenoliths and xenocrysts of melatheralitic host rock into the nephelinesyenitic magma followed by crystal-melt diffusive exchange.KEYWORDS: mineral chemistry; agpaitic rocks; Serra do Mar alkaline province. Ca (6,10 apfu), enriquecimento moderado de elementos terras raras (0,67 apfu) e concentrações relativamente baixas de Na (11,(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)28 de Fe, RESUMO: A suíte alcalina do Monte de Trigo é uma associação sienítico-gabroide que pertence à província alcalina da Serra do Mar. Minerais do grupo da eudialita (EGMs) ocorrem em um dique de nefelina microssienito associados a egirina-augita, wöhlerita, lavenita, magnetita, zircão, titanita, britolita e pirocloro. As principais variações composicionais incluem Si (25,09-25,57 apfu), Nb (0,31-0,76 apfu), Fe (1,40-2,13 apfu) e Mn (1,36-2,08 apfu). Os EGMs também contêm concentrações relativamente altas de

show abstract

Section: Petrologic Implicationssupporting

confidence: 63%

Eudialyte-group minerals from the Monte de Trigo alkaline suite, Brazil: composition and petrological implications

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Plagioclase major and trace element contents were calculated using Eq. 33 of Namur et al (2011) with T-X dependent partition coefficients from Wood (1991, 1994) and Bédard (2006). Calculated PEC paths reproduce the coupled Al 2 O 3 -Sr depletion and TiO 2 -FeO t -REE enrichment observed in natural samples that have experienced PEC (Nielsen 1995;Nielsen 2011), but lie at high angles to melt inclusion trends from the Hvítárvatn tephra layer (Figs.…”

Section: Post-entrapment Crystallisationmentioning

confidence: 67%

The evolution and storage of primitive melts in the Eastern Volcanic Zone of Iceland: the 10 ka Grímsvötn tephra series (i.e. the Saksunarvatn ash)

Neave

Maclennan

Thordarson

et al. 2015

Contrib Mineral Petrol

View full text Add to dashboard Cite

evolved assemblage is close to being in equilibrium with the matrix glass, trace element disequilibrium between primitive and evolved assemblages indicates that they were derived from different distributions of mantle melt compositions. Juxtaposition of disequilibrium assemblages probably occurred during disaggregation of incompatible trace element-depleted mushes (mean La/Yb melt = 2.1) into aphyric and incompatible trace element-enriched liquids (La/Yb melt = 3.6) shortly before the growth of the evolved macrocryst assemblage. Post-entrapment modification of plagioclase-hosted melt inclusions has been minimal and high-Mg# inclusions record differentiation and mixing of compositionally variable mantle melts that are amongst the most primitive liquids known from the EVZ. Coupled highfield strength element (HFSE) depletion and incompatible trace element enrichment in a subset of primitive plagioclase-hosted melt inclusions can be accounted for by inclusion formation following plagioclase dissolution driven by interaction with plagioclase-undersaturated melts. Thermobarometric calculations indicate that final crystal-melt equilibration within the evolved assemblage occurred at ~1140 °C and 0.0-1.5 kbar. Considering the large volume of the erupted tephra and textural evidence for rapid crystallisation of the evolved assemblage, 0.0-1.5 kbar is considered unlikely to represent a pressure of long-term magma accumulation and storage. Multiple thermometers indicate that the primitive assemblage crystallised at high temperatures of 1240-1300 °C. Different barometers, however, return markedly different crystallisation depth estimates. Raw clinopyroxene-melt pressures of 5.5-7.5 kbar conflict with apparent melt inclusion entrapment pressures of 1.4 kbar. After applying a correction derived from published experimental data, clinopyroxene-melt equilibria return mid-crustal pressures of 4 ± 1.5 kbar, which are consistent with pressures estimated from the major element Abstract Major, trace and volatile elements were measured in a suite of primitive macrocrysts and melt inclusions from the thickest layer of the 10 ka Grímsvötn tephra series (i.e. Saksunarvatn ash) at Lake Hvítárvatn in central Iceland. In the absence of primitive tholeiitic eruptions (MgO > 7 wt%) within the Eastern Volcanic Zone (EVZ) of Iceland, these crystal and inclusion compositions provide an important insight into magmatic processes in this volcanically productive region. Matrix glass compositions show strong similarities with glass compositions from the AD 1783-1784 Laki eruption, confirming the affinity of the tephra series with the Grímsvötn volcanic system. content of primitive melt inclusions. Long-term storage of primitive magmas in the mid-crust implies that low CO 2 concentrations measured in primitive plagioclase-hosted inclusions (262-800 ppm) result from post-entrapment CO 2 loss during transport through the shallow crust. In order to reconstruct basaltic plumbing system geometries from petrological data with greater confidence, mineral-mel...

show abstract

“…In contrast, the Group II samples show negligible or slightly negative Eu and Sr anomalies (Fig. 5a), which may possibly be produced by fractional crystallization of a substantial amount of plagioclase (e.g., Bédard, 2006;Bindeman and Davis, 2000) or the occurrence of some residual plagioclase in the magmatic source. However, the similar or higher Al 2 O 3 and Sr contents of Group II rocks suggest that they could not have been generated by fractional crystallization of plagioclase from magmas compositionally similar to Group I rocks.…”

Section: Adakitic (Groups I and Ii) Rocksmentioning

confidence: 99%

Petrogenesis of the Early Eocene adakitic rocks in the Napuri area, southern Lhasa: Partial melting of thickened lower crust during slab break-off and implications for crustal thickening in southern Tibet

Wang

Jiang

et al. 2014

Lithos

View full text Add to dashboard Cite

Trace element partitioning in plagioclase feldspar

Cited by 201 publications

References 120 publications

Eudialyte-group minerals from the Monte de Trigo alkaline suite, Brazil: composition and petrological implications

Eudialyte-group minerals from the Monte de Trigo alkaline suite, Brazil: composition and petrological implications

The evolution and storage of primitive melts in the Eastern Volcanic Zone of Iceland: the 10 ka Grímsvötn tephra series (i.e. the Saksunarvatn ash)

Petrogenesis of the Early Eocene adakitic rocks in the Napuri area, southern Lhasa: Partial melting of thickened lower crust during slab break-off and implications for crustal thickening in southern Tibet

Contact Info

Product

Resources

About