Granulite facies lower crustal xenoliths from the Eifel, West Germany: petrological and geochemical aspects

Loock, G.; Stosch, H.-G.; Seck, H. A.

doi:10.1007/bf00320964

Cited by 65 publications

(32 citation statements)

References 41 publications

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“…Apatites have high total LREE contents (around 7300 ppm) and sig nificant amounts of Sr (300 ppm) and Th (32 ppm) (Table4). They have high CeN/YbN ratios (15) and low Eu/Eu* values (0.13), the latter being much lower than in other mafi c granulites (Loock et al, 1990;Upton et aI., 2001), and typical of equilibration with the modally abundant pla gioclase (Storkey et al, 2005).…”

Section: Accessoriesmentioning

confidence: 92%

“…Plagioclase in the charnockites have low LREE contents, in the range of 7-50 ppm (Table 2), as is common in metaluminous gran ulites (Pride & Muecke, 1981;Loock et al, 1990), whereas plagioclases in SCS peraluminous granulites show much higher LREE contents, in the range of 150-550 ppm (Villaseca et aI., 2003) (Fig. 4c).…”

Section: An (A)mentioning

confidence: 93%

“…Clinopyroxene from charnockite 102131 has a fl atter REE pattern and a marked positive Eu anomaly. Clinopyroxene showing neg ative Eu anomalies are common in mafic granulite xeno liths (Loock et al, 1990;Upton et al, 2001;Storkey et al, 2005), whereas those with positive anomalies are more unusual and have been interpreted as indicative of high oxygen fugacity during high-T metamorphism (Rogers & Hawkesworth, 1982;Loock et al, 1990) or by metamor phic reaction with feldspar in plagioclase-rich granulites (Ulianov et al, 2006).…”

Section: An (A)mentioning

confidence: 99%

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Metaluminous pyroxene-bearing granulite xenoliths from the lower continental crust in central Spain: their role in the genesis of Hercynian I-type granites

Villaseca¹,

García²,

Paterson³

et al. 2007

ejm

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Basic and intermediate meta-igneous xenoliths are very scarce within the granulite population transported by the Per mian alkaline lamprophyric dyke swarm of the Spanish Central System (SCS). These xenoliths are metalurninous pyroxene-bearing chamockites (sensu lato). They show LREE-poor plagioclase and orthopyroxene-clinopyroxene. Crystallization conditions were estimated at about 850 to 1000 °C and 9 to 11 kbar, a slightly higher range than that estimated for the associated peralurninous granulites, but indicating derivation from the lowerrnost crust.\¥hole-rock geochemistry suggests that the chamockite samples are not a cogenetic suite. The more basic varieties have affinities with cumulates from previous calc-alkaline underplated protoliths, whereas intermediate charnockites have a restitic origin. The similarity in Sr-Nd-Pb isotopic signatures between these restitic chamockites and some SCS I-type granites suggests a genetic relationship. This study, including Pb isotopic data from the whole granulite xenolith suite, reinforces the lower-crustal derivation of the SCS Hercynian granitic batholith.

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Section: Accessoriesmentioning

confidence: 92%

Section: An (A)mentioning

confidence: 93%

Section: An (A)mentioning

confidence: 99%

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Metaluminous pyroxene-bearing granulite xenoliths from the lower continental crust in central Spain: their role in the genesis of Hercynian I-type granites

Villaseca¹,

García²,

Paterson³

et al. 2007

ejm

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“…Recurring distribution-coefficients for the trace element and REE between garnet and a coexisting mineral (clinopyroxene, amphibole, biotite) for different samples from rocks similar in composition can be used as a indication of equilibrium between the two minerals (e.g., Kretz et al 1999, Loock et al 1990, Tribuzio 1992, Yang et al 1999. As has been shown by Kretz et al (1999), distribution coefficients of the rare earths between coexisting minerals are mainly thermodynamically dependent, and a close match for similar rocks suggests attainment of, or approach to, equilibrium.…”

Section: Abundance and Pattern Of Distribution Of The Ree In Amphibolesmentioning

confidence: 99%

“…Only a few determinations of the REE in amphiboles from granulite-facies rocks have been reported (Loock et al 1990, Pride & Muecke 1981, and data on REE abundance in amphiboles from amphibolite-facies rocks are virtually absent (Kretz et al 1999, Sorensen & Grossman 1989.…”

Section: Introductionmentioning

confidence: 99%

Patterns of Trace-Element Distribution in Calcic Amphiboles as a Function of Metamorphic Grade

Скублов¹,

Drugova²

2003

The Canadian Mineralogist

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The distribution of the rare earths and other trace elements in calcic amphiboles from the Njurundukan mafic complex, northwestern Baikal region, in Russia, depends on metamorphic grade. Both total REE and La/Yb in amphiboles decrease with decreasing temperature of metamorphism. Consistent partition-coefficients for trace elements in amphibole and coexisting garnet, suggestive of equilibrium, are best developed in granulite-facies rocks. Such a consistent distribution of the REE is disturbed in amphibolite-facies rocks owing to incipient metasomatism. Amphiboles from metasomatic rocks show REE distributions that differ from those in amphiboles belonging to the metamorphic culmination, and commonly are inherited from precursor minerals. This property leads to the establishment of the sequence of mineral formation in metasomatically altered rocks. Comparison with amphiboles from the high-pressure Lapland granulite complex, Baltic Shield, suggests that pressure does not affect REE abundance and distribution in amphiboles.Keywords: trace elements, rare-earth elements, calcic amphibole, Njurundukan mafic complex, Baikal, Russia. SOMMAIRELa distribution des terres rares et autres éléments traces dans les amphiboles calciques du complexe mafique de Njurundukan, dans le nord-ouest de la région de Baïkal, en Russie, dépend du degré de métamorphisme. La teneur en terres rares et le rapport La/Yb des amphiboles diminuent à mesure que diminue la température du métamorphisme. Des coefficients de partage conséquents pour les éléments traces dans l'amphibole et le grenat coexistant, indications possible d'un équilibre, sont les mieux développés dans les roches sujettes à un métamorphisme dans le faciès granulite. Une telle distribution conséquente des terres rares est dérangée au cours d'épisodes de métamorphisme dans le faciès amphibolite à cause d'un début de métasomatose. Dans les amphiboles des roches métasomatiques, la distribution des terres rares diffère de celle des amphiboles développées menant à la culmination métamorphique; elle est apte à être héritée de minéraux précurseurs. Cette propriété mène à l'établissement d'une séquence de formation des minéraux dans des roches altérées par métasomatose. Une comparaison avec les amphiboles provenant du socle granulitique de haute pression en Lapponie, Bouclier Baltique, nous fait penser que la pression n'affecte pas l'abondance et la distribution des terres rares dans les amphiboles.(Traduit par la Rédaction)

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Characterization and Petrological Constraints of the Midlithospheric Discontinuity

Rader

Emry

Schmerr

et al. 2015

Geochem Geophys Geosyst

109

143

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Within continental lithosphere, widespread seismic evidence suggests a sharp discontinuous downward decrease in seismic velocity at 60–160 km depth. This midlithospheric discontinuity (MLD) may be due to anisotropy, melt, hydration, and/or mantle metasomatism. We survey global seismologic observations of the MLD, including observed depths, velocity contrasts, gradients, and locales across multiple seismic techniques. The MLD is primarily found in regions of thick continental lithosphere and is a decrease in seismic shear velocity (2–7% over 10–20 km) at 60–160 km depth, the majority of observations clustering at 80–100 km. Of xenoliths in online databases, 25% of amphibole‐bearing xenoliths, 90% of phlogopite‐bearing xenoliths, and none of carbonate‐bearing xenoliths were formed at pressures associated with these depth (2–5 GPa). We used Perple_X modeling to evaluate the elastic moduli and densities of multiple petrologies to test if the MLD is a layer of crystallized melt. The fractional addition of 5–10% phlogopite, 10–15% carbonate, or 45–100% pyroxenite produce a 2–7% velocity decrease. We postulate this layer of crystallized melt would originate at active margins of continents and crystallize in place as the lithosphere cools. The concentration of mildly incompatible elements (Y, Ho, Er, Yb, and Lu) in xenoliths near the MLD is consistent with higher degrees of melting. Thus, we postulate that the MLD is the seismological signature of a chemical interface related to the paleointersection of a volatile‐rich solidus and progressively cooling lithosphere. Furthermore, the MLD may represent a remnant chemical tracer of the lithosphere‐asthenosphere boundary (LAB) from when the lithosphere was active and young.

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Granulite facies lower crustal xenoliths from the Eifel, West Germany: petrological and geochemical aspects

Cited by 65 publications

References 41 publications

Metaluminous pyroxene-bearing granulite xenoliths from the lower continental crust in central Spain: their role in the genesis of Hercynian I-type granites

Metaluminous pyroxene-bearing granulite xenoliths from the lower continental crust in central Spain: their role in the genesis of Hercynian I-type granites

Patterns of Trace-Element Distribution in Calcic Amphiboles as a Function of Metamorphic Grade

Characterization and Petrological Constraints of the Midlithospheric Discontinuity

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