Rare-earth and LIL element fractionation in high-grade charnockitic gneisses, south Norway

Field, D.; Drury, S. A.; Cooper, D.C.

doi:10.1016/0024-4937(80)90074-2

Cited by 70 publications

(20 citation statements)

References 32 publications

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“…Traditionally, this block has been included in the Bamble sector (Starmer 1996), but granulite-facies meta-igneous gneisses at Tromøy differ from their mainland counterparts in protolith age and composition (e.g. Field et al 1980;Knudsen & Andersen 1999;Andersen et al 2004a). The Kongsberg-Marstrand block is made up by the Mesoproterozoic Kongsberg complex (Jacobsen & Heier 1978;Nordgulen 1999) west of the Oslo Rift, and the Østfold-Marstrand belt (as of Åhäll et al 1995) east of the rift.…”

Section: A Revised Non-genetic Nomenclaturementioning

confidence: 99%

Terrane analysis, regional nomenclature and crustal evolution in the Southwest Scandinavian Domain of the Fennoscandian Shield

Andersen¹

2005

GFF

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Tectonostratigraphic terrane analysis of an orogenic belt involves the use of a well-defined nomenclature which is related to the internal structure and relative displacement of blocks in the orogenic "puzzle". The tectonostratigraphic terrane is the central concept in terrane analysis, and the term should be restricted to units fulfilling the definition, i.e. to fault-bounded crustal blocks which have distinct lithologic and stratigraphic successions and which have geologic histories different from neighbouring terranes. Application of terrane analysis to a complex, poly-orogenic region such as the Southwest Scandinavian Domain of the Fennoscandian Shield (SSD) must include information on the entire crustal evolution history of potential terranes, including petrological, geochemical and other non-geochronological information. At the present state of knowledge, no crustal block within the SSD fulfil the criteria as a Gothian or Sveconorwegian tectonostratigraphic terrane. Until basic evidence of terrane status is established for a given block of crust, the use of a descriptive regional nomenclature is therefore preferred. A revised, non-genetic nomenclature is proposed, which does not assign terrane status to any of its units, and which will hopefully help eliminating confusing differences in usage, and be helpful in future analysis of Gothian and Sveconorwegian tectonics and crustal evolution in the region. To reach a stage where terrane analysis of the Gothian and Sveconorwegian evolution of the SSD becomes meaningful, it is necessary to carry out both structural studies and isotopic dating of the ductile deformation zones which are potential terrane boundaries.

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Section: A Revised Non-genetic Nomenclaturementioning

confidence: 99%

Terrane analysis, regional nomenclature and crustal evolution in the Southwest Scandinavian Domain of the Fennoscandian Shield

Andersen¹

2005

GFF

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“…1) (Field et al 1980(Field et al , 1985Smalley et al 1983;Lamb et al 1986). Region A (amphibolite facies) and region B (granulite facies) consist primarily of acid to intermediate host gneisses with a broadly granitic mineralogy separated by an orthopyroxene isograd in the metabasite intrusives.…”

Section: Geological Settingmentioning

confidence: 99%

“…1 The Bamble Sector, SE Norway showing metamorphic regions B and C (cf. Field et al 1980;Smalley et al 1983). The boundary between regions B and C has been adjusted to re¯ect new observations on the distribution of orthopyroxene in the granulite facies gneisses by and Nijland et al (1998).…”

Section: Geological Settingmentioning

confidence: 99%

Titaniferous magnetite–ilmenite thermometry and titaniferous magnetite–ilmenite–orthopyroxene–quartz oxygen barometry in granulite facies gneisses, Bamble Sector, SE Norway: implications for the role of high-grade CO2-rich fluids during granulite genesis

Harlov

2000

Contrib Mineral Petrol

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Oxygen fugacities have been estimated for a wide distribution of samples from the granulite facies terrane (region C) of the Bamble Sector, SE Norway using both the titaniferous magnetite±ilmenite and orthopyroxene±titaniferous magnetite±quartz oxygen barometers. These oxygen fugacities are estimated using temperatures calculated from the titaniferous magnetite±ilmenite thermometer of Ghiorso and Sack (1991) and are both internally consistent with each other as well with the thermometer. In samples for which the estimated temperature is high, the two oxygen barometers show good agreement whereas agreement is poor for low temperature samples. In these low temperature samples, oxygen fugacities estimated from titaniferous magnetite± ilmenite are considerably less than those estimated from orthopyroxene±titaniferous magnetite±quartz. An increase in this discrepancy with decrease in temperature appears to re¯ect preferential resetting of the hematite component in the ilmenite grains without signi®cant alteration of the more numerous titaniferous magnetite grains. This is due, in part, to greater re-equilibration of the ilmenite grains during retrograde interoxide resetting between the ilmenite grains and the titaniferous magnetite grains. The mean temperature for the non-reset samples, 791 17°C (1r), is in good agreement with temperatures obtained from garnet±orthopyroxene K D exchange thermometry in the same region, 785±795°C (1r) (Harlov 1992(Harlov , 2000a. Most non-reset oxygen fugacities range from log 10 f O 2 )14 to )11.8 or approximately 0.5±1.5 log units above quartz±fayalite± magnetite at 7.5 kbar. Both these temperatures and the range of oxygen fugacities are in good agreement with those estimated using the titaniferous magnetite±ilmen-ite thermometer/oxygen barometer of Andersen et al. (1991). The QUIlP equilibrium (quartz±ulvoÈ spinel± ilmenite±pyroxene) is used to project self-consistent equilibrium temperatures and oxygen fugacities for samples reset due to hematite loss from the ilmenite grains. These projected temperatures and oxygen fugacities agree reasonably well with the non-reset samples. The mean projected QUIlP temperature is 823 6°C (1r). This result supports the conclusion that low titaniferous magnetite±ilmenite temperatures (down to 489°C) and accompanying low oxygen fugacities are the result of hematite loss from the ilmenite grains. Non-reset oxygen fugacities lie approximately 1.5 log 10 units above the upper graphite stability curve indicating that the stable C±O±H¯uid phase interacting with these gneisses, whether regionally or locally, was CO 2 . This is borne out by the presence of numerous CO 2 -rich¯uid inclusions in these rocks.

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“…It is relevant to briefly review the models that have been proposed for the derivation of the or thogneisses of transition and granulite zones: (a) Intracrustal partial melting (Fyfe, 1973;Pride and Muecke, 1980); (b) Primary fractionation of andesite-dacite magma (Holland and Lambert, 1975;Field et al, 1980); (c) Partial melting of a mafic source rich in hornblende and/or garnet (Weaver and Tarney, 1980;Condie et al, 1982); and (d) Fractional crystallization of wet basaltic magma or diorite magma (Barker and Arth, 1976;Arth et al, 1978;Jahn et al, 1988). In the light of the data presented and discussion of the above models an attempt is made to arrive at a reasonable model.…”

Section: Mode Of Protolith Formationmentioning

confidence: 99%

Nature and origin of lower crustal rocks of Dharmapuri area, Tamil Nadu, southern India-a goechemical approach.

1991

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The early Proterozoic gneiss-charnockites from Dharmapuri area, southern India are investigated to understand the crustal evolution processes of the area. The granulite facies metamorphism which con verted the tonalitic gneisses to enderbites in the area was isochemical, except for the depletion of LIL elements. The enderbites of granulite zone have high K / Rb, Ba / Rb, K / U and K / Th but low U, Th, K / Sr, Rb / Sr and Th / U compared to the tonalitic gneisses of the transition zone.The petrochemical studies show a compositional continuum, without bimodal distribution pattern, from mafic gneisses to enderbites/tonalitic gneisses. Their variation suggests that the rocks were derived from igneous protoliths. The REE pattern of tonalitic rocks show LREE enrichment, HREE depletion and.variable positive Eu anomalies. The REE concentrations, however, do not show any signs of frac tionation with increasing grade of metamorphism. It is also observed that ages obtained from whole rock Rb-Sr and Sm-Nd systematics remain same, which probably suggests that the high grade metamor phism followed crustal generation processes within a short span.The protolithic orthogneisses were probably derived either by fractional crystallization of basaltic/ dioritic magma involving hornblende, plagioclase and iron oxides as the major precipitating phases, or by partial melting of an amphibolite source leaving plagioclase and clinopyroxene as the main residual phases. A fractional crystallization model is more preferred because of the presence of horn blende cumulate rocks and because there is a continuous compositional range from gabbro to granodiorite through tonalite.

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Rare-earth and LIL element fractionation in high-grade charnockitic gneisses, south Norway

Cited by 70 publications

References 32 publications

Terrane analysis, regional nomenclature and crustal evolution in the Southwest Scandinavian Domain of the Fennoscandian Shield

Terrane analysis, regional nomenclature and crustal evolution in the Southwest Scandinavian Domain of the Fennoscandian Shield

Titaniferous magnetite–ilmenite thermometry and titaniferous magnetite–ilmenite–orthopyroxene–quartz oxygen barometry in granulite facies gneisses, Bamble Sector, SE Norway: implications for the role of high-grade CO2-rich fluids during granulite genesis

Nature and origin of lower crustal rocks of Dharmapuri area, Tamil Nadu, southern India-a goechemical approach.

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