Petrological, geochemical and source criteria for the classification of granitic rocks: a discussion

Bowden, Peter; Batchelor, Richard A.; Chappell, B. W.; Didier, Jean; Lameyre, J.

doi:10.1016/0031-9201(84)90029-3

Cited by 83 publications

(44 citation statements)

References 19 publications

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“…Taken by themselves the ratios of the major elements can form a powerful tool in establishing consanquinity in rock suites, and displayed in discrimination diagrams they are capable of revealing contrasted magmatic associations (LARo-CHE 1980; DEBON & LE FORT 1982;LAMEYRE & BOW-DEN 1982). BOWDEN et al (1984) offer a guide to the available methods recommending a Q'-ANOR plot devised by STRECKEISEN and LE MAITRE (1979) as adequate to separate these associations. By such a discrimination we are refining Shand's broad division into aluminous, metaluminous and alkaline, but more precisely expressed in plots which highlight specific features such as, for example, the broad spectrum of compositions existing within the aluminous association of the continental crustal environment (LA RocHE et al 1980; ANDERSON & ROWLEY 1981).…”

Section: The Categories Of Granitic Rocksmentioning

confidence: 99%

Granites and yet more granites forty years on

Pitcher

1987

Geol Rundsch

182

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With 1 figure ZusammenfassungDas Thema dieser synoptischen LTbersicht behandelt das Verh~iltnis zwischen Ursache, Prozess, Herkunft und dem geologischen Rahmen w~ihrend der Genese granitischer Gesteine.Es besteht hier eine enge Beziehung, weil Granite das Endstadium sehr unterschiedlicher Entstehungsprozesse sein k6nnen, die verschiedene Ausgangsgesteine einbeziehen und yon denen jeder einer speziellen tektonischen Situation entspricht.Geologisch ausgedriickt kann man die Unterschiede dazu verwenden, eine genetische Klassifikation zu erstellen, um damit den Einflufl basischen Magmas im richtigen Verh~iltnis zu sehen, die Bedeutung des vulkanisch-plutonischen Grenzbereiches aufzuzeigen, die Wichtigkeit der Textur herauszustreichen und den Typ der Mineralisation vorherzusagen. Auf diese Weise l~if~t rich das Verst~.ndnis fiir den Modus der Platznahme erzielen und der Einflui~ verschiedener Ausgangsgesteine abschiitzen. AbstractThe theme of this synoptic review is the relationship between cause, process, source and the geological context during the genesis of the granitic rocks. A close environmental relationship occurs because granites can arise as the end-stage of several generative processes, involving different source rocks, each appropriate to a particular tectonic situation. Expressed in geological terms the differences can be used to erect a genetic classification, to set in perspective the intervention of basic magma, to reveal the importance of the volcanoplutonic interface, to evaluate the significance of the texture, to predict the type of mineralisation, to understand the mode of emplacement and to determine the contribution of the various source rocks.

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Section: The Categories Of Granitic Rocksmentioning

confidence: 99%

Granites and yet more granites forty years on

Pitcher

1987

Geol Rundsch

182

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“…The K~erven rocks are similar to the sodic alkaline silica oversaturated trend of Lameyre and Bowden (1982) and Bowden et al (1984). In contrast to the provinces of Niger, Nigeria, Oslo and Corsica, the K~erven suite is not peralkaline.…”

Section: Petrographymentioning

confidence: 73%

The Tertiary Kærven Syenite Complex, Kangerdlugssuaq, East Greenland: Mineral Chemistry and Geochemistry

Holm¹,

Prægel²

1988

Mineral. mag.

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The K~erven syenite complex, which reflects the hitherto earliest recorded stages in the Tertiary of East Greenland, outcrops in the middle reaches of the Kangerdlugssuaq Fjord as a peripheral intrusion to the Kangerdlugssuaq intrusion. The rocks of the K~erven complex range from syenite through alkali feldspar quartz-syenite to alkali feldspar granite. The general sequence of crystallization of the K~erven magmas was: alkali feldspar + olivine(Fa96_99 ) + plagioclase(An41_10, clinopyroxene (augite, ferrosalite, ferrohedenbergite), quartz and amphibole. Whole-rock major and trace-element data show coherent geochemical trends which suggest comagmatism. The data reveal that the K~erven rocks are distinct from the rocks from the adjacent Kangerdlugssuaq intrusion (e.g. higher TiO2, FeO T in low-SiO z samples, lower Na20 , approx, constant Zr/Nb). The mineral chemistry supports this conclusion, as the K~erven samples typically have calcic amphiboles and clinopyroxenes with a very limited Na-enrichment in contrast to the sodic trends of the Kangerdlugssuaq intrusion. Normative feldspar compositions plot near to the Ab-Or cotectic in the Q-Ab-Or system and a maximum pressure of crystallization of 3-5 kbar with moderate to low Pn~o is indicated.Trace elements preferently incorporated in plagioclase and alkali feldspar, i.e. Sr, Ba and Rb, show systematics which are not compatible with an evolution of the rock suite by crystal fractionation of these phases, though possibly alkali feldspar may be partially accumulated in a few very evolved rocks. Numerical calculations do not suggest a magmatic evolution by fractional crystallization of the observed phases. The variation of Sr, Ba and Rb as well as of the incompatible elements Nb, Zr and Th support a derivation of the rock suite mainly by mixing two components, a syenitic and a granitic end-member. It is concluded that magma mixing was the most significant process in the formation of the Kzerven rock suite accompanied by some crystal fractionation. Evidence for crustal contamination is detected in a few samples from the outer part of the intrusion but has not affected the main suite of rocks.

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“…Grantic rocks have been associated with varied orogenic periods based on discrimination diagrams (Harris et al, 1986;Pearce et al, 1984;Bowden et al, 1984). The leucogranite, the granites (fine-and medium-grained) and the igneous charnockites plot within the VAG+(syn-COLG) field of the Nb-Y discrimination diagram (Fig.…”

Section: Tectonic Settingmentioning

confidence: 99%

Trace element geochemistry and tectonic characterization of the granulite facies rocks from Southwest Obudu Plateau, southeastern Nigeria

Ukwang

Ekwueme

2009

Chin. J. Geochem.

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The trace elements characteristics of the migmatitic gneisses (biotite-garnet-and hornblende-biotite), granulite facies rocks (charnockitic gneisses) and meta-peridotite in the area of Southwest Obudu Plateau indicate that the area exhibits a high degree of geochemical variability. Compatible trace elements (Ni and Cr) are comparatively high in the granulite facies rocks and meta-peridotite. Ni ranges from 28×10 -6 to 266×10 -6 whilst Cr ranges from 62×10 -6 to 481×10 -6 for the granulite facies rocks (charnockitic gneisses), and for the meta-peridotite Ni varies between 2045×10 -6 and 2060×10 -6 . Incompatible trace elements show a higher variability in these rocks. The rocks in the area of Southwest Obudu Plateau generally are characterized by the high concentrations of Ba, Ce, Sr, Rb, Ga, Ni, Cr, Co, Zr, Pr and moderate concentrations of Cu, Sm and Th. The available data show that the charnockitic gneisses are of lower crustal origin. The enrichment of the meta-peridotite in compatible trace elements suggests the primitive mantle would be the source region, with slight contamination during ascent. These diverse origins collaborate the tectonic setting of the area as shown by discrimination diagrams. The diverse tectonic settings range from arc to collisional. Alkaline to sub-alkaline magmatism in the area was probably contemporaneous with the tectonic events that occurred in the area during the Proterozoic.

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Petrological, geochemical and source criteria for the classification of granitic rocks: a discussion

Cited by 83 publications

References 19 publications

Granites and yet more granites forty years on

Granites and yet more granites forty years on

The Tertiary Kærven Syenite Complex, Kangerdlugssuaq, East Greenland: Mineral Chemistry and Geochemistry

Trace element geochemistry and tectonic characterization of the granulite facies rocks from Southwest Obudu Plateau, southeastern Nigeria

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