Chemical and petrologic trends in anorthositic and associated rocks of the Nain massif, Labrador

Waard, Dirk de; Wheeler, Everett P.

doi:10.1016/0024-4937(71)90120-4

Cited by 18 publications

(5 citation statements)

References 10 publications

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“…Re moval of plagioclase is unanimously acce pte d as the main me chanism of diffe re ntiation of the anorhositic suite , but the nature of the parental magma re mains a controversial proble m. Compositions ranging from gabbroic to quartz-monzodioritic [1] or e ve n granodioritic liquids [2] have been propose d. Thèse estimâtes are based principally upon imprécise évalua tions of volume proportions of the related rock s and the hypothesis of their consanguinity. Criteria of con sanguinity and resulting proportions differ consider ably.…”

Section: Introductionmentioning

confidence: 99%

Rare-earth data on monzonoritic rocks related to anorthosites and their bearing on the nature of the parental magma of the anorthositic series

Duchesne

Roelandts

Demaiffe

et al. 1974

Earth and Planetary Science Letters

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Major and trace éléments have been determined in monzonoritic rocks (hypersthenemonzodiorite or jotunite) frqm two intrusions belonging to the South R ogaland anorthositic complex (Norway). The rarcearth abundance pattern reveals no Eu anomaly, or only a very small one, This fact together with field observations suggest that thèse rocks represent the parental magma of the anorthositic suite. High Ti and P abundances, low Si content, high l'e/Mg and K20/Si02 ratios are charactcristics of the major élément geochemistry. Absolute amounts of some trace éléments abundances vary distinctly between the two intrusions. K/R b ratios as high as 1700 are observed. Partial fusion of upper mantle kaersutite is proposed as a possible mechanism of magma génération. Partition coefficients between plagioclase phenocrysts and liquid are determined. 335 Printed in The Netherlands * Similar values (Th = 0.48 ppm; U = 0.25 ppm) have been measured [36] in a monzonoritic dyke related to the E-R main body.

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Section: Introductionmentioning

confidence: 99%

Rare-earth data on monzonoritic rocks related to anorthosites and their bearing on the nature of the parental magma of the anorthositic series

Duchesne

Roelandts

Demaiffe

et al. 1974

Earth and Planetary Science Letters

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“…A relatively early study on anorthositic suites suggested that monzodioritic rocks would represent intermediate derivatives of magmas parental to the entire AMCG series (De Waard and Romey 1969). Regardless of the suggested parental magma composition and source, many studies have since then described the bimodal (mafic-felsic) origin of AMCG rock types (e.g., Emslie et al 1994; Ashwal and Bybee 2017 and reference therein).…”

Section: Alternative Modes Of Origin For the Monzodioritic Rocks In Amentioning

confidence: 99%

“…Despite the focus of most previous studies on anorthosite petrogenesis, the monzodioritic rocks have also received warranted research interest since they are likely to bear key evidence on the petrogenesis of AMCG suites (e.g., de Waard and Romey 1969;Duchesne et al 1974;Demaiffe and Hertogen 1981;Ashwal 1982;Duchesne 1984;Owens and Dymek 1992;McLelland et al 1994;Mitchell et al 1996;Markl 2001;Fred et al 2019). The amount of monzodioritic rocks is usually minor relative to the other rock types in AMCG suites, and they are observed as dikes or other small intrusions in the contacts of associated anorthositic rocks or between the anorthositic and granitic rocks (Duchesne 1984).…”

Section: Introductionmentioning

confidence: 99%

“…Although the monzodioritic rocks usually show uniform field, mineralogical, and geochemical characteristics, several options for their origin and relationship with the anorthosites have been proposed. They either represent (1) anorthosite parental magmas (e.g., Duchesne et al 1974;Duchesne and Demaiffe 1978;Demaiffe and Hertogen 1981), (2) residual magmas after anorthosite fractionation (e.g., Ashwal 1982;Morse 1982;Duchesne 1984;Owens and Dymek 1992;McLelland et al 1994;Mitchell et al 1996;Vander Auwera et al 1998;Dymek and Owens 2001;Markl 2001;Heinonen et al 2010b), (3) intermediate derivatives in the evolution from anorthosite to magnerite (e.g., de Waard and Romey 1969;Philpotts 1981), (4) derivatives from mangeritic magmas (e.g., Emslie 1975;Duchesne et al 1989), (5) immiscible liquids formed after plagioclase fractionation (e.g., Philpotts 1981), or (6) later intrusions of coeval but not comagmatic magmas with the anorthosites (e.g., Emslie 1978;Duchesne et al 1990).…”

Section: Introductionmentioning

confidence: 99%

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Equilibrium crystallization of massif-type anorthosite residual melts: a case study from the 1.64 Ga Ahvenisto complex, Southeastern Finland

Fred

Heinonen

2020

Contrib Mineral Petrol

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Fe–Ti–P-rich mafic to intermediate rocks (monzodiorites and oxide–apatite–gabbronorites, OAGNs) are found as small intrusions in most AMCG (anorthosite–magnerite–charnokite–granite) suites. The origin of the monzodioritic rocks is still debated, but in many studies, they are presumed to represent residual liquid compositions after fractionation of anorthositic cumulates. In the 1.64 Ga Ahvenisto complex, SE Finland, monzodioritic rocks occur as minor dike-like lenses closely associated with anorthositic rocks. We report new field, petrographic, and geochemical (XRF, ICP-MS, EMPA) data complemented with crystallization modeling (rhyolite-MELTS, MAGFRAC) for the monzodioritic rocks, apatite–oxide–gabbronorite, and olivine-bearing anorthositic rocks of the Ahvenisto complex. The presented evidence suggest that the monzodioritic rocks closely represent melt compositions while the apatite–oxide–gabbronorite and olivine-bearing anorthositic rocks are cumulates. The monzodioritic rocks seem to form a liquid line of descent (LLD) from primitive olivine monzodiorites to more evolved monzodiorites. Petrological modeling suggests that the interpreted LLD closely corresponds to a residual melt trend left after fractional crystallization (FC) and formation of the cumulate anorthositic rocks and minor apatite–oxide–gabbronorite in shallow magma chambers. Consequent equilibrium crystallization (EC) of separate monzodioritic residual magma batches can produce the observed mineral assemblages and the low Mg numbers measured from olivine (Fo25–45) and pyroxenes (En48–63, Mg#cpx 60–69). The monzodioritic rocks and apatite–oxide–gabbronorites show similar petrological and geochemical characteristics to corresponding rock types in other AMCG suites, and the model described in this study could be applicable to them as well.

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“…The basic information used in the present overview are collected from the published literature, for example, Raith et al (1997), Bhattacharya et al (1998), Dobmeier (2006 and Nasipuri and Bhattacharya (2007) on Bolangir complex; Sarkar et al (1981), Mukherjee et al (1999), Raith et al (2007), Chatterjee et al (2008) on Chilka complex; Nanda and Panda (1999), and Joshi et al (2006) on Jugsaipatna complex; Maji (1997), Maji et al (1997) and Maji and Sarkar (2004) on Turkel complex; De Waard (1970), Seifert et al (1977), Simmons and Hanson (1978), Ashwal and Seifert (1980), Ashwal and Wooden (1983), Morrison and Valley (1988), Ashwal (1993) and McLelland et al (2004) on Marcy massif; Papezik (1965), Heath and Fairbairn (1969), Barton and Doigs (1972), Martignole (1974) and Seifert et al (1977) on Morin massif; De Waard and Wheeler (1971), Wiebe (1978), Xue and Morse (1993), Emslie et al (1994), andBedard (2001) on Nain massif; Demaiffe and Hertogen (1981), Duchesne et al (1985), Demaiffe et al (1986), and Demaiffe and Javoy (1980) on Hidra massif.…”

Section: Introductionmentioning

confidence: 96%

An overview on geochemistry of Proterozoic massif-type anorthosites and associated rocks

2010

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A critical study of 311 published WR chemical analyses, isotopic and mineral chemistry of anorthosites and associated rocks from eight Proterozoic massif anorthosite complexes of India, North America and Norway indicates marked similarities in mineralogy and chemistry among similar rock types. The anorthosite and mafic-leucomafic rocks (e.g., leuconorite, leucogabbro, leucotroctolite, anorthositic gabbro, gabbroic anorthosite, etc.) constituting the major part of the massifs are characterized by higher Na 2 O + K 2 O, Al 2 O 3 , SiO 2 , Mg# and Sr contents, low in plagioclase incompatible elements and REE with positive Eu anomalies. Their δ 18 O (5.7-7.5), initial 87 Sr/ 86 Sr (0.7034-0.7066) and ε Nd values (+1.14 to +5.5) suggest a depleted mantle origin. The Fe-rich dioritic rocks occurring at the margin of massifs have isotopic, chemical and mineral composition more close to anorthosite-mafic-leucomafic rocks. However, there is a gradual decrease in plagioclase content, An content of plagioclase and X Mg of orthopyroxene, and an increase in mafic silicates, oxide minerals content, plagioclase incompatible elements and REE from anorthositemafic-leucomafic rocks to Fe-rich dioritic rocks. The Fe-rich dioritic rocks are interpreted as residual melt from mantle derived high-Al gabbro melt, which produced the anorthosite and mafic-leucomafic rocks. Mineralogically and chemically, the K-rich felsic rocks are distinct from anorthosite-mafic-leucomafic-Fe-rich dioritic suite. They have higher δ 18 O values (6.8-10.8 ) and initial 87 Sr/ 86 Sr (0.7067-0.7104). By contrast, the K-rich felsic suites are products of melting of crustal precursors.

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Chemical and petrologic trends in anorthositic and associated rocks of the Nain massif, Labrador

Cited by 18 publications

References 10 publications

Rare-earth data on monzonoritic rocks related to anorthosites and their bearing on the nature of the parental magma of the anorthositic series

Rare-earth data on monzonoritic rocks related to anorthosites and their bearing on the nature of the parental magma of the anorthositic series

Equilibrium crystallization of massif-type anorthosite residual melts: a case study from the 1.64 Ga Ahvenisto complex, Southeastern Finland

An overview on geochemistry of Proterozoic massif-type anorthosites and associated rocks

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