Mantle metasomatism—continuing chemical change within the Earth

Bailey, D. K.

doi:10.1038/296525a0

Cited by 204 publications

(52 citation statements)

References 46 publications

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“…An open question regarding metasomatism is its relationship with associated alkaline magmas: is metasomatism a consequence of or a precursor of alkaline magmatism (Bailey 1982;Harte et al 1993;Menzies 1983;Wilshire 1987)? The trace element distribution of continental or oceanic alkaline magmas is characterized by specific anomalies such as elevated Nb/Th or Ce/Pb ratios compared to MORB-type asthenospheric melts.…”

Section: Metasomatism As a Consequence Or As A Precursor Of Alkaline mentioning

confidence: 99%

Liquid line of descent of a basanitic liquid at 1.5 Gpa: constraints on the formation of metasomatic veins

Pilet

Ulmer

Villiger

2009

Contrib Mineral Petrol

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Section: Metasomatism As a Consequence Or As A Precursor Of Alkaline mentioning

confidence: 99%

Liquid line of descent of a basanitic liquid at 1.5 Gpa: constraints on the formation of metasomatic veins

Pilet

Ulmer

Villiger

2009

Contrib Mineral Petrol

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“…The presence of hydrous phases in pyroxenite or mafic granulite xenoliths has been commonly attributed to crystallization of interstitial hydrous melt during solidification of basaltic magma within the upper mantle or lower crust (Best, 1975;Basu and Murthy, 1977;Bergman et al, 1981). However, microstructural evidence sometimes suggests a secondary origin for the amphibole by subsolidus reaction of the anhydrous assemblage with hydrous fluids derived from crystallizing basaltic melts (Roden et al, 1984;Menzies et al, 1985) or a deeper mantle source (Lloyd and Bailey, 1975;Boettcher and O'Neil, 1980;Bailey, 1982). In contrast, Wass and Hollis (1983) argued that the presence of essentially pure CO2 fluid inclusions in some amphibole-bearing granulites and pyroxenites suggested they represent partially dehydrated assemblages resulting from the influx of a CO2-rich fluid.…”

Section: Introductionmentioning

confidence: 99%

Fluid activity in the lower crust and upper mantle: mineralogical evidence bearing on the origin of amphibole and scapolite in ultramafic and mafic granulite xenoliths

Stolz

1987

Mineral. mag.

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Xenoliths in an olivine nephelinite from the McBride Province, North Queensland, include Cr-diopside lherzolites, spinel and garnet websterites, felsic, 2-pyroxene and garnet granulites, and hornblendites. The spinel and garnet websterites are interpreted as crystal segregations from olivine basalt or alkali olivine basalt magma at ~ 12 kbar followed by isobaric cooling (to approximately 900-1000 ~ and subsolidus reequilibration. Garnet and 2-pyroxene granulites are mineralogically and texturally distinct and are considered to represent relatively large degrees of crystallization of basaltic magmas at comparable or slightly lower pressures (8-12 kbar). Mafic and ultramafic xenoliths have been modified to varying degrees following the relatively recent influx of a H20-and CO2-bearing fluid. Variable amounts of amphibole and mica developed in response to the introduced fluid and it is argued that some hornblendites are the end-products of this process acting on spinel websterites. Felsic and 2-pyroxene granulite xenoliths display only minor evidence of increased PH20-Mineralogical and textural evidence indicates high-sulphur Ca-rich scapolite in several garnet granulites did not form in response to the increased fluid activities. It is proposed the scapolite was a primary cumulate phase precipitated from alkali basaltic magma under elevatedfo2 and fso2 conditions.

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“…However, alkaline melts themselves require a enriched source. Although some mantle xenoliths have been metasomatized by their host magma, the author believe that most metasomatic processes in the mantle are not caused by alkaline magma; on the contrary, the author share Bailey's view that mantle metasomatism is a precursor of alkaline magmatism (Bailey, 1982).…”

Section: Metasomatism and Relationship Between The High Kina And Low mentioning

confidence: 83%

“…A large number of mantle xenoliths from a wide variety of localities and alkaline rock types have been observed to be metasomatized (Boyd & Nixon 1973;Lloyd & Bailey, 1975;Francis, 1976;Erlank & Richard, 1977;Jones, 1982;Haggerty et al 1983;Harte, 1983;Menzies, 1983;Menzies et al 1985;Erlank et al, 1987;Harte, et al, 1987). The model that mantle metasomatism as an integrated part of alkaline magmatism has been widely studied and accepted in the last decade (Allègre, 1982;Allègre, et al, 1982Allègre, et al, , 1983Bailey 1982;Holm & Munksgaard, 1982;O'Reilley & Griffin, 1984;Sun, 1984;Roden & Murthy 1985;Hawkesworth et al 1984Hawkesworth et al , 1987Davidson, 1987;Menzies, et al, 1987;Woodhead, et al, 1987;Dupuy, et al, 1989;Haggerty, 1989;Meen et al 1989;Francis <& Ludden 1990).…”

Section: Chemical Characteristics Of the Sources Of The Basanites Andmentioning

confidence: 99%

Petrogenese des roches alcalines mafiques d age meso-cenozoique dans les provinces de Hunan et Guangxi Chine septentrionale

Liu¹

1992

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PETROGENESIS OF MESOZOIC-CENOZOIC MAFIC ALKALINE ROCKS IN HUNAN-GUANGXI PROVINCES, SOUTHERN CHINA Junsuo LiuMesozoic-Cenozoic mafic alkaline rocks are exposed widely in the form of subvolcanic dykes and diatremes in the area of southern Hunan and Guangxi Provinces in southern China. These subvolcanic rocks occur about 1000 km to the west of the eastern Chinese coast, and, therefore, are called the inland subvolcanic belt to distinguish them from the alkaline mafic rocks of the Circum-Pacific coastal belt. These inland rocks can be divided into basanites, trachybasalts (alkaline basaltic affinity), and lamproitic rocks.The basanites and trachybasalts are Cenozoic magmatic products (51-28 Ma). They are relatively Fe rich, with a #Mg < 66. The basanites have high MgO (9-10 wt%) and Ni (~ 200 ppm) contents, and carry numerous small mantle-derived peridotite xenoliths. This indicates that the basanites have experienced little differentiation. The trachybasalts have wider MgO (5.5-8.4 wt%) and Ni (163-251 ppm) variations, much lower CaO (6.5-7.3 wt%) and Sc (~13 ppm) contents than the basanites; but AI2O3 is quite high (-15 wt%).These variations in composition may be due to fractional crystallization of calcium clinopyroxene. The basanites and trachybasalts have very similar incompatible element contents and have highly enriched and differentiated spidergrams. La, Nb, Ta, K, U, Th and Ba are 100-130 times enriched relative to the primitive mantle, that is 2-3 times more than in most island-arc or ocean-island alkaline basaltic rocks. These trace element distribution patterns are similar to that of rift-related Kenya basanite. An important characteristic of the trace element enrichment patterns of the basanites and trachybasalts is that the LILEs (Ba, Th, U) are at about the same level or slightly lower than the La. This is difficult to explain by partial melting of a primitive mantle source. By the same argument, zone refining may be excluded also. Furthermore, the low #Mg feature does not agree with a primitive mantle peridotite source either. However, most mantle amphiboles have similar #Mg as the basanites and trachybasalts. Amphibole-veined mantle peridotite xenoliths are often carried by alkaline volcanic rocks. Such veined peridotite are often also enriched in incompatible trace elements. So partial melting of amphibole-veined peridotite might have generated the basanites and trachybasalts.The lamproites are Mesozoic products (~ 132-135 Ma). They are very rich in and CaO (11-14 wt%), low in AI2O3 (8.1-8.8 wt%). K/Na and K/Al ratios are much higher than the basanites II and trachybasalts. These rocks are more enriched and differentiated in incompatible elements than the basanites and trachybasalts: Ba is 210-450 times more than in primitive mantle; La has a similar level as that in the basanites; the HREEs contents are only about half as much as those of the basanites. Such highly enriched trace element chemistry, especially the LILEs, require an extremely small degree of partial melting, if a primitive...

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Mantle metasomatism—continuing chemical change within the Earth

Cited by 204 publications

References 46 publications

Liquid line of descent of a basanitic liquid at 1.5 Gpa: constraints on the formation of metasomatic veins

Liquid line of descent of a basanitic liquid at 1.5 Gpa: constraints on the formation of metasomatic veins

Fluid activity in the lower crust and upper mantle: mineralogical evidence bearing on the origin of amphibole and scapolite in ultramafic and mafic granulite xenoliths

Petrogenese des roches alcalines mafiques d age meso-cenozoique dans les provinces de Hunan et Guangxi Chine septentrionale

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