Basaltic and peridotitic komatiites and stromatolites above a basal unconformity in the Belingwe greenstone belt, Rhodesia

Bickle, M. J.; Martín, Alexis; Nisbet, E. G.

doi:10.1016/0012-821x(75)90024-2

Cited by 171 publications

(45 citation statements)

References 10 publications

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“…[Clague et al, 1991;Norman and Garcia, 1999;Murata and Richter, 1966;Wright, 1972Wright, , 1973Wright and Fiske, 1971;Wright et al, 1975], and Theistareykir, Iceland [Slater et al, 2001;Maclennan et al, 2003]. Crosses indicate Archean Al-undepleted komatiites [Bickle et al, 1975Nisbet et al, 1977Nisbet et al, , 1987Lesher and Arndt, 1995;Lahaye and Arndt, 1996]. Small red circles indicate incremental additions and subtractions of olivine for Archean komatiites, Hawaii, Iceland, and EPR, and incremental additions of troctolite (olivine + plagioclase) for MAR.…”

Section: Parental and Primary Magmas From Different Tectonic Environmmentioning

confidence: 99%

Temperatures in ambient mantle and plumes: Constraints from basalts, picrites, and komatiites

Herzberg

Asimow

Arndt

et al. 2007

Geochem Geophys Geosyst

629

449

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International audienceSeveral methods have been developed to assess the thermal state of the mantle below oceanic ridges, islands, and plateaus, on the basis of the petrology and geochemistry of erupted lavas. One leads to the conclusion that mantle potential temperature (i.e., TP) of ambient mantle below oceanic ridges is 1430°C, the same as Hawaii. Another has ridges with a large range in ambient mantle potential temperature (i.e., TP = 1300–1570°C), comparable in some cases to hot spots (Klein and Langmuir, 1987; Langmuir et al., 1992). A third has uniformly low temperatures for ambient mantle below ridges, ∼1300°C, with localized 250°C anomalies associated with mantle plumes. All methods involve assumptions and uncertainties that we critically evaluate. A new evaluation is made of parental magma compositions that would crystallize olivines with the maximum forsterite contents observed in lava flows. These are generally in good agreement with primary magma compositions calculated using the mass balance method of Herzberg and O'Hara (2002), and differences reflect the well-known effects of fractional crystallization. Results of primary magma compositions we obtain for mid-ocean ridge basalts and various oceanic islands and plateaus generally favor the third type of model but with ambient mantle potential temperatures in the range 1280–1400°C and thermal anomalies that can be 200–300°C above this background. Our results are consistent with the plume model

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Section: Parental and Primary Magmas From Different Tectonic Environmmentioning

confidence: 99%

Temperatures in ambient mantle and plumes: Constraints from basalts, picrites, and komatiites

Herzberg

Asimow

Arndt

et al. 2007

Geochem Geophys Geosyst

629

449

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“…Komatiites have also been regarded as the products of volcanism in back arc basins (Upadhyay & Neale, 1979). There is clear evidence in Rhodesia, the Sahara and Canada of komatiites having erupted onto an older gneiss or granulite basement (Bickle et al, 1975;Chayka, 1976;Schwarz & Fujiwara, 1977). It is proposed also that komatiites form part of the volcanism of continental margins (Bickle et al, 1975) or gråbens (Nisbet et al, 1977;Naldrett & Turner, 1977), but since Schau (1977) has also observed komatiites with quartzites, they must also have erupted in stable environments.…”

Section: Discussionmentioning

confidence: 99%

“…Further finds of komatiites have been made in Rhodesia (Bickle et al, 1975), Australia (Nesbitt, 1971) Canada (Pyke et al, 1973), India (Dessai & Deshpande, 1979) and Greenland (McGregor & Mason, 1977), and they have also been observ-ed to exist in the Baltic Shield, both in the Soviet Union (Suslova, 1976) and in Finland (Mutanen, 1976).…”

Section: Introductionmentioning

confidence: 99%

Komatiitic and tholeiitic metavolcanics of the Siivikkovaara area in the Archean Kuhmo greenstone belt, eastern Finland

Hanski¹

1980

Bull Geol Soc Finland

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HANSKI, EERO 1980: Komatiitic and tholeiitic metavolcanics of the Siivikkovaara area in the Archean Kuhmo greenstone belt, eastern Finland. Bull. Geol. Soc. Finland 52, Komatiitic metavolcanics are abundant and well-preserved in the Siivikkovaara area, which lies in the middle part of the Archean Kuhmo greenstone belt. Together with the underlying tholeiites, these form the Kellojärvi Group, which is divided into two formations, those of Pahakangas and Siivikkovaara. The Pahakangas Formation consists of pillowed and massive metalavas and intercalated banded iron formations. The metalavas are chemically typical Archean low-potassium tholeiites. The overlying Siivikkovaara Formation has three subunits, the Siivikko, Mäkinen and Raivio Members. The metavolcanics of the Siivikko Member, which are mainly peridotitic komatiites (MgO ^ 18 °/o), have many structures typical of extrusive rocks, including breccias, pillows, spinifex textures and polygonal jointing. The microspinifex-textured rocks richest in magnesium contain about 20 °/o MgO. The Mäkinen Member consists of basaltic and pyroxenitic komatiites (MgO < 18 °/o), which occur in the form of variolitic pillow lavas. The Raivio Member is composed of ultramafic to mafic metatuffs. The spinifex textures in the Siivikkovaara area were originally formed by clinopyroxene. Zones Ai, A-z, Bi and BL > can be distinguished in the spinifex-textured lava flows, and Ao has further subunits dominated by dendritic, platy or acicular hornblende pseudomorphs after clinopyroxene. The liquid composition of the spinifextextured flows is deduced to be in the range of pyroxenitic komatiite. These flows are differentiated mainly by olivine and minor pyroxene and chromite precipitation. Albite in the spinifex-textured rocks is formed through sodium metasomatism caused by sea-water. There are many indicators to support the notion of a deep-sea origin for the lavas of the Kellojärvi Group. Despite the relatively low MgO content of the komatiites in the Siivikkovaara Formation, two nickel-copper occurences have been found in the formation.

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“…Le faciès coussiné, très fréquent dans les laves basaltiques, est plutôt rare dans les séquences komatiitiques (Arndt et al 1979) puisque la formation de coussins implique une viscosité un peu plus élevée. Les komatiites de Baby, tout comme celles de Belingwe (Bickle et al 1975) La présence des phénocristaux d'olivine augmente à la fois la viscosité de la lave, ainsi que la teneur en MgO de la roche totale, ce qui explique facilement la présence des komatiites à faciès coussiné dans le Groupe de Baby.…”

Section: Les Komatiites Et Les Basaltes Komatiitiauesunclassified

Les komatiites et tholeiites a la base du groupe de baby Temiscamingue

Mainville¹

1994

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Basaltic and peridotitic komatiites and stromatolites above a basal unconformity in the Belingwe greenstone belt, Rhodesia

Cited by 171 publications

References 10 publications

Temperatures in ambient mantle and plumes: Constraints from basalts, picrites, and komatiites

Temperatures in ambient mantle and plumes: Constraints from basalts, picrites, and komatiites

Komatiitic and tholeiitic metavolcanics of the Siivikkovaara area in the Archean Kuhmo greenstone belt, eastern Finland

Les komatiites et tholeiites a la base du groupe de baby Temiscamingue

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