Emplacement conditions of komatiite magmas from the 3.49 Ga Komati Formation, Barberton Greenstone Belt, South Africa

Parman, S. W.; Dann, Jesse C.; Grove, T. L.; Wit, Maarten J. de

doi:10.1016/s0012-821x(97)00104-0

Cited by 236 publications

(85 citation statements)

References 35 publications

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“…In addition, stable isotope analyses suggest a MOR basalt protolith for the eclogites, providing further evidence for a subduction-zone source for the eclogites. This evidence that subduction processes were involved in earliest craton formation is buttressed by laboratory petrological experiments (Parman et al 1997(Parman et al ,2001Grove et al 2000). Those studies show that the high-MgO komatiite magmas of the Kaapvaal probably formed within an Archaean subduction zone via a single melt generation process similar to that by which high Mg-number boninites are formed in very young modern subduction zones.…”

Section: Primary Results From Geochemistry and Petrologymentioning

confidence: 86%

“…The mafic and ultramafic volcanic rocks of the Barberton region have been interpreted by de Wit and coworkers de Wit & Hart 1993) as the products of midocean ridge (MOR) magmatism, preserved by subsequent obduction onto an arc-like terrane. Recent field studies combined with laboratory experiments suggest, however, that the Barberton komatiites and associated basalts were the products of wet melting in an Archaean subduction zone, a process that can also lead to high degrees of depletion in the upper mantle (Parman et al 1997(Parman et al , 2001Grove et al 2000).…”

Section: Cratonsmentioning

confidence: 99%

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Formation and evolution of Archaean cratons: insights from southern Africa

James

Fouch

2002

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Archaean cratons are the stable remnants of Earth's early continental lithosphere, and their structure, composition and survival over geological time make them unique features of the Earth's surface. The Kaapvaal Project of southern Africa was organized around a broadly diverse scientific collaboration to investigate fundamental questions of craton formation and mantle differentiation in the early Earth. The principal aim of the project was to characterize the physical and chemical nature of the crust and mantle of the cratons of southern Africa in geological detail, and to use the 3D seismic and geochemical images of crustal and mantle heterogeneity to reconstruct the assembly history of the cratons. Seismic results confirm that the structure of crust and tectospheric mantle of the cratons differs significantly from that of post-Archaean terranes. Three-dimensional body-wave tomographic images reveal that high-velocity mantle roots extend to depths of at least 200 kin, and locally to depths of 250 300 km beneath cratonic terranes. No low-velocity channel has been identified beneath the cratonic root. The Kaapvaal Craton was modified approximately 2.05Ga by the Bushveld magmatic event, and the mantle beneath the Bushveld Province is characterized by relatively low seismic velocities. The crust beneath undisturbed Archaean craton is relatively thin (c. 35-40km), unlayered and characterized by a strong velocity contrast across a sharp Moho, whereas post-Archaean terranes and Archaean regions disrupted by large-scale Proterozoic magmatic or tectonic events are characterized by thicker crust, complex Moho structure and higher seismic velocities in the lower crust. A review of Re Os depletion model age determinations confirms that the mantle root beneath the cratons is Archaean in age. The data show also that there is no apparent age progression with depth in the mantle keel, indicating that its thickness has not increased over geological time. Both laboratory experiments and geochemical results from eclogite xenoliths suggest that subduction processes played a central role in the formation of Archaean crust, the melt depletion of Archaean mantle and the assembly of early continental lithosphere. Co-ordinated geochronological studies of crustal and mantle xenoliths have revealed that both crust and mantle have experienced a multi-stage history. The lower crust in particular retains a comprehensive record of the tectonothermal evolution of the lithosphere. Analysis of lower-crustal xenoliths has shown that much of the deep craton experienced a dynamic and protracted history of tectonothermal activity that is temporally associated with events seen in the surface record. Cratonization thus occurred not as a discrete event, but in stages, with final stabilization postdating crustal formation.

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Section: Primary Results From Geochemistry and Petrologymentioning

confidence: 86%

Section: Cratonsmentioning

confidence: 99%

Formation and evolution of Archaean cratons: insights from southern Africa

James

Fouch

2002

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“…The accretion of oceanic volcanic arcs may explain a geochemical similarity between some komatiites and modern arc related volcanic rocks. Lines of petrographic evidence indicate a substantial water content in some komatiite magmas (Parman et al, 1997;Stone et al, 1997;Shimizu et al, 2001), which suggests wet melting for komatiite magmas. The high water content in some komatiite magmas has led to the proposal that these komatiites were formed by a subduction related melting process.…”

Section: Tectonic Setting Inferred For Basaltic Komatiitementioning

confidence: 99%

Petrology and geochemistry of metamorphosed basaltic pillow lava and basaltic komatiite in the Mauranipur area: subduction related volcanism in the Archean Bundelkhand craton, Central India

Malviya

Arima

Pati

et al. 2006

Journal of Mineralogical and Petrological Sciences

102

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The occurrence of metamorphosed basaltic pillow lava in close association with serpentinized ultramafic rock, metamorphosed basaltic komatiite, volcaniclastic metasediment, and banded iron formation (BIF) in the Mauranipur area is the first explicit evidence for subduction related submarine volcanism in the Archean Bundelkhand craton, Central India. The Mauranipur pillow lava underwent greenschist to amphibolite facies metamorphism while retaining a geochemical signature of its igneous protolith. The pillow lava and associated massive volcanic rock is subalkalic, low − K tholeiitic basalt to basaltic andesite with SiO 2 = 51.9 − 55.9 wt% and Mg/(Mg + Fe .44, and depicts a nearly flat chondrite normalized HREE pattern with a low MREE/HREE ratio (Gd/Yb) N = 1.24 − 1.58. The basaltic komatiite displays remarkably similar geochemical characteristics to modern boninite. The present study, combined with available geological data, suggests that the supracrustal rocks of the Mauranipur area represent an Archean ophiolite sequence formed in a plate convergent setting.

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“…They are often considered to be windows to secular development of dynamic mantle (Mole et al 2014) and are fundamental to our understanding of the thermal, chemical, and tectonic evolution of the early Earth. Since the discovery of komatiites in South Africa (Viljoen and Viljoen 1969), numerous studies conducted on komatiites from southern Africa, Canada, Australia, India, Finland, and Brazil (Jahn et al 1980(Jahn et al , 1982Barnes et al 1988;Arndt 1994;Hill et al 1995;Lesher and Arndt 1995;Fan and Kerrich 1997;Grove et al 1997;Parman et al 1997;Polat et al 1999;Polat and Kerrich 2000;Chavagnac 2004;Barnes 2006b;Arndt et al 2008;Jayananda et al 2008;Dostal and Mueller 2012;Furnes et al 2013;Maier et al 2013), together with experimental works (Ohtani et al 1989;Herzberg and O'Hara 1998), have greatly contributed to our understanding of the origin of both komatiite magmas and Archaean mantle. However, the tectonic context of magma generation and eruption of komatiite magmas is still not fully resolved (Polat et al 1999;Arndt 2003;Parman et al 2004;Arndt et al 2008) although most workers consider komatiite magmas to have originated from anomalously hot mantle upwellings (Nesbit et al 1993, Herzberg 1995Arndt et al 2008), probably analogous to modern mantle plumes.…”

Section: Introductionmentioning

confidence: 99%

Physical volcanology and geochemistry of Palaeoarchaean komatiite lava flows from the western Dharwar craton, southern India: implications for Archaean mantle evolution and crustal growth

Jayananda

Duraiswami

Aadhiseshan

et al. 2016

International Geology Review

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Palaeoarchaean (3.38-3.35 Ga) komatiites from the Jayachamaraja Pura (J.C. Pura) and Banasandra greenstone belts of the western Dharwar craton, southern India were erupted as submarine lava flows. These high-temperature (1450-1550°C), low-viscosity lavas produced thick, massive, polygonal jointed sheet flows with sporadic flow top breccias. Thick olivine cumulate zones within differentiated komatiites suggest channel/conduit facies. Compound, undifferentiated flow fields developed marginal-lobate thin flows with several spinifex-textured lobes. Individual lobes experienced two distinct vesiculation episodes and grew by inflation. Occasionally komatiite flows form pillows and quench fragmented hyaloclastites. J.C. Pura komatiite lavas represent massive coherent facies with minor channel facies, whilst the Bansandra komatiites correspond to compound flow fields interspersed with pillow facies. The komatiites are metamorphosed to greenschist facies and consist of serpentine-talc ± carbonate, actinolite-tremolite with remnants of primary olivine, chromite, and pyroxene. The majority of the studied samples are komatiites (22.46-42.41 wt.% MgO) whilst a few are komatiitic basalts (12.94-16.18 wt.% MgO) extending into basaltic (7.71 -10.80 wt.% MgO) composition. The studied komatiites are Al-depleted Barberton type whilst komatiite basalts belong to the Al-undepleted Munro type. Trace element data suggest variable fractionation of garnet, olivine, pyroxene, and chromite. Incompatible element ratios (Nb/Th, Nb/U, Zr/Y Nb/Y) show that the komatiites were derived from heterogeneous sources ranging from depleted to primitive mantle. CaO/Al 2 O 3 and (Gd/Yb) N ratios show that the Al-depleted komatiite magmas were generated at great depth (350-400 km) by 40-50% partial melting of deep mantle with or without garnet (majorite?) in residue whilst komatiite basalts and basalts were generated at shallow depth in an ascending plume. The widespread Palaeoarchaean deep depleted mantle-derived komatiite volcanism and sub-contemporaneous TTG accretion implies a major earlier episode of mantle differentiation and crustal growth during ca. 3.6-3.8 Ga.ARTICLE HISTORY

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Emplacement conditions of komatiite magmas from the 3.49 Ga Komati Formation, Barberton Greenstone Belt, South Africa

Cited by 236 publications

References 35 publications

Formation and evolution of Archaean cratons: insights from southern Africa

Formation and evolution of Archaean cratons: insights from southern Africa

Petrology and geochemistry of metamorphosed basaltic pillow lava and basaltic komatiite in the Mauranipur area: subduction related volcanism in the Archean Bundelkhand craton, Central India

Physical volcanology and geochemistry of Palaeoarchaean komatiite lava flows from the western Dharwar craton, southern India: implications for Archaean mantle evolution and crustal growth

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