Inherited 142Nd anomalies in Eoarchean protoliths

Roth, Antoine S. G.; Bourdon, Bernard; Mojzsis, Stephen J.; Touboul, M.; Sprung, P.; Guitreau, Martin; Blichert‐Toft, Janne

doi:10.1016/j.epsl.2012.11.023

Cited by 93 publications

(74 citation statements)

References 30 publications

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“…Stan Hart observed this common end-member in the isotopic ratio space and named it FOZO for focal zone (Hart et al, 1992). Boyet et al, 2003;Caro et al, 2003;Boyet and Carlson, 2005) and negative 142 Nd in similarly ancient samples from Nuvvuagituk, Quebec (O 'Neil et al, 2008;Roth et al, 2013), compared to homogenous present day mantle-derived samples. This suggests an efficient mixing by convection of all primordial isotopic heterogeneities produced by melting during the Hadean.…”

Section: Relationship With Lithophile Elements and The Question Of A mentioning

confidence: 99%

Noble gas constraints on the origin and evolution of Earth’s volatiles

Moreira¹

2013

GeochemPersp

107

163

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Section: Relationship With Lithophile Elements and The Question Of A mentioning

confidence: 99%

Noble gas constraints on the origin and evolution of Earth’s volatiles

Moreira¹

2013

GeochemPersp

107

163

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“…This could have formed only early in the Hadean when the parent isotope 146 Sm was extant. However, Roth et al [102] were unable to replicate these 142 Nd/ 144 Nd measurements.…”

Section: (D) Non-standard Gabbroic Mush Ocean With Platesmentioning

confidence: 95%

Terrestrial aftermath of the Moon-forming impact

Sleep

Zahnle

Lupu

2014

Phil. Trans. R. Soc. A.

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Much of the Earth's mantle was melted in the Moon-forming impact. Gases that were not partially soluble in the melt, such as water and CO 2 , formed a thick, deep atmosphere surrounding the post-impact Earth. This atmosphere was opaque to thermal radiation, allowing heat to escape to space only at the runaway greenhouse threshold of approximately 100 W m −2 . The duration of this runaway greenhouse stage was limited to approximately 10 Myr by the internal energy and tidal heating, ending with a partially crystalline uppermost mantle and a solid deep mantle. At this point, the crust was able to cool efficiently and solidified at the surface. After the condensation of the water ocean, approximately 100 bar of CO 2 remained in the atmosphere, creating a solar-heated greenhouse, while the surface cooled to approximately 500 K. Almost all this CO 2 had to be sequestered by subduction into the mantle by 3.8 Ga, when the geological record indicates the presence of life and hence a habitable environment. The deep CO 2 sequestration into the mantle could be explained by a rapid subduction of the old oceanic crust, such that the top of the crust would remain cold and retain its CO 2 . Kinematically, these episodes would be required to have both fast subduction (and hence seafloor spreading) and old crust. Hadean oceanic crust that formed from hot mantle would have been thicker than modern crust, and therefore only old crust underlain by cool mantle lithosphere could subduct. Once subduction started, the basaltic crust would turn into dense eclogite, increasing the rate of subduction. The rapid subduction would stop when the young partially frozen crust from the rapidly spreading ridge entered the subduction zone.

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“…Alternatively, such highly depleted mantle reservoirs were attributed to early global differentiation of silicate earth by Boyet and Carlson (2005). More recent studies also document the existence of terrestrial crust as old as 4.37 Ga (Holden et al 2009;Iizuka et al 2011;Roth et al 2013). Consequently the above arguments suggest that the Palaeoarchaean mantle was highly heterogeneous but generally variably depleted.…”

Section: Implications For the Archaean Mantlementioning

confidence: 96%

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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Inherited 142Nd anomalies in Eoarchean protoliths

Cited by 93 publications

References 30 publications

Noble gas constraints on the origin and evolution of Earth’s volatiles

Noble gas constraints on the origin and evolution of Earth’s volatiles

Terrestrial aftermath of the Moon-forming impact

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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