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Hadean geodynamics inferred from time-varying 142Nd/144Nd in the early Earth rock record

N.S. Saji1,#,

1Centre for Star and Planet Formation, University of Copenhagen, Copenhagen, Denmark
#Now at: School of Earth and Ocean Sciences, Cardiff University, UK

K. Larsen1,

1Centre for Star and Planet Formation, University of Copenhagen, Copenhagen, Denmark

D. Wielandt1,

1Centre for Star and Planet Formation, University of Copenhagen, Copenhagen, Denmark

M. Schiller1,

1Centre for Star and Planet Formation, University of Copenhagen, Copenhagen, Denmark

M.M. Costa1,

1Centre for Star and Planet Formation, University of Copenhagen, Copenhagen, Denmark

M.J. Whitehouse2,

2Swedish Museum of Natural History, Stockholm, Sweden

M.T. Rosing3,

3Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark

M. Bizzarro1

1Centre for Star and Planet Formation, University of Copenhagen, Copenhagen, Denmark

Affiliations  |  Corresponding Author  |  Cite as  |  Funding information

Saji, N.S., Larsen, K., Wielandt, D., Schiller, M., Costa, M.M., Whitehouse, M.J., Rosing, M.T., Bizzarro, M. (2018) Hadean geodynamics inferred from time-varying 142Nd/144Nd in the early Earth rock record. Geochem. Persp. Let. 7, 43–48.

European Research Council (Consolidator grant 616027-STARDUST2ASTEROIDS to MB); Danish National Research Foundation (#DNRF97 to MB).

Geochemical Perspectives Letters v7  |  doi: 10.7185/geochemlet.1818
Received 02 March 2018  |  Accepted 23 July 2018  |  Published 5 September 2018
Copyright © The Authors

Published by the European Association of Geochemistry
under Creative Commons License CC BY-NC-ND 4.0




Figure 1 The μ142Nd composition relative to JNdi-1 for terrestrial rock standards and rocks from Isua Supracrustal Belt. Error bars for each sample indicate the internal errors (2 SE). The grey band for modern samples is the 2 SD external reproducibility (Saji et al., 2016

Saji, N.S., Wielandt, D., Paton, C., Bizzarro, M. (2016) Ultra-high-precision Nd-isotope measurements of geological materials by MC-ICPMS. Journal of Analytical Atomic Spectrometry 31, 1490-1504.

). The light purple band represent the weighted mean and 2σ uncertainty (MSWD = 0.9) of the Palaeoarchean (~3.4 Ga) samples whereas the light blue band represent the weighted mean and 2σ uncertainty (MSWD = 0.5) of the Eoarchean (3.7-3.8 Ga) samples.
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Figure 2 Two stage coupled 147,146Sm–142,143Nd systematics for ~3.75 Ga Isua amphibolites. Solid black lines are loci of constant model ages calculated with bulk silicate Earth parameters of μ142Nd = 0 and 147Sm/144Nd = 0.196. Dashed curves represent loci of constant time-integrated (147Sm/144Nd) source ratios. The red line is a linear regression for all samples and corresponds to a model age of 4390 ± 20 Ma. The Ujaraaluk data point is the mean of faux amphibolites from O’Neil et al. (2008)

O'Neil, J.,  Carlson, R.W.,  Francis, D.,  Stevenson, R.K. (2008) Neodymium-142 evidence for hadean mafic crust. Science 31, 1828-1831.

. The Saglek data point is the mean of Eoarchean amphibolites from Morino et al. (2017)

Morino, P.,  Caro, G.,  Reisberg, L.,  Schumacher, A. (2017) Chemical stratification in the post-magma ocean Earth inferred from coupled 146,147Sm-142,143Nd systematics in ultramafic rocks of the Saglek block (3.25–3.9 Ga; northern Labrador, Canada). Earth and Planetary Science Letters 463, 136-150.

. The Ukaliq data corresponds to enriched, boninitic and transitional mafic rocks as well as Voizel suite TTGs from Caro et al. (2017)

Caro, G., Morino, P., Mojzsis, S.J., Cates, N.L., Bleeker, W. (2017) Sluggish Hadean geodynamics: Evidence from coupled 146,147Sm–142,143Nd systematics in Eoarchean supracrustal rocks of the Inukjuak domain (Québec). Earth and Planetary Science Letters 457, 23-37.

. The ε143Nd (3.75 Ga) value for Isua amphibolites is from Moorbath et al. (1997)

Moorbath, S., Whitehouse, M.J., Kamber, B.S. Extreme (1997) Nd-isotope heterogeneity in the early Archaean-fact or fiction? Case histories from northern Canada and West Greenland. Chemical Geology 135, 213-231.

.
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Figure 3 μ142Nd evolution of the depleted mantle and complementary crust as calculated by a continually interacting crust-mantle box model. The different coloured curves correspond to crustal residence times between 500 to 4000 Myr. The evolution of Isua μ142Nd data is best fitted for residence times between 1000-2000 Myr. Sensitivity of the inferred residence times to model parameters is detailed in Table S-5. The Hadean crustal component identified in Eoarchean Ujaraaluk and Ukaliq units in Nuvvuagittuq Supracrustal Belt and Neoarchean North Easter Superior Province (NESP) granitoids are also in agreement with crustal residence time of 1000-2000 Myr (O’Neil et al., 2012

O’Neil, J., Carlson, R.W., Paquette, J. L., Francis, D. (2012) Formation age and metamorphic history of the Nuvvuagittuq Greenstone Belt. Precambrian Research 221, 23-24.

; Caro et al., 2017

Caro, G., Morino, P., Mojzsis, S.J., Cates, N.L., Bleeker, W. (2017) Sluggish Hadean geodynamics: Evidence from coupled 146,147Sm–142,143Nd systematics in Eoarchean supracrustal rocks of the Inukjuak domain (Québec). Earth and Planetary Science Letters 457, 23-37.

; O’Neil and Carlson, 2017

O’Neil, J., Carlson, R.W. (2017) Building Archean cratons from Hadean mafic crust. Science 355, 1199-1202.

). Inferred crustal residence times are also consistent within error with the μ142Nd data for Theo’s Flow (Debaille et al., 2013

Debaille, V., O’Neill, C., Brandon, A.D., Haenecour, P., Yin, Q., Mattielli, N., Trieman, A.H. (2013) Stagnant-lid tectonics in early Earth revealed by 142Nd variations in late Archean rocks. Earth and Planetary Science Letters 373, 83-92.

).
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Figure 4 A schematic diagram illustrating the evolution of Isua Hadean depleted mantle and proto-crust. The Hadean depleted mantle (DM) and proto-crust formed by primary differentiation at ~4.45-4.36 Ga following the Moon-forming event. The Hadean proto-crust acts as a stagnant-lid due to its buoyancy and is reworked and recycled into the mantle during large-scale deep mantle upwellings in a lid-overturn tectonic regime (Bédard, 2018

Bédard, J.H. (2018) Stagnant lids and mantle overturns: Implications for Archaean tectonics, magmagenesis, crustal growth, mantle evolution, and the start of plate tectonics. Geoscience Frontiers 9, 19-49.

). Basaltic magmatism thickens the oceanic crust (OC) and results in formation of continental crust (CC) by intra-crustal melting and ensures stabilisation of cratons with a depleted subcontinental lithospheric mantle (SCLM) keel. ISB amphibolites are derived in the Eoarchean from the convecting Hadean DM metasomatised by crust-derived fluids. The NSB rocks possibly formed during reworking of the Hadean proto-crust in mantle overturn episodes recycling portions of the crust into the mantle. Ameralik dykes form in the Palaeoarchean during a delamination episode triggering decompression melting of the Isua Hadean DM.
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