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Onset of new, progressive crustal growth in the central Slave craton at 3.55 Ga

J.R. Reimink1,

1Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington DC, 20015, USA

D.G. Pearson2,

2Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB, Canada T6G2E3

S.B. Shirey1,

1Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington DC, 20015, USA

R.W. Carlson1,

1Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington DC, 20015, USA

J.W.F. Ketchum3

3Northwest Territories Geological Survey, Yellowknife, NT, Canada X1A1K3

Affiliations  |  Corresponding Author  |  Cite as  |  Funding information

Reimink, J.R., Pearson, D.G., Shirey, S.B., Carlson, R.W., Ketchum, J.W.F. (2019) Onset of new, progressive crustal growth in the central Slave craton at 3.55 Ga. Geochem. Persp. Let. 10, 8–13.

Research funded by NSF-OCE 1524384.

Geochemical Perspectives Letters v10  |  doi: 10.7185/geochemlet.1907
Received 1 November 2018  |  Accepted 20 February 2019  |  Published 28 March 2019
Copyright © The Authors

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




Figure 1 Geologic map of the Slave craton highlighting the major domains that contain basement gneisses. Map modified from St. Onge et al. (1988)

St. Onge, M.R., King, J.E., Lalonde, A.E. (1988) Geology, East - Central Wopmay Orogen, District of Mackenzie, Northwest Territories. Geological Survey of Canada, Open File 1923, doi: 10.4095/130452.

; Bleeker et al. (1999a

Bleeker, W., Ketchum, J.W., Davis, W.J. (1999a) The Central Slave Basement Complex, Part II: age and tectonic significance of high-strain zones along the basement-cover contact. Canadian Journal of Earth Sciences 36, 1111–1130

,b

Bleeker, W., Ketchum, J.W., Jackson, V.A., Villeneuve, M.E. (1999b) The Central Slave Basement Complex, Part I: its structural topology and autochthonous cover. Canadian Journal of Earth Sciences 36, 1083–1109.

). Major basement complexes are shown along with crustal province boundaries inferred from Nd and Pb isotope data (Davis and Hegner, 1992

Davis, W.J., Hegner, E. (1992) Neodymium isotopic evidence for the tectonic assembly of Late Archean crust in the Slave Province, northwest Canada. Contributions to Mineralogy and Petrology 111, 493–504.

; Thorpe et al., 1992

Thorpe, R.I., Cumming, G.L., Mortensen, J.K. (1992) A Significant Pb Isotope Boundary in the Slave Province and Its Probable Relation To Ancient Basement in the western Slave Province. Geological Survey of Canada, Open File 2484, 179–184, doi:10.4095/133349.

). Red stars indicate key locations sampled in this study and coloured circles are locations where detrital zircons have been analysed for their U-Pb-Hf systematics as described in Figure 3 and the Supplementary Information.
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Figure 2 (a) Molar K-Na-Ca diagram. Orange squares are CSBC samples from this study. Green symbols are <3.6 Ga samples from the Acasta Gneiss Complex, small squares are samples measured by Reimink et al. (2016b)

Reimink, J.R., Davies, J.H.F.L., Chacko, T., Stern, R.A., Heaman, L.M., Sarkar, C., Schaltegger, U., Creaser, R.A., Pearson, D.G. (2016b) No evidence for Hadean continental crust within Earth’s oldest evolved rock unit. Nature Geoscience 9, 777–780.

and dark green circles are samples added in this study. Contour density fields are high pressure TTGs (black), medium pressure TTGs (medium grey), low pressure TTGs (light grey), and potassic Archean grey gneisses (pink). Data used to construct these fields are taken from Moyen (2011)

Moyen, J.-F. (2011) The composite Archaean grey gneisses: Petrological significance, and evidence for a non-unique tectonic setting for Archaean crustal growth. Lithos 123, 21–36.

. The blue field outlines sodic trondhjemites. (b) La/Yb versus Sr/Y for rocks from the Slave basement gneisses. Symbols as in (a).
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Figure 3 Zircon Hf isotope data from Slave basement gneisses. Orange symbols are analyses from the CSBC, blue are new analyses from the AGC, grey diamonds are a compilation of Acasta Hf isotope data (sources in the text), and small circles are single detrital zircon analyses from sediments of the Slave Craton Cover Group sequence (Pietranik et al., 2008

Pietranik, A.B., Hawkesworth, C.J., Storey, C.D., Kemp, A.I.S., Sircombe, K.N., Whitehouse, M.J., Bleeker, W. (2008) Episodic, mafic crust formation from 4.5 to 2.8 Ga: New evidence from detrital zircons, Slave craton, Canada. Geology 36, 875–878.

). Note that detrital zircon analyses are grouped by sediment location (see Supplementary Information). Grey field is the evolution of Hadean mafic protocrust, while orange and blue lines show our interpretations (sloped lines for time-integrated isotope evolution, vertical lines for mixing) for systematic petrogenetic differences between the two portions of the Slave basement gneisses. The Archean depleted mantle evolution line shown here is the connector line between a chondritic source at 4.4 Ga and modern MORB εHf values of +17. Calculated with respect to this model evolution for the depleted mantle, the inset shows the maximum crustal residence times (depleted mantle model ages calculated using a source 176Lu/177Hf of 0.015, and then subtracting the U-Pb crystallisation age from this model age) for all Slave craton Hf isotope data. The transition from long to short crustal residence times occurs at 3.6 Ga.
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