Abstract
Reconstructing the emergence and weathering of continental crust in the Archaean eon is crucial for our understanding of early ocean chemistry, biosphere evolution and the onset of plate tectonics. However, considerable disagreement exists between elemental and isotopic proxies that have been used to trace crustal input into marine sediments, and data are scarce before 3 Ga. Here we show that chemical weathering modified the Sr isotopic composition of seawater as recorded in 3.52–3.20 Ga stratiform barite deposits from three different cratons. Using a combination of Sr, S and O isotope data, barite petrography and a hydrothermal mixing model, we calculate a Sr isotope evolution trend of Palaeoarchaean seawater that is much more radiogenic than the curve previously determined from carbonate rocks. Our findings suggest that evolved crust containing high Rb/Sr was subaerial and weathering into the oceans from approximately 3.7 ± 0.15 Ga onwards with impacts on ocean chemistry and the nutrient supply to the marine biosphere.
| Original language | English |
|---|---|
| Pages (from-to) | 227-232 |
| Number of pages | 6 |
| Journal | Nature Geoscience |
| Volume | 15 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - 24 Feb 2022 |
Bibliographical note
Funding Information:We thank A. Hoffman (University of Johannesburg, South Africa) for Sargur barite samples, S. H. Dundas for ICP-MS analyses, and J. Hoek and J. Farquhar (University of Maryland, United States) for multiple S isotope analyses. A. Beinlich, D. van Hinsbergen, H. Tsikos and M. van Zuilen are thanked for critically reading through an earlier version of the manuscript and providing constructive comments. This research was funded by the Research Council of Norway through the Centre for Geobiology (grant number 179560, D.L.R.), and fieldwork in South Africa was supported by the Dr Schürmann Foundation (grant number 46/2007 and 132/2018, P.R.D.M.).
Funding Information:
We thank A. Hoffman (University of Johannesburg, South Africa) for Sargur barite samples, S. H. Dundas for ICP-MS analyses, and J. Hoek and J. Farquhar (University of Maryland, United States) for multiple S isotope analyses. A. Beinlich, D. van Hinsbergen, H. Tsikos and M. van Zuilen are thanked for critically reading through an earlier version of the manuscript and providing constructive comments. This research was funded by the Research Council of Norway through the Centre for Geobiology (grant number 179560, D.L.R.), and fieldwork in South Africa was supported by the Dr Sch?rmann Foundation (grant number 46/2007 and 132/2018, P.R.D.M.).
Publisher Copyright:
© 2022, The Author(s), under exclusive licence to Springer Nature Limited.
Funding
We thank A. Hoffman (University of Johannesburg, South Africa) for Sargur barite samples, S. H. Dundas for ICP-MS analyses, and J. Hoek and J. Farquhar (University of Maryland, United States) for multiple S isotope analyses. A. Beinlich, D. van Hinsbergen, H. Tsikos and M. van Zuilen are thanked for critically reading through an earlier version of the manuscript and providing constructive comments. This research was funded by the Research Council of Norway through the Centre for Geobiology (grant number 179560, D.L.R.), and fieldwork in South Africa was supported by the Dr Schürmann Foundation (grant number 46/2007 and 132/2018, P.R.D.M.). We thank A. Hoffman (University of Johannesburg, South Africa) for Sargur barite samples, S. H. Dundas for ICP-MS analyses, and J. Hoek and J. Farquhar (University of Maryland, United States) for multiple S isotope analyses. A. Beinlich, D. van Hinsbergen, H. Tsikos and M. van Zuilen are thanked for critically reading through an earlier version of the manuscript and providing constructive comments. This research was funded by the Research Council of Norway through the Centre for Geobiology (grant number 179560, D.L.R.), and fieldwork in South Africa was supported by the Dr Sch?rmann Foundation (grant number 46/2007 and 132/2018, P.R.D.M.).
