Were ancient granitoid compositions influenced by contemporaneous atmospheric and hydrosphere oxidation states?
Article first published online: 29 OCT 2012
© 2012 Blackwell Publishing Ltd
Volume 25, Issue 2, pages 95–101, April 2013
How to Cite
Terra Nova, 25, 95–101, 2013
- Issue published online: 11 MAR 2013
- Article first published online: 29 OCT 2012
- Accepted manuscript online: 24 SEP 2012 10:36PM EST
- Received 4 January 2012; revised version accepted 20 September 2012
Terra Nova, 00, 1–7, 2012
A feedback loop between subducted oceanic plate composition, subduction zone processes, arc magma chemistry, and the newly formed continental crust composition links to atmospheric and hydrosphere oxidation conditions through the low temperature weathering mechanisms of seafloor basalts. Sea-floor weathering and the Na/K of the altered oceanic crust strongly depends on f(O2) conditions during alteration, that changed with earth history. The rise of oxygen at ∼2600–2400 Ma triggered associated changes in f(O2) seafloor alteration conditions providing a possible explanation for the observed change from the Na-rich tonalite-trondhjemite-granodiorite (TTG) rocks in the Archean to the K-rich granodiorite-granite (GG) granitoids in post-Archean times.