A reviewof temporal constraints for the Palaeoproterozoic large, positive carbonate carbon isotope excursion (the Lomagundi-Jatuli Event)

摘要

The Palaeoproterozoic Lomagundi-Jatuli Event is one of the largest magnitude and earliest known positive carbonate carbon isotope excursions, preserving δ~(13)C values between +5 and +16‰ and even higher. It is recorded in sedimentary rocks on all continents bar Antarctica and spans stratigraphic thicknesses ranging fromseveral tomany tens ofmetres. This unique positive δ~(13)C interval signals fundamental changes in the global carbon cycle and is a key event in Earth system evolution following oxygenation of Earth's atmosphere. Here we present a comprehensive reviewof the age constraints on the Lomagundi-Jatuli Event, the first such effort in two decades. This newchronology compilation focuses on the U-Pb and Re-Os chronometers and demonstrates that global synchronicity of the Lomagundi-Jatuli Event is permissible, an interpretation supported by the apparent wide dispersion of Lomagundi-Jatuli Event-bearing successions in the most recent Palaeoproterozoic plate reconstructions. Assuming the Lomagundi-Jatuli Event is synchronous worldwide, then the bounds on its duration range from a maximum of 249 ± 9 Myr (2306 ± 9 Ma to 2057 ± 1 Ma) to a minimum of 128 ± 9.4 Myr (2221 ± 5 Ma to 2106 ± 8 Ma).