Timing and tempo of the Great Oxidation Event.
The first significant buildup in atmospheric oxygen, the Great Oxidation Event (GOE), began in the early Paleoproterozoic in association with global glaciations and continued until the end of the Lomagundi carbon isotope excursion ca. 2,060 Ma. The exact timing of and relationships among these events are debated because of poor age constraints and contradictory stratigraphic correlations. Here, we show that the first Paleoproterozoic global glaciation and the onset of the GOE occurred between ca. 2,460 and 2,426 Ma, ∼100 My earlier than previously estimated, based on an age of 2,426 ± 3 Ma for Ongeluk Formation magmatism from the Kaapvaal Craton of southern Africa. This age helps define a key paleomagnetic pole that positions the Kaapvaal Craton at equatorial latitudes of 11° ± 6° at this time. Furthermore, the rise of atmospheric oxygen was not monotonic, but was instead characterized by oscillations, which together with climatic instabilities may have continued over the next ∼200 My until ≤2,250-2,240 Ma. Ongeluk Formation volcanism at ca. 2,426 Ma was part of a large igneous province (LIP) and represents a waning stage in the emplacement of several temporally discrete LIPs across a large low-latitude continental landmass. These LIPs played critical, albeit complex, roles in the rise of oxygen and in both initiating and terminating global glaciations. This series of events invites comparison with the Neoproterozoic oxygen increase and Sturtian Snowball Earth glaciation, which accompanied emplacement of LIPs across supercontinent Rodinia, also positioned at low latitude.
Department of Geology, Lund University, Lund 223 62, Sweden; ashley.gumsley@geol.lu.se.
Ashley P
0000-0003-1395-3065
AP
Gumsley
Department of Geology and Geophysics, University of Wyoming, Laramie, WY 82071.|Faculty of Geology and Geography, Tomsk State University, Tomsk 634050, Russia.
Kevin R
KR
Chamberlain
Geological Survey of Canada, Ottawa, ON K1A 0E8, Canada.
Wouter
W
Bleeker
Department of Geology, Lund University, Lund 223 62, Sweden.|Department of Geosciences, Swedish Museum of Natural History, Stockholm 104 05, Sweden.
Ulf
U
Söderlund
Department of Geology, University of Johannesburg, Auckland Park 2006, South Africa.
Michiel O
MO
de Kock
Department of Geology, Lund University, Lund 223 62, Sweden.
Emilie R
ER
Larsson
Department of Earth Sciences, University of California, Riverside, CA 92521.|Department of Geology, University of Johannesburg, Auckland Park 2006, South Africa.
Andrey
A
Bekker
Great Oxidation Event; Kaapvaal Craton; Paleoproterozoic; Snowball Earth; Transvaal Supergroup