TY - JOUR
T1 - The grandest of them all
T2 - the Lomagundi-Jatuli Event and Earth's oxygenation
AU - Prave, A.R.
AU - Kirsimäe, K.
AU - Lepland, A.
AU - Fallick, A.E.
AU - Kreitsmann, T.
AU - Deines, Yu.E.
AU - Romashkin, A.E.
AU - Rychanchik, D.V.
AU - Medvedev, P.V.
AU - Moussavou, M.
AU - Bakakas, K.
AU - Hodgskiss, M.S.W.
N1 - Funding: K.K., A.L. and T.K. received funding from Estonian Science Agency Project PRG447 and Yu.D., A.R., D.R. and P.M. were supported by the state assignment of the Institute of Geology, Karelian Research Centre of the Russian Academy of Sciences.
PY - 2021/6/21
Y1 - 2021/6/21
N2 - The Paleoproterozoic Lomagundi–Jatuli Event (LJE) is generally
considered the largest, in both amplitude and duration, positive
carbonate C-isotope (δ13Ccarb) excursion in Earth
history. Conventional thinking is that it represents a global
perturbation of the carbon cycle between 2.3–2.1 Ga linked directly
with, and in part causing, the postulated rise in atmospheric oxygen
during the Great Oxidation Event. In addition to new high-resolution δ13Ccarb measurements from LJE-bearing successions of NW Russia, we compiled 14 943 δ13Ccarb
values obtained from marine carbonate rocks 3.0–1.0 Ga in age and from
selected Phanerozoic time intervals as a comparator of the LJE. Those
data integrated with sedimentology show that, contra to consensus, the δ13Ccarb
trend of the LJE is facies (i.e. palaeoenvironment) dependent.
Throughout the LJE interval, the C-isotope composition of open and
deeper marine settings maintained a mean δ13Ccarb value of +1.5 ± 2.4‰, comparable to those settings for most of Earth history. In contrast, the 13C-rich
values that are the hallmark of the LJE are limited largely to
nearshore-marine and coastal-evaporitic settings with mean δ13Ccarb values of +6.2 ± 2.0‰ and +8.1 ± 3.8‰, respectively. Our findings confirm that changes in δ13Ccarb are linked directly to facies changes and archive contemporaneous
dissolved inorganic carbon pools having variable C-isotopic
compositions in laterally adjacent depositional settings. The
implications are that the LJE cannot be construed a priori as
representative of the global carbon cycle or a planetary-scale
disturbance to that cycle, nor as direct evidence for oxygenation of the
ocean–atmosphere system. This requires rethinking models relying on
those concepts and framing new ideas in the search for understanding the
genesis of the grandest of all positive C-isotope excursions, its
timing and its hypothesized linkage to oxygenation of the atmosphere.
AB - The Paleoproterozoic Lomagundi–Jatuli Event (LJE) is generally
considered the largest, in both amplitude and duration, positive
carbonate C-isotope (δ13Ccarb) excursion in Earth
history. Conventional thinking is that it represents a global
perturbation of the carbon cycle between 2.3–2.1 Ga linked directly
with, and in part causing, the postulated rise in atmospheric oxygen
during the Great Oxidation Event. In addition to new high-resolution δ13Ccarb measurements from LJE-bearing successions of NW Russia, we compiled 14 943 δ13Ccarb
values obtained from marine carbonate rocks 3.0–1.0 Ga in age and from
selected Phanerozoic time intervals as a comparator of the LJE. Those
data integrated with sedimentology show that, contra to consensus, the δ13Ccarb
trend of the LJE is facies (i.e. palaeoenvironment) dependent.
Throughout the LJE interval, the C-isotope composition of open and
deeper marine settings maintained a mean δ13Ccarb value of +1.5 ± 2.4‰, comparable to those settings for most of Earth history. In contrast, the 13C-rich
values that are the hallmark of the LJE are limited largely to
nearshore-marine and coastal-evaporitic settings with mean δ13Ccarb values of +6.2 ± 2.0‰ and +8.1 ± 3.8‰, respectively. Our findings confirm that changes in δ13Ccarb are linked directly to facies changes and archive contemporaneous
dissolved inorganic carbon pools having variable C-isotopic
compositions in laterally adjacent depositional settings. The
implications are that the LJE cannot be construed a priori as
representative of the global carbon cycle or a planetary-scale
disturbance to that cycle, nor as direct evidence for oxygenation of the
ocean–atmosphere system. This requires rethinking models relying on
those concepts and framing new ideas in the search for understanding the
genesis of the grandest of all positive C-isotope excursions, its
timing and its hypothesized linkage to oxygenation of the atmosphere.
KW - Lomagundi-Jatuli Event
KW - Palaeoproterozoic
KW - Carbon isotope excursions
KW - Great Oxidation Event
U2 - 10.1144/jgs2021-036
DO - 10.1144/jgs2021-036
M3 - Article
SN - 0016-7649
VL - Online First
JO - Journal of the Geological Society
JF - Journal of the Geological Society
M1 - jgs2021-036
ER -