TY - JOUR
T1 - Evolution of the Cenozoic carbon cycle
T2 - the roles of tectonics and CO2 fertilization
AU - Li, Gaojun
AU - Ji, Junfeng
AU - Chen, Jun
AU - Kemp, David B
PY - 2009/3
Y1 - 2009/3
N2 - Cenozoic carbon fluxes associated with rock weathering, sediment burial, and volcanic degassing are calculated from the mass balance equations coupling marine isotopic records of carbon (both organic and inorganic), strontium, and osmium. The result is confirmed by the good match between modeled carbonate sedimentation rates and carbonate sedimentation rates previously integrated from ocean basins worldwide. The coevolution between weathering and burial of carbonate suggests that marine carbonate accumulation was regulated mainly by the recycling of carbonate rocks, which mediated the bicarbonate ion concentration of the oceans. A reduction in CO2 effusion to the atmosphere caused by reduced volcanic degassing from 52 to 15 Ma and tectonically enhanced organic rock exhumation since 15 Ma is also observed. These changes in CO2 effusion are balanced by concomitant changes in CO2 sequestration by silicate weathering and organic carbon burial. Importantly, we demonstrate a clear decoupling of modeled silicate weathering rates from global climate over the last ∼15 Ma. This observation is inconsistent with temperature-mediated mineral dissolution acting as the key mechanism facilitating the CO2 silicate weathering feedback process. However, we instead observe a clear coupling (positive correlation) between modeled silicate weathering, organic carbon burial, and atmospheric CO 2 concentration. We suggest that CO2 fertilization effects on terrestrial biomass productivity and plant weathering could have represented a major negative feedback process helping to balance atmospheric CO 2, at least during the Cenozoic ice house periods.
AB - Cenozoic carbon fluxes associated with rock weathering, sediment burial, and volcanic degassing are calculated from the mass balance equations coupling marine isotopic records of carbon (both organic and inorganic), strontium, and osmium. The result is confirmed by the good match between modeled carbonate sedimentation rates and carbonate sedimentation rates previously integrated from ocean basins worldwide. The coevolution between weathering and burial of carbonate suggests that marine carbonate accumulation was regulated mainly by the recycling of carbonate rocks, which mediated the bicarbonate ion concentration of the oceans. A reduction in CO2 effusion to the atmosphere caused by reduced volcanic degassing from 52 to 15 Ma and tectonically enhanced organic rock exhumation since 15 Ma is also observed. These changes in CO2 effusion are balanced by concomitant changes in CO2 sequestration by silicate weathering and organic carbon burial. Importantly, we demonstrate a clear decoupling of modeled silicate weathering rates from global climate over the last ∼15 Ma. This observation is inconsistent with temperature-mediated mineral dissolution acting as the key mechanism facilitating the CO2 silicate weathering feedback process. However, we instead observe a clear coupling (positive correlation) between modeled silicate weathering, organic carbon burial, and atmospheric CO 2 concentration. We suggest that CO2 fertilization effects on terrestrial biomass productivity and plant weathering could have represented a major negative feedback process helping to balance atmospheric CO 2, at least during the Cenozoic ice house periods.
UR - http://www.scopus.com/inward/record.url?scp=67249122253&partnerID=8YFLogxK
U2 - 10.1029/2008GB003220
DO - 10.1029/2008GB003220
M3 - Article
AN - SCOPUS:67249122253
SN - 0886-6236
VL - 23
JO - Global Biogeochemical Cycles
JF - Global Biogeochemical Cycles
IS - 1
M1 - GB1009
ER -