Geoscience Systems: Modeling oxygen and carbon dioxide over the past 600 million years Robert A. Berner Yale University December 20, 2010

Atmosphere C Ocean C Soil C Biota C Gas exchange Terrestrial Photosynthesis Terrestrial Respiration Litter fall Root decay Calcification Degassing River transport Marine respiration Marine photosynthesis Short Term Carbon Cycle

Carbon Masses  FORM10 18 moles C  Sedimentary rock CaCO  Sedimentary rock CaMg(CO 3 )  Sedimentary organic carbon1250  Oceanic HCO CO  Soil organic carbon 0.3  Life 0.04  Atmospheric CO

Long Term Carbon Cycle Over millions of years HCO 3 -

Rock Carbonate C Rock Organic C Ocean Atmosphere Biota Soils C Carbonate C Burial Organic C Burial Volcanic, Metamorphic, Diagenetic Degassing Organic C Weathering Volcanic,Metamorphic, Diagenetic, Degassing Long Term Carbon Cycle Carbonate C Weathering

Weathering plus Sedimentation  CaSiO CO 2 + H 2 O ---> Ca HCO SiO 2 Ca HCO > CaCO 3 + CO 2 + H 2 O Overall Silicate Reaction CO 2 + CaSiO 3 ---> CaCO 3 + SiO 2

CO 2 Reactions Weathering and sedimentation CO 2 + (Ca,Mg)SiO  Ca,Mg)CO 3 + SiO 2 Metamorphism/volcanism/diagenesis (Ca.Mg)CO 3 + SiO 2 ---> CO 2 + (Ca,Mg)SiO 3 Organic matter burial CO 2 + H 2 O ---> CH 2 O + O 2 Organic matter weathering & metamorphism/volcanism/diagenesis CH 2 O + O 2 ---> CO 2 + H 2 O

Jacques Ebelmen Founder of long term C and S cycles

Mountain Building & Erosion Climate (T + pptn) Weathering Ca-Mg Silicates Volc/Met/Diag Degassing Weathering Org C CO 2 Land Plants Organic C sed. Burial Solar Radiation Long Term Long Term Ca-Mg carbonate burial +/- A B Continental drift +/- CO 2 System = Negative response

Surficial System C Mass Balance Fwc + Fmc + Fwg + Fmg = Fbc + Fbg  cFwc +  cFmc +  gFwg +  gFmg =  bcFbc +  bgFbg w = weathering; m= metamorphism: b= burial c = carbonate : g = organic matter  = measure of 13 C/ 12 C

Sedimentary Pyrite Formation and Weathering 2Fe 2 O Ca HCO SO O 2 + 4FeS CaCO 3 + 8H 2 O Organic Matter Burial and Weathering CO 2 + H 2 O CH 2 O + O 2 Controls on Atmospheric O 2

Rock Organic C Rock Carbonate C Rock Sulfide S Rock Sulfate S Oceanic Carbon and Sulfur Sulfide Burial (+O 2 ) CaSO 4 Burial Org C Burial (+O 2 ) CaCO 3 Burial Weathering ( - O 2 ) Weathering ( - O 2 ) Volc/met gas oxidation (-O 2 )Volc/met gas Isotope Mass Balance

SO 4 CaSO 4 dissolution

O2O2 Carbon Isotope fractionation  C Sulfur Isotope Fractionation  S Pyrite S burial Organic C burial Isotope Feedback for Atmospheric O 2 F borg F bpyr = K/ 

O2O2 Burial of Organic C Pyrite S Weathering of Organic C Pyrite S Uplift Sea level drop Rapid Recycling and O 2

Phanerozoic Oxygen

Weathering Organic C Organic C sed. Burial O2O2 Weathering Phosphorus Geological Forcing and Oxygen Volc-Met- Diagen Degassing Continental Relief and Erosion Weathering FeS 2 Burial

Animal Gigantism

Modern dragonfly

Land Plants Organic C sed. Burial O2O2 Plants, Fires and Oxygen Feedbacks Charcoal Fires Erosion

P Tr

Sulfate reduction H 2 S In air Land plants Plant-derived Organic burial O 2 in air O 2 In sea CO 2 In air Ocean stratification & anoxicity Ocean Temp. Volcanism a b c d e f g i j k h Permo-Triassic Extinction feedbacks

EFFECTS OF RISE AND SPREAD OF LARGE LAND PLANTS 1. Atmospheric CO 2 removal by increased silicate weathering 2. Additional CO 2 removal by increased burial of organic matter 3. Extra O 2 added to atmosphere by increased organic burial 4. CO 2 drop induced global cooling via the greenhouse effect 5. Elevated O 2 induced animal gigantism

Oxford University Press, 2004