Authigenic carbonate and the history of the global carbon cycle.
We present a framework for interpreting the carbon isotopic composition of sedimentary rocks, which in turn requires a fundamental reinterpretation of the carbon cycle and redox budgets over Earth's history. We propose that authigenic carbonate, produced in sediment pore fluids during early diagenesis, has played a major role in the carbon cycle in the past. This sink constitutes a minor component of the carbon isotope mass balance under the modern, high levels of atmospheric oxygen but was much larger in times of low atmospheric O(2) or widespread marine anoxia. Waxing and waning of a global authigenic carbonate sink helps to explain extreme carbon isotope variations in the Proterozoic, Paleozoic, and Triassic.
Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USA. daniel_schrag@harvard.edu
Daniel P
DP
Schrag
John A
JA
Higgins
Francis A
FA
Macdonald
David T
DT
Johnston
D000693:Anaerobiosis; D001272:Atmosphere / Q000737:chemistry; D057486:Carbon Cycle; D002247:Carbon Isotopes / Q000032:analysis*; D002254:Carbonates / Q000737:chemistry*; D019015:Geologic Sediments / Q000737:chemistry*; D008697:Methane / Q000737:chemistry; D010084:Oxidation-Reduction; D010100:Oxygen / Q000032:analysis
D002247:Carbon Isotopes; D002254:Carbonates; D008697:Methane; D010100:Oxygen