labs_title

Caldeira Lab Research:Paleoclimate and geochemical cycles

Major perturbation of ocean chemistry and a "Strangelove Ocean" after the end-Permian mass extinction

Michael R. Rampino & Ken Caldeira

Following the end-Permian mass extinction, there was a fast moving 3% reduction in the carbon isotope 13C that continued for 500,000 years. Comparisons between a model and measured 13C levels following the extinction suggest that such a change in ocean chemistry could have been caused by a cessation of ocean productivity.


Rampino, M.R., and K. Caldeira, Major perturbation of ocean chemistry and a “Strangelove Ocean” after the end-Permian mass extinction, Terra Nova 17 (6) 554-559, 2005.

Atmospheric CO2 and carbonate accumulation: In the model, a collapse in ocean productivity caused carbon transport from the surface ocean to the deep sea to almost entirely cease. This caused a buildup of surface level carbon and reduced carbonate saturation, which in turn caused the sharp drop in carbonate accumulation seen above.

Reduction in carbon isotopes simulated by the model and determined by observation: In the model, changes in 13C concentration were caused by a cessation of ocean productivity that greatly changed the carbon cycle. The values determined by the model are graphed above next to 13C levels in the Permian obtained through observation. The values match up well, implying the likelihood that a reduction in ocean productivity following the Permian extinction caused the negative excursion of 13C.

Abstract

The severe mass extinction of marine and terrestrial organisms at the end of the Permian Period (c. 251 Ma) was accompanied by a rapid (<100,000 years and possibly <10,000 years) negative excursion of c.3 per mil in the δ13C of the global surface oceans and atmosphere that persisted for some 500,000 years into the Early Triassic. Simulations with an ocean–atmosphere/ carbon-cycle model suggest that the isotope excursion can be explained by collapse of ocean primary productivity, and changes in the delivery and cycling of carbon in the oceans and on land. Model results suggest that severe reduction of marine productivity led to an increase in surface-ocean dissolved inorganic carbon and a rapid, short-term increase in atmospheric pCO2 (from a Late Permian base of 850 ppm to c. 2500 ppm). Increase in surface ocean alkalinity may have stimulated the widespread microbial and abiotic shallow-water carbonate deposition seen in the earliest Triassic. The model is also consistent with a long-term (>1 Ma) decrease in sedimentary burial of organic carbon in the early Triassic.