Carbon addition and removal during the Late Palaeocene Thermal Maximum: basic theory with a preliminary treatment of the isotope record at ODP Site 1051, Blake Nose

Abstract The late Palaeocene Thermal Maximum (LPTM) was a brief interval at c. 55 Ma characterized by a −2.5 to −3‰ shift in the δ13C of global carbon reservoirs. The geochemical perturbation probably represents a massive input of 12C-rich carbon to the exogenic carbon cycle. Largely unresolved issues concerning this carbon injection during the LPTM are the rates of carbon input and removal. Simple expressions are developed here to describe a δ13C excursion in the exogenic carbon cycle after carbon input. A change in global δ13C (dδEx/dt) can be explained to a first approximation by a set of parameters: the initial mass and isotopic composition of the global carbon cycle (MEx(o), δEx(o)), and the fluxes and isotopic compositions of external carbon inputs, outputs and injected carbon (FIn, δIn, FOut, δOut, FAdd, δAdd). In general, for a given exogenic carbon cycle, a large FAdd or low δAdd results in a larger δ13C excursion. Likewise, for a given negative δ13C excursion, a large MEx or low δEx requires a greater input of 12C. Differences in FIn, δIn, FOut and δOut cause changes in the response of δEx over time. For a negative δ13C excursion of given magnitude, a greater FIn requires a greater input of 12C and lessens the time for δEx to return to initial conditions. A decrease in δOut (caused by an increase in the relative output of organic matter and carbonate) has a similar effect. Variable dMAdd/dt produces transients in δEx that are related to the source function but modified by carbon removal. In theory, a well-dated and representative global δ13C excursion could be used to derive the carbon inputs and ouputs. Ocean Drilling Program (ODP) Site 1051 has an expanded early Palaeogene section, and recent work at this location has provided a well-dated δ13C record across the LPTM. This δ13C record contains transient variations of apparently global nature. These observed transients are best explained by a pulsed injection of CH4 into an exogenic carbon cycle with a greater carbon throughput or enhanced burial of organic matter after carbon addition.

[1]  P. Gingerich,et al.  Evidence for rapid climate change in North America during the latest Paleocene thermal maximum: oxygen isotope compositions of biogenic phosphate from the Bighorn Basin (Wyoming) , 1998 .

[2]  Michael A. Arthur,et al.  Interpreting carbon-isotope excursions: carbonates and organic matter , 1999 .

[3]  Gerald R. Dickens,et al.  Direct measurement of in situ methane quantities in a large gas-hydrate reservoir , 1997, Nature.

[4]  I. Fung,et al.  Potential distribution of methane hydrates in the world's oceans , 1994 .

[5]  K. Kvenvolden.  Gas hydrates—geological perspective and global change , 1993 .

[6]  F. Armstrong,et al.  Chemical Oceanography , 1959, Nature.

[7]  D. Mallinson,et al.  Geochemical consequences of increased Late Cenozoic weathering rates and the global CO2 balance since 100 Ma , 1996 .

[8]  J. Zachos,et al.  Abrupt Climate Change and Transient Climates during the Paleogene: A Marine Perspective , 1993, The Journal of Geology.

[9]  G. Dickens,et al.  The Source and Fate of Massive Carbon Input During the Latest Paleocene Thermal Maximum. , 1999, Science.

[10]  U. Siegenthaler.  Modelling the Present-Day Oceanic Carbon Cycle , 1993 .

[11]  G. Dickens,et al.  Methane hydrate stability in seawater , 1994 .

[12]  J. Kasting,et al.  Effects of fuel and forest conservation on future levels of atmospheric carbon dioxide. , 1992, Global and planetary change.

[13]  J. P. Kennett,et al.  Abrupt deep-sea warming, palaeoceanographic changes and benthic extinctions at the end of the Palaeocene , 1991, Nature.

[14]  G. Dickens.  Methane oxidation during the late Palaeocene thermal maximum , 2000 .

[15]  Ellen Thomas.  Biogeography of the Late Paleocene Benthic Foraminiferal Extinction , 1998 .

[16]  W. Broecker,et al.  What Caused the Glacial to Interglacial CO2 Change , 1993 .

[17]  W. Berger,et al.  Deep-sea carbonates: Reading the carbon-isotope signal , 1986 .

[18]  R. M. Owen,et al.  Dissociation of oceanic methane hydrate as a cause of the carbon isotope excursion at the end of the Paleocene , 1995 .

[19]  J. Zachos,et al.  Evolution of Early Cenozoic marine temperatures , 1994 .

[20]  J. Zachos,et al.  Late Paleocene to Eocene paleoceanography of the equatorial Pacific Ocean: Stable isotopes recorded at Ocean Drilling Program Site 865, Allison Guyot , 1995 .

[21]  C. Bjerrum,et al.  Massive dissociation of gas hydrate during a Jurassic oceanic anoxic event , 2000, Nature.

[22]  J. Rodhe.  The large-scale circulation in the Skagerrak; interpretation of some observations , 1987 .

[23]  A. Klaus,et al.  Proceedings of the Ocean Drilling Program 171B Initial Reports , 1998 .

[24]  G. Dickens,et al.  A blast of gas in the latest Paleocene: simulating first-order effects of massive dissociation of oceanic methane hydrate. , 1997, Geology.

[25]  E. Sundquist.  Geologic Analogs: Their Value and Limitations in Carbon Dioxide Research , 1986 .

[26]  J. Zachos,et al.  High-resolution records of the late Paleocene thermal maximum and circum-Caribbean volcanism: is there a causal link? , 1997 .

[27]  G. Esser.  Sensitivity of global carbon pools and fluxes to human and potential climatic impacts , 1987 .

[28]  J. Overpeck,et al.  Abrupt Climate Change , 2003, Science.

[29]  Ursula Röhl,et al.  Carbon cycling and chronology of climate warming during the Palaeocene/Eocene transition , 1999, Nature.

[30]  Corfield,et al.  Mechanisms of climate warming at the end of the paleocene , 1999, Science.

[31]  P. Gingerich,et al.  Correlation between isotope records in marine and continental carbon reservoirs near the Palaeocene/Eocene boundary , 1992, Nature.

[32]  N. Shackleton,et al.  The Paleocene-Eocene benthic foraminiferal extinction and stable isotope anomalies , 1996, Geological Society, London, Special Publications.

[33]  Wallace S. Broecker,et al.  Neutralization of Fossil Fuel CO2 by Marine Calcium Carbonate , 1977 .

[34]  Paul B. Hays,et al.  A negative feedback mechanism for the long‐term stabilization of Earth's surface temperature , 1981 .

[35]  Tjeerd H. van Andel,et al.  Mesozoic/cenozoic calcite compensation depth and the global distribution of calcareous sediments , 1975 .