Carbonate Fluxes to the Eastern Equatorial Pacific during the Eocene: using the GENIE Earth System Model to investigate carbonate accumulation event mechanisms and dynamics revealed by the Pacific Equatorial Age Transect (PEAT)
Abstract
The Pacific Equatorial Age Transect (PEAT) recovered sediments and data from a set of Sites that form a palaeo-depth transect for most of Cenozoic time. We are using the data from IODP Expedition 320 and ODP Leg 199 sites to refine the dynamics of the carbonate compensation depth (CCD) during the Eocene. We are able to use the PEAT depth transect approach to determine the intensity of carbonate fluxes at the seafloor for the previously identified carbonate accumulation events (CAEs) of Lyle et al (ODP Leg 199 SR, 2005). Using the reconstructed depths for the drilled sites we are able to determine the amplitude of the CCD fluctuations to be about 500m in depth, and carbonate accumulation rates fluctuate between near zero and ~1.5 g/cm2/kyr. Each event lasts for a time period of around 1 Myr, with sharp transitions into and out of these cycles of enhanced carbonate accumulation. To investigate the potential mechanisms for these events we use an Earth System Model of Intermediate complexity (GENIE), as previously employed to study the carbon cycle during the PETM (Panchuk et al., Geology 2008). Using estimated values for ocean water Ca and Mg concentrations, we ran ensemble simulations for different pCO2 concentrations, different Alkalinity and different CaCO3:POC scenarios. We find that different CaCO3:POC ratios are able to explain many of the observed dissolution/preservation events, and are able to use these to constrain other parameters in the Earth System.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFMPP23A1722P
- Keywords:
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- 0428 BIOGEOSCIENCES / Carbon cycling;
- 1051 GEOCHEMISTRY / Sedimentary geochemistry;
- 4912 PALEOCEANOGRAPHY / Biogeochemical cycles;
- processes;
- and modeling;
- 4928 PALEOCEANOGRAPHY / Global climate models