With the advent of computationally fast “intermediate complexity” models of Earth's climate and carbon cycle the marine record can be interpreted much more directly than before. Specifically, the mechanistic simulation of deep-sea sediment cores provides an important step in bridging the model-data divide. Here I use this methodology to help interpret the excursion in carbonate compensation depth (CCD) during the Paleocene-Eocene thermal maximum that is recorded in cores recovered from Walvis Ridge in the South Atlantic. By explicitly simulating the expected geological record of a massive CO2 release in an Earth system model I show how reduction in the intensity of subsurface mixing of the sediment by benthic animals substantially magnifies the recorded shoaling of the CCD. Conversely, to quantify correctly the carbon release consistent with the observed CCD changes, one must account for any bioturbational changes. A reduction in sediment mixing intensity also appears to be important to reproducing the sharpness of the contact between carbonate-rich late Paleocene sediments and the overlying early Eocene clay layer at Walvis Ridge. Assuming a relatively rapid (approximately 1 ka duration) CO2 release further helps to account for some of the paleoceanographic observations. Finally, interbasin differences in bioturbational regime help resolve some of the observed disparity in carbonate preservation between Walvis Ridge and sites outside of the Atlantic, although changes in ocean ventilation and circulation are also likely to play a critical role in this.
|Translated title of the contribution||Interpreting transient carbonate compensation depth changes by marine sediment core modeling|
|Pages (from-to)||1 - 10|
|Number of pages||10|
|Publication status||Published - Oct 2007|