OXYGENATION OF THE OCEAN AND CARBON ISOTOPIC EXCURSIONS: ARE THEY LINKED VIA DISSOLVED ORGANIC MATTER CYCLING?

The cycling of carbon in the Precambrian ocean could have been very different from what we see today. Prior to the advent of an efficient biological ‘pump' and under a relatively low pO2 atmosphere, the pool of carbon in the form of dissolved organic matter (DOM) could have been substantial. Because DOM is relatively isotopically depleted, the oxidative destruction of such a reservoir has been proposed as an explanation for carbon isotopic anomalies recorded in late Precambrian carbonates and at the Cambrian-Precambrian boundary. Here we investigate potential controls on the size of the ocean DOM reservoir using a coupled carbon-climate model and directly test whether oxidation of this material could help explain the observed isotope signals.