2.1 DANIEL Isabelle

Origin, forms, quantities and movements of reduced carbon in Earth

The Deep Energy Community (DEC) of the Deep Carbon Observatory was originally founded to elucidate the sources of methane and other hydrocarbons. In particular, the goal was to better understand the relative contributions of biotic and abiotic sources of methane to Earth’s total CH4 budget.

The decadal goals of the DEC are to:

1) utilize field-based investigations of representative terrestrial and marine environments to determine the origin, form, quantities, and movements of abiotic gases and organic species in Earth’s crust and uppermost mantle;

2) implement revolutionary instrumentation to discriminate abiotic from biotic methane gas and other organic compounds in terrestrial and marine settings;

3) quantify the physicochemical conditions that produce H2 and abiotic forms of methane gas as well as more complex organic compounds;

4) integrate our advances in understanding with a global deep carbon model.

Eight years on, the DEC can claim considerable progress towards attaining these decadal goals. Understanding abiotic CH4 and higher-order alkane production relies on detailed characterization of geological sources of carbon and hydrogen. This in turn necessitates investigations of the chemistry of water-rock reactions at all scales. An important goal of the DEC is to combine field studies around the globe, experiments in the laboratory, and novel analytical techniques to identify the physicochemical pathways for the formation of hydrogen and reduced carbon at depth. These pathways to hydrocarbon formation must be compared and contrasted with biological pathways that may overlap in space and time with abiotic pathways.