Proposing a classic clay mineral proxy for quantifying kerogen reburial in the geologic past

Kerogen exhumed on Earth's surface is subject to oxidation and microbial utilization and is also remobilized and reburied into new geological strata. In the former case, carbon is introduced to the atmosphere and biosphere, while in the latter, neither is carbon released, nor is oxygen consumed. Therefore, kerogen exhumation and its entailing fate contributes to the balance of atmospheric CO2 and O2 over geological timescales as well as the overall geochemical fingerprint of sedimentary organic matter containing both biospheric and reburied kerogen components. Until now, quantitative constraints on kerogen reburial have been largely limited to the Holocene. Here, we propose the usage of illite and chlorite abundance for quantitatively constraining kerogen reburial in the geologic past. Orogenic source terrains typically shed this lithoclast assemblage, which shows a strongly linear relationship between kerogen and illite+chlorite content in marine foreland basin sediments as observed for the Taiwan Orogeny. By applying this relationship to sedimentary archives of orogenic foreland basins, we envision that quantitative changes in organic carbon cycling can be inferred from the clay mineral record.