Refractory DOC (DOCr) in Santa Barbara Basin sediment pore waters is largely produced from degradation of sediment particulate organic carbon (POC). In addition, there is an upward basal flux of DOCr that is strongly depleted in 14C (−810‰). The Δ14C value of DOCr varies according to its source, ranging from +60‰ (a component of surface sediment POC enriched with radiocarbon from nuclear weapons testing in the 1960’s) to −810‰ (the basal DOC flux). Each contributes to the DOCr benthic flux, which has a weighted-average Δ14C value of −40‰. The model-determined DOCr benthic flux is roughly half of the total DOC benthic flux, consistent with observations in the literature that sediments are a source of both labile and refractory DOC to bottom waters. These results support previous arguments that sediment benthic fluxes represent an important source of refractory DOC to the oceans. The benthic flux of refractory DOC from these sediments may also contribute pre-aged DOC to the water column if the different sub-components of the anoxic pore water DOCr pool with differing radiocarbon ages have differing reactivities in the oxic marine water column.