Relationships between grain size and organic carbon 14C heterogeneity in continental margin sediments

Highlights • Continental margin-scale spatial variability in C values among grain size fractions is presented. • Two different hydrodynamic modes influencing in 14C heterogeneity are identified. • A new index (H14 index) is defined to describe overall 14C heterogeneity within marine surface sedimentary OC. Abstract The deposition and long-term burial of sedimentary organic matter (OM) on continental margins comprises a fundamental component of the global carbon cycle. A key unknown in interpretation of carbon isotope records of sedimentary OM is the extent to which OM accumulating in continental shelf and slope sediments is influenced by dispersal and redistribution processes. Here, we present results from an extensive survey of organic carbon (OC) characteristics of grain size fractions (ranging from