From land to sea: provenance, composition, and preservation of organic matter in a marine sediment record from the North-East Greenland shelf spanning the Younger Dryas-Holocene

The organic matter content of marine sediments is often used to infer past changes in ocean conditions. However, the organic carbon pool preserved in coastal sediments is a complex mixture derived from different sources and may not reflect in situ processes. In this study, we combine taxonomic identification of reworked palynomorphs with pyrolysis organic geochemistry and reflected-light organic petrographic microscopy to investigate the provenance, composition and preservation of organic matter in a marine sediment core retrieved from the NE Greenland shelf. Our study reveals continuous yet variable input of land-derived organic carbon to the marine environment throughout the late Younger Dryas-Holocene, with the highest input of inert carbon in the late Younger Dryas. Although the sediments contain some recent marine palynomorphs, there is no other evidence of fresh marine organic carbon. In contrast, our results indicate that these shelf sediments represent a significant sink of recycled organic carbon. The results of pyrolysis geochemistry revealed that similar to 90% of the total organic carbon in the sediments is inert. The organic petrography analyses revealed that >70-84% of the organic carbon in the sediment core is terrigenous. Reworked dinoflagellate cysts showed a continuous provenance of Cretaceous land-derived material, most likely from the nearby Clavering Island. Our study points to the importance of constraining the organic matter origin, composition and preservation in marine sediments to achieve more accurate palaeoenvironmental reconstructions based on organic proxies.

Automated summary

The origin, composition and preservation of organic matter in a marine sediment core recovered from the NE Greenland shelf were investigated using different techniques. The study revealed the continuous but variable input of land-derived organic carbon to the marine environment, with the highest input during the late Younger Dryas. The sediments represented a significant sink of recycled organic carbon, with a large proportion of inert carbon and terrigenous organic carbon.