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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 ~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. [ABSTRACT FROM AUTHOR]

The Fram Strait is one of the largest gateways through which meltwater and sea ice are exported to the subarctic North Atlantic, transiting the North-East Greenland shelf via the southward flowing East Greenland Current. Observations indicate a recent freshening of the East Greenland Current that may have implications for wider oceanic circulation regimes. The North-East Greenland shelf is an opportune region to assess these changes back through time. Paleoceanographic reconstructions from the North-East Greenland shelf are sparse and their temporal coverage is limited to the Holocene, limiting our ability to assess the impact of rapid climatic variations on marine conditions, such as during the Younger Dryas/Holocene transition. Here, we present data from a well-dated marine sediment core retrieved from the North-East Greenland shelf (74°N; east of Young Sound-Tyrolerfjord system) that captures the late Younger Dryas Stadial through to the Mid-Holocene at sub-centennial resolution. We apply a multi-proxy approach to reconstruct changes in productivity, surface and bottom ocean conditions. We show that at 74° N the presence of warm Atlantic waters on the inner North-East Greenland shelf was limited to the late Younger Dryas, as the Greenland Ice Sheet retreated landward and isostatic rebound caused the area to uplift. A unique dimension to this record is its location within one of the few biological hotspots on the East Greenland shelf today; the Sirius Water polynya. Archaeological studies indicate the polynya was forming as early as 4500 years ago, but nothing is known about its evolution from a marine perspective. Cooling of bottom waters, increasing sea-surface productivity and more frequent open water conditions indicate an Early Holocene onset of the Sirius Water (ca. 10–8.7 ka BP). • First paleoceanographic study from the Sirius Water polynya on the North-East Greenland shelf. • Multi-proxy approach to reconstruct productivity and bottom water conditions. • Sub-centennial resolution over the Younger Dryas/Holocene transition. • Extensive Atlantic Water influence during the late Younger Dryas. • Indications of recurrent Sirius Water Polynya formation since the Early Holocene (∼10–8.7 ka BP). [ABSTRACT FROM AUTHOR]