Аннотация:The Younger Dryas Boundary (YDB), dated to ~12.8 ka, marks the onset of an abrupt return to near-glacial conditions across much of the Northern Hemisphere. Numerous terrestrial sites contain unusual assemblages of high-temperature materials and geochemical anomalies near this boundary, but marine records remain comparatively sparse. Here we report a multiproxy investigation of four sediment cores (52, 64, 67, and 77) from Baffin Bay, a climatically sensitive region adjacent to the Laurentide Ice Sheet and downstream of major North Atlantic circulation pathways. Within glaciogenic marine sediments dated to the YD onset, we identify distinct layers enriched in inferred impact-related proxies, including meltglass, spherules, carbonaceous particles, metallic dust particles, cometary dust particles, and platinum-group element (PGE) anomalies. Nanoparticles (The Younger Dryas Boundary (YDB), dated to ~12.8 ka, marks the onset of an abrupt return to near-glacial conditions across much of the Northern Hemisphere. Numerous terrestrial sites contain unusual assemblages of high-temperature materials and geochemical anomalies near this boundary, but marine records remain comparatively sparse. Here we report a multiproxy investigation of four sediment cores (52, 64, 67, and 77) from Baffin Bay, a climatically sensitive region adjacent to the Laurentide Ice Sheet and downstream of major North Atlantic circulation pathways. Within glaciogenic marine sediments dated to the YD onset, we identify distinct layers enriched in inferred impact-related proxies, including meltglass, spherules, carbonaceous particles, metallic dust particles, cometary dust particles, and platinum-group element (PGE) anomalies. Nanoparticles (<1 μm) extracted from bulk sediments were analyzed using single-particle inductively coupled plasma time-of-flight mass spectrometry (SP-ICP-TOF-MS), allowing determination of elemental masses and ratios within individual particles. Concentrations of Pt, Ir, Ni, and Co show pronounced peaks associated with the YDB interval across all cores. Elemental mass ratios within nanoparticles, including Ir/Pt, Pt/Pd, Pt/Fe, Co/Ni, and Ni/Fe, also increase sharply within the same stratigraphic interval, with maxima typically occurring slightly above peaks in microspherules and carbonaceous particles. The diagnostic ratio of Pt/Fe is most similar to that of metal-rich extraterrestrial compositions, including comets, and is also strongly enriched relative to average crustal material. The stratigraphic coherence of these enrichments across cores spanning shelf to deep-basin environments indicates a basin-wide depositional signal rather than localized sedimentary processes. The slight offset between peaks in larger melted spherules and submicron nanoparticles is consistent with delayed atmospheric fallout of fine material and subsequent settling through the water column, potentially enhanced by aggregation into marine snow. Background nanoparticle abundances outside the YDB interval are comparatively low, suggesting that the observed enrichments represent a short-lived pulse of metal-rich particulate input. Taken together, the multiproxy evidence from Baffin Bay supports the presence of an unusual depositional layer at the onset of the Younger Dryas marked by high-temperature materials and PGE-enriched nanoparticles. While these anomalies and individual proxies may have alternative explanations, their co-occurrence, stratigraphic confinement, and replication across multiple, widely separated marine cores argue for a common origin. The data are consistent with the addition of extraterrestrial material from a high-energy event capable of injecting large quantities of fine particulate matter into the atmosphere and ocean. Such an event could have contributed to rapid environmental perturbations at the Younger Dryas onset, including atmospheric dust loading and disruption of regional climate. These findings extend the geographic range of YDB proxies into the marine realm of Baffin Bay and provide independent evidence for a sudden, basin-wide depositional episode at ~12.8 ka.
