TY - JOUR T1 - A new 30,000-year chronology for rapidly deposited sediments on the Lomonosov Ridge using bulk radiocarbon dating and probabilistic stratigraphic alignment JF - Geochronology Y1 - 2020 A1 - Muschitiello, Francesco A1 - O'Regan, Matt A1 - Martens, Jannik A1 - West, Gabriel A1 - Gustafsson, Örjan A1 - Jakobsson, Martin AB - We present a new marine chronostratigraphy from a high-accumulation rate Arctic Ocean core at the intersection of the Lomonosov Ridge and the Siberian margin, spanning the last ∼ 30 kyr. The chronology was derived using a combination of bulk 14C dating and stratigraphic correlation to Greenland ice-core records. This was achieved by applying an appositely developed Markov chain Monte Carlo algorithm for Bayesian probabilistic alignment of proxy records. The algorithm simulates depositionally realistic alignments that are consistent with the available radiocarbon age estimates and allows deriving uncertainty bands associated with the inferred alignment. Current composite chronologies from this region are reasonably consistent with our age model during the Holocene and the later part of deglaciation. However, prior to ∼ 14 kyr BP they yield too old age estimates with offsets that linearly increase up to ∼ 40 kyr near the onset of Marine Isotope Stage (MIS) 2. Our results challenge the robustness of previous regional chronostratigraphies and provide a new stratotype for correlation of sediment cores from this sector of the Lomonosov Ridge and East Siberian slope. In particular, they call for a re-interpretation of events in recent sea-ice proxy reconstructions (Xiao et al., 2015) inaccurately attributed to MIS 3 and the Last Glacial Maximum. VL - 2 UR - https://gchron.copernicus.org/articles/2/81/2020/ IS - 1 ER - TY - JOUR T1 - Remobilization of old permafrost carbon to Chukchi Sea sediments during the end of the last deglaciation JF - Global Biogeochemical Cycles Y1 - 2018 A1 - Martens, Jannik A1 - Wild, Birgit A1 - Pearce, Christof A1 - Tesi, Tommaso A1 - Andersson, August A1 - Broder, Lisa A1 - O’Regan, Matt A1 - Jakobsson, Martin A1 - Sköld, Martin A1 - Gemery, Laura A1 - Cronin, Thomas M. A1 - Semiletov, Igor A1 - Dudarev, Oleg V. A1 - Gustafsson, Örjan KW - carbon isotope KW - climate change feedback KW - coastal erosion KW - Deglaciation KW - past carbon cycling KW - permafrost AB - Climate warming is expected to destabilize permafrost carbon (PF‐C) by thaw‐erosion and deepening of the seasonally thawed active layer and thereby promote PF‐C mineralization to CO2 and CH4. A similar PF‐C remobilization might have contributed to the increase in atmospheric CO2 during deglacial warming after the last glacial maximum. Using carbon isotopes and terrestrial biomarkers (Δ14C, δ13C, and lignin phenols), this study quantifies deposition of terrestrial carbon originating from permafrost in sediments from the Chukchi Sea (core SWERUS‐L2‐4‐PC1). The sediment core reconstructs remobilization of permafrost carbon during the late Allerød warm period starting at 13,000 cal years before present (BP), the Younger Dryas, and the early Holocene warming until 11,000 cal years BP and compares this period with the late Holocene, from 3,650 years BP until present. Dual‐carbon‐isotope‐based source apportionment demonstrates that Ice Complex Deposit—ice‐ and carbon‐rich permafrost from the late Pleistocene (also referred to as Yedoma)—was the dominant source of organic carbon (66 ± 8%; mean ± standard deviation) to sediments during the end of the deglaciation, with fluxes more than twice as high (8.0 ± 4.6 g·m−2·year−1) as in the late Holocene (3.1 ± 1.0 g·m−2·year−1). These results are consistent with late deglacial PF‐C remobilization observed in a Laptev Sea record, yet in contrast with PF‐C sources, which at that location were dominated by active layer material from the Lena River watershed. Release of dormant PF‐C from erosion of coastal permafrost during the end of the last deglaciation indicates vulnerability of Ice Complex Deposit in response to future warming and sea level changes. UR - https://onlinelibrary.wiley.com/doi/abs/10.1029/2018GB005969https://onlinelibrary.wiley.com/doi/pdf/10.1029/2018GB005969https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1029%2F2018GB005969https://onlinelibrary.wiley.com/doi/pdf/10.1029/2018GB005969 ER -