EGU25-11308, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-11308
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
Poster | Thursday, 01 May, 08:30–10:15 (CEST), Display time Thursday, 01 May, 08:30–12:30
 
Hall X1, X1.20
Distribution patterns of GDGTs and n-alkanes in the central Arctic Ocean during Marine Isotope Stages 1, 2, and 3
Akanksha Singh1, Ludvig Löwemark1,2, Sze Ling Ho3, Min-Te Chen4, Pei-Ling Wang2,3,5, Martin Jakobsson6, and Richard Gyllencreutz6
Akanksha Singh et al.
  • 1Department Of Geosciences, National Taiwan University, Taipei, Taiwan (akanksha.deva@gmail.com)
  • 2Research Center for Future Earth, National Taiwan University, Taipei, Taiwan
  • 3Institute of Oceanography, National Taiwan University, Taipei, Taiwan
  • 4Institute of Earth Sciences, & Center of Excellence for the Oceans & Center of Excellence for Ocean Engineering, National Taiwan Ocean University, Keelung, Taiwan
  • 5Science and Technology Research Institute for Decarbonization, National Taiwan University, Taipei, Taiwan
  • 6Department of Geological Sciences and Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden

Arctic sea ice plays a crucial role in regulating the Earth’s energy budget, influencing Arctic marine productivity, and the global thermohaline circulation. Its distribution also affects the transport of sediment and organic matter (OM) across the Arctic Ocean. Lipid biomarkers are essential proxies for tracing OM transport in the central Arctic. However, their sources and patterns of spatial and temporal variability during the last glacial cycle remain poorly understood. To address these knowledge gaps, our study conducted a multiproxy analysis—including total organic carbon (TOC), n-alkanes, and glycerol dialkyl glycerol tetraethers (GDGTs) on nine sediment cores from the central Arctic. The GDGT record suggests that branched GDGTs (brGDGTs) in the central Arctic are predominantly of marine origin, challenging the previously held assumption of a terrigenous source. To determine the origin of brGDGTs in this region, two indices were applied, yielding contrasting results. Elevated IIIa/IIa values during MIS 3–1 indicate a marine source, whereas #ringstetra ratios point to a terrestrial origin. However, the reliability of #ringstetra ratios in the central Arctic is likely compromised due to their sensitivity to pH variations, making the IIIa/IIa ratio a more reliable indicator of in situ brGDGT production in the region. TOC, along with terrestrial biomarkers (long-chain n-alkanes) and marine biomarkers (isoprenoid and branched GDGTs), showed the highest concentrations in the Central Lomonosov Ridge (CLR) cores, located closer to the Siberian shelves. These concentrations decreased in Lomonosov Ridge Offshore (LRG) and Morris Jesup Rise (MJR) cores, further from the shelves. This spatial pattern, combined with evidence of low productivity in the central Arctic, suggests that both marine- and terrestrial-derived biomarkers were primarily transported via sea ice drift from the Siberian shelves. This transport process persisted through MIS 3–1, albeit with reduced intensity during glacial periods. Moreover, elevated Branched Isoprenoid Tetraether (BIT) index values in the central Arctic during glacial periods likely reflect changes in crenarchaeol and brGDGT production on the shelves and/or the selective degradation of crenarchaeol during transport.

How to cite: Singh, A., Löwemark, L., Ho, S. L., Chen, M.-T., Wang, P.-L., Jakobsson, M., and Gyllencreutz, R.: Distribution patterns of GDGTs and n-alkanes in the central Arctic Ocean during Marine Isotope Stages 1, 2, and 3, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11308, https://doi.org/10.5194/egusphere-egu25-11308, 2025.