9:30 AM - 9:45 AM
[ACC27-03] Comparison of physical layered structures between Dome Fuji, Dome C and GRIP ice cores
Keywords:ice core, ice dynamics, crystal orientation fabric
Ice cores drilled in dome regions preserve environmental records in good condition. Furthermore, because ice deformation occurs solely through vertical compression due to its own weight, the development of physical parameters such as crystal orientation distribution (COF) is relatively straightforward, making it easier to discuss the development of deformation regimes and microstructures.
Among the ice cores obtained in Antarctica and Greenland, those drilled in dome regions with detailed physical analyses down to the bedrock are the Dome Fuji Core (Azuma et al., 2000), Dome C Core (Durand et al., 2009), and GRIP Core (Thorsteinsson et al., 1997). While there are reports suggesting similarity in the deep COF between Dome C and GRIP ice cores, details remain unclear due to limited information of deep sections. Additionally, the analysis conducted by Azuma et al. (2000) reached a depth of 2500 m, and physical analysis of the deep layers of the Dome Fuji core has not been conducted.
We conducted a comprehensive physical analysis of the entire Dome Fuji ice core, obtaining profiles of COF, crystal size, and other parameters. We could detect small fluctuations in the COF and their relation with layered structures by using the dielectric tensor method, which allows continuous measurements with high spatial resolution, and the X-ray Laue diffraction method, capable of determining crystal orientations completely (Saruya et al., 2023). Based on the COF profiles, we classified the Dome Fuji ice core into the following five layers: (1) ice-sheet surface to 100 m: firn zone, (2) 100 to 2400 m: dislocation creep zone, (3) 2400 to 2650 m: transition zone, (4) 2650 to 2950 meters: dislocation creep and recrystallization zone, (5) 2950 m to bedrock: ice-bedrock interface zone. The contribution of metamorphism of snow and firn, plastic deformation, and recrystallization to the COF development is thought to vary in each region. Especially at depths below 2400 m, dynamic recrystallization process dominated the COF variations.
In this presentation, we will discuss the development of physical layered structures, such as deformation regimes and microstructures, in the Dome Fuji ice core while comparing them with the Dome C and GRIP ice cores.
Among the ice cores obtained in Antarctica and Greenland, those drilled in dome regions with detailed physical analyses down to the bedrock are the Dome Fuji Core (Azuma et al., 2000), Dome C Core (Durand et al., 2009), and GRIP Core (Thorsteinsson et al., 1997). While there are reports suggesting similarity in the deep COF between Dome C and GRIP ice cores, details remain unclear due to limited information of deep sections. Additionally, the analysis conducted by Azuma et al. (2000) reached a depth of 2500 m, and physical analysis of the deep layers of the Dome Fuji core has not been conducted.
We conducted a comprehensive physical analysis of the entire Dome Fuji ice core, obtaining profiles of COF, crystal size, and other parameters. We could detect small fluctuations in the COF and their relation with layered structures by using the dielectric tensor method, which allows continuous measurements with high spatial resolution, and the X-ray Laue diffraction method, capable of determining crystal orientations completely (Saruya et al., 2023). Based on the COF profiles, we classified the Dome Fuji ice core into the following five layers: (1) ice-sheet surface to 100 m: firn zone, (2) 100 to 2400 m: dislocation creep zone, (3) 2400 to 2650 m: transition zone, (4) 2650 to 2950 meters: dislocation creep and recrystallization zone, (5) 2950 m to bedrock: ice-bedrock interface zone. The contribution of metamorphism of snow and firn, plastic deformation, and recrystallization to the COF development is thought to vary in each region. Especially at depths below 2400 m, dynamic recrystallization process dominated the COF variations.
In this presentation, we will discuss the development of physical layered structures, such as deformation regimes and microstructures, in the Dome Fuji ice core while comparing them with the Dome C and GRIP ice cores.