Active geophysics on Ekströmisen and Halfvarryggen, Antarctica

• Main Authors: Eisen, Olaf, Blenkner, R., Diez, Anja, Drews, Reinhard, Hofstede, Coen, Kristoffersen, Y., Jansen, Daniela, Lambrecht, A., Mayer, Christoph, Neckel, Niklas, Steinhage, Daniel, Witt, Ralf
• Format: Conference Object
• Language: unknown
• Published: 2010
• Subjects: Ekströmisen; Halvfarryggen; Antarc*; Antarctica; ice core
• Online Access: https://epic.awi.de/id/eprint/22271/; https://epic.awi.de/id/eprint/22271/1/Eis2010b.pdf; https://hdl.handle.net/10013/epic.34574; https://hdl.handle.net/10013/epic.34574.d001

Halfvarryggen is a small ice dome bordering the catchment area of Ekströmisen. It is a candidate for drilling one IPICS 2k/40k ice core. Near the actual dome, three ice divides merge in a triple point. Halvfarryggens internal structure has been imaged with airborne radio-echo sounding (RES) in the past years, which indicate upwarping internal layers, so-called isochrone arches (or partly Raymond bumps), which develop into a double bump at larger depths. Modelling studies (Martin et al., 2009, JGR-F) indicate that the crystal orientation fabric (COF) at larger depths at ice domes like Halvfarryggen should be highly anisotropic. As changes in COF not only change the dielectric permittivity, but also the acoustic impedance contrast, such changes should also be detectable with seismic methods. We present an overview and preliminary results of a geophysical LIMPICS campaign at Halfvarryggen in 2009/10, involving reflection seismics, shallow ground-penetrating radar (GPR) and other glaciological studies. Main scientific goals were to detect internal reflection horizons along a profile nearby the ice dome with seismics and GPR, image the internal layer architecture along hexagons crossing all three ice divides, detect the ice-bed interface and image the upper tens of meters of the underlying bedrock.