![]() ![]() We compared the core orientation with logging data from core break matching and the pattern of the stereographic projections of the crystals’ c-axis orientations. As the EastGRIP ice core is drilled through the Northeast Greenland Ice Stream, we use information about the directional structures to perform a full geographical re-orientation. We provide a method to reconstruct ice core orientation using visual stratigraphy and borehole geometry. However, this method fails for deep ice cores, such as the EastGRIP ice core in Northeast Greenland. For shallow ice cores, it is usually possible to match the adjacent core breaks, which preserves the orientation of the ice column. In general, the orientation of an ice core is lost as the drill is free to rotate during transport to the surface. At the test site, 2-week drilling operations resulted in a borehole that reached bedrock at a depth of 198 m.Įver since the first deep ice cores were drilled, it has been a challenge to determine their original, in-situ orientation. The ASDR was tested during the 2018–2019 summer season near Zhongshan Station, East Antarctica. The ASDR is designed to be transported to the chosen site via snow vehicles and would be ready for drilling operations within 2–3 d after arrival. The entire ASDR system weighs ~55 tons, including transport packaging. To facilitate helicopter unloading of the research vessel, the shelter and workshop can be disassembled, with individual parts weighing <2–3 tons. All of the drilling equipment is installed inside a movable, sledge-mounted, temperature-controlled and wind-protected drilling shelter and workshop. ![]() The newly developed and tested Antarctic subglacial drilling rig (ASDR) is designed to recover ice and bedrock core samples from depths of up to 1400 m. Basal and subglacial materials contain important paleoclimatic and paleoenvironmental records and provide a unique habitat for life they offer significant information regarding the sediment deformation beneath glaciers and its effects on the subglacial hydraulic system and geology. The mechanical and electrical properties and environmental suitability of the cable were determined through laboratory testing and joint testing with the probe.ĭrilling to the bedrock of ice sheets and glaciers offers unique opportunities for examining the processes occurring in the bed. The maximal breaking force under straight tension is ~12.2 kN. The permissible bending radius is as low as 17–20 mm. ![]() The outer diameter of the final version of the cable is ~6.1 mm. To hold these aramid fibers in place, a sheathing layer was produced from a polyamide fabric cover net. The 0.65 mm thick strength member is made from aramid fibers woven together. The outer insulation layer is coated by polyurethane jacket to seal the connections between the cable and electrical units. Two polyfluoroalkoxy jackets are used for electrical insulation (one for insulation between conductors, and the other for insulation of the outer conductor). The final version of the cable consists of two concentric conductors that can be used as the power and signal lines. A series of new synthetic armored cables were developed and tested to ensure that they were suitable for use with the RECoverable Autonomous Sonde (RECAS), which is a newly designed freezing-in thermal ice probe. ![]()
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