Ever since the first deep ice cores were drilled, it has been a challenge to determine their original, in-situ orientation. In general, the orientation of an ice core is lost as the drill is free to rotate during transport to the surface. For shallow ice cores, it is usually possible to match the adjacent core breaks, which preserves the orientation of the ice column. However, this method fails for deep ice cores, such as the EastGRIP ice core in Northeast Greenland. We provide a method to reconstruct ice core orientation using visual stratigraphy and borehole geometry. 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 compared the core orientation with logging data from core break matching and the pattern of the stereographic projections of the crystals’ c-axis orientations. Both comparisons agree very well with the proposed orientation method. The method works well for 441 out of 451 samples from a depth of 1375–2120 m in the EastGRIP ice core. It can also be applied to other ice cores, providing a better foundation for interpreting physical properties and understanding the flow of ice.

中文翻译：

---

基于地层学的冰芯方位重建方法

自从钻出第一个深冰芯以来，确定它们的原始原位方向一直是一项挑战。一般来说，冰芯的方向会随着钻头在运输到地面的过程中自由旋转而丢失。对于浅冰芯，通常可以匹配相邻的芯断裂，从而保持冰柱的方向。然而，这种方法不适用于深冰芯，例如格陵兰岛东北部的 EastGRIP 冰芯。我们提供了一种使用视觉地层学和钻孔几何来重建冰芯方向的方法。随着 EastGRIP 冰芯钻穿格陵兰岛东北冰流，我们使用有关定向结构的信息来执行完整的地理重新定向。C轴方向。两种比较都与所提出的定向方法非常吻合。该方法适用于 EastGRIP 冰芯 1375-2120 m 深度的 451 个样本中的 441 个。它也可以应用于其他冰芯，为解释冰的物理性质和了解冰的流动提供更好的基础。