Debris entrainment at the ice-bedrock interface in sub-freezing temperature conditions (Terre Adélie, Antarctica)
Debris entrainment at the ice-bedrock interface in sub-freezing temperature conditions (Terre Adélie, Antarctica)
复制标题
低于冰点温度条件下冰-基岩界面处的碎片夹带（南极洲阿德利岛）
作者：
J. Tison;J. Petit;J. Barnola;W. Mahaney
摘要本文描述了从82 m深的CAROLINE冰芯底部6 m到基岩的富含碎屑的冰，以及从5个2 m长的表层冰芯在Terre Adélie（南极洲）的Moraine Prudhomme，并与来自DIO岩心钻探现场的含碎屑的冰进行了比较。同位素，总气体含量，CO2浓度和SEM调查嵌入的颗粒，连同冰的纹理和织物，排除了“压力熔化”regimetry床障碍物或“冻结”周围的可能机制的碎片夹带在冰基岩界面。有人建议，碎片截留纯机械手段（如剪切）是一个有效的过程中形成的基础冰层（BIL）在冰点以下的温度。这一过程可能在南极冰盖边缘占主导地位，那里没有冰架存在，斜坡终点或支撑海岸救济诱导压缩流。
Abstract The debris-rich ice from the bottom 6 m of the 82 m deep CAROLINE (Coastal Antarctic Record of Last Interglacial Natural Environment) ice core reaching bedrock, and from five 2 m long surface cores at Moraine Prudhomme in Terre Adélie (Antarctica) is described and compared to debris-laden ice from the core-drilling site DIO. Isotopic, total-gas content, CO2 concentration and SEM investigations of embedded particles, together with ice textures and fabrics, rule out “pressure-melting” regelation around bed obstacles or “freezing-on” as possible mechanisms for the debris entrainment at the ice-bedrock interface. It is suggested that the debris entrapment by purely mechanical means (e.g. shearing) is an efficient process in forming basal ice layers (BIL) at sub-freezing temperatures. This process might be dominant at the margin of the Antarctic ice sheet where no ice shelf exists and where a ramp terminus or a buttressing coastal relief induces compressive flow.