Subgrain boundaries and related microstructural features in EDML (Antarctica) deep ice core@en

Subgrain boundaries revealed as shallow sublimation grooves on ice sample surfaces are a direct and easily observable feature of intracrystalline deformation and recrystallization. Statistical data obtained from the EPICA Dronning Maud Land (EDML) deep ice core drilled in East Antarctica cannot detect a depth region of increased subgrain-boundary formation. Grain-boundary morphologies show a strong influence of internal strain energy on the microstructure at all depths. The data do not support the classical view of a change of dominating recrystallization regimes with depth. Three major types of subgrain boundaries, reflecting high mechanical anisotropy, are specified in combination with crystal-orientation analysis.冰样表面以浅升华凹槽形式显现的亚晶界（Subgrain boundaries），是晶内变形与再结晶的直接且易于观测的特征。从东南极洲钻探的欧洲冰芯钻探计划（EPICA）毛德皇后地（EDML）深冰芯中获取的统计数据，未能检测到亚晶界形成增强的深度区间。所有深度下的晶界形貌均体现出内应变能对微观结构的强烈影响。该数据不支持‘主导再结晶机制随深度发生转变’的经典观点。结合晶体取向分析，明确了三类反映高机械各向异性的主要亚晶界类型。