Abstract Glacitectonically thrusted blocks of unlithified sediment are commonly inferred to have been frozen during thrusting, with implications for paleoclimate and glacier dynamics. We inferred strain patterns within thrusted blocks of glaciolacustrine mud in the Rubjerg Knude and Mons Klint glacitectonic complexes of coastal Denmark to try to assess whether the mud was frozen during thrusting. Fabrics based on the anisotropy of magnetic susceptibility (AMS) of the muds are interpreted with results of ring-shear experiments and models of AMS fabric development during layer-parallel shortening (LPS). In intact distal stratigraphy, fabrics indicate moderate LPS. Fabrics where thrusts have disrupted more proximal stratigraphy indicate rotation of mud sheets during thrusting with insufficient penetrative strain to reset the LPS fabric. The exception is within decimeters of faults at Rubjerg Knude where shear overprinted the LPS fabric. Although these data indicate that mud sheets were mostly rigid during thrusting, this is not necessarily evidence of permafrost. Critical-taper theory indicates that even a gentle slope of the proglacial surface away from the glacier margin would have allowed slip without internal deformation of thrust sheets, requiring only minimal pore-water pressures.

中文翻译：

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冰川冲断沉积物中的应变模式和冲断过程中的条件

摘要 冰川构造冲断的未岩化沉积物块通常被推断在冲断过程中已经冻结，这对古气候和冰川动力学有影响。我们在丹麦沿海的 Rubjerg Knude 和 Mons Klint 冰川构造复合体中推断出冲断的冰川泥块内的应变模式，以尝试评估冲断过程中泥浆是否被冻结。基于泥浆磁化率 (AMS) 各向异性的织物用环剪切实验结果和层平行缩短 (LPS) 期间 AMS 织物发展模型进行解释。在完整的远端地层中，织物显示中等 LPS。推力破坏了更近端地层的织物表明在推力过程中泥板旋转，穿透应变不足以重置 LPS 织物。例外是在 Rubjerg Knude 的断层范围内，在那里剪切套印 LPS 织物。尽管这些数据表明在逆冲过程中泥板大多是刚性的，但这不一定是永久冻土的证据。临界锥度理论表明，即使是远离冰川边缘的前冰期表面的缓坡，也可以在没有推力片内部变形的情况下滑动，只需要最小的孔隙水压力。