Landforms and sediments on the palaeo–ice stream beds of central Alberta record glacitectonic raft production and subsequent progressive disaggregation and moulding, associated substrate ploughing, and grooving. We identify a subglacial temporal or developmental hierarchy that begins with incipient rafts, including en échelon hill-hole complexes, hill-hole pairs, and strike-slip raft complexes, all of which display patterns typical of transcurrent fault activation and pull apart. Many display jigsaw puzzle–style fragmentation, indicative of substrate displacement along shallow décollement zones and potentially related to patchy ice stream freeze-on. Their gradual fragmentation and smoothing produces ice flow-transverse ridges (ribbed moraine), hill-groove pairs, and paraxial ridge and groove associations. Initiator scarp and megafluting associations are indicative of raft dislodgement and groove ploughing, leading to the formation of murdlins, crag-and-tails, stoss-and-lee type flutings and drumlins, and Type 1 hogsback flutings. Downflow modification of rafts creates linear block trains (rubble stripes), stoss-and-lee type megaflutings, horned crag-and-tails, rubble drumlinoids, and murdlins, diagnostic of an immature palaeo–ice stream footprint. Lateral ice stream margin migration ingests disaggregated thrust masses to form ridged spindles, ladder-type morphologies, and narrow zones of ribbed terrain and Type 2 hogsback flutings, an assemblage diagnostic of ice stream shear margin moraine formation.

中文翻译：

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冰川构造筏及其在第四纪冰下床型和沉积物中的作用

阿尔伯塔省中部古冰河床的地貌和沉积物记录了冰川构造筏的产生以及随后的逐步分解和成型，相关的基质犁耕和开槽。我们确定了一个冰下时间或发育层次，从初始筏开始，包括梯形山洞复合体、山洞对和走滑筏复合体，所有这些都显示出典型的横贯断层激活和拉开模式。许多显示拼图式的碎片，表明沿浅层分离区的基质位移，并可能与斑片状冰流冻结有关。它们逐渐破碎和平滑产生冰流横向脊（棱纹冰碛）、山沟对和近轴脊和沟组合。引发剂陡坡和巨型凹槽关联表明筏板移位和凹槽耕作，导致形成murdlins，crag-and-tails，stoss-and-lee型凹槽和drumlins，以及1型猪背凹槽。筏板的下流修改产生线性块列（碎石条纹）、stoss-and-lee 型巨型槽、有角的峭壁和尾巴、碎石鼓轮和 murdlins，诊断为未成熟的古冰流足迹。横向冰流边缘迁移吸收分解的推力块形成脊纺锤形、梯形形态和狭窄的带肋地形和 2 型猪脊槽，这是冰流剪切边缘冰碛形成的组合诊断。stoss-and-lee 型凹槽和鼓形凹槽，以及 1 型 hogsback 凹槽。筏板的下流修改产生线性块列（碎石条纹）、stoss-and-lee 型巨型槽、有角的峭壁和尾巴、碎石鼓轮和 murdlins，诊断为未成熟的古冰流足迹。横向冰流边缘迁移吸收分解的推力块形成脊纺锤形、梯形形态和狭窄的带肋地形和 2 型猪脊槽，这是冰流剪切边缘冰碛形成的组合诊断。stoss-and-lee 型凹槽和鼓形凹槽，以及 1 型 hogsback 凹槽。筏板的下流修改产生线性块列（碎石条纹）、stoss-and-lee 型巨型槽、有角的峭壁和尾巴、碎石鼓轮和 murdlins，诊断为未成熟的古冰流足迹。横向冰流边缘迁移吸收分解的推力块形成脊纺锤形、梯形形态和狭窄的带肋地形和 2 型猪脊槽，这是冰流剪切边缘冰碛形成的组合诊断。