Abstract Marine-terminating ice stream behaviour often defines the stability of ice sheets and is driven by a complex interplay of climatic, oceanic, topographic and glaciological factors. Here, we use new integrated high resolution, extensive (2100 km2) and continuous geophysical, sedimentological and geotechnical data to reconstruct past glacial environments during the Last Glacial Maximum from a well-preserved palaeo-landscape. The data is from the axial centre of the Irish Sea Ice Stream (ISIS), which drained > 17% of the former British-Irish Ice Sheet. Recent geochronological data of the palaeo-ISIS show a build-up and advance of ice to marine-terminating maximum limits in the southern Celtic Sea 27–25 ka BP, followed by rapid ice margin retreat into the northern Irish Sea Basin (ISB) by 20.8 ± 0.7 ka BP. However, the flow dynamics in the central and axial bed of the ISIS through this timeframe are not well understood. Here, we use our new glacial landscape reconstruction to identify the spatial and temporal patterns of flow re-organisation and re-activations for the marine-terminating ISIS. From this we infer how ice streaming was driven by a variety of factors through advance, deglaciation and towards a temporary lift-off of ice from its bed and an ultimate demise. Overprinted subglacial bedforms with differing ice flow directions indicate an on/off behaviour to the ice-streaming, an increasing topographical influence and substantial realignment of ice flows. Subsurface geophysical data reveal the erosive capability of the ice stream through time, with a first erosive component in the formation of mega-scale glacial lineations leaving bedrock exposed at the ice stream bed. The depositional component of MSGL crest building occurred in the same ice-flow phase. Whilst the ice stream was laterally constricted in two locations, likely contributing to changes in ice margin retreat rates, we also propose that changes in basal drag associated with exposed bedrock at the ice‒bed interface influenced the retreat dynamics, particularly when this exposure was near the grounding zone. The wider implications of this work are that episodic and highly erosive ice streaming during ice advance and early retreat can change ice‒bed conditions radically and in turn influence glacial dynamics during later retreat episode, thus constituting a feedback process to be considered in modelling the dynamics of marine-terminating ice streams.

中文翻译：

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快速冰流期间的床侵蚀调节了爱尔兰海冰流的退缩动态

摘要 终止于海洋的冰流行为通常定义了冰盖的稳定性，并受到气候、海洋、地形和冰川因素的复杂相互作用的驱动。在这里，我们使用新的综合高分辨率、广泛（2100 平方公里）和连续的地球物理、沉积学和岩土工程数据，从保存完好的古景观重建末次盛冰期过去的冰川环境。数据来自爱尔兰海冰流 (ISIS) 的轴心，该冰流排出了超过 17% 的前英国-爱尔兰冰盖。古 ISIS 的最新地质年代学数据显示，在凯尔特海南部 27-25 ka BP，冰的积聚和前进到海洋终止的最大极限，随后冰缘迅速退缩到北爱尔兰海盆地（ISB） 20.8 ± 0.7 ka BP。然而，在这个时间范围内 ISIS 中心和轴向床的流动动力学尚不清楚。在这里，我们使用我们新的冰川景观重建来确定终止海洋的 ISIS 的流动重组和重新激活的时空模式。由此我们推断出冰流是如何通过推进、冰川消退以及冰从其床上暂时升起并最终消亡的各种因素驱动的。具有不同冰流方向的叠印冰下河床表明冰流的开/关行为、日益增加的地形影响和冰流的实质性重新排列。地下地球物理数据揭示了冰流随时间推移的侵蚀能力，在形成大型冰川线的过程中，第一个侵蚀成分使基岩暴露在冰河床。MSGL 波峰的沉积成分发生在同一冰流阶段。虽然冰流在两个位置横向收缩，可能导致冰缘后退率的变化，但我们还提出，与冰床界面暴露基岩相关的基础阻力变化影响了后退动力学，特别是当这种暴露接近接地区。这项工作的更广泛意义是，在冰进退过程中偶发性和高度侵蚀性的冰流可以从根本上改变冰床条件，进而影响后期退缩期间的冰川动态，