The sedimentary record of Icelandic ice-contact environments provides critical insights into past glacier margin dynamics and position, relative sea level, and the geomorphic processes that drive the evolution of proglacial environments. This important archive has been little exploited, however, with most glacier and sea-level reconstructions based on limited sedimentary exposures, coring and surface geomorphic evidence. We report an extensive (42 km of data within a 24-km² study area) and deep (reflections recorded at depths up to 100 m) low-frequency (40 and 100 MHz) ground-penetrating radar (GPR) survey of the Sandgígur moraines, SE Iceland. GPR profiles reveal a much larger (67 m high) and extensive (1.25 km wide) buried moraine ridge than that suggested by surface topography (typically 125 m wide and 7 m high). These data reveal that the Sandgígur moraines was deposited during a major Holocene re-advance of Skeiðarárjökull. The moraine ridge is buried by sediments dominated by glacifluvial deposits with an estimated sediment volume of 1.04 km³. We combine GPR-derived subsurface architecture and the surface morphology to develop a conceptual model detailing the geomorphic evolution of the moraine and surrounding region. These results provide new insights into the Holocene evolution of Skeiðarársandur, identifying the presence of a former major ice-margin position, as well as a past relative sea-level limit. Furthermore, we establish that sediment supply and available terrestrial accommodation space are dominant drivers in the formation and evolution of vast sandar environments.

中文翻译：

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冰岛东南部 Skeiðarársandur 的大规模埋冰边缘陆地系统的探地雷达 (GPR) 调查

冰岛冰接触环境的沉积记录提供了对过去冰川边缘动态和位置、相对海平面以及推动前冰期环境演变的地貌过程的重要见解。然而，这个重要的档案很少被利用，大多数冰川和海平面重建都是基于有限的沉积暴露、取芯和地表地貌证据。^{我们报告了一个广泛的（24 公里2}范围内的 42 公里数据）研究区）和深部（在高达 100 m 的深度记录的反射）低频（40 和 100 MHz）探地雷达 (GPR) 对冰岛东南部 Sandgígur 冰碛的勘测。探地雷达剖面揭示了比地表地形（通常宽 125 米，高 7 米）所暗示的更大（67 米高）和广泛（1.25 公里宽）的埋藏冰碛脊。这些数据表明，Sandgígur 冰碛是在全新世的一次重大的 Skeiðarárjökull 重新推进期间沉积的。冰碛脊被以冰川沉积物为主的沉积物掩埋，估计沉积物体积为 1.04 km ³. 我们将 GPR 衍生的地下结构和地表形态相结合，开发了一个概念模型，详细描述了冰碛和周边地区的地貌演变。这些结果为Skeiðarársandur的全新世演化提供了新的见解，确定了前主要冰缘位置的存在，以及过去的相对海平面限制。此外，我们确定沉积物供应和可用的陆地住宿空间是广阔沙地环境形成和演变的主要驱动力。