Glacial Lake Outburst Floods (GLOFs) constitute a major hazard in glacierized regions. They are particularly pronounced in the Baker River watershed (Chilean Patagonia, 48°S), where 23 events occurred between 2008 and 2020. Although GLOF deposits have previously been studied in lake settings, how modern GLOFs are recorded in fjord sediments remains mostly unknown. To address this issue, ten sediment cores collected in the fjord immediately downstream of the Baker River (Martínez Channel) were investigated and compared to the recent GLOF history of the river. Results show that sediments accumulate at 2.0 to 3.4 cm year⁻¹ and that GLOF deposits can be distinguished from background sediments by their finer grain size (5.98 ± 0.82 μm) and lower organic carbon content (0.31 ± 0.06%), reflecting the release and transport in suspension of high amounts of glacial rock flour during GLOFs. Although 21 GLOFs from Cachet 2 Lake occurred between 2008 and 2017, the first events left a stronger imprint in the sediment, suggesting that more sediment of glacial origin was released during those initial events, possibly due to lake-bed erosion. An older GLOF deposit was tentatively linked to the outburst of Las Lengas Lake in 1988. The sediment cores also contain fine-grained turbidites, especially in the prodelta area. These turbidites confirm recent channel activity, but most of them seem to have been triggered by processes other than GLOFs. Overall, the results of this study suggest that GLOF deposits are distinct from typical flood turbidites. They are best identified by their low grain size and total organic carbon content, and best archived on the delta slope, away from any submarine channel influence. Finally, these results highlight the potential of fjord sediment archives to establish pre-historical GLOF records and ultimately improve GLOF hazard assessments.

中文翻译：

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峡湾沉积物中现代冰川湖溃决洪水的特征（智利南部贝克河）

冰川湖溃决洪水 (GLOF) 是冰川地区的主要灾害。它们在贝克河流域（智利巴塔哥尼亚，南纬 48°）尤为明显，2008 年至 2020 年间发生了 23 次事件。虽然之前已经在湖泊环境中研究了 GLOF 沉积物，但现代 GLOF 是如何在峡湾沉积物中记录的，目前仍然未知。为了解决这个问题，对贝克河（马丁内斯海峡）下游峡湾中收集的十个沉积物岩心进行了调查，并与该河最近的 GLOF 历史进行了比较。结果表明，沉积物积聚在 2.0 至 3.4 cm 年^-1并且 GLOF 沉积物可以通过其更细的粒度 (5.98 ± 0.82 μm) 和较低的有机碳含量 (0.31 ± 0.06%) 与背景沉积物区分开来，这反映了 GLOF 期间大量冰川岩粉在悬浮液中的释放和运输。尽管 Cachet 2 湖的 21 次 GLOF 发生在 2008 年至 2017 年之间，但第一次事件在沉积物中留下了更强烈的印记，表明在这些初始事件中释放了更多冰川沉积物，可能是由于湖床侵蚀。一个较旧的 GLOF 矿床初步与 1988 年 Las Lengas 湖的爆发有关。沉积物核心还包含细粒浊积岩，尤其是在前三角洲地区。这些浊岩证实了最近的通道活动，但其中大部分似乎是由 GLOF 以外的过程触发的。总体，这项研究的结果表明 GLOF 沉积物不同于典型的洪水浊积岩。它们最好通过其低粒度和总有机碳含量来识别，最好在三角洲斜坡上存档，远离任何海底通道的影响。最后，这些结果突出了峡湾沉积物档案在建立史前 GLOF 记录并最终改进 GLOF 危害评估方面的潜力。