Abstract. An asthenospheric window underneath much of the South American continent increases the heat flow in the southern Patagonian Andes where glacial–interglacial cycles drive the building and melting of the Patagonian Icefields since the latest Miocene. The Last Glacial Maximum (LGM) was reached ∼26 000 yr BP (years before present). Significant deglaciation onsets between 21 000 and 17 000 yr BP were subject to an acceleration since the Little Ice Age (LIA), which was ∼400 yr BP. Fast uplift rates of up to 41±3 mm yr−1 are measured by global navigation satellite system (GNSS) around the Southern Patagonian Icefield and are currently ascribed to post-LIA lithospheric rebound, but the possible longer-term post-LGM rebound is poorly constrained. These uplift rates, in addition, are 1 order of magnitude higher than those measured on other glaciated orogens (e.g. the European Alps), which raises questions about the role of the asthenospheric window in affecting the vertical surface displacement rates. Here, we perform geodynamic thermo-mechanical numerical modelling to estimate the surface uplift rates induced by post-LIA and post-LGM deglaciation, accounting for temperature-dependent rheologies and different thermal regimes in the asthenosphere. Our modelled maximum post-glacial rebound matches the observed uplift rate budget only when both post-LIA and post-LGM deglaciation are accounted for and only if a standard continental asthenospheric mantle potential temperature is increased by 150–200 °C. The asthenospheric window thus plays a key role in controlling the magnitude of presently observed uplift rates in the southern Patagonian Andes.

中文翻译：

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由于长期和短期的冰川消融以及下方的软流圈窗口，巴塔哥尼亚安第斯山脉南部快速隆起

摘要。南美大陆大部分地区下方的软流圈窗口增加了巴塔哥尼亚安第斯山脉南部的热流，自中新世晚期以来，冰川-间冰期循环推动了巴塔哥尼亚冰原的形成和融化。末次盛冰期（LGM）在距今约 26 000 年（距今几年前）达到。距今 21 000 至 17 000 年之间发生的显着冰消作用自小冰期（LIA）（距今约 400 年）以来加速。全球导航卫星系统（GNSS）在南巴塔哥尼亚冰原周围测量到高达 41±3 mm yr−1 的快速抬升率，目前归因于 LIA 后岩石圈反弹，但末次盛冰期后可能出现的更长期反弹是约束不好。此外，这些抬升率比其他冰川造山带（例如欧洲阿尔卑斯山）测量的抬升率高1个数量级，这引发了关于软流圈窗口在影响垂直表面位移率中的作用的问题。在这里，我们进行了地球动力学热力数值模拟，以估计 LIA 后和 LGM 后冰消作用引起的表面隆起速率，并考虑了软流圈中与温度相关的流变性和不同的热状况。仅当同时考虑了 LIA 后和 LGM 后的消冰作用并且仅当标准大陆软流圈地幔潜在温度增加 150-200 °C 时，我们模拟的最大冰期后反弹才与观测到的抬升率预算相匹配。因此，软流圈窗口在控制巴塔哥尼亚安第斯山脉南部目前观测到的隆升速率的大小方面起着关键作用。