Using offshore detrital apatite (U‐Th)/He thermochronometry and 3D thermo‐kinematic modeling of the catchment topography, we constrain the timing of major topographic change at Bourgeois Fjord, Antarctic Peninsula (AP). While many mid‐latitude glacial landscapes developed primarily in response to global cooling over the last ~2.6 Ma, we find that kilometer‐scale landscape evolution at Bourgeois Fjord began ~30–12 Ma ago and <2 km of valley incision has occurred since ~16 Ma. This early onset of major topographic change occurred following the initiation of alpine glaciation at this location and prior to the development of a regional polythermal ice sheet inferred from sedimentary evidence offshore of the AP. We hypothesize that topographic change relates to (i) feedbacks between an evolving topography and glacial erosion processes, (ii) effects of glacial‐interglacial variability, and (iii) the prevalence of subglacial meltwater. The timing and inferred spatial patterns of long‐term exhumation at Bourgeois Fjord are consistent with a hypothesis that glacial erosion processes were suppressed at the AP during global Plio‐Pleistocene cooling, rather than enhanced. Our study examines the long‐term consequences of glacial processes on catchment‐wide erosion as the local climate cooled. Our findings support the hypothesis that landscapes at different latitudes had different responses to global cooling. Our results also suggest that erosion is enhanced along the plateau flanks of Bourgeois Fjord today, which may be due to periglacial processes or mantling via subglacial till. If regional warming persists and meltwater becomes more pronounced, we predict that enhanced erosion along the plateau flank will accelerate topographic change.

中文翻译：

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碎屑热年代法揭示了南极半岛的地形不是更新世的风景

利用离岸碎屑磷灰石（U‐Th）/ He热计时法和集水区地形的3D热运动学模型，我们限制了南极半岛（AP）布尔乔亚峡湾主要地形变化的时间。尽管许多中纬度冰川景观主要是由于过去约2.6 Ma的全球变冷而发展的，但我们发现Bourgeois Fjord的千米级景观演变始于约30–12 Ma之前，并且自〜以来发生了<2 km的山谷切口16 Ma。主要地形变化的早期发作发生在该位置的高山冰川形成之后，以及根据美联社离岸沉积证据推断出的区域多热冰盖形成之前。我们假设地形变化与（i）不断变化的地形和冰川侵蚀过程之间的反馈有关，（ii）冰川-冰川间变化的影响，以及（iii）冰川下融水的盛行。布尔乔亚峡湾长期掘尸的时间安排和推断的空间格局与以下假设一致：在全球上新世-更新世冷却期间，AP的冰川侵蚀过程受到抑制，而不是增强。我们的研究考察了冰川过程对当地气候变冷对集水区侵蚀的长期影响。我们的发现支持以下假设：不同纬度的景观对全球变冷的反应不同。我们的研究结果还表明，今天布尔乔亚峡湾的高原腹地侵蚀加剧，这可能是由于冰缘过程或通过冰下耕作造成的。如果区域变暖持续并且融化水变得更加明显，