Abstract The pattern, timing, and origin of Southern Hemisphere climate change during the last glaciation remains a pressing problem, with implications for the role of orbital forcing in ice-age cycles. Here, we present geomorphological and cosmogenic exposure age data from East Falkland in the South Atlantic region that show onset of glacial conditions by marine isotope stage 4 (∼60–70 ka), with expansion of ice to its maximum extent of the last glaciation. At least seven geomorphological units marked by multiple crests on composite moraines indicate glacier expansion on Mt. Usborne, the highest peak of East Falkland. From ∼20 to 45 ka, glaciers fluctuated on a millennial timescale with near-maximum conditions being reached repeatedly. Overall ice extent appears to have shrunk slightly through time, with evidence of glaciation at ∼20 ka preserved only in the highest-elevation cirques. This long glacial maximum is inconsistent both with local orbital control and orbital forcing as expressed in the traditional Milankovitch hypothesis. The timing of millennial glacier expansions occurred between Northern Hemisphere Heinrich Stadials and resembles that documented for New Zealand glaciers, suggesting at least a trans-Pacific expression. We postulate that periodic recessions corresponded with southward expansion of the southern westerlies during Heinrich Stadials and warming air and ocean temperatures over the South Atlantic region.

中文翻译：

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山上~20-45 ka 范围内的多个冰川最大值。乌斯本，东福克兰，南大西洋地区

摘要 末次冰期南半球气候变化的模式、时间和起源仍然是一个紧迫的问题，对轨道强迫在冰河时代循环中的作用有影响。在这里，我们展示了来自南大西洋地区东福克兰群岛的地貌和宇宙成因暴露年龄数据，这些数据显示了海洋同位素第 4 阶段（~60-70 ka）的冰川条件开始，随着冰的扩张达到最后一次冰期的最大程度。至少有七个以复合冰碛上的多个波峰为标志的地貌单元表明山上的冰川扩张。乌斯本，东福克兰最高峰。从~20 到 45 ka，冰川在千年时间尺度上波动，反复达到接近最大值的条件。随着时间的推移，整体冰范围似乎略有缩小，大约 20 ka 的冰川作用的证据仅保存在海拔最高的冰斗中。这种长冰川最大值与传统米兰科维奇假说中表达的局部轨道控制和轨道强迫不一致。千禧年冰川扩张的时间发生在北半球 Heinrich Stadials 之间，类似于新西兰冰川的记录，表明至少是跨太平洋的表现形式。我们假设周期性衰退与 Heinrich Stadials 期间南部西风带向南扩张以及南大西洋地区的空气和海洋温度升高相对应。千禧年冰川扩张的时间发生在北半球 Heinrich Stadials 之间，类似于新西兰冰川的记录，表明至少是跨太平洋的表现形式。我们假设周期性衰退与 Heinrich Stadials 期间南部西风带向南扩张以及南大西洋地区的空气和海洋温度升高相对应。千禧年冰川扩张的时间发生在北半球 Heinrich Stadials 之间，类似于新西兰冰川的记录，表明至少是跨太平洋的表现形式。我们假设周期性衰退与 Heinrich Stadials 期间南部西风带向南扩张以及南大西洋地区的空气和海洋温度升高相对应。