以色列内盖夫大学Liran Goren团队通过古分水岭位置记录揭示了间歇性分水岭迁移及其与古气候指标的联系。2025年3月3日出版的《美国科学院院刊》发表了这项成果。
分水岭迁移改变了流域的几何形状，影响了地球表面水、侵蚀、沉积物和生态系统的分布。分水岭迁移率受分水岭侵蚀率差异的影响，因此对构造和气候的时空变化很敏感。然而，用于量化分水岭迁移率的既定方法只提供了分水岭运动的间接证据，也只提供了迁移率的平均值。因此，分水岭迁移中的短暂性无法解决，阻碍了探索驱动这种潜在短暂性动态的环境变化的能力。
研究组分析了一组可追溯的阶地，这些阶地被确定为古分水岭位置的标志，为分水岭的古运动提供了直接证据。阶地的位置和年龄表明，在104至105年的时间尺度上，存在间歇性的分水岭迁移，其快速迁移阶段的速度是平均速度的两倍以上，这与有记录的区域古气候波动相吻合。这些发现突显了地貌时间尺度上分水岭迁移动态的间歇性及其对气候变化的潜在敏感性，强调了这些变化对流域平面演变的影响。
附：英文原文
Title: Record of paleo water divide locations reveals intermittent divide migration and links to paleoclimate proxies
Author: Harel, Elhanan, Goren, Liran, Crouvi, Onn, Porat, Naomi, Qu, Tianyue, Ginat, Hanan, Shelef, Eitan
Issue&Volume: 2025-3-3
Abstract: Drainage divide migration alters the geometry of drainage basins, influencing the distribution of water, erosion, sediments, and ecosystems across Earth’s surface. The rate of divide migration is governed by differences in erosion rates across the divide and is thus sensitive to spatiotemporal variations in tectonics and climate. However, established approaches for quantifying divide migration rates offer only indirect evidence for the motion of the divide and provide only migration rate averages. Consequently, transience in divide migration cannot be resolved, hindering the ability to explore environmental changes that drive the dynamics of such potential transience. Here, we study a set of datable terraces identified as markers of paleo-divide locations, which provide direct evidence for the paleo motion of the divide. The location and age of the terraces reveal intermittent divide migration at timescales of 104 to 105 y, with phases of rapid migration—at rates more than twice the average—which coincide with documented regional paleoclimate fluctuations. These findings highlight the intermittent nature of divide migration dynamics over geomorphic timescales and its potential sensitivity to climate changes, underscoring the impact of such changes on the planform evolution of drainage basins.
DOI: 10.1073/pnas.2408426122
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2408426122