Late Pleistocene fans and terraces in the Majes valley, southern Peru, and their relation to climatic variations
Late Pleistocene fans and terraces in the Majes valley, southern Peru, and their relation to climatic variations
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秘鲁南部马赫斯山谷晚更新世扇和阶地及其与气候变化的关系
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
F. Preusser
中科院分区：
文献类型：
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作者：
D. Steffen;F. Schlunegger;F. Preusser
本研究调查了秘鲁南部马杰斯山谷沙漠环境中沉积物沉积、侵蚀和气候之间的联系。阶地和扇的发光测年表明，沉积沉积与高原的湿润时间间隔有关，表明气候对沉积-退化循环有影响。沉积主要发生在~110 ~ 100、~60 ~ 50和~ 12 ~ 8 ka之间。Majes流域降水增多导致侵蚀加剧，泥沙从山坡向干流运移。结果，泥沙负荷超过了马杰斯河的输沙能力，在河流坡度较小的下游开始淤积。山坡沉积物库的枯竭导致干流携沙和输沙能力的相对增加，导致先前沉积的沉积物被侵蚀。因此，尽管气候变化可能启动沉积物积累阶段，但退化可以由自循环负反馈触发，而不必由气候变化驱动。
This study investigates the connection between sediment aggradation, erosion and climate in a desert environment of the Majes valley, southern Peru. Luminescence dating of terraces and fans shows that sediment aggradation correlates with wet time intervals on the Altiplano, suggesting a climatic influence on the aggradation–degradation cycles. Major periods of aggradation occurred between ~110–100, ~60–50 and 12–8 ka. More precipitation in the Majes catchment resulted in increased erosion and transportation of sediment from the hillslopes into the trunk river. As a result, the sediment loads exceeded the transport capacity of the Majes River and aggradation started in the lower reaches where the river gradient is less. Depletion of the hillslope sediment reservoirs caused a relative increase in the capacity of the trunk river to entrain and transport sediment, resulting in erosion of the previously deposited sediment. Consequently, although climate change may initiate a phase of sediment accumulation, degradation can be triggered by an autocyclic negative feedback and does not have to be driven by climatic change.