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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Pliocene erosional pulse and glacier-landscape feedbacks in the western Alaska Range
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Pliocene erosional pulse and glacier-landscape feedbacks in the western Alaska Range

机译：在阿拉斯加西部范围内的全面侵蚀脉冲和冰川景观反馈

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Pliocene-Pleistocene glaciation modified the topography and erosion of most middle- and high-latitude mountain belts, because the evolution of catchment topography controls long-term glacier mass balance and erosion. Hence, characterizing how erosion rates change during repeated glaciations can help test hypothesized glacier erosion-landscape feedbacks across a range of settings. To better understand how glaciations and landscapes coevolve on geologic timescales, I quantify erosion rates in the glaciated western Alaska Range with low-temperature thermochronometric data and modeling. Zircon (U-Th)/He and apatite fission track data suggest mountain-building was underway by the early Miocene. In contrast, lower-temperature apatite (U-Th)/He age-elevation and grain age-kinetic data indicate that erosion accelerated coincident with regional Pliocene glaciation ca. 4 Ma. Furthermore, erosion rates calculated within an eroding half-space indicate slow erosion at a rate = 0.3 km/m.y. before 4.2 Ma, an initial pulse of rapid erosion at a rate of 1.0-1.6 km/m.y. during 4.2-2.9 Ma, and more moderate erosion at a rate of 0.4-0.7 km/m.y. since 2.9 Ma. The initial erosion pulse suggests a significant transient landscape adjustment to the introduction of efficient glacial erosion. The subsequent decrease in Pleistocene erosion rates is consistent with a negative feedback between continuing glaciation and glacier size/erosivity: If glacial erosion outpaces rock uplift, glacier erosion decreases over time as topography, mass balance, valley gradients, and ice flux are reduced. These findings imply that in areas of moderate rock uplift rates, the onset of local Plio-Pleistocene glaciation may have been punctuated by an initial pulse of rapid landscape change, after which change became more gradual. Published by Elsevier B.V.
机译：全肾上腺素冰川冰川修改了大多数中高纬度山腰的地形和侵蚀，因为集水形貌的演变控制了长期冰川大规模平衡和侵蚀。因此，表征在重复冰川期间的侵蚀率如何变化有助于在一系列设置中测试假设冰川侵蚀景观反馈。为了更好地了解如何在地质时间尺度上共存的冰川般的冰川和景观，我用低温热量数据和建模量化冰川西部阿拉斯加范围内的侵蚀率。锆石（U-TH）/ HE和磷灰石裂变轨道数据建议山地建筑正在进行中间内科。相比之下，较低温度的磷灰石（U-TH）/他年龄升高和晶粒时代动力学数据表明侵蚀加速与区域普罗替省冰川冻结巧合。 4马。此外，在腐蚀半空间内计算的侵蚀率表示以速率且速率慢侵蚀。= 0.3 km / m.y。在4.2 mA之前，以1.0-1.6 km / m.y的速率，初始脉冲的初始脉冲。在4.2-2.9 mA期间，以0.4-0.7 km / m.y的速度更适中的侵蚀。自2.9马。初始侵蚀脉冲表明对引入有效的冰川侵蚀的显着瞬态景观调整。随后的渗透率降低符合继续冰川和冰川尺寸/侵蚀性之间的负反馈：如果冰川侵蚀分离摇滚隆起，随着地形，质量平衡，谷梯度和冰通量减少了冰川侵蚀。这些发现意味着，在适度的岩石隆起速率的区域，局部地块冰川冰川的起始可能已被初始横向变化的初始脉冲打断，之后变得更加渐进。由elsevier b.v出版。

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