Neogene‐Quaternary Uplift and Landscape Evolution in Northern Greenland Recorded by Subglacial Valley Morphology
Neogene‐Quaternary Uplift and Landscape Evolution in Northern Greenland Recorded by Subglacial Valley Morphology
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冰下山谷形态记录的格陵兰岛北部新近纪第四纪隆升与地貌演化
DOI：
10.1029/2021jf006395
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Austermann, Jacqueline
中科院分区：
文献类型：
--
作者：
Paxman, Guy J. G.;Tinto, Kirsty J.;Austermann, Jacqueline
隐藏在格陵兰冰盖下的景观仍然是地球上地图绘制最稀少的地区之一，但它提供了大范围冰川之前和期间的环境条件以及冰盖对气候变化的反应的独特记录。特别是，在格陵兰岛上观察到的冰下山谷可能保存了与地貌和冰盖演化有关的地貌信息。在这里，我们分析了格陵兰北部冰下山谷网络的形态，使用多年航空无线电回波探测期间获得的海床高程测量。河道剖面形态与网络的主要河流起源相一致，并有证据表明冰和/或融水对其进行了局部修改。重力和磁力异常表明，河谷网络的空间组织受到区域尺度地质结构的影响，这意味着一个长期而完善的水文系统。我们还记录了河谷纵向剖面中的两个狭长地带和网络下部河道底部以上的梯田。这些观测结合水流动力模拟表明，格陵兰北部在新近纪经历了两次相对基准面下降(约12-3.7Ma的∼150m和约8.2-2.8m的∼380m)，导致了通过切割和狭长地带撤退的河道剖面调整。推断的基准面下降的时间与其他陆上和近海的抬升、剥蚀和/或相对海平面变化的记录相关，我们认为构造和/或地幔驱动的抬升在格陵兰北部现代景观的形成中发挥了重要作用。
The landscape hidden beneath the Greenland Ice Sheet remains one of the most sparsely mapped regions on Earth, but offers a unique record of environmental conditions prior to and during widespread glaciation, and of the ice sheet's response to changing climates. In particular, subglacial valleys observed across Greenland may preserve geomorphological information pertaining to landscape and ice sheet evolution. Here we analyze the morphology of a subglacial valley network in northern Greenland using bed elevation measurements acquired during multi‐year airborne radio‐echo sounding surveys. Channel profile morphologies are consistent with a primarily fluvial origin of the network, with evidence for localized modification by ice and/or meltwater. Gravity and magnetic anomalies suggest that the spatial organisation of the valley network is influenced by regional‐scale geological structure, implying a long‐lived and well‐established hydrological system. We also document two knickzones in the valley longitudinal profile and terraces above the channel floor in the lower course of the network. These observations, combined with stream power modeling, indicate that northern Greenland experienced two episodes of relative base level fall during the Neogene (∼150 m at ca. 12–3.7 Ma and ∼380 m at ca. 8.2–2.8 Ma) that resulted in channel profile adjustment via incision and knickzone retreat. The timing of the inferred base level fall correlates with other onshore and offshore records of uplift, denudation, and/or relative sea level change, and we suggest that tectonic and/or mantle‐driven uplift played an important role in the genesis of the modern landscape of northern Greenland.
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抬高的被动大陆边缘：不是裂肩，而是断层后偶发埋藏和折返的表现
影响因子：
3.9
作者：
P. Japsen;J. Chalmers;P. Green;J. Bonow
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DOI：
--
发表时间：
2015
期刊：
影响因子：
--
作者：
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影响因子：
5.8
作者：
B. Keisling;L. T. Nielsen;C. Hvidberg;R. Nuterman;R. DeConto
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R. DeConto
影响因子：
5.8
作者：
Livingstone, Stephen J.;Chu, Winnie;Kingslake, Jonathan
通讯作者：
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影响因子：
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作者：
F. Beaud;G. Flowers;J. Venditti
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J. Venditti