Erosion of the Rwenzori Mountains, East African Rift, from in situ‐produced cosmogenic10Be
Erosion of the Rwenzori Mountains, East African Rift, from in situ‐produced cosmogenic10Be
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原位产生的宇宙成因10Be对东非裂谷鲁文佐里山脉的侵蚀
DOI：
10.1029/2011jf002117
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发表时间：
2012
影响因子：
--
通讯作者：
M. Hinderer
中科院分区：
文献类型：
--
作者：
S. Roller;H. Wittmann;M. Kastowski;M. Hinderer
[1]高起伏和陡峭的地形被认为会导致高侵蚀率。在东非阿尔伯特裂谷的鲁文佐里山脉，在鲁文佐里断块抬升过程中形成了3公里以上的起伏，总体上剥蚀率很低。我们在山区流域测量了28.2到131毫米/KYR的原地宇宙成因剥蚀速率，在邻近的低起伏东非高原测量了7.8到17.7毫米/KYR的剥蚀速率。这些比率大约比其他类似救济的情况下低一个数量级。通过广泛的地貌分析，发现剥蚀率与地形、坡度和河道陡度呈正相关，表明河流切割控制着侵蚀过程。在大多数高于第四纪ELA水平(>；4500 ma.s.l)的上游水源地，盛行着从几个较老的和最近的较小冰期继承的冰川印记。然而，在海拔4500英里以下的地区，温和的气候条件阻碍了霜冻的破碎，有利于茂密的植被，并最大限度地减少了裸露的岩石区域和相关的大量浪费。我们得出的结论是，鲁文佐里山脉的侵蚀速度明显慢于其他高地貌山脉，这是由于多种因素的综合作用：极其茂密的山云林植被，高强度的片麻岩和角闪岩岩性，以及由于伸展构造环境而导致的低内部破裂。这种特殊的组合是这种延伸的热带环境所独有的，导致了意想不到的低侵蚀率，无法超过上新世后鲁文佐里断块正在进行的岩石抬升。
[1] High relief and steep topography are thought to result in high erosion rates. In the Rwenzori Mountains of the Albert Rift, East Africa, where more than 3 km of relief have formed during uplift of the Rwenzori fault block, overall low denudation rates prevail. We measured in situ-derived cosmogenic denudation rates of 28.2 to 131 mm/kyr in mountainous catchments, and rates of 7.8 to 17.7 mm/kyr on the adjacent low-relief East African Plateau. These rates are roughly an order of magnitude lower than in other settings of similar relief. We present an extensive geomorphological analysis, and find that denudation rates are positively correlated with relief, hillslope gradient, and channel steepness, indicating that river incision controls erosional processes. In most upper headwater reaches above Quaternary ELA levels (>4500 m a.s.l.), glacial imprinting, inherited from several older and recent minor glaciation stages, prevails. In regions below 4500 m a.s.l., however, mild climatic conditions impede frost shattering, favor dense vegetation, and minimize bare rock areas and associated mass wasting. We conclude that erosion of the Rwenzori Mountains is significantly slower than corresponding rates in other mountains of high relief, due to a combination of factors: extremely dense mountain cloud forest vegetation, high rock strength of gneiss and amphibolite lithologies, and low internal fracturing due to the extensional tectonic setting. This specific combination, unique to this extensional tropical setting, leads to unexpected low erosion rates that cannot outpace post-Pliocene ongoing rock uplift of the Rwenzori fault block.
瑞士阿尔卑斯山冰川雕刻的上罗讷河谷中宇宙成因核素衍生的扩散和偶发侵蚀率
影响因子：
3.3
作者：
Norton;von Blanckenburg
通讯作者：
von Blanckenburg