Coupled spatial variations in precipitation and long-term erosion rates across the Washington Cascades
Coupled spatial variations in precipitation and long-term erosion rates across the Washington Cascades
复制标题
DOI：
10.1038/nature02111
复制
发表时间：
2003-12
期刊：
影响因子：
64.8
通讯作者：
P. Reiners;T. Ehlers;S. Mitchell;D. Montgomery
中科院分区：
文献类型：
--
作者：
P. Reiners;T. Ehlers;S. Mitchell;D. Montgomery
过去对构造活动山脉的研究表明，气候、构造和地形之间存在着强烈的耦合和反馈作用。例如，岩石隆起产生地形起伏，从而增加降水，这集中了侵蚀，反过来又影响了进一步岩石隆起的速度和空间格局。尽管气候、侵蚀和隆起之间的理论联系受到了广泛关注，，在这里，我们表明，强烈变化的长期（>106- 107年）侵蚀率推断从磷灰石（U-Th）/He冷却年龄横跨喀斯喀特山脉的华盛顿州密切跟踪现代平均年降水率。侵蚀和降水率变化幅度超过一个数量级的范围，最大值为0.33毫米yr-1和3.5米yr-1，分别与两个最大值位于50公里以西（迎风）的地形波峰的范围。这些数据表明，在山脉尺度上，降水和长期侵蚀率之间存在着强烈的耦合。如果该山脉目前处于地形稳定状态，则西侧的岩石抬升速度比该山脉其他地方快三到十倍，这可能是对气候集中侵蚀的反应。
Past studies of tectonically active mountain ranges have suggested strong coupling and feedbacks between climate, tectonics and topography,,,,. For example, rock uplift generates topographic relief, thereby enhancing precipitation, which focuses erosion and in turn influences rates and spatial patterns of further rock uplift. Although theoretical links between climate, erosion and uplift have received much attention,,,,,, few studies have shown convincing correlations between observable indices of these processes on mountain-range scales,. Here we show that strongly varying long-term (>106–107yr) erosion rates inferred from apatite (U–Th)/He cooling ages across the Cascades mountains of Washington state closely track modern mean annual precipitation rates. Erosion and precipitation rates vary over an order of magnitude across the range with maxima of 0.33 mm yr-1and 3.5 m yr-1, respectively, with both maxima located 50 km west (windward) of the topographic crest of the range. These data demonstrate a strong coupling between precipitation and long-term erosion rates on the mountain-range scale. If the range is currently in topographic steady state, rock uplift on the west flank is three to ten times faster than elsewhere in the range, possibly in response to climatically focused erosion.