Millennial lag times in the Himalayan sediment routing system
Millennial lag times in the Himalayan sediment routing system
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DOI：
10.1016/j.epsl.2013.08.044
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发表时间：
2013-11
影响因子：
5.3
通讯作者：
J. Blöthe;O. Korup
中科院分区：
文献类型：
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作者：
J. Blöthe;O. Korup
如果不对中间储存量进行估计，任何关于从山区地带到其前地和近海汇的沉积物路线的理解都是不完整的，中间储存量决定性地缓冲了侵蚀速率产生的沉积物，衰减了水和沉积物通量，并保护了底层基岩免受切割。我们第一次量化的沉积物存储在> 38 000主要是冰后期喜马拉雅山谷填充，根据经验的体积面积缩放的山谷填充轮廓自动提取的数字地形数据。估计的总体积为690（/− 242+ 452）km 3，主要包含在少数大于1 km 3的大型山谷填充物中，而灾难性的质量消耗又增加了177（±31）km 3。沉积物储存量沿造山带走向沿着差异很大。喜马拉雅山的大部分沉积物储存在冰川冲刷的山谷中，这些山谷为快速挖掘和切割的合生带上游的总体积提供了44%的容纳空间。相反，喜马拉雅山脉中部的阶梯状长波地形限制了冰川的范围，从而限制了任何远离构造盆地的重要冰川沉积物储存。我们表明，喜马拉雅山谷填充物的独家删除可以滋养当代沉积物通量从印度河和雅鲁藏布江流域> 1 kyr，虽然个别填充物可能达到停留时间> 100 kyr。这些千年的滞后时间在喜马拉雅沉积物路由系统可能足以缓冲信号的短期地震以及气候干扰，从而复杂的简单相关性和解释的沉积档案从喜马拉雅造山带，其前陆，其海底扇系统。
Any understanding of sediment routing from mountain belts to their forelands and offshore sinks remains incomplete without estimates of intermediate storage that decisively buffers sediment yields from erosion rates, attenuates water and sediment fluxes, and protects underlying bedrock from incision. We quantify for the first time the sediment stored in> 38 000 mainly postglacial Himalayan valley fills, based on an empirical volume-area scaling of valley-fill outlines automatically extracted from digital topographic data. The estimated total volume of 690 (/− 242+ 452) km 3 is mostly contained in few large valley fills> 1 km 3, while catastrophic mass wasting adds another 177 (±31) km 3. Sediment storage volumes are highly disparate along the strike of the orogen. Much of the Himalaya's stock of sediment is sequestered in glacially scoured valleys that provide accommodation space for∼ 44% of the total volume upstream of the rapidly exhuming and incising syntaxes. Conversely, the step-like long-wave topography of the central Himalayas limits glacier extent, and thus any significant glacier-derived storage of sediment away from tectonic basins. We show that exclusive removal of Himalayan valley fills could nourish contemporary sediment flux from the Indus and Brahmaputra basins for> 1 kyr, though individual fills may attain residence times of> 100 kyr. These millennial lag times in the Himalayan sediment routing system may sufficiently buffer signals of short-term seismic as well as climatic disturbances, thus complicating simple correlation and interpretation of sedimentary archives from the Himalayan orogen, its foreland, and its submarine fan systems.