Erosional variability along the northwest Himalaya
Erosional variability along the northwest Himalaya
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DOI：
10.1029/2008jf001010
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发表时间：
2009-03
影响因子：
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通讯作者：
R. Thiede;T. Ehlers;B. Bookhagen;M. Strecker
中科院分区：
文献类型：
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作者：
R. Thiede;T. Ehlers;B. Bookhagen;M. Strecker
由于变形位置和气候的变化，山区地带的侵蚀剥露和地形在数百万年的时间尺度上是时空变化的。我们调查的时空变化，在折返横跨150 × 250公里的车厢西北喜马拉雅山，印度。24个新的和241个以前发表的磷灰石和锆石裂变径迹和白色云母Ar-40/Ar-39年龄与1-D数值模型集成，以量化在小，高，特提斯喜马拉雅几个主要结构沿走向折返的速率和时间。热时计数据的分析表明，主要的时间变化发生在早中新世和上新世更新世过渡期的剥露。(1)最值得注意的是，北方高喜马拉雅地区的折返速率在2 - 3 -19 Ma和3-0 Ma之间较高（2-3 mm a（-1）），在19-3 Ma之间较低（0.5-0.7 mm a（-1））。(2)然而，沿着喜马拉雅山南坡，自11 Ma以来存在1-2 mm a（-1）的高折返速率。(3)我们的热年代学数据集与现今降雨量、局部地形和特定水流功率的相关性较差，这可能是由于（1）在高折返率下，地壳冷却变化对侵蚀空间变化缺乏敏感性（> 1 mm a（-1）），（2）侵蚀的时空变化不模仿当今的地形或气候条件，或（3）该区域中的热时计样品在仅与现代地形弱相似的地形下冷却。
Erosional exhumation and topography in mountain belts are temporally and spatially variable over million year timescales because of changes in both the location of deformation and climate. We investigate spatiotemporal variations in exhumation across a 150 x 250 km compartment of the NW Himalaya, India. Twenty-four new and 241 previously published apatite and zircon fission track and white mica Ar-40/Ar-39 ages are integrated with a 1-D numerical model to quantify rates and timing of exhumation alongstrike of several major structures in the Lesser, High, and Tethyan Himalaya. Analysis of thermochronometer data suggests major temporal variations in exhumation occurred in the early middle Miocene and at the Plio-Pleistocene transition. (1) Most notably, exhumation rates for the northern High Himalayan compartments were high (2-3 mm a(-1)) between similar to 23-19 and similar to 3-0 Ma and low (0.5-0.7 mm a(-1)) in between similar to 19-3 Ma. (2) Along the southern High Himalayan slopes, however, high exhumation rates of 1-2 mm a(-1) existed since 11 Ma. (3) Our thermochronology data sets are poorly correlated with present-day rainfall, local relief, and specific stream power which may likely result from (1) a lack of sensitivity of changes in crustal cooling to spatial variations in erosion at high exhumation rates (>similar to 1 mm a(-1)), (2) spatiotemporal variation in erosion not mimicking the present-day topographic or climatic conditions, or (3) the thermochronometer samples in this region having cooled under topography that only weakly resembled the modern-day topography.