The distribution of active rock uplift in the interior of the western Qilian Shan, NE Tibetan Plateau: Inference from bedrock channel profiles
The distribution of active rock uplift in the interior of the western Qilian Shan, NE Tibetan Plateau: Inference from bedrock channel profiles
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DOI：
10.1016/j.tecto.2019.04.001
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发表时间：
2019-05
期刊：
影响因子：
2.9
通讯作者：
Yizhou Wang;D. Zheng;Huiping Zhang;Chaopeng Li;Linxiang Xiao;Youjuan Li;Y. Hao
中科院分区：
文献类型：
--
作者：
Yizhou Wang;D. Zheng;Huiping Zhang;Chaopeng Li;Linxiang Xiao;Youjuan Li;Y. Hao
西祁连山内部岩石隆升速率的分布至今尚未完全解决，这限制了我们对青藏高原东北部隆升格局和景观演化的认识。河流动力切割模型表明，岩石抬升速率的空间差异对河道坡度起主要控制作用，从而为活动造山带岩石抬升模式的绘制提供了一种有效的方法。本文分析了祁连山西部的河流纵剖面，发现了一种空间分异格局，其陡度指数沿着平行山脉（如党河南山、大雪山、妥莱山和北方祁连山）较高，而在山内盆地较低。陡度指数的变化，岩性和年降水量的比较显示有限的相关性，在这个景观的通道坡度与岩性阻力和气候。我们还观察到没有系统的陡度指数与流域面积，泥沙通量，或通道凹。我们认为，系统的变化，在通道陡度指数是构造控制，而不是可变的沉积物通量，气候，或岩性的后果。因此，西祁连山归一化河道陡度模式反映了岩石隆升主要局限于以活动逆冲断层为边界的山脉，暗示着新生代地壳缩短的分布。通过对比NNE-SSW向高程条带剖面和河道陡度模式，我们认为北方祁连山的构造隆升速率应大于内部山脉。因此，我们的研究提供了地貌证据，有利于分布地壳缩短和亚洲地幔岩石圈俯冲的主要机制来解释在青藏高原东北部的景观演化。
The distribution of rock uplift rates in the interior of the western Qilian Shan is not yet fully resolved, which limits our knowledge about the uplift pattern and landscape evolution in the northeastern Tibetan Plateau. The stream power incision model suggests that the spatially differential rock uplift rate usually can exert a primary control on channel gradient, thus providing a powerful approach to map the rock uplift pattern of active orogens. Here we analysed the river longitudinal profiles in the western Qilian Shan and found a spatially differential pattern with higher steepness indices along the parallel ranges (e.g. the Danghe Nanshan, Daxue Shan, Tuolai Shan, and the Northern Qilian Shan) but lower values in the intramontane basins. Comparison of steepness indices to variations in lithology and annual precipitation revealed limited correlation of channel gradient with lithologic resistance and climate in this landscape. We also observed no systematic relationship between steepness indices with drainage area, sediment flux, or channel concavities. We argued that the systematic changes in channel steepness indices are tectonically controlled rather than the consequence of variable sediment flux, climate, or lithology. Thus, the normalized channel steepness pattern of the western Qilian Shan could reflect that the rock uplift is largely restricted to mountain ranges bounded by active thrust faults and imply distributed Cenozoic crustal shortening. By comparing the NNE-SSW-directed elevation swath profiles and the channel steepness pattern, we concluded that tectonic uplift rate should be higher in the Northern Qilian Shan than in the internal ranges. Thus, our study provides geomorphic evidence to favor both distributed crustal shortening and Asian mantle lithosphere underthrusting as the primary mechanisms to explain the landscape evolution in the NE Tibetan Plateau.