Constraints on the tectonic and landscape evolution of the Bhutan Himalaya from thermochronometry
Constraints on the tectonic and landscape evolution of the Bhutan Himalaya from thermochronometry
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DOI：
10.1002/2015tc003853
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发表时间：
2015-06-01
期刊：
影响因子：
4.2
通讯作者：
Wartho, J.
中科院分区：
文献类型：
--
作者：
Adams, B. A.;Hodges, K. V.;Wartho, J.
不丹喜马拉雅山脉的观测地貌和计算的热历史为检验关于构造和气候对汇聚山脉演化的影响的想法提供了一个极好的平台。然而，关于不丹喜马拉雅山脉的晚新生代历史，几乎没有达成共识。一些研究人员认为，观察到的地质关系表明变形速度正在放缓，因此从地貌角度来看，范围正在衰落，而另一些人则认为范围在扩大和陡峭。我们认为，通过地貌和热计时数据的综合解释，通过比较造山系统的地貌演化模型和热运动学模型的预测，可以更好地理解这一问题。不丹各地新的热计时数据与侵蚀速度的显著下降最为一致，从2至3公里/Ma降至0.1-0.3公里/Ma，约为6-4 Ma。我们将这种模式解释为，由于不丹以南约100公里的隆起区西隆高原收缩构造的激活，岩石隆升速率降低。然而，整个不丹腹地的低起伏、河流景观记录了地表抬升的晚期脉冲，可能是由于最近岩石抬升速度的增加。来自我们最年轻的温度计时仪的限制表明，这种岩石抬升和地表抬升的增加发生在最后的1.75 Ma内。这些结果表明，不丹喜马拉雅高原和锡隆高原的动力学在晚新生代期间是联系在一起的，这两个地区的构造要素在这段时间内以不同的方式和时间活动。
The observed geomorphology and calculated thermal histories of the Bhutan Himalaya provide an excellent platform to test ideas regarding the influence of tectonics and climate on the evolution of a convergent mountain range. However, little consensus has been reached regarding the late Cenozoic history of the Bhutan Himalaya. Some researchers have argued that observed geologic relationships show slowing deformation rates, such that the range is decaying from a geomorphic perspective, while others see the range as growing and steepening. We suggest that a better understanding is possible through the integrated interpretation of geomorphic and thermochronometric data from the comparison of predictions from models of landscape evolution and thermal-kinematic models of orogenic systems. New thermochronometric data throughout Bhutan are most consistent with a significant decrease in erosion rates, from 2 to 3km/Ma down to 0.1-0.3km/Ma, around 6-4Ma. We interpret this pattern as a decrease in rock uplift rates due to the activation of contractional structures of the Shillong Plateau, an uplifted region approximately 100km south of Bhutan. However, low-relief, fluvial landscapes throughout the Bhutanese hinterland record a late pulse of surface uplift likely due to a recent increase in rock uplift rates. Constraints from our youngest thermochronometers suggest that this increase in rock uplift and surface uplift occurred within the last 1.75Ma. These results imply that the dynamics of the Bhutan Himalaya and Shillong Plateau have been linked during the late Cenozoic, with structural elements of both regions active in variable ways and times over that interval.