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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Reappraisal of the relative importance of dynamic topography and Andean orogeny on Amazon landscape evolution
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Reappraisal of the relative importance of dynamic topography and Andean orogeny on Amazon landscape evolution

机译：重新评估动态地形和Andean Orogeny对亚马逊景观演变的相对重要性

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摘要

The Cenozoic landscape of northern South America evolved under the influence of different geodynamic processes, culminating in the formation of the largest drainage basin on Earth, the Amazon drainage system. The orogeny of the Andean cordillera and the increase in surface denudation induced an asymmetric influx of sediments in Amazonia, which caused an eastward propagation of the Andean sedimentary wedge, reversing the topographic gradient and driving the drainage flow towards the Atlantic Equatorial margin. The low-relief topography of lowlands in Amazonia is also a factor that propitiates this reversal. Concomitantly, variations in the subduction angle of the Nazca plate under the continental lithosphere during the Miocene also contributed to create dynamic topography that perturbed the surface and modified the drainage pattern through time. In the last decade, both surface processes during Andean orogeny and dynamic topography were invoked independently to explain the formation of the present Amazon drainage system connecting the Andes and the equatorial margin. However, hitherto these mechanisms were not considered in a single model, hampering the evaluation of the contribution of each factor on the evolution of the Amazon River. To quantify the combined effect of the different geodynamic processes, in the present work we used numerical models that integrate orogeny, surface processes, dynamic topography and flexural isostasy of the lithosphere. In our results, we present new numerical scenarios for the Cenozoic landscape evolution of Amazonia, showing that the dynamic topography may have affected the environmental evolution in western Amazonia, favoring the development of a megawetland in this region before the establishment of the Amazon River as a transcontinental river. We conclude that, although the formation of the Amazon drainage system can be explained without the influence of mantle convection, variations in dynamic topography may have anticipated the establishment of the transcontinental drainage system a few million years. Furthermore, the stratigraphic evolution and the total Cenozoic sedimentation preserved in the Solimoes Basin is a function of the temporal variations in the amplitude of dynamic topography in northern South America. (C) 2020 Elsevier B.V. All rights reserved.
机译：南美洲北部的新生代景观在不同地球动力学过程的影响下发展，最终在地球上最大的排水盆地形成，亚马逊排水系统。 Andian Cordillera的organoy和表面剥落的增加诱导亚马逊沉积物的不对称涌入，这导致了Andean沉积楔的东方传播，逆转了地形梯度并驱动了排水流向大西洋赤道边缘。亚马逊低地的低浮雕地形也是提出这种逆转的一个因素。同时，在中世内的陆地岩层下纳扎卡板的脱落角的变化也有助于创造动态地形，从而扰乱了表面并通过时间修改了排水模式。在过去十年中，独立调用Andean Orogeny和动态地形期间的表面过程，以解释连接ANDES和赤道边距的现有亚马逊排水系统的形成。然而，迄今为止，这些机制未在一个模型中考虑，阻碍了对亚马逊河流演变的每个因素的评估。为了量化不同地球动力学过程的组合效果，在本作的工作中，我们使用了数控模型，这些模型整合了山际，表面过程，动态地形和岩石圈的弯曲露面。在我们的结果中，我们为亚马逊的新生代景观演变提供了新的数值方案，表明动态地形可能影响了西亚马逊西部的环境演变，在建立亚马逊河之前，这一地区的开发是一个巨大的兆塔横贯大陆河。我们得出结论，尽管可以在没有地幔对流的影响的情况下解释亚马逊排水系统的形成，但动态地形的变化可能预期了几百万年的横道排水系统的建立。此外，索因盆地保存的地层演变和总新生代沉降是南美洲北部动态地形幅度的时间变化的函数。 （c）2020 Elsevier B.v.保留所有权利。

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