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首页> 外文期刊>Journal of South American earth sciences >Chemical weathering and erosion rates in the Lesser Antilles: An overview in Guadeloupe, Martinique and Dominica
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Chemical weathering and erosion rates in the Lesser Antilles: An overview in Guadeloupe, Martinique and Dominica

机译：小安的列斯群岛的化学风化和侵蚀率：瓜德罗普岛，马提尼克岛和多米尼加概述

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摘要

Guadeloupe, Martinique and Dominica islands, like numerous tropical environments, have extreme weathering regimes. Physical denudation is mainly controlled by landslides, which reflect the torrential dynamics of the rivers. In Guadeloupe, the mechanical weathering rates vary between 800 and 4000 t/ km~2/yr. The lithology is very porous with high infiltration rates, which suggests that most of the element fluxes are produced in the subsurface, with chemical erosion rates 2-5 times higher than the rates from surface water. We show how the kinetics of chemical weathering rates depend on the age of the lava and subsurface circulation. In addition, erosion timescales were calculated from U-series analyses of river sediments. Our results show a broad range: 0-150 ka in Martinique and 0-60 ka in Guadeloupe. We evaluated residence times in river water on the basis of the dissolved load analyses. It appears that water circulation is globally 3-fold longer for subsurface water than for surficial water (Rad et al. 2011a,b). Moreover, these islands are highly impacted by agriculture. However, contrary to what one might think, our results show that human activity does not disturb critical zone processes. Indeed, we show that among the combined impacts of all parameters (climate, runoff, slope, vegetation, etc.), the basin's age seems to be the control parameter for chemical weathering and land use-the younger the basin, the higher the weathering rates. We could observe a combined effect between the higher erodibility and a higher climate erosivity of the younger reliefs.
机译：像许多热带环境一样，瓜德罗普岛，马提尼克岛和多米尼加岛都有极端的风化条件。物理剥蚀主要由滑坡控制，反映了河流的洪流动态。在瓜德罗普岛，机械风化率在800至4000 t / km〜2 / yr之间变化。岩性非常多孔，渗透率高，这表明大部分元素通量都在地下产生，化学侵蚀速率比地表水的侵蚀速率高2-5倍。我们展示了化学风化速率的动力学如何取决于熔岩的年龄和地下循环。此外，侵蚀时间尺度是根据河流沉积物的U系列分析得出的。我们的结果显示范围很广：马提尼克岛为0-150 ka，瓜德罗普岛为0-60 ka。我们根据溶解负荷分析评估了在河水中的停留时间。似乎地下水的水循环总体上比表层水长3倍（Rad等，2011a，b）。此外，这些岛屿受到农业的严重影响。但是，与人们可能想到的相反，我们的结果表明，人类活动不会干扰关键区域的过程。实际上，我们表明，在所有参数（气候，径流，坡度，植被等）的综合影响中，流域的年龄似乎是化学风化和土地利用的控制参数-流域越年轻，风化度越高费率。我们可以观察到较年轻的浮雕的较高可蚀性和较高的气候侵蚀性之间的综合影响。

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