The relationship between climate, landscape connectivity and sediment export from mountain ranges is key to understanding the propagation of erosion signals downstream into sedimentary basins. We explore the role of connectivity in modulating the composition of sediment exported from the Frontal Cordillera of the south‐central Argentine Andes by comparing three adjacent and apparently similar semi‐glaciated catchment‐fan systems within the context of an along‐strike precipitation gradient. We first identify that the bedrock exposed in the upper, previously glaciated reaches of the cordillera is under‐represented in the lithological composition of gravels on each of three alluvial fans. There is little evidence for abrasion or preferential weathering of sediment sourced from the upper cordillera, suggesting that the observed bias can only be explained by sediment storage in these glacially widened and flattened valleys of the upper cordillera (as revealed by channel steepness mapping). A detailed analysis of the morphology of sedimentary deposits within the catchments reveals catchment‐wide trends in either main valley incision or aggradation, linked to differences in hillslope–channel connectivity and precipitation. We observe that drier catchments have poor hillslope–channel connectivity and that gravels exported from dry catchments have a lithological composition depleted in clasts sourced from the upper cordillera. Conversely, the catchment with the highest maximum precipitation rate exhibits a high degree of connectivity between its sediment sources and the main river network, leading to the export of a greater proportion of upper cordillera gravel as well as a greater volume of sand.

中文翻译：

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气候对景观形态，沉积物迁移和沉积记录的影响

气候，景观连通性和山脉沉积物输出之间的关系是了解侵蚀信号向下游流向沉积盆地的传播的关键。通过比较沿走动降水梯度范围内的三个相邻且看似相似的半冰川集水扇系统，我们探索了连通性在调节从阿根廷中南部安第斯山脉的锋线山脉输出的沉积物成分中的作用。我们首先确定，在三层冲积扇中的每一个上，砾岩的岩性成分不足以表示山脉中上部冰川先前裸露的基岩。几乎没有证据表明来自上部山脉的沉积物有磨损或优先风化，这表明观察到的偏差只能由上部山脉的这些冰川拓宽和平坦的山谷中的沉积物存储来解释（如通道陡度图所示）。对流域内沉积物形态的详细分析揭示了主要山谷切口或集水区流域范围内的趋势，这与山坡-河道连通性和降水的差异有关。我们观察到，较干燥的流域的坡道与通道之间的连通性较差，并且从干燥流域出口的砾石的岩性成分已被上部山脉的碎屑所消耗。相反，最大降水率最高的流域在其沉积物来源与主要河网之间表现出高度的连通性，