Department of Geology and Environmental Science, University of Pittsburgh, Pittsburgh, PA, 15260, USA.
Eurasia Institute of Earth Science, Istanbul Technical University, 34469, Istanbul, Turkey.
Sci Rep. 2022 Sep 12;12(1):15306. doi: 10.1038/s41598-022-19795-0.
Tectonics imparts a first-order control on the overall morphology of alluvial fan systems in extensional settings by influencing sediment flux and accommodation space, while other factors such as climate, catchment lithology, and fault footwall characteristics are secondary. Previous alluvial fan modeling studies have focused on the link between the three-dimensional development of alluvial fans and rock uplift, however, despite the potential influence of tectonics on the overall three-dimensional morphology of alluvial fans, the controlling mechanisms, as well as their relative importance, remain largely unquantified in a natural setting with a targeted source-to-sink approach. Here, we examine 45 alluvial fans and their catchments along the southern mountain front of the Aydın Range, delimited by segmented normal faults in the western Anatolia Extensional Province, to quantify the role of rock uplift. We quantify river incision rates and catchment-wide erosion rates together with a series of topographic analyses across the southern flank of the Aydın Range as a proxy for rock uplift. Our results indicate that the spatial distribution of thicker and steeper alluvial fans fit well with higher rock uplift rates along the strike of the mountain front. In contrast, a lower uplift rate is responsible for prograding alluvial fans with decreasing thickness and gradients. Also, our data shows that alluvial fan thickness compared to other alluvial fan metrics strongly associated with the pattern of the rock uplift. This study demonstrates a field-based, quantitative linkage between three-dimensional alluvial fan morphology and rock uplift which has significant implications for improving alluvial fan models and understanding how alluvial fans respond to tectonics in extensional regions.
构造通过影响沉积物通量和容空间，对伸展环境中冲积扇系统的整体形态施加一级控制，而气候、流域岩石学和断层下盘特征等其他因素则是次要的。以前的冲积扇建模研究主要关注冲积扇的三维发育与岩石隆升之间的联系，然而，尽管构造对冲积扇的整体三维形态有潜在影响，但在具有目标源汇方法的自然环境中，控制机制及其相对重要性在很大程度上仍未得到量化。在这里，我们研究了沿西部安纳托利亚伸展区的艾登山脉南缘的 45 个冲积扇及其流域，这些冲积扇由分段正断层限定，以量化岩石隆升的作用。我们量化了河流侵蚀率和流域范围内的侵蚀率，以及在艾登山脉南缘进行的一系列地形分析，作为岩石隆升的代理。我们的结果表明，较厚和较陡的冲积扇的空间分布与山前地带的岩石隆升速率较高吻合较好。相比之下，较低的上升速率导致前缘推进的冲积扇厚度减小和坡度变缓。此外，我们的数据表明，与其他冲积扇指标相比，冲积扇厚度与岩石隆升的模式密切相关。这项研究展示了基于实地的、三维冲积扇形态与岩石隆升之间的定量联系，这对改进冲积扇模型和理解冲积扇在伸展区对构造的响应具有重要意义。
