Patterns of erosion in the Western Alps and quantification of sediment reworking in the associated Po River foreland basin

构造活动的山区地带产生的沉积物在流向海洋的途中，间歇性地储存在前陆盆地中，在那里经历了临时储存和改造的阶段。这种改造的结果在缓冲的侵蚀泥沙通量，这是由扩散输沙和渠道漫滩相互作用，造成源汇连接的缺失环节。因此，像气候循环这样控制沉积物输出的力量不能直接与保存的沉积序列联系起来。波河流域是一个很好的试验场，以评估时间尺度和规模的沉积物运输和混合模式，因为它集成了快速侵蚀的西欧和中欧阿尔卑斯山，以及北方亚平宁山脉，和低浮雕波河漫滩存储大量的后造山碎屑。到目前为止，广泛回收阿尔卑斯碎屑在亚平宁增生楔和低磷灰石和锆石肥力的亚平宁山脉相比，阿尔卑斯山限制了应用，例如，重矿物套源岩的歧视和沉积物运输。在这里，我们建议使用矿物肥力分析和三重原位产生的宇宙成因核素的独特组合来解决这一挑战。我们将首先描述他们的侵蚀信号的来源地区使用宇宙成因10 Be，然后将分析其下游的变化，在相对沉积物的贡献在Po平原使用26铝/10 Be的比例比较，然后已知的宇宙成因和岩相源区指纹，最后，我们将确定稳定的21氖浓度，将允许评估沉积物的停留时间在Po前陆盆地。这种方法将导致更好地理解沉积矿床的改造和沉积物储存的时间尺度，从而改变源区的侵蚀信号。预计这一建议的结果将提高人们对以下事实的认识：1）碎屑沉积物在源区侵蚀后不会立即转移到海洋中，2）这种沉积物的地球化学指纹可能在未知的转移时间内是完整的，和3）最后，沉积档案可能不一定保存侵蚀事件的直接产物，但这些产物可能在洪泛平原期间被修改转移

Tectonically active mountain belts generate sediment that is, on its journey to the sea, intermittently stored in foreland basins, where it undergoes episodes of temporary storage and reworking. This reworking results in buffering of the eroded sediment fluxes that is caused by diffusive sediment transport and channel-floodplain interaction, causing a missing link in the source-sink connection. As a result, forces like climate cycling controlling sediment export cannot be linked directly to preserved sedimentary successions. The Po drainage basin is an excellent test site to evaluate the timescales and magnitudes of sediment transport and mixing patterns, as it integrates over the rapidly eroding Western and Central European Alps, as well as the Northern Apennines, and the low-relief Po floodplain storing vast amounts of post-orogenic detritus. Until now, widespread recycling of Alpine detritus in the Apenninic accretionary wedge and low apatite and zircon fertility in the Apennines compared to the Alps limited the application of e.g. heavy mineral suites for source rock discrimination and sediment transport. Here, we propose to use a unique combination of mineral fertility analysis and triple in situ-produced cosmogenic nuclides to resolve this challenge. We will first characterize the source areas for their erosion signal using cosmogenic 10Be, then will analyze their downstream changes in relative sediment contributions in the Po plain by using 26Al/10Be ratios in comparison to then known cosmogenic and petrographic source-area fingerprints, and finally, we will determine stable 21Ne concentrations that will allow to assess the residence time of sediment in the Po foreland basin. This approach will lead to a better understanding of reworking of sedimentary deposits and time scales of sediment storage potentially buffering and thus modifying the source area´s erosional signal. Outcomes of this proposal are expected to increase the awareness for the fact that 1) detrital sediments are not transported instantaneously to the sea after their erosion in the source area, 2) that the geochemical fingerprint of such sediments might be integrative over an unknown transfer time, and 3) finally that the sedimentary archive may not necessarily preserve the direct products of erosion episodes but that these may have been modified during floodplain transfer.