Understanding sedimentary routing systems at continental margins can be challenging in tectonically active regions such as forearc basins. Here, we combine sand modal composition and detrital zircon U-Pb data from the Kumano Basin and surrounding Nankai Trough region of Japan to explore sedimentation in an active forearc and its linkages to the regional tectonic history. Our analyses are on Miocene-to-Pleistocene samples collected by the Integrated Ocean Drilling Program (IODP) at inner and outer forearc basin sites C0009 and C0002, river samples from onshore Honshu, and published results from other Nankai IODP sites. Results show the sediments of many IODP samples are similar to that of the modern rivers. Data from C0009 demonstrate that the early accretionary prism already contained slope basins fed by sediments similar to those in the modern Kumano River by 7.1 Ma. The more distal C0002 section was predominantly fed by a system similar to the modern Yodo River, located to the west-southwest. We conclude that the section was therefore tectonically transported, in agreement with the ‘mobile model’ of oblique tectonic convergence across SW Japan during late Miocene time. Deposition resumed after a ca. 5.6–3.8 Ma hiatus, with sediments primarily fed from the paleo-Kumano River, with some input from the paleo-Tenryu and Kiso/Nagara rivers located to the northeast. Input from the paleo-Tenryu and Kiso/Nagara rivers was likely re-routed towards the trench by ca. 1.3 Ma. Sediments similar to those of the distal Yodo River also make up part of the Kumano basin fill and are best explained by erosion of uplifted older accretionary prism sediments along the Megasplay Fault that bounds the forearc basin. Despite the temporal variability in sedimentation routed to the basin, basin-fill dynamics appear to have been governed primarily by the critical-wedge style dynamics driven by variations in frontal accretion and in- or out-of-sequence thrusting response.

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日本南海弧前区沉积物来源、路径和构造联系

了解大陆边缘的沉积路径系统在构造活跃的地区（例如弧前盆地）可能具有挑战性。在这里，我们结合来自日本熊野盆地和南海海槽周围地区的砂岩模态组成和碎屑锆石 U-Pb 数据，探索活动前弧的沉积及其与区域构造历史的联系。我们的分析是对综合海洋钻探计划 (IODP) 在弧内和弧前盆地内部和外部 C0009 和 C0002 站点收集的中新世到更新世样本、来自本州陆上的河流样本以及其他南海 IODP 站点的已发表结果进行的分析。结果表明，许多 IODP 样品的沉积物与现代河流的沉积物相似。来自 C0009 的数据表明，早期增生棱柱体在 7.1 Ma 之前已经包含由类似于现代熊野河中的沉积物供给的斜坡盆地。更远的 C0002 部分主要由类似于现代淀河的系统供水，位于西南偏西。我们得出的结论是，该剖面因此被构造运移，与晚中新世时期日本西南部倾斜构造辐合的“移动模型”一致。大约 1 小时后恢复沉积。5.6-3.8 Ma 间断，沉积物主要来自古熊野河，部分来自位于东北部的古天龙河和木曾/长良河。来自古天龙河和木曾/长良河的输入很可能在约 1.3 马。类似于远端淀川沉积物的沉积物也构成了熊野盆地填充物的一部分，最好的解释是沿弧前盆地边界的 Megasplay 断层抬升的较老的增生棱柱状沉积物的侵蚀。尽管沉积到盆地的时间变化，盆地填充动力学似乎主要受临界楔型动力学控制，该动力学由锋面增生和序列内或失序逆冲响应的变化驱动。