Abstract The landscape of foreland basins adjacent to active mountain ranges evolves under the control of basinward tectonic propagation of the structural fronts, in competition with climate dynamics. The resulting palimpsest landscapes record the sequence of geomorphic evolutionary steps, and the spatial-temporal relations between the active geological processes. However, a precise evolutionary sequence is hard to decipher from low-relief settings, like the wide alluvial plains worldwide. About these topics we investigate the sequence of tectonic- and climate-driven processes which shaped the palimpsest landscape of a large Quaternary foreland basin, the Po Plain in Northern Italy. Above the average glacio-fluvial and alluvial plain of the basin, Late Quaternary intra-basin reliefs emerge, owing to syndepositional ramp folding and uplift driven by N-wards propagation of the outermost thrust fronts of the active N-Apennine chain. The incremental tectono-morphological and depositional history of the region permits to describe the propagation of the structural front as a polyphase process, involving uplift, wrenching and late collapse of the reliefs. This history is documented by: relicts of uplifted planation surfaces covered by latest Pleistocene weathered loess units; polygonal facets, landslides and slope wedges along faults delineating the slopes of the largest among the intra-basin reliefs (San Colombano hill); hydrographic anomalies on the relief network (river diversions, piracy and perching of valleys, paleovalley fills), river diversions and cross-cut relations on the adjacent alluvial plain. These features testify the thrust-fold-related, pre-LGM uplift of the Late Pleistocene alluvial stratigraphy, the subsequent segmentation of the relief in differently uplifting blocks along Riedel faults, owing to activation of a transfer fault zone, and the LGM extensional collapse of the relief, along inherited fault systems. A late, post-glacial outwards propagation of the Apennine thrusts was buttressed by the opponent Alpine thrust-belt front and induced the entrenchment of the river network. River diversions on the plain were controlled by the orientation of the San Colombano hill fault systems. The distribution of historical earthquakes and the present-day geodetic data are coherent with this evolution. The study documents how, in foreland basins, the syndepositional propagation of “blind” orogenic fronts shapes the palimpsest landscape with superimposed morphological, tectonic, and stratigraphic features of paleoseismic significance, and permits comparisons with the other low-relief basin settings worldwide.

中文翻译：

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波平原-北亚平宁边界（意大利伦巴第）晚第四纪构造的形态结构证据

摘要 与活动山脉相邻的前陆盆地地貌在构造锋向盆地构造传播的控制下，与气候动力学竞争演化。由此产生的复本景观记录了地貌演化步骤的顺序，以及活动地质过程之间的时空关系。然而，很难从低地势环境（例如全球广阔的冲积平原）中解读出精确的进化序列。关于这些主题，我们研究了构造和气候驱动过程的序列，这些过程塑造了意大利北部波平原的大型第四纪前陆盆地的最原始景观。在盆地的平均冰川-河流和冲积平原之上，出现了晚第四纪盆地内浮雕，由于活动 N-亚平宁链最外推力前沿的 N 向传播驱动的同沉积斜坡折叠和隆起。该地区递增的构造形态和沉积历史允许将构造锋的传播描述为一个多相过程，包括地貌的隆起、扭曲和晚期坍塌。这段历史记载如下： 最新更新世风化黄土单元覆盖的抬升的平坦表面的遗迹；沿着断层的多边形面、滑坡和斜坡楔形，勾勒出盆地内浮雕（圣科伦巴诺山）中最大的斜坡；救济网络上的水文异常（河流改道、海盗和河谷栖息、古河谷填充）、河流改道和相邻冲积平原的横切关系。这些特征证明了晚更新世冲积地层与逆冲褶皱相关的前 LGM 隆起，由于转移断层带的激活，随后沿 Riedel 断层的不同隆起块中的地势分割，以及 LGM 伸展塌陷地势，沿继承的断层系统。亚平宁逆冲带的晚期冰川后向外传播受到对手高山逆冲带前缘的支持，并导致河网的形成。平原上的河流改道由圣科伦巴诺山断层系统的方向控制。历史地震的分布和当今的大地测量数据与这种演变是一致的。该研究记录了如何在前陆盆地中，