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Reconstruction of the Tiber Deltaic stratigraphic successions near Ostia using the PADM chart and tracking of the bedload-derived facies (Rome, Italy)
Geomorphology ( IF 3.1 ) Pub Date : 2020-09-01 , DOI: 10.1016/j.geomorph.2020.107227
Ferréol Salomon , Cécile Vittori , Brice Noirot , Elisa Pleuger , Carlo Rosa , Ilaria Mazzini , Pierre Carbonel , Hatem Djerbi , Piero Bellotti , Jean-Philippe Goiran

Abstract Located between the deltaic plain and the subaqueous delta, base level is one of the most important factors that affect depositional elements and the sedimentary architecture of river deltas. In this respect, its changes are essential to reconstruct delta evolution during the Holocene. In this paper, we study three cores drilled in the Tiber delta (Italy). Palaeoenvironmental analyses were performed and included new sedimentological data (laser grain size, loss-on-ignition, magnetic susceptibility), new data from bioindicators (ostracods and macrofauna), and 11 new radiocarbon dates. The three cores were analysed and replaced in a cross section between the Inner and Outer Tiber delta, i.e.,in the palaeolagoon and in the progradational delta plain. First, we have mapped the Holocene transgression and progradation of the Ostia area using palaeoenvironmental age-depth modelling techniques (PADMs). PADM charts help to interpret a stratigraphic succession in a river delta. They contribute to the understanding of the links between depositional environments, sedimentation rate, and sea level rise and to reconstruct coastline trajectories. More precisely, they contribute to the interpretation of the consequences of the sea level jumps dated to the 9000–8000 cal. BP period on coastal environments and help to identify progradational phases (around 4 k, and from 2.8 to 2.6 k cal. BP). Second, we identify indirect (freshwater bioindicators) and direct (bedload-derived facies) evidence of fluvial activity in the studied cross section. The studied deep cores indicate that at least one palaeochannel of the Tiber River was already flowing in the middle/southern part of the delta from 4 k cal. BP. Finally, a first map of the lateral mobility of the palaeochannels of the Tiber River is proposed for the last 6 k cal. BP using the new data and a synthesis of all the data available at the scale of the delta.

中文翻译:

使用 PADM 图表重建 Ostia 附近的台伯河三角洲地层序列并跟踪床载衍生相(意大利罗马)

摘要 底位位于三角洲平原和水下三角洲之间,是影响​​河流三角洲沉积要素和沉积结构的最重要因素之一。在这方面,它的变化对于重建全新世三角洲演化至关重要。在本文中,我们研究了在台伯河三角洲(意大利)中钻探的三个岩心。进行了古环境分析,包括新的沉积学数据(激光粒度、燃烧损失、磁化率)、来自生物指标(介形动物和大型动物)的新数据和 11 个新的放射性碳数据。这三个岩心在台伯河内三角洲和外台伯河三角洲之间的横截面中进行了分析和置换,即在古泻湖和进积三角洲平原中。第一的,我们使用古环境年龄深度建模技术 (PADM) 绘制了 Ostia 地区全新世海侵和进积图。PADM 图表有助于解释河流三角洲的地层序列。它们有助于了解沉积环境、沉积速率和海平面上升之间的联系,并重建海岸线轨迹。更准确地说,它们有助于解释可追溯到 9000-8000 cal 的海平面跳跃的后果。海岸环境的 BP 时期,有助于确定进积阶段(大约 4 k,从 2.8 到 2.6 k cal. BP)。其次,我们在研究的横截面中确定了河流活动的间接(淡水生物指标)和直接(河床衍生相)证据。研究的深部岩心表明,台伯河的至少一个古河道已经从 4 千卡流向三角洲的中/南部。BP。最后,提出了台伯河古河道横向流动性的第一张图,用于最后 6 千卡。BP 使用新数据和所有可用数据的综合,以三角洲的规模。
更新日期:2020-09-01
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