Abstract The foreland basin of the southern European Alps is characterized by large fan-shaped alluvial systems fed by the main montane valleys and these depositional systems present an extent of 300–3000 km2, with a length of 30–70 km. Most of them are megafans, characterized by evident longitudinal differentiation in which steep piedmont sector consists of amalgamated gravels, while the distal portion has a gradient

Alluvial Fans and Megafans Along the Southern Side of the Alps

Global sea-level control on local parasequence architecture from the Holocene record of the Po Plain, Italy

The Late Pleistocene Po River lowstand wedge in the Adriatic Sea: Controls on architecture variability and sediment partitioning

Previous sequence-stratigraphic work has emphasized the key role of paleosols and associated sand-dominated fluvial bodies as key features for interpreting alluvial architecture. The temporal resolution of the ancient record is, however, insufficient to fully explain the complex relationship between soil formation and the evolution of fluvial systems under changing sea-level and climate conditions. In this paper, we present a detailed record of paleosol−channel belt relationships reconstructed from the subsurface of a rapidly subsiding region (Po Plain, Italy) that spans almost all of the last glacial-interglacial cycle (∼120 k.y.). The studied succession preserves a systematic bipartite zonation into a thick paleosol-bearing segment close to the basin margin and a sand-dominated interval, with vertically amalgamated channel belts, in an axial position. Individual paleosols are weakly developed and represent key stratigraphic markers that can be traced basinwide into adjacent, essentially contemporaneous, unconfined channel-belt deposits. Unlike conventional models of late Quaternary alluvial−coastal plain systems, no persistent incised valley was established in the Po system during the last glacial-interglacial cycle. Continuous accommodation was the key depositional control on alluvial stratigraphy during the prolonged (∼90 k.y.) phase of late Pleistocene sea-level fall, which led to the deposition of a thick, dominantly aggradational alluvial succession. The development of shallowly incised, short-lived valley systems took place only at the transition to glacial stages associated with substantial sea-level drop (marine oxygen isotope stage [MIS] 3-2 transition, and possibly MIS 5-4 transition). This study shows that in rapidly subsiding settings with high rates of sedimentation, incised valley systems may be replaced by aggradationally stacked, essentially nonincised fluvial bodies. In these cases, overbank packages bounded by immature paleosols represent the most likely alternative to the highly weathered interfluve paleosol predicted by classic sequence-stratigraphic models. Fourth-order sequence boundaries and lower-rank erosional surfaces may be easily confused at the ∼100 k.y. scale, and transgressive surfaces, defining the onset of retrogradation, may become the most readily identifiable sequence-stratigraphic surfaces.

Paleosols and associated channel-belt sand bodies from a continuously subsiding late Quaternary system (Po Basin, Italy): New insights into continental sequence stratigraphy

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Early Holocene transgressive palaeogeography in the Po coastal plain (northern Italy)

Late Quaternary aggradation rates and stratigraphic architecture of the southern Po Plain, Italy

Though clinothem geometry represents a key control on fluid flow in reservoir modelling, tracing clinothem boundaries accurately is commonly limited by the lack of sufficiently precise outcrop or subsurface data. This study shows that in basin systems with strongly heterogeneous compositional signatures, the combination of bulk‐sediment geochemistry and benthic foraminiferal distribution can help identify clinothem architecture and generate realistic models of 3D deltaic upbuilding and evolution. Middle‐late Holocene deposits in the Po Delta area form an aggradational to progradational parasequence set that reveals the complex interaction of W–E Po Delta progradation, S‐directed longshore currents (from Alpine rivers) and Apennines rivers supply. Unique catchment lithologies (ophiolite rocks and dolostones) were used to delineate basin‐wide geochemical markers of sediment provenance (Cr and Mg) and to assess distinctive detrital signatures. The geochemical characterization of cored intervals across different components of the sediment routing system enabled a direct linkage between clinothem growth, transport pathways and provenance mixing to be established. On the other hand, abrupt microfaunal variations at clinothem boundaries were observed to reflect the palaeoenvironmental response to sharp changes in sediment flux and fluvial influence. This study documents the ability of an integrated geochemical and palaeoecological approach to delineate three distinct sources (Po, Alps and Apennines) that contributed to coastal progradation and to outline the otherwise lithologically cryptic geometries of clinothems that using conventional sedimentological methods it would be virtually impossible to restore.

Tracing clinothem geometry and sediment pathways in the prograding Holocene Po Delta system through integrated core stratigraphy

Understanding the causes and mechanisms of land subsidence is crucial, especially in densely populated coastal plains. In this work, we calculated subsidence rates (SR) in the Po coastal plain, averaged over the last 5.6 and 120 kyr, providing information about land movements on intermediate (103–105 years) time scales. The calculation of SR relied upon core-based correlation of two lagoon horizons over tens of km. Subsidence in the last 120 kyr appears to be controlled mainly by the location of buried tectonic structures, which in turn controlled sedimentation rates and location of highly compressible depositional facies. Numerical modelling shows that subsidence in the last 5.6 kyr is mainly due to compaction of the Late Pleistocene and Holocene deposits (uppermost 30 m).

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Factors controlling natural subsidence in the Po Plain

https://onlinelibrary.wiley.com/doi/pdf/10.1111/sed.12784

Bianca Costagli

Papers

Late Quaternary aggradation rates and stratigraphic architecture of the southern Po Plain, Italy

Tracing clinothem geometry and sediment pathways in the prograding Holocene Po Delta system through integrated core stratigraphy

Factors controlling natural subsidence in the Po Plain

Deformation patterns of upper Quaternary strata and their relation to active tectonics, Po Basin, Italy