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

Abstract

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.

Ephemeral rollover points and clinothem evolution in the modern Po Delta based on repeated bathymetric surveys

“…Anderson et al, ), sediment core stratigraphy (e.g. Amorosi et al, ), outcrop studies (e.g. Plink‐Björklund, ), sediment budget calculations (e.g.…”

“…In the Po Delta depositional system, the 3-D complexity of HST prograding clinothem sets across the delta plain/delta front transition is reflected along-strike in the juxtaposition of seaward-bowed delta lobes and associated strand plain sand bodies developed on centennial to millennial time scales (Amorosi et al, 2017;Amorosi, Maselli, & Trincardi, 2016;Correggiari et al, 2005a;Stefani & Vincenzi, 2005). In this context, clinothem boundaries mark abrupt shifts in depositional systems configuration and sediment dispersal pathways that are typically represented by hiatal stratigraphic surfaces of short duration and small areal extent (Amorosi et al, 2019;Correggiari et al, 2005b;Pellegrini et al, 2017;Trincardi et al, 2004).…”

“…This lobe prograded rapidly (10 km) during the last 120 years, since the end of the Little Ice Age, reaching a thickness of 30 m. Like older lobes of the Po Delta, the offshore distribution of the Po di Pila clinothem is markedly asymmetric, reflecting a dominance of coastal currents to the south (Correggiari, Cattaneo, & Trincardi, , ; Trincardi, Cattaneo, & Correggiari, ). Previous studies concentrated on the stacking pattern of millennial‐scale parasequences in the delta plain (Amorosi et al, ; Stefani & Vincenzi, ) and on the stacking of offshore prodelta lobes in water depths greater than 10 m (Correggiari, Cattaneo, & Trincardi, ; Trincardi et al, ), leaving the most proximal subaqueous portion of the depositional system substantially unexplored. By investigating the transition between the delta mouth bar and the upper reaches of the muddy foreset, we aim at discussing the definition of rollover point, its origin and preservation potential, and to show its strong morphological variability in space and time within a modern fluvio‐deltaic system.…”

Clinoforms and clinothems: Fundamental elements of basin infill

“…Furthermore, condensed intervals appear pervasive even in fine‐grained clinothems deposited under fairly continuous sedimentation over the last few Centuries (e.g. Amorosi et al, 2019).…”

“…Clinothems, particularly in their upper foreset area, are characterized by some of the highest short‐term sediment accumulation rates on Earth, as documented in particular from Quaternary systems (e.g. Alexander et al, 1991; Amorosi et al, 2019; Berné, Jouet, Bassetti, Dennielou, & Taviani, 2007; Cattaneo et al, 2003; Cattaneo, Trincardi, Asioli, & Correggiari, 2007; Fanget et al, 2014; Goodbred, Kuehl, Steckler, & Sarker, 2003; Kuehl et al, 1997; Liu et al, 2009; Michels, Kudrass, Hübscher, Suckow, & Wiedicke, 1998; Neil & Allison, 2005; Nittrouer et al, 1996; Palamenghi, Schwenk, Spiess, & Kudrass, 2011; Pellegrini et al, 2015; Ta et al, 2002; Tanabe et al, 2003; Walsh et al, 2004; Xue, Liu, DeMaster, Nguyen, & Ta, 2010).…”