Stratigraphy and depositional setting of slurry and contained (reflected) beds in the Marnoso-arenacea Formation (Langhian-Serravallian) Northern Apennines, Italy

Abstract

This work presents the stratigraphy and facies analysis of an interval of about 2500 m in the Langhian and Serravallian stratigraphic succession of the foredeep turbidites of the Marnoso‐arenacea Formation. A high‐resolution stratigraphic analysis was performed by measuring seven stratigraphic logs between the Sillaro and Marecchia lines (60 km apart) for a total thickness of about 6700 m. The data suggest that the stratigraphy and depositional setting of the studied interval was influenced by syndepositional structural deformations. The studied stratigraphic succession has been subdivided into five informal stratigraphic units on the basis of how structurally controlled topographic highs and depocentres, a consequence of thrust propagation, change over time. These physiographic changes of the foredeep basin have also been reconstructed through the progressive appearance and disappearance of thrust‐related mass‐transport complexes and of five bed types interpreted as being related to structurally controlled basin morphology. Apart from Bouma‐like Type‐4 beds, Type‐1 tripartite beds, characterized by an internal slurry unit, tend to increase especially in structurally controlled stratigraphic units where intrabasinal topographic highs and depocentres with slope changes favour both mud erosion and decelerations. Type‐2 beds, with an internal slump‐type chaotic unit, characterize the basal boundary of structurally controlled stratigraphic units and are interpreted as indicating tectonic uplift. Type‐3 beds are contained‐reflected beds that indicate different degrees of basin confinement, while Type‐5 are thin and fine‐grained beds deposited by dilute reflected turbulent flows able to rise up the topographic highs. The vertical and lateral distribution of these beds has been used to understand the synsedimentary structural control of the studied stratigraphic succession, represented in the Marnoso‐arenacea Formation by subtle topographic highs and depocentres created by thrust‐propagation folds and emplacements of large mass‐transport complexes.

Influence of flow containment and substrate entrainment upon sandy hybrid event beds containing a co-genetic mud-clast-rich division

“…Hybrid event beds (HEB) are now recognised as a significant component of deepwater systems from a variety of settings (e.g., Haughton et al, 2003Haughton et al, , 2009Talling et al, 2004Talling et al, , 2012aAmy and Talling, 2006;Davis et al, 2009;Hodgson, 2009;Muzzi Magalhaes and Tinterri, 2010;Patacci et al, 2014). Frequently these deposits comprise a mud-clast-rich (MCR) argillaceous (clay-rich) sandstone which directly overlies unstratified to stratified relatively cleaner (clay-poor) sandstones; both facies are co-genetic, having been emplaced during a single gravity-driven current event (Haughton et al, 2003Talling et al, 2004;Talling, 2013).…”

“…HEBs are considered to reflect deposition beneath a passing flow event which evolved significantly in terms of composition and rheology (e.g., becoming increasingly argillaceous, MCR and turbulence-suppressed ). Such flow evolution has been attributed to distal or lateral flow transformations, following significant entrainment of a muddy substrate, and or declining turbulence energy (e.g., Ricci Lucchi and Valmori, 1980;Haughton et al, 2003Haughton et al, , 2009Amy and Talling, 2006;Barker et al, 2008;Hodgson, 2009;Muzzi Magalhaes and Tinterri, 2010;Patacci et al, 2014). HEBs are of great significance as they are characterised by marked heterogeneity in depositional character, and thus reservoir quality, on an intra-bed scale (e.g., Sylvester and Lowe, 2004) and can be an indicator of cleaner, better reservoir quality sandstone farther upstream (e.g., Haughton et al, 2003;Hodgson, 2009).…”

Untitled

“…Such hybrid or linked turbidite-debrite beds were described previously (e.g., Wood and Smith, 1958;Middleton, 1979, 1980;RicciLucchi and Valmori, 1980;Zeng et al, 1991), but only recently has it become apparent that they are common in many locations worldwide (Haughton et al, 2003(Haughton et al, , 2009Sylvester and Lowe, 2004;Talling et al, 2004Talling et al, , 2007cTalling et al, , 2010Amy and Talling, 2006;Ito, 2008;Zeng et al, 1991;Amy et al, 2009;Hodgson, 2009;Jackson et al, 2009;Pyles and Jennette, 2009;Muzzi Magalhaes and Tinterri, 2010). Understanding these hybrid fl ows is important because they are a common feature of the most important processes for delivering sediment to the deep ocean.…”

Progress in the analysis of turbidites over wide areas using bed-by-bed correlation method

“…) ，三浦層群安野層(徳橋・岩脇，1975) ・清澄層 (徳橋， 1976a, 1976bTokuhashi, 1979 (Talling et al, 2004(Talling et al, , 2007b(Talling et al, , 2007cAmy and Talling, 2006;Muzzi Magalhaes and Tinterri, 2010;Tinterri and Muzzi Magalhaes, 2011) ．また，現世海底堆積物コアの研究では，現在の海底 面を正確な同一時間面としてタービダイト単層が対比され ている (Wynn et al, 2002(Wynn et al, , 2012Frenz et al, 2009 …”