Lower–Middle Miocene temperate marine carbonates occur in the Matese Mountains, Southern Apennines (Italy). These carbonates formed in an open shelf depositional system with an uneven margin, 10 km long and up to 6 km wide. Shelf margin morphology shows multiple sub-marine channelized carbonate deposits which are dominated by coralline red algae and subordinate bryozoans. Two main channel networks (Pietraroia and Regia Piana channels) with their sedimentary bodies were analyzed. The studied sub-marine channels grew by sediment accumulation as prograding bodies on a tectonic modelled substrate. Shallow-water rhodalgal skeletal debris, from moderately re-mobilized up to significantly re-worked, built up the complex channel-system fills in which sedimentary lenses overlapped and partially amalgamated one another when they were still unlithified. The early channelized succession is characterized by parautochthonous bryozoan floatstone and rhodolith/bryozoan floatstone representing soft muddy substrates in a low water turbulence and high turbidity setting. The rhodoliths, dominated by melobesioid coralline algae, are sub-discoidal and sub-spheroidal in shape with a characteristic loosely packed inner arrangement. These sediments, whose latter portion underwent submarine diagenetic processes (incipient to evoluted hardgrounds), were eroded and successively covered by shallower-water gravitative deposits constituted by rhodolith floatstone/rudstone. Their rhodoliths, constituted by melobesioids, mastophoroids and subordinate lithophylloids and sporolithaceans, are mainly spheroidal/sub-spheroidal in shape with subordinate sub-discoidal specimens, with massive and laminar inner arrangements. The lack in early lithification can be draw back to the physiography of the channelized shelf margin, to the active tectonic as well as to the temperate-type carbonate dominant biogenic components. The depositional surface profile and local hydrodynamic conditions were the major factors controlling sedimentary facies, which differ in their relative proportions of dominant components, their internal structures and sedimentary-body geometries.
Sedimentological and palaeoecological integrated analysis of a Miocene canalized coralline red algal carbonate margin (Matese Mountains, Southern Apennines, Italy).
BASSI, Davide;
2010
Abstract
Lower–Middle Miocene temperate marine carbonates occur in the Matese Mountains, Southern Apennines (Italy). These carbonates formed in an open shelf depositional system with an uneven margin, 10 km long and up to 6 km wide. Shelf margin morphology shows multiple sub-marine channelized carbonate deposits which are dominated by coralline red algae and subordinate bryozoans. Two main channel networks (Pietraroia and Regia Piana channels) with their sedimentary bodies were analyzed. The studied sub-marine channels grew by sediment accumulation as prograding bodies on a tectonic modelled substrate. Shallow-water rhodalgal skeletal debris, from moderately re-mobilized up to significantly re-worked, built up the complex channel-system fills in which sedimentary lenses overlapped and partially amalgamated one another when they were still unlithified. The early channelized succession is characterized by parautochthonous bryozoan floatstone and rhodolith/bryozoan floatstone representing soft muddy substrates in a low water turbulence and high turbidity setting. The rhodoliths, dominated by melobesioid coralline algae, are sub-discoidal and sub-spheroidal in shape with a characteristic loosely packed inner arrangement. These sediments, whose latter portion underwent submarine diagenetic processes (incipient to evoluted hardgrounds), were eroded and successively covered by shallower-water gravitative deposits constituted by rhodolith floatstone/rudstone. Their rhodoliths, constituted by melobesioids, mastophoroids and subordinate lithophylloids and sporolithaceans, are mainly spheroidal/sub-spheroidal in shape with subordinate sub-discoidal specimens, with massive and laminar inner arrangements. The lack in early lithification can be draw back to the physiography of the channelized shelf margin, to the active tectonic as well as to the temperate-type carbonate dominant biogenic components. The depositional surface profile and local hydrodynamic conditions were the major factors controlling sedimentary facies, which differ in their relative proportions of dominant components, their internal structures and sedimentary-body geometries.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
