Spectacular seismic-scale outcrops in the «Montagna della Maiella» allow to observe directly an average 1000 m high Cretaceous escarpment, abruptly separating shallow-water deposits from slope to basin ones. In plain view, three km-scale amphitheatre-like indentations have been recognized. In section view, along the large scalloped indentations, the escarpment geometry has an exponential profile which changes downslope from high angle (~60°) to sub-horizontal. Along ridges, between different scallops, the escarpment profile is more regular, with average angles of 35° and locally steeper (> 45°). We interpret the Maiella escarpment and related morphologies, that are similar in shape and size to those observed in modern scalloped platform margins, as the result of different scale gravity-driven processes occurred during different stages. The larger indentations formed as the result of Albian platform margin collapses, exposing Lower Cretaceous inner platform facies directly to open marine conditions and exporting related products (megabreccias) many kilometres basinward. During the Upper Cretaceous, the inherited physiography controlled the spatial distribution of marginal facies, stratal geometries, basinward exportation of loose sediments and influenced the stratal stacking patterns in both platform and slope-basin settings. An overall aggrading margin characterized by the stacking of rudist dominated facies, re-shaped by smaller scale collapses, and a by-pass slope, developed up to the Campanian. At this time, the basin was almost completely filled and the platform started to prograde.
Large-scale gravity-driven structures: control on margin architecture and related deposits of a Cretaceous carbonate platform (Montagna della Maiella, Central Apennines, Italy).
MORSILLI, Michele;BOSELLINI, Alfonso
2002
Abstract
Spectacular seismic-scale outcrops in the «Montagna della Maiella» allow to observe directly an average 1000 m high Cretaceous escarpment, abruptly separating shallow-water deposits from slope to basin ones. In plain view, three km-scale amphitheatre-like indentations have been recognized. In section view, along the large scalloped indentations, the escarpment geometry has an exponential profile which changes downslope from high angle (~60°) to sub-horizontal. Along ridges, between different scallops, the escarpment profile is more regular, with average angles of 35° and locally steeper (> 45°). We interpret the Maiella escarpment and related morphologies, that are similar in shape and size to those observed in modern scalloped platform margins, as the result of different scale gravity-driven processes occurred during different stages. The larger indentations formed as the result of Albian platform margin collapses, exposing Lower Cretaceous inner platform facies directly to open marine conditions and exporting related products (megabreccias) many kilometres basinward. During the Upper Cretaceous, the inherited physiography controlled the spatial distribution of marginal facies, stratal geometries, basinward exportation of loose sediments and influenced the stratal stacking patterns in both platform and slope-basin settings. An overall aggrading margin characterized by the stacking of rudist dominated facies, re-shaped by smaller scale collapses, and a by-pass slope, developed up to the Campanian. At this time, the basin was almost completely filled and the platform started to prograde.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
