The northern part of the Crotone Basin (southern Italy) was characterized by the activity of Pliocene growth faults bounding half-graben sub-basins. The thickest unit deposited during growth fault activity is the lower Pliocene Belvedere Formation (up to 450 m thick), which shows a small-scale, highly regular rhythmic cyclicity. This sandstone unit was deposited in a shallow-marine environment, and its accumulation was mostly influenced by storm processes and locally by flows in tectonically confined areas. The meter-scale cycles are represented by rhythmic alternations between shell-rich intervals, characterized by storm structures or largescale cross sets, and shell-poor sandy intervals that are commonly burrowed and poorly stratified. The better preserved cycles commonly show a fining-upward trend with minor progradation in their upper part, and may be bounded at the base by a shell lag. The deposition of large-scale cross sets is thought to be the consequence of the creation of fault scarps, which led to tectonic confinement in the half-graben basins. In the tectonically confined areas, tidal currents were enhanced and large subaqueous dunes migrated. The evidence suggests that the observed cyclicity was generated by sea-level and climatic variations that controlled the sediment input into the basin. The relationship between large-scale cross sets and tectonic confinement demonstrates that local extensional tectonics significantly influenced the sedimentation. The excellent preservation of the observed small-scale cycles is thought to be the consequence of deposition in the highly subsiding half-graben sub-basins. On the structural highs, this cyclicity is amalgamate and less appreciable. The data presented may be significant for a better understanding of the role of subsidence in preserving sedimentary successions in these growth-faulted settings.

Relationships between fault-controlled subsidence and preservation of shallow-marine small-scale cycles: example from the lower Pliocene of the Crotone Basin (southern Italy)

Zecchin M
2005

Abstract

The northern part of the Crotone Basin (southern Italy) was characterized by the activity of Pliocene growth faults bounding half-graben sub-basins. The thickest unit deposited during growth fault activity is the lower Pliocene Belvedere Formation (up to 450 m thick), which shows a small-scale, highly regular rhythmic cyclicity. This sandstone unit was deposited in a shallow-marine environment, and its accumulation was mostly influenced by storm processes and locally by flows in tectonically confined areas. The meter-scale cycles are represented by rhythmic alternations between shell-rich intervals, characterized by storm structures or largescale cross sets, and shell-poor sandy intervals that are commonly burrowed and poorly stratified. The better preserved cycles commonly show a fining-upward trend with minor progradation in their upper part, and may be bounded at the base by a shell lag. The deposition of large-scale cross sets is thought to be the consequence of the creation of fault scarps, which led to tectonic confinement in the half-graben basins. In the tectonically confined areas, tidal currents were enhanced and large subaqueous dunes migrated. The evidence suggests that the observed cyclicity was generated by sea-level and climatic variations that controlled the sediment input into the basin. The relationship between large-scale cross sets and tectonic confinement demonstrates that local extensional tectonics significantly influenced the sedimentation. The excellent preservation of the observed small-scale cycles is thought to be the consequence of deposition in the highly subsiding half-graben sub-basins. On the structural highs, this cyclicity is amalgamate and less appreciable. The data presented may be significant for a better understanding of the role of subsidence in preserving sedimentary successions in these growth-faulted settings.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.14083/2515
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