Anomalous patterns of the sedimentary archi- tecture have been recognized in passive margins, and only recently they have been associated with plate reorganiza- tion or compressional deformations propagating from dis- tant margins. With the aim of discussing the sedimentary architecture and the potential tectonic perturbations to the passive margin pattern, we present the revision of the stratigraphy of a fossil passive margin, involved in the retrobelt of the Alpine orogeny. The main events at the transition from rifted to passive margin have been con- trolled by palaeoceanography, i.e. the trophic state of sur- face waters that hampered the carbonate photozoan productivity for a long period between Toarcian and Callovian. Toward the latest Bajocian–earliest Bathonian, the platform productivity increased, dominated by ooids. A regressional trend up to the Middle Bathonian allowed the rapid infilling of the previous rift basin. The successive aggradation in the platform was still dominated by non- skeletal grains until the Early Oxfordian. The Middle Oxfordian to Early Kimmeridgian was a time of recovery of the palaeoceanographic conditions allowing the estab- lishment of a hydrozoan/coral rich platform. The sedi- mentation rates in the platform increased at the margin of the productive Friuli–Adriatic Platform. From Late Kim- meridgian on, the sedimentation rates at the platform margin returned to the pre-Oxfordian values. At the scale of the whole Adriatic Platform, the Middle Oxfordian to Early Kimmeridgian interval is variable in thickness from 0 to 800 m, and it depicts a couple of folds of around 80–100 km of wavelength. The subsidence analysis of wells and composite logs from literature suggests this interval as a perturbation to the passive margin trend of around 3 Myr of duration. We interpret this folding event, superimposed to the passive margin subsidence, as the far field expression of the transition from intraoceanic to continental obduction, occurred at the eastern Adria active margin.

Jurassic stratigraphy of the Belluno Basin and Friuli Platform: a perspective on far-field compression in the Adria passive margin

COBIANCHI, MIRIAM
2017-01-01

Abstract

Anomalous patterns of the sedimentary archi- tecture have been recognized in passive margins, and only recently they have been associated with plate reorganiza- tion or compressional deformations propagating from dis- tant margins. With the aim of discussing the sedimentary architecture and the potential tectonic perturbations to the passive margin pattern, we present the revision of the stratigraphy of a fossil passive margin, involved in the retrobelt of the Alpine orogeny. The main events at the transition from rifted to passive margin have been con- trolled by palaeoceanography, i.e. the trophic state of sur- face waters that hampered the carbonate photozoan productivity for a long period between Toarcian and Callovian. Toward the latest Bajocian–earliest Bathonian, the platform productivity increased, dominated by ooids. A regressional trend up to the Middle Bathonian allowed the rapid infilling of the previous rift basin. The successive aggradation in the platform was still dominated by non- skeletal grains until the Early Oxfordian. The Middle Oxfordian to Early Kimmeridgian was a time of recovery of the palaeoceanographic conditions allowing the estab- lishment of a hydrozoan/coral rich platform. The sedi- mentation rates in the platform increased at the margin of the productive Friuli–Adriatic Platform. From Late Kim- meridgian on, the sedimentation rates at the platform margin returned to the pre-Oxfordian values. At the scale of the whole Adriatic Platform, the Middle Oxfordian to Early Kimmeridgian interval is variable in thickness from 0 to 800 m, and it depicts a couple of folds of around 80–100 km of wavelength. The subsidence analysis of wells and composite logs from literature suggests this interval as a perturbation to the passive margin trend of around 3 Myr of duration. We interpret this folding event, superimposed to the passive margin subsidence, as the far field expression of the transition from intraoceanic to continental obduction, occurred at the eastern Adria active margin.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11571/1188189
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