Stratigraphic Architecture of a Transtensional Continental Basin In Low-Latitude Semiarid Conditions: The Permian Succession of the Central Orobic Basin (Southern Alps, Italy)

Berra, Fabrizio; Felletti, Fabrizio; Tessarollo, Andrea

doi:10.2110/jsr.2016.26

Cited by 21 publications

(31 citation statements)

References 43 publications

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“…The Variscan basement including the two intrusions is overlain by up to 1,250‐m‐thick volcanic and sedimentary rocks of the Early Permian Collio Formation (Sciunnach, ). The stratigraphic terminology has recently been revised and Collio Formation has been replaced by different names for different basins (see Berra et al, ; Gaetani et al, ); however, we will use the old term for simplicity. The Collio Formation was deposited in two basins (or subbasins of one large basin), the Orobic Basin, including our study area, and the Collio Basin further southeast (Figure ).…”

Section: Introductionmentioning

confidence: 99%

Kinematics and Age of Syn‐Intrusive Detachment Faulting in the Southern Alps: Evidence for Early Permian Crustal Extension and Implications for the Pangea A Versus B Controversy

Pohl

Froitzheim²,

Obermüller³

et al. 2018

Tectonics

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Permian basin formation and magmatism in the Southern Alps of Italy have been interpreted as expressions of a WSW-ENE-trending, dextral megashear zone transforming Early Permian Pangea B into Late Permian Pangea A between~285 and 265 Ma. In an alternative model, basin formation and magmatism resulted from N-S crustal extension. To characterize Permian tectonics, we studied the Grassi Detachment Fault, a low-angle extensional fault in the central Southern Alps. The footwall forms a metamorphic core complex affected by upward-increasing, top-to-the-southeast mylonitization. Two granitoid intrusions occur in the core complex, the synmylonitic Val Biandino Quartz Diorite and the postmylonitic Valle San Biagio Granite. U-Pb zircon dating yielded crystallization ages of 289.1 ± 4.5 Ma for the former and 286.8 ± 4.9 Ma for the latter. Consequently, detachment-related mylonitic shearing took place during the Early Permian and ended at~288 Ma, but kinematically coherent brittle faulting continued. Considering 30°anticlockwise rotation of the Southern Alps since Early Permian, the extension direction of the Grassi Detachment Fault was originally~N-S. Even though a dextral continental wrench system has long been regarded as a viable model at regional scale, the local kinematic evidence is inconsistent with this and, rather, supports N-S extensional tectonics. Based on a compilation of >200 U-Pb zircon ages, we discuss the evolution and tectonic framework of Late Carboniferous to Permian magmatism in the Alps.

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Section: Introductionmentioning

confidence: 99%

Kinematics and Age of Syn‐Intrusive Detachment Faulting in the Southern Alps: Evidence for Early Permian Crustal Extension and Implications for the Pangea A Versus B Controversy

Pohl

Froitzheim²,

Obermüller³

et al. 2018

Tectonics

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“…Recently, two different sedimentary cycles were identified in the Pizzo del Diavolo formation of the central Orobic Basin (Trabuchello–Cabianca Anticline) by Berra & Felletti () and Berra et al . () (Fig. D).…”

Section: Geological Settingmentioning

confidence: 85%

New occurrences of tetrapod ichnotaxa from the Permian Orobic Basin (Northern Italy) and critical discussion of the age of the ichnoassociation

Marchetti

2016

Papers in Palaeontology

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Abstract:The late Cisuralian (Artinskian-Kungurian) is a key time interval for Permian tetrapod evolution. In all the main low-latitude Pangean sites, the fossil footprint record clearly shows a diversification and dispersal of non-synapsid amniote tracks compared to the early Cisuralian (AsselianSakmarian). However, data on latest Cisuralian (i.e. late Kungurian) sites are quite fragmentary. A new ichnotaxonomic study was carried out in the central part of the Orobic Basin, where the highly-fossiliferous Pizzo del Diavolo formation crops out and can potentially cover this gap in knowledge. The following tetrapod ichnogenera were identified: Amphisauropus, Batrachichnus, cf. Dimetropus, Dromopus, Erpetopus, Hyloidichnus, Limnopus, cf. Merifontichnus and Varanopus; they can be attributed to seymouriamorph and temnospondyl amphibians; pelycosaur synapsids; and diapsid, parareptile and captorhinid reptiles. Dimetropus and Merifontichnus are identified for the first time in the Permian of Italy. The ichnoassociation, in agreement with the radiometric dating of the underlying Cabianca formation, suggests a late Kungurian (latest Cisuralian) age for the Pizzo del Diavolo formation. It includes the youngest and most diverse non-synapsid amniote ichnofauna of the Cisuralian with five different ichnogenera and possibly six ichnospecies, and thus constitutes a key area for the study of eureptile and parareptile dispersal at low latitudes of Pangaea in the time span that immediately pre-dates the first therapsid synapsid radiation.

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“…therein). S2 is truncated by siliciclastic Permian sequences, including conglomerates, arenites, and volcaniclastites, which are divided by unconformity in two cycles, dated lower-and mid-upper Permian, respectively [54,[60][61][62]. The basement and sedimentary rocks were subsequently deformed and poorly metamorphosed during Alpine convergence (e.g., [63][64][65]), which was responsible for the development of D3 and D4 structures [56,[66][67][68][69].…”

Section: Geological Settingmentioning

confidence: 99%

“…The mid-upper Permian Verrucano Lombardo is part of the second sedimentary cycle capping most of the Orobic basement; it consists of poorly stratified fluvial conglomerates and sandstones ( [62] and refs. therein) that grade into shallow sea deposits (Servino Formation) in early Triassic times [79].…”

Section: Geological Settingmentioning

confidence: 99%

“…Structural mapping was carried out on the right sloping bank of the Oglio river in upper Val Camonica, west of Cedegolo and Sellero villages (Figure 3). The aim was to The mid-upper Permian Verrucano Lombardo is part of the second sedimentary cycle capping most of the Orobic basement; it consists of poorly stratified fluvial conglomerates and sandstones ( [62] and refs. therein) that grade into shallow sea deposits (Servino Formation) in early Triassic times [79].…”

Section: Lithostratigraphy and Deformation Historymentioning

confidence: 99%

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Cld-St-And-Bearing Assemblages in the Central Southalpine Basement: Markers of an Evolving Thermal Regime during Variscan Convergence

et al. 2021

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Multiscale structural analysis was carried out to explore the sequence of superposed pre-Alpine chloritoid–staurolite–andalusite metamorphic assemblages in the polydeformed Variscan basement of the upper Val Camonica, in the central Southalpine domain. The dominant fabric in the upper Val Camonica basement is the late-Variscan S2 foliation, marked by greenschist facies minerals and truncated by the base of Permian siliciclastic sequences. The intersection with the sedimentary strata defines a Permianage limit on the pre-Alpine tectonometamorphic evolution and exhumation of the Variscan basement. The detailed structural survey revealed that the older S1 foliation was locally preserved in low-strained domains. S1 is a composite fabric resulting from combining S1a and S1b: in the metapelites, S1a was supported by chloritoid, garnet, and biotite and developed before S1b, which was marked by staurolite, garnet, and biotite. S1a and S1b developed at intermediate pressure amphibolite facies conditions during the Variscan convergence, S1a at T = 520–550 °C and P ≃ 0.8 GPa, S1b at T = 550–650 °C and P = 0.4–0.7 GPa. The special feature of the upper Val Camonica metapelites is andalusite, which formed between the late D1b and early D2 tectonic events. Andalusite developed at T = 520–580 °C and P = 0.2–0.4 GPa in pre-Permian times, after the peak of the Variscan collision and before the exhumation of the Variscan basement and the subsequent deposition of the Permian covers. It follows that the upper Val Camonica andalusite has a different age and tectonic significance as compared to that of other pre-Alpine andalusite occurrences in the Alps, where andalusite mostly developed during exhumation of high-temperature basement rocks in Permian–Triassic times.

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Stratigraphic Architecture of a Transtensional Continental Basin In Low-Latitude Semiarid Conditions: The Permian Succession of the Central Orobic Basin (Southern Alps, Italy)

Cited by 21 publications

References 43 publications

Kinematics and Age of Syn‐Intrusive Detachment Faulting in the Southern Alps: Evidence for Early Permian Crustal Extension and Implications for the Pangea A Versus B Controversy

Kinematics and Age of Syn‐Intrusive Detachment Faulting in the Southern Alps: Evidence for Early Permian Crustal Extension and Implications for the Pangea A Versus B Controversy

New occurrences of tetrapod ichnotaxa from the Permian Orobic Basin (Northern Italy) and critical discussion of the age of the ichnoassociation

Cld-St-And-Bearing Assemblages in the Central Southalpine Basement: Markers of an Evolving Thermal Regime during Variscan Convergence

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