The crystalline basement of the Adria microplate in the eastern Alps: a review of the palaeostructural evolution from the Neoproterozoic to the Cenozoic

Spiess, Richard; Cesare, Bernardo; Mazzoli, Claudio; Sassi, Raffaele; Sassi, Francesco

doi:10.1007/s12210-010-0100-6

Cited by 33 publications

(22 citation statements)

References 74 publications

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“…Permo-Triassic continental gabbros are located in the Austroalpine and Southalpine domains of the whole Alpine realm ( Figure 2) and are associated with subcontinental peridotites emplaced at different structural levels ( Figure 4c and Table S2; Bonin et al, 1993;McCarthy & Muntener, 2015;Rottura et al, 1998;Spalla et al, 2014;Spiess, Cesare, Mazzoli, Sassi, & Sassi, 2010;Staehle et al, 2001). Although the gabbros are generally considered to be generated from variably contaminated mantle sources in an extensional tectonic regime under a high thermal state, associated with lithospheric thinning and rifting (Spalla et al, 2014, and references therein), from a geochemical point of view, most of the gabbros have a tholeiitic signature (Spalla et al, 2014, and references therein).…”

Section: Permo-triassic Continental Gabbrosmentioning

confidence: 99%

What drives Alpine Tethys opening? Clues from the review of geological data and model predictions

et al. 2018

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Permo‐Triassic remnants (300–220 Ma) of high‐temperature metamorphism associated with large gabbro bodies occur in the Alps and indicate a high thermal regime compatible with lithospheric thinning. During the Late Triassic–Early Jurassic, an extensional tectonics leads to the break‐up of Pangea continental lithosphere and the opening of Alpine Tethys Ocean (170–160 Ma), as testified by the ophiolites outcropping in the Central–Western Alps and Apennines. We revise geological data from the Permian to Jurassic of the Alps and Northern Apennines, focusing on continental and oceanic basement rocks, and predictions of existing numerical models of post‐collisional extension of continental lithosphere and successive rifting and oceanization. The aim is to test whether the transition from the Permo‐Triassic extensional tectonics to the Jurassic opening of Alpine Tethys occurred. We enforce the interpretation that a forced extension of 2 cm/year of the post‐collisional lithosphere results in a thermal state compatible with the Permo‐Triassic high‐temperature event suggested by pressure and temperature conditions of metamorphic rocks and widespread igneous activity. Extensional or transtensional tectonics is also in agreement with the generalized subsidence indicated by the deposition of sedimentary successions with deepening upward facies occurred in the Alps from the Permian to Jurassic. Furthermore, a rifting developed on a thermally perturbed lithosphere agrees with a hyperextended configuration of the Alpine Tethys rifting and with the duration of the extension necessary to the oceanization. The review supports the interpretation of Alpine Tethys opening developed on a lithosphere characterized by a thermo‐mechanical configuration inherited by the post‐Variscan extension which affected Pangea during the Permian and Triassic. Therefore, a long‐lasting period of active extension can be envisaged for the breaking of Pangea supercontinent, starting from the unrooting of the Variscan belts, followed by the Permo‐Triassic thermal high, and ending with the crustal break‐up and the formation of the Alpine Tethys Ocean.

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Section: Permo-triassic Continental Gabbrosmentioning

confidence: 99%

What drives Alpine Tethys opening? Clues from the review of geological data and model predictions

et al. 2018

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“…Most of the pre-Alpine continental lithosphere recycled during the Alpine subduction shows a pre-Mesozoic metamorphic evolution compatible with the evolution of the European Variscan belt (von Raumer et al, 2003;Spalla and Marotta, 2007;Spiess et al, 2010;Spalla et al, 2014;Roda et al, 2018a). von Raumer et al (2003) suggested that the present day Alpine domains (Helvetic, Penninic, Austroalpine and Southalpine) were probably located along the northern margin of Gondwana.…”

Section: Variscan Tectono-metamorphic Evolution In the Alpsmentioning

confidence: 98%

How many subductions in the Variscan orogeny? Insights from numerical models

Regorda¹,

Lardeaux

Roda³

et al. 2020

Preprint

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The Variscan belt is the result of the Pangea accretion, a prominent feature of the European continental lithosphere (von Raumer et al., 2003) . The debate on the number of oceans and the geodynamic evolution of the Variscan belt is still open (Faure et al., 2009; Franke et al., 2017). Two scenarios have been proposed:<ol><li> Monocyclic scenario: assumes a single long-lasting south-dipping subduction of a large oceanic domain. Armorica remained more or less closed to Gondwana during its northward drift, in agreement with lack of biostratigraphic and paleomagnetic data that suggests a narrow oceanic domain (lesser than 1000 km; Matte, 2001; Lardeaux, 2014); </li> <li> Polycyclic scenario: this geodynamic reconstruction envisages two main oceanic basins opened by the successive northward drifting of two Armorican microcontinent and closed by two opposite subductions (Lardeaux, 2014; Franke et al., 2017). The northern oceanic basin is identified as the Saxothuringian ocean, while the southern basin is identified as the Medio-European ocean (Lardeaux, 2014). </li> </ol>Models of single and double subduction have been developed to verify which scenario better fits with Variscan P-T evolutions from the Alps and the French Central Massif (FCM). From the comparison between model predictions and natural Variscan P-T-t estimates results that data from the Alps with high P/T ratios better fit with the double subduction model, supporting that a polycyclic scenario is more suitable for the Variscan belt evolution. Differently, data from the FCM with high P/T ratios that fit with both models have poorly constrained geological ages and, therefore, are not suitable to actually discriminate between mono- and polycyclic scenarios (Regorda et al., 2020). Moreover, the predictions of the models open to the possibility that rocks of the Upper Gneiss Unit of the FCM could derive from tectonic erosion of the upper plate and not only from the ocean-continent transition of the lower plate.ReferencesFaure M., Lardeaux J.-M. and Ledru P.; 2009: A review of the pre-Permian geology of the Variscan French Massif Central. Comptes Rendus Geoscience, 341, 202-213.Franke W., Cocks L.R.M. and Torsvik T.H.; 2017: The Palaeozoic Variscan oceans revisited. Gondwana Research, 48, 257-284.Lardeaux J.-M.; 2014: Deciphering orogeny: a metamorphic perspective. Examples from European Alpine and Variscan belts. Part II: Variscan metamorphism in the French Massif Central &#8211; A review. Bull. Soc. g&#233;ol. France, 185(5), 281-310.Matte P.; 2001: The Variscan collage and orogeny (480-290 Ma) and the tectonic definition of theArmorica microplate: A review. Terra Nova, 13(2), 122-128.Regorda A., Lardeaux J-.M., Roda M., Marotta A.M. and Spalla M.I.; 2020: How many subductions in the Variscan orogeny? Insights from numerical models. Geoscience Frontiers, 10.1016/j.gsf.2019.10.005.von Raumer J. F., Stampfli G.M. and Bussy, F.; 2003: Gondwana-derived microcontinents &#8211; the constituents of the Variscan and Alpine collisional orogens. Tectnophysics, 365, 7-22.

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“…The outcropping crystalline basement consists of metamorphic rocks (phyllades and mica-schists) and igneous granitic (s.l.) intrusions formed during the Variscan orogeny [9,10]. The basement is covered by Permian volcanics consisting of ignimbrites, mainly rhyolitic in composition, of the Athesian Volcanic Group [11,12], and by Triassic sedimentary rocks [13,14], sometimes crosscut by Early Triassic basic dykes [15].…”

Section: Geological Outlinesmentioning

confidence: 99%

Trace-Element Distribution on Sulfide Mineralization in Trento Province, NE Italy

et al. 2019

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Sulfide mineralization in the province of Trento (northeastern Italy) includes various mineral assemblages that are often silver-rich and have been exploited in different phases from the Middle Ages until the 20th century. This study investigates mineralized rocks from three historically important sites (Calisio mount, Erdemolo lake, and the locality of Cinque Valli), providing new analytical data (Inductively Coupled Plasma-Mass Spectrometry on bulk rocks, and Scanning Electron Microscopy on thin sections) that demonstrate that parageneses do not only include galena, chalcopyrite, and sphalerite but also accessory minerals, such as tetrahedrite, tennantite, acanthite, and sulfosalts (matildite/polybasite). This explains the high content of As (up to 278 ppm), Bi (up to 176 ppm), and Sb (up to 691 ppm) that are associated with Pb–Cu–Zn mineralization. Notably, trace-element ratios indicate that, although closely associated from a geographical point of view, the studied sites are not genetically related and have to be referred to in distinct mineralization events, possibly induced by three diverse magmatic and hydrothermal phases that occurred in the Variscan post-orogenic setting. Besides geological and petrogenetic reconstruction, the new data outline potential geochemical risks, as they reveal a high concentration of elements characterized by marked toxicity that can be transferred into the local soil and water. Therefore, future studies should be devoted to better investigating the metal distribution in the surroundings of ancient mining sites and their geochemical behavior during the weathering processes.

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The crystalline basement of the Adria microplate in the eastern Alps: a review of the palaeostructural evolution from the Neoproterozoic to the Cenozoic

Cited by 33 publications

References 74 publications

What drives Alpine Tethys opening? Clues from the review of geological data and model predictions

What drives Alpine Tethys opening? Clues from the review of geological data and model predictions

How many subductions in the Variscan orogeny? Insights from numerical models

Trace-Element Distribution on Sulfide Mineralization in Trento Province, NE Italy

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