Origin of Triassic magmatism of the Southern Alps (Italy): Constraints from geochemistry and Sr-Nd-Pb isotopic ratios

Lustrino, Michele; Abbas, Hassan; Agostini, Samuele; Caggiati, Marcello; Carminati, Eugenio; Gianolla, Piero

doi:10.1016/j.gr.2019.04.011

Cited by 35 publications

(34 citation statements)

References 98 publications

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“…Just east of Lake Garda in the area of Recoaro (north of Verona; Fig. 1) there are rhyolites to dacites and minor basaltic lava flows and small intrusives with shoshonitic affinity (De Vecchi & Sedea, 1983;Bellieni et al 2010;Lustrino et al 2019). They lie on the pelagic units of the Nodosus Formation, which have been assigned a late Ladinian age by De Vecchi & Sedea (1983).…”

Section: B Triassic Magmatism In the Southern Alps And Western Alcapamentioning

confidence: 99%

“…Doglioni, 1987;Vai, 1991;Gianolla et al 1998;Bortolotti & Principi, 2005;Beltrando et al 2015) and the apparent orogenic geochemical fingerprints of many of the magmatic products studied so far (e.g. De Vecchi & Sedea, 1983;Castellarin et al 1988;Sloman, 1989;Gasparotto & Simboli, 1991;Bonadiman et al 1994;Armienti et al 2003;Casetta et al 2018b;Lustrino et al 2019). What gained the interest of the geological community is the fact that this magmatism took place shortly before the break-up of Pangea, in a lithosphere that was previously affected by the Variscan collision and possibly by even older orogenic events.…”

Section: Introductionmentioning

confidence: 99%

“…Geochemical and petrographic data about this magmatism have increased over the last decades (e.g. Sloman, 1989;Bonadiman et al 1994;Cassinis et al 2008;Miller et al 2011;Beltràn-Triviño et al 2016;Bianchini et al 2018;Casetta et al 2018aCasetta et al , b, 2019Lustrino et al 2019). However, a clear picture of its geodynamic context is hindered by the widespread hydrothermal alteration of the outcrops, the complex palaeogeography and the lack of a comprehensive review of the geology of this area.…”

Section: Introductionmentioning

confidence: 99%

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Triassic magmatism in the European Southern Alps as an early phase of Pangea break-up

et al. 2020

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Magmatic rocks from the Dolomites, Carnic and Julian Alps, Italy, have been sampled to investigate the origin and geodynamic setting of Triassic magmatism in the Southern Alps. Basaltic, gabbroic and lamprophyric samples have been characterized for their petrography, mineral chemistry, whole-rock major and trace elements, and Sr, Nd and Pb isotopic compositions. Geothermobarometric estimates suggest that the basaltic magmas crystallized mostly at depths of 14–20 km. Isotopic data show variable degrees of crustal contamination decreasing westwards, probably reflecting a progressively more restitic nature of the crust, which has been variably affected by melting during the Permian period. Geochemical and isotopic data suggest that the mantle source was metasomatized by slab-derived fluids. In agreement with previous studies and based on geological evidence, we argue that this metasomatism was not contemporaneous with the Ladinian–Carnian magmatism but was related to previous subduction episodes. The lamprophyres, which likely originated some 20 Ma later by lower degrees of melting and at higher pressures with respect to the basaltic suite, suggest that the mantle source regions of Triassic magmatism in the Dolomites was both laterally and vertically heterogeneous. We conclude that the orogenic signatures of the magmas do not imply any coeval subduction in the surrounding of Adria. We rather suggest that this magmatism is related to the Triassic rifting episodes that affected the western Mediterranean region and that were ultimately connected to the rifting events that caused the break-up of Pangea during the Late Triassic – Early Jurassic period.

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Section: B Triassic Magmatism In the Southern Alps And Western Alcapamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Triassic magmatism in the European Southern Alps as an early phase of Pangea break-up

et al. 2020

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“…Important igneous events mark the geodynamic evolution of the area now referred to the Southern Alps during Triassic times. In particular, a diffuse igneous activity with orogenic, shoshonitic to K-rich calc-alkaline, affinity developed during the Middle Triassic (~243-235 Ma) in the Eastern (Dolomites area) and Central (Brescian PreAlps) sectors ( [127,128,129,130,131,132]. These events occurred under mainly transtensional regime, which determined the partial melting of mantle regions metasomatised by crustal components during the Variscan orogenic cycle [129,130,131].…”

Section: Geodynamic Implicationsmentioning

confidence: 99%

“…In particular, a diffuse igneous activity with orogenic, shoshonitic to K-rich calc-alkaline, affinity developed during the Middle Triassic (~243-235 Ma) in the Eastern (Dolomites area) and Central (Brescian PreAlps) sectors ( [127,128,129,130,131,132]. These events occurred under mainly transtensional regime, which determined the partial melting of mantle regions metasomatised by crustal components during the Variscan orogenic cycle [129,130,131]. In the westernmost sector of the Southern Alps, the record of this tectono-magmatic activity is poorly documented, being essentially limited to Ladinian-Carnian ages provided by magmatic (e.g., 239-232 Ma; [60,63,133]) and metamorphic zircons, e.g., [134,135] from the deepest crustal rocks of IVZ, namely those of the Finero Complex, and by zircons from tuffitic layers occurring in the carbonate platform (241 Ma; [132,136]).…”

Section: Geodynamic Implicationsmentioning

confidence: 99%

Mantle-derived Corundum-bearing Felsic Dykes May Survive Only within the Lower (refractory/inert) Crust: Evidence from Zircon Geochemistry and Geochronology (Ivrea-Verbano Zone, Southern Alps, Italy)

Bonazzi¹,

Langone²,

Tumiati³

et al. 2020

Preprint

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Corundum-rich (up to 55 vol.%) felsic dykes formed by albite, ±K-feldspar, ±hercynite and ±biotite-siderophyllite cut the lower crustal rocks exposed in the Ivrea-Verbano Zone (NW Italy). Zircon is an abundant accessory mineral and its investigation through LA-ICP-(MC)MS has allowed to directly constrain the timing of emplacement, as well as petrology and geochemistry of parental melts. Zircons are characterised by very large concentration in REE, Th, U, Nb and Ta, and negative Eu anomaly. U–Pb analysis points to Norian emplacement ages (223±7 Ma and 224±6 Ma), whereas large positive εHf(t) values (+13 on average) indicate a derivation from depleted to mildly enriched mantle source. The mantle signature and the corundum oversaturation were preserved thanks to limited crustal contamination of the host, HT refractory granulites and mafic intrusives. According to the geochemical data and to the evidence of the development of violent explosions into the conduits, it is proposed that dykes segregated from peraluminous melts produced by exsolution processes affecting volatile-rich differentiates during alkaline magmatism. This work provides robust evidence about the transition of the geochemical affinity of Southern Alps magmatism from orogenic-like to anorogenic during Norian, linked to a regional uprising of the asthenosphere and change of tectonic regime.

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Modelling ancient magma plumbing systems through clinopyroxene populations: a case study from Middle Triassic volcanics (Dolomites, Italy)

Nardini,

Casetta,

Petrone

et al. 2024

Contrib Mineral Petrol

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Modelling plumbing systems dynamics of active volcanoes through textural and chemical studies of mineral phases is crucial to unravel their eruptive behaviour, but it is rarely applied in ancient volcanic and volcano-plutonic systems. Here, we present an investigation of the architecture, magma dynamics and pre-eruptive timing of Middle Triassic plumbing systems in the Dolomites area (Southern Alps) through a detailed investigation of textures and compositional zoning of clinopyroxenes in lavas and dykes from Predazzo, Mt. Monzoni, Cima Pape and Sciliar volcano-plutonic complexes. The clinopyroxene composition varies between low-Mg# (67–78), low-Cr augite and high-Mg# (77–91), Cr-rich diopside. Diopside is less frequent and appears as variably thick single or multiple bands between augitic cores and rims or as resorbed homogeneous, or patchy-zoned and mottled cores. Rims are homogeneous or oscillatory zoned, with augitic composition. The mid- to low-crustal plumbing systems of all volcanic centres were characterised by the presence of a mildly evolved trachyandesitic magma (Mg# 45; T = 1044–1118 °C), where augitic clinopyroxene formed. Periodic mafic injections of more primitive and hotter trachybasaltic magma (Mg# 56; T = 1056–1170 °C) caused frequent crystallisation of diopsidic bands around augitic cores. The presence of resorbed or patchy-zoned mottled diopsidic cores in clinopyroxene phenocrysts, as well as of rare clinopyroxenitic xenoliths with analogous diopsidic composition, indicates the recycling and remobilisation of antecrysts from the deeper part of the plumbing system, which was probably located at a depth of 10–17 km. Diffusion chronometry models based on Fe–Mg interdiffusion in clinopyroxene revealed that the time elapsed from the mafic injection into the shallow portion of the plumbing systems to the eruption ranges from decades to < 1 year. Our findings enabled us to resolve the different plumbing system dynamics acting at the local scale beneath each volcanic centre. Our data indicate a striking similarity with magma dynamics and timing of pre-eruptive processes at active volcanoes: therefore, we posit that this work sets a starting point to deepen our knowledge of the volcano-plutonic links and, in turn improves our ability to interpret the main processes acting in active plumbing systems.

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Origin of Triassic magmatism of the Southern Alps (Italy): Constraints from geochemistry and Sr-Nd-Pb isotopic ratios

Cited by 35 publications

References 98 publications

Triassic magmatism in the European Southern Alps as an early phase of Pangea break-up

Triassic magmatism in the European Southern Alps as an early phase of Pangea break-up

Mantle-derived Corundum-bearing Felsic Dykes May Survive Only within the Lower (refractory/inert) Crust: Evidence from Zircon Geochemistry and Geochronology (Ivrea-Verbano Zone, Southern Alps, Italy)

Modelling ancient magma plumbing systems through clinopyroxene populations: a case study from Middle Triassic volcanics (Dolomites, Italy)

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