Intrusion of shoshonitic magmas at shallow crustal depth: T–P path, H2O estimates, and AFC modeling of the Middle Triassic Predazzo Intrusive Complex (Southern Alps, Italy)

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

“…Based on Sr, Nd and Pb isotope data, we therefore suggest that magma-crust interaction in the Dolomites was limited to <5% of carbonate contamination for the basaltic lava flows, dykes and sills, and could reach up to 10% for the plutonic complex of Mount Monzoni. Similar values have been suggested by Casetta et al (2018a) for the Predazzo intrusive complex. No significant interaction with silicic crustal material is required.…”

“…Further east, the area of the Dolomites includes well-exposed intermediate to acid intrusions (Mount Monzoni and Predazzo intrusive complexes), pyroclastic layers, basaltic lava flows, numerous basaltic dykes and sills with shoshonitic affinity, and lamprophyric dykes, often including mantle xenoliths (e.g. Sloman, 1989;Gasparotto & Simboli, 1991;Bonadiman et al 1994;Visonà, 1997;Carraro & Visonà, 2003;Casetta et al 2018aCasetta et al , b, 2019Lustrino et al 2019;Storck et al 2019). In the Dolomites, Triassic sills and lava flows lie between the Livinnallongo and Conglomerato della Marmolada formations (of Ladinian age, according to Gasparotto & Simboli, 1991).…”

“…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.…”

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)

“…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].…”

“…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]).…”