Shoshonitic magmatism in the Paleoproterozoic of the south-westernSiberian Craton: An analogue of the modern post-collision setting

Ivanov, A.V.; Levitskii, I.V.; Levitski, V.I.; Fernando, C.; Demonterova, E.I.; Reznitskii, L.Z.; Pavlova, L.A.; Kamenetsky, V.S.; Savatenkov, V.M.; Powerman, V.I.

Авторы: Ivanov Alexei V., Levitskii Ivan V., Levitski Valery I., Fernando Corfu, Demonterova Elena I., Reznitskii Leonid Z., Pavlova Ludmila A., Kamenetsky Vadim S., Savatenkov Valery M., Powerman Vladislav I.
Журнал: Lithos
Том: 328
Год издания: 2019
Издательство: Elsevier BV
Местоположение издательства: Netherlands
Первая страница: 88
Последняя страница: 100
DOI: 10.1016/j.lithos.2019.01.015
Аннотация: The Siberian Craton was assembled in a Paleoproterozoic episode at about 1.88 Ga by the collision of older blocks,followed at about 1.86 Ga by post-collisional felsic magmatism. We have found a set of extremely fresh mica-bearing lamprophyre-looking rocks within the Sharyzhalgay metamorphic complex of the south-western Sibe-rian Craton. Zircon from these rocks yields a U\\Pb TIMS age of 1864.7 ± 1.8 Ma, which coincides perfectlywith the peak of the post-collisional granite ages and postdates by ~15 Ma the peak of ages obtained for meta-morphism. The same ages were reported earlier for a mafic dyke with ocean island basalt (OIB) geochemical sig-natures and a Pt-bearing mafic-ultramafic intrusion found in the same region. Mineralogy, major and traceelement geochemistry and Sr-Nd-Pb isotopes show that the studied rocks (1) have shoshonitic affinity, (2) arehybrid rocks with mineral assemblages which could not be in equilibrium, (3) where derived by recycling ofan Archean crustal source and (4) resemble post-collision Tibetan shoshonitic series. The genesis of theserocks is considered to be due to melting of crustal lithologies and metasomatized lithospheric mantle within asubducted slab. Some of the resulting melts ascended through the lithospheric column and fractionated tolow-Mg absarokites, whereas other melts were contaminated by orthopyroxenitic mantle material and attainedunusual high-Mg mafic compositions. According to our model, the post-collisional magmatism (shoshonite- andOIB-type) occurred due to upwelling of hot asthenosphere through a slab window, when the active collisionceased as a result of the slab break off and loss of the slab pull force. Overall, our study shows that in thePaleoproterozoic shoshonitic melts were emplaced within a similar tectonic setting as seen today in modern oro-genic systems
Добавил в систему: vladislav.powerman@gmail.com

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Shoshonitic magmatism in the Paleoproterozoic of the south-westernSiberian Craton: An analogue of the modern post-collision settingстатья Исследовательская статья

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