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Gabbro-granite intrusive series and their indicator importance for geodynamic reconstructions |
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| Authors: | A G Vladimirov A E Izokh G V Polyakov G A Babin A S Mekhonoshin N N Kruk V V Khlestov S V Khromykh A V Travin D S Yudin R A Shelepaev I V Karmysheva E I Mikheev |
| Institution: | 17176. Sobolev Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia 47176. Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia 57176. Tomsk State University, pr. Lenina 50, Tomsk, 634050, Russia 37176. Siberian Research Institute of Geology, Geophysics, and Mineral Resources, Krasnyi pr. 67, Novosibirsk, 630104, Russia 27176. Vinogradov Institute of Geochemistry, Siberian Branch, Russian Academy of Sciences, ul. Favorskogo 1a, Irkutsk, 664033, Russia 67176. Irkutsk State Technical University, ul. Lermontova 83, Irkutsk, 664074, Russia |
| Abstract: | One of the problems faced by researchers when paleogeodynamic reconstructions are carried out for deeply eroded orogenic terranes is the limited usage of geological and isotopic geochemical data on volcanic associations. The utilization of information on gabbroids and granitoids considered separately also fails to resolve this problem. The convergence of features of arc, collisional, and within-plate magmatic processes leads the researcher to search for indicator plutonic associations, such as paired gabbrogranite intrusive series. The latter were distinguished using geoinformation databases (including those compiled by the authors of this paper), which were composed for the Early Caledonides in the Altai-Sayan folded area and adjacent territories. This makes it possible to characterize mantle-crustal magmatism in suprasubductional and collisional environments and the conditions under which these geodynamic regimes (plate- and plume-tectonic factors) interact. This paper presents estimates of the composition of the parental basic magmas, distinctive features of their differentiation, and the compositional specifics of the accompanying extensive granite-forming processes. The example of the Altai-Sayan folded area and adjacent territories is employed to correlate the composition of the basic-ultrabasic and granitoid magmas and, on this basis, distinguish (a) differentiated gabbro-tonalite-plagiogranite intrusive series corresponding to accretionary-collisional geodynamic environments, and (b) gabbro-monzonite-granosyenite-potassic granite intrusive series, which were produced when the accretionary-collisional system was affected by a plume. |
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