Abstract
This study presents comparison of distribution and composition of Neoarchean sanukitoid massifs from Karelian (Fennoscandian Shield) and Bundelkhand (Indian Shield) Cratons. It has been established, that sanukitoid massifs from both the studied cratons are localised in linear zones, which orientation is close to the greenstone belts. Neoarchean (2.56-2.53 Ga) sanukitoids from Bundelkhand are geochemically similar to those from Central and Western Karelian zones (2.72-2.68 Ga; Karelian Craton) while they are less differentiated as compared to the sanukitoids fromEastern Karelia(2.74-2.73 Ga). The geochemical similarities in sanukitoids from both these cratons along with their association with similar age volcanics and localised in linear zones indicate that subduction related processes were responsible for their formation in both Karelian as well as Bundelkhand craton.
Highlights
Sanukitoids (High Mg, Ba, Sr diorites-granodiorites-monzogranites) are typical Archean rocks as are komatiites, tonalite-tondhjemite-granodiorites (TTGs), and Banded Iron Formations (BIFs)
We 1) compare the petrology, geochemistry and distribution of Neoarchean sanukitoids from the Karelian (Fennoscandian Shield) and Bundelkhand (Indian Shield) Cratons; 2) try to establish a time-space relationship between sanukitoid massifs and volcanogenic complexes; and further 3) synthesize the data obtained to understand the geodynamic processes that were operative for the formation of sanukitoids
Cr-enriched) varieties that occur below BIF соntain numerous igneous zircons from granitoids of Paleoarchean (3.43 and 3.25 Ga) age and display a similar Sm-Nd model age [Slabunov et al, 2017а], indicating that they were formed by recycling Paleoarchean granitoids and Mesoarchean mafic-ultramafic rocks in the period 2.8–2.7 Ga
Summary
Sanukitoids (High Mg, Ba, Sr diorites-granodiorites-monzogranites) are typical Archean rocks as are komatiites, tonalite-tondhjemite-granodiorites (TTGs), and Banded Iron Formations (BIFs). They are sodic, rich in silica often have high LaN/YbN abundances and moderate to high Sr/Y at low Y abundances [Hoffmann et al, 2011; Condie, 2014] The origin of these rocks has been widely debated with models ranging from subducting hydrous basaltic slab [Arth and Hanson, 1972; Martin and Moyen, 2002 and references therein; Foley et al, 2002; Laurie and Stevens, 2012] to an over thickened mafic crust [Hoffman et al, 2011] as a source in plume related plateau basalt [Condie, 2005, 2014; Foley, 2008; Smithies et al, 2009; Willbold et al, 2009] or within tectonically thickened island arc crust [Adam et al, 2012; Nagel et al, 2012; Hoffmann et al, 2014], while some propose a role of intracrustal differentiation which later evolved by crystal fractionation of primitive andesitic melt [Kelemen et al, 2014]. We 1) compare the petrology, geochemistry and distribution of Neoarchean sanukitoids from the Karelian (Fennoscandian Shield) and Bundelkhand (Indian Shield) Cratons; 2) try to establish a time-space relationship between sanukitoid massifs and volcanogenic complexes; and further 3) synthesize the data obtained to understand the geodynamic processes that were operative for the formation of sanukitoids
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