Ancient volcanic glasses of the Urals |
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| Authors: | V G Korinevskii |
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| Institution: | 1.Institute of Mineralogy, Ural Branch,Russian Academy of Sciences,Miass, Chelyabinsk Oblast,Russia |
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| Abstract: | The existing data on findings of unaltered volcanic glasses in the Paleozoic (from Late Ordovician to Late Devonian inclusive)
volcanic strata of the Ural fold belt are systematized. These glasses have compositions that correspond to tholeiitic basalts,
potassic alkaline basaltoids, andesites, and rhyolites. Relic portions of glasses of cenotypal appearance are preserved in
thick glassy crusts of pillow lava flows, in fragments among hyaloclastites, in bombs from tuffs, and in extrusive bodies
and dykes. Chemical analysis showed that the amount of dissolved water was low (1–1.3 wt %) in the primary tholeiitic magma
and higher (8–10 wt %) in the magma that formed island-arc hyalobasalts, potassic alkaline basaltoids, andesites and rhyolites. |
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