Abstract
At Parys Mountain, Snowdonia and Avoca, bimodal associations of Upper Ordovician basalt and rhyolite with a submarine origin occur within the Caledonian orogenic belt. The rocks have undergone hydrothermal alteration and low-grade metamorphism. The basalts are transitional between volcanic arc and within-plate types; one group of rhyolites (low Zr) is originally of high-K, subalkaline type, the other (high Zr) originally peralkaline. The evidence suggests magma production in a complex tectonic setting, transitional between an active continental margin/island arc and an extensional environment. Associated sulphide mineralization is volcanogenic and probably synsedimentary, the convecting fluids probably driven by high-level rhyolitic magma chambers.-R.E.S.
Original language | English |
---|---|
Pages (from-to) | 259-273 |
Number of pages | 15 |
Journal | Journal of the Geological Society |
Volume | 143 |
Issue number | 2 |
Publication status | Published - 1986 |