Ordovician gabbro-tonalite-trondhjemite complex and associated volcanic rocks in the paleozoic suture between Urals and Kazakhstan

Abstract

This paper reports new data on the Early Ordovician age established for granitoids of the gabbro-tonalite-trond- hjemite complex in the Denisovka ophiolite zone (suture) on the boundary between the Paleozoic structures (Paleozoides) of the Urals and Kazakhstan. The ages of 482.6 ± 3.6 Ma and 486.2 ± 6.7 Ma were established by the U/Pb method (SHRIMP II) on the age data for zircon extracted from granitoids. The plutonic complex associates with the Early-Middle Ordovician effusive complex, composed of a series of rocks differentiated from basalts to rhyolites. The volcano-plutonic association was formed in the supra-subduction settings, as is evidenced by the composition of the rocks.