Dike complexes in ophiolites of the Urals

Abstract

The structure of dike complexes and their relationships with country rocks are considered for ophiolitic sections of the Polar and the Southern Urals. It has been established that composition of country rocks intruded by dikes is related to geodynamic settings of spreading. The Ordovician dike complexes of the Polar Urals and the Early Devonian complexes in the Southern Urals formed in the prearc setting contain screens of mantle, lower crustal, and upper crustal rocks pertaining to the ophiolitic section. The Late Sil urian-Early Devonian complex of dikes and volcanic rocks in the Aktau-Tanalyk Zone of the Southern Urals was formed in the course of rifting in an island arc structure. Rocks intruded by dikes are represented by island arc gabbro, plagiogranite, and calc alkaline volcanics. The Early-Middle Devonian dike complex of the West Mugodzhary Zone and the Early Devonian complex of the Dombarovsky Zone in the Southern Urals were formed in spreading zones of backarc basins, where dikes intruded the upper crustal gabbro and volcanic rocks.