Geology and ore deposits of the Urals

Abstract

The Urals is a N-S trending mountain range forming thegeographic boundary between Europe and Asia. It repre-sents a 2000 km long Paleozoic orogen, extending from theIslands of Novaya Zemlya in the north to the Aral Sea in thesouth. For a long time the information about Uralian geol-ogy was very scarce in the international literature. A signif-icant breakthrough took place at the end of 20th centurywhen the EUROPROBE and GEODE international projectsstarted. In the frame of these projects, several seismic crosssections trough the Urals, together with detailed geologicalinvestigations, were carried out. The main results of thesestudies were published in a special Issue of Tectonophysics(1997) and in the Geophysical Monograph 132 “MountainBuilding in the Uralides: Pangea to the Present” publishedby American Geophysical Union (AGU) in 2002 and innumerous other papers. In the last decade a lot of newmineralogical, petrological and geochemical data, particu-larly in isotope geochemistry andgeochronology,weregath-ered. These new data represents the base for the need for afurther look onto Uralian geology. This special issue ofMineralogy & Petrology contains a profound collections ofnew data, interpretations and discussional aspects on Urali-an geology since 2002.The Urals belongs to the western flank of the hugetranscontinental Uralo-Mongolian fold belt and comprisesat least three billion years of geological history. Today wecan distinguish between five major structural levels andepochs of the Urals development (see Puchkov 2013). Theearliest Archean and later Meso-Neoproterozoic complexes,although related to the development of the Baltic craton andits eastern periphery, far before the Uralides existed, areincorporated in the Uralian orogen structure and sometimesthey display traces of young Paleozoic events of the foldbelt. The Archean rocks are represented by granulites of theTaratash complex, showing similarities to the granulites inthe basement of the East-European platform. The Meso-Neoproterozoic sedimentary and magmatic complexes wit-ness the geotectonic development along the eastern marginof the Baltic Shield. This time was very productive regard-ing the formation of some important mineral deposits, suchas siderite and magnesite within metasedimentary sequences(Prochaska and Krupenin 2012) and titano-magnetite oreassociated with rift-related layered gabbro intrusions andothers.The Paleozoic–Lower Jurassic period of time may beconsidered as the main stage of the development of theUralides, covering a complete Wilson cycle: starting fromthe rifting of the Baltic continent after the Timanian oroge-ny, through formation of an oceanic basin, a passive conti-nental margin and microcontinental blocks, to subduction,accompanied by a significant amount of volcanic eruptions,then arc-continent collision, continent–continent collisionwith granite magmatism, formation of a long chain of bath-oliths, and finally post-collisional extension with flood-basalt magmatism. The most important and famous volca-nic, intrusive, metamorphic and sedimentary complexes andrelated deposits in the Urals were formed during this periodof time. The world-class podiform chromite deposits relatedto the Kempirsay ophiolite complex in the Southern Uralswere formed during oceanic-island arc development. Thegiant Gay, Sibay and Uchaly volcanic massive sulfidedeposits and many numerous small ones are located withinthe Devonian island-arc volcanics of the Magnitogorsk zone