Subalkalic and calc-alcalic Early-Eifelian volcanicity and related pyrite-pollymetallic mineralization in the Magnitogorsk Megazone, the Southern Urals
Until now, there is a problem of the stratigraphic position and the serial petrogenetic affiliation of the Dzhusinsky volcanic complex and the correlation of the section of the Dzhusa-Dombarovka pyrite-palevolcanic belt of the East Magnitogorsk zone (EMZ) with an similar to age section of the Tanalyk paleovolcanic uplift of the Western Magnitogorsk zone (WMZ). The urgency of this problem is justified by the fact that the Early-Eifelian South Irendyk paleovolcanic complex and the Sukrakovo subcomplex, which completes the section of the South Irendyk complex, contain the large Podolsk pyrite deposit of the Urals (Cu > Zn) type and the average barite-polymetallic East-Podolsk deposit (Zn-Cu-Pb-Ba), located in the Sukrakovo subcomplex. In the Djusa ore-bearing zone, average barite-polymetallic deposits (Dzhusinskoye and Barsuchiy Log) localized in the Dzhusinsky complex, according to our data, also is of Early-Eifelian age. The problem of the geological position of the Dzhusinsky pyrite-bearing complex is of great importance for the prognostic assessment of EMZ for pyrite mineralization. The paper is based on materials of geological survey and science studies, in which the authors took part, as well as on published and fund materials of other researchers. Geological and paleovolcanological materials were obtained by the authors in the process of creating a paleovolcanological map of the Southern Urals at a scale of 1 : 500,000 and compiling numerous more detailed maps for individual ore regions and pyrite ore fields at a scale of 1: 100,000 to 1 : 10,000. Samples for chemical analyzes were selected in Process of thematic works. The study of petrogenic, rare and rare-earth elements was carried out by methods of wet chemistry, atomic absorption, X-ray-fluorescent analysis, ICP-MS. The paper gives a brief facial and petrological-geochemical description of the Sukrakovo, Dzhusa and Lower Zingei paleovolcanic complexes and subcomplexes, provides information on the geology and composition of pyrite barite-polymetallic of East Podolsky, Dzhusinsky and Barsuchiy Log deposits and their stratigraphic position on the basis of conodont fauna materials. The Sukrakovo trachydacitic subcomplex (D2ef1ir5), containing the East-Podolsky barite-polymetallic deposit, belongs to the calc-alkaline transition to the shoshonite petrochemical series. The Dzhusa shoshonite-latite-trachyte trachyriolite complex (D2ef1dj), which contains the pyrite-barite polymetallic deposits (Dzhusinsky and Barsuchi Log), is located in the southern part of the East Magnitogorsk zone. In the middle and northern parts of the EMZ there are barren basalt-andesibasaltic Lower-Zingeisky and Irendyksky complexes of calc-alkaline series (D2ef1zg; D2ef1ir). Synchronous Early-Eifelian age of the Irendyksky Formation of the West-Magnitogorsk Zone, the Dzhusa and Lower Zingei Volcanic Complexes of the East-Magnitogorsk Zone, geodynamic reconstructions were established. The upper stratum of the Irendyk Formation WMZ, the Sukrakovo, the Dzhusa and the Lower Zingei (with the Irendyksky) complexes of the EMZ form the rear island arc, which split in the Late-Eifelian time. Dzhusa complex together with age analogs of the EMZ form a residual (split off) island arc
