2011

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Relations of Precambrian endogenous mineralization in the Ukrainian shield with geodynamic settings

Sheremet E.M., Antsiferov A.V.

UkrNIMI, National Academy of Sciences of Ukraine

EvgSheremet@yandex.ru

Western part of Ukrainian shield.

According to [1], its features are the main role plaid by deep faults, which are traced down to the mantle, and terminating magmatism. The probability is that deep faults were transport channels along which heat-carrying fluids and ore components moved. To judge by the basic rocks of gabbro-anorthosite rapakivi-granite korostensky complex, at the terminating stage of the forming of Nemirovsko-Kocherovskaya suture zone the magmatism was deep and therefore more enriched with ore components than typical palingenetic granites (Zhitomirsky complex). Places of titanium-zirconium ore occurrence and tantalum-niobium mineralization incline mainly to deep faults – Vilensky, Tsentralny, Pogrebishchensky, Brusilovsky, Velikoerchikovsky and also to gabbro-anorthosites of the Volodarsky-Valynsky massif of Korostensky complex.

All of deep faults are characterized by manifestations of fault metаsomatosis. It expresses itself in manifestation of quartz-sulfide veins in host rocks, formation of feldspar metasomatites, and occurrence of greysening zones. Variety of mineralizations and occurrences of Ta and Nb, Be, Sn and W are related to feldspar metasomatites, skarning and greysening zones confined to submeridional fault zones – Vilenskaya, Kocherovskaya, Brusilovskaya and Tsentralnaya. Most of Be, Sn and W occurrences are related to skarns and quarts-feldspar metasomatites.

Central part of Ukrainian shield.

Metallogeny of the central part of Ukrainian shield is complex and individual in connection with the complicated history of geological evolution of the region [2]. For ~2.1–2.0 milliard years collision geodynamic settings had been dominating at the shield. In those conditions in Inguletsky block, located between two suture zones ‑ Krivorozhsko-Kremenchugskaya (KKSZ) and Golovanevskaya (GSZ), jaspilite deposits and carbonite-magnetite ores of the Middle Pobuzhie and Ananievskoe iron-ore areas and also rich, basically metamorphic, saksagansky-type ores in KKSZ had been forming. In the same period of basin closure as a result of its crust being intook under the bay limits in its flanks (GSZ) symmetrically located gold-ore deposits Maiskoe in the west, Klintsovskoe and Vostochno-Yurievskoe in the east have been formed. To the terminating stage of basin closure (2.1–2.0 milliard years ago) with Late orogeny ultrametamorphism and magmatism related are fields of spodumene pegmatites of Shpolyansko-Tashlyksky area and uranium deposits of potassium group in pegmatoids both in the west in Pobuzhie (Yuzhnoe, Lozovatskoe, Kalinovskoe) and in the east – in the Zapadno-Inguletskaya region (Chervony Shakhtar). In Inguletsky block to alkaline sodium methsomatosis uranium and gold mineralizations confined to metasomatic albitites in the area of north closure of Novoukrainsky massif parallel to contact of the latter with Korsun-Novomirgorodsky pluton are related. To the earlier (Late Proterosoic) activation attributed are manifestations of kimberlites in bedrocks at the area of Lelikovsky fault (within the lateral Subbotsko-Masharinskaya zone). Structural position of kirovogradskie kimberlite dikes is closely related to tectonic clusters along Lelikovsky fault near Korsun-Novomirgorodsky pluton being the main “breakthrough” channel [3].

Eastern part of Ukrainian shield.

Structure, mineralogical composition and metallogeny of the eastern part of Ukrainian shield are specified by both more ancient (Archaean) events – formation of granite-greenstone areas of the Middle Pridneprovsky and the Priazovsky megablocks [4] and later events which have been overlapped on Proterosoic active continental margin (Priazovsky megablock) connected with the influence of platform sub-alkaline and alkaline magmatism.

In OPSZ, in adjoining to it part of the Middle Pridneprovsky megablock, and in the Western Azov Sea Region widely spread are numerous jaspilite deposits reflecting paleotectonic and paleogeodynamic megablock zoning; deposits of lithium in pegmatites (Balka Krutaya, Shevchenkovskoe) belonging to the zone of lateral magmatic zoning III according to Zonenshain et al. [6]; deposits of high-grade iron ores of saksagansky type (Severo- and Yuzhnobelozerskoe, Pereverzevskoe) and carbonatite-type apatite (Novopoltavskoe); carbonatites (Chernigovskoe deposit) formed in collision setting; highly promising gold mineralization probably of Archaean age in greenstone belts (Gaichurskoe, Gulyaipolskoe, Surozhskoe and others).

In the Central Azov Sea and Eastern Azov Sea Regions to iron deposits (Mariupolskaya group) and gold mineralization in the Tsentralno-Priazovskaya and Maloyanisolskaya fault zones some more graphite deposits are added at the flanks of Mangushsky synclinorium. In the back part of the Priazovsky megablock (Eastern Azov Sea Region) developed are zirconium-rare-earth deposits in intrusives with the area of development of rare-metal granite massifs of Kamennomogilsky complex and Yuzhno-Kalchiksky and Oktyabrsky complexes (with Azov Sea Region rare-earth deposit) succeeding probably zone IV of lateral magmatic zoning [6].

Study of indicator minerals of kimberlites has shown that Eastern Azov Sea Region is potentially diamond-bearing [5]. The upper mantle within its limits is composed mainly of pyrope and chrome-spinel-pyrope lherzolites. In its lower part (down to the depth of more than 140 km) available are harzburgites and presumably cataclastic lherzolites and in the uppermost part of the section – eclogites and pyroxenites. Rocks of the upper mantle underwent considerable methasomatosis in Devonian.

Taken as a whole, geological position of the abovementioned deposits of the latter region is specified presumably by the Tsentralno-Priazovskay stretching zone which has formed at the active continental margin of the Andes type and has closed possibly at the collision stage. From paleogeodynamic standpoint the Central Azov Sea Region corresponds to typical for the Andes tectonotype active continental margin stretching area that divides zones of limestone-alkaline and alkaline magmatism.

References:

1. Antsiferov A.V., Sheremet E.M., Yesipchuk K.Ye. et al. Geologic-geophysical model of the Nemirovsko-Kocherovskaya suture zone of Ukrainian Shield. Donetsk, Veber, 2009, 253 p. (In Russian).

2. Azarov N.Ya., Antsiferov A.V., Sheremet E.M. et al. Geologic-geophysical model of the Krivorozhsko-Kremenchugskaya suture zone of Ukrainian Shield. Kiev, Naukova dumka, 2006, 196 p. (In Russian).

3. Azarov N.Ya., Antsiferov A.V., Sheremet E.M. et al. Geologic-geophysical model of the Orekhovo-Pavlogradskaya suture zone of Ukrainian Shield. Kiev, Naukova dumka, 2005, 190 p. (In Russian).

4. Kalashnik A.A., Moskalenko G.M. Geologic-structural features of space placement of kimberlite occurrence and uranium-ore objects in Kirivogradsky ore area of Ukrainian Shield. In: Mineralnye resursy Ukrainy (Mineral Resources of Ukraine), no. 2, 2010, p. 8-18. (In Russian).

5. Geiko Yu.V., Gursky D.S., Lykov L.I. et al. Ptospects of diamond presence in bedrocks. Kiev, Tsentr Evropy, 2006, 223 p. (In Russian).

6. Zonenshain L.P., Kuzmin M.I., Moralev V.M. Global tectonics, magmatism and metallogeny. Moscow, Nedra, 1976, 231 p. (In Russian).