GEOCHEMISTRY AND PETROLOGY OF PROTEROZOIC AND PHANEROZOIC

RARE-METAL GRANITES

 E. M. Sheremet

Ukrainian State Research and Design Institute of Mining Geology, Rock Mechanics and Mine Surveying, National Academy of Sciences of Ukraine (UkrNIMI, NAS of Ukraine), Donetsk, Ukraine

EvgSheremet@jandex.ru

 

V. I. Kovalenko was the first who described and gave the basic rare-metal definitions, classifications and terms in 1977 [1]. The same year L. V. Tauson suggested independent types of agpaite and plumasite granites [2].

In Pre-Cambrian regions of the Proterozoic tectonomagmatic growing activity the features of plumasite rare-metal granites are inherent to the following intrusive complexes: the Ukrainian Shield – Perzhanian, Leznikowsky, Russko-Polyansky, Kamennomogilsky; the Belarusian crystalline core-area – Zhitkovichsky; the Baltic Shield, Kola Peninsula – Yuvoaivsky complex; southern part of the Baltic Shield – leukogranites of the final phase of the Salminsky massif of rapakivi granites, leukogranites of the final phase of the Laitila massif (Eurajoki stock, Finland).

In the regions of the Phanerozoic tectonomagmatic growing activity all features of the rare-earth granitoids are inherent to the Mesozoic intrusive complexes of the Transbaikalia – Gudzhirsky, Kukulbeisky; Hercynian intrusive complexes of Erzgebirge/Ore Mountains (FRG, Czechia) – Erzgebirge complex: Altenberg, Sadisdorf, Ehrenfriedersdorf, Frauenstein, Teplice rhyolites of Tharander Wald (Czechia).

The origin of the rare-metal granites of Phanerozoic regions is considered from a perspective of plate tectonics. Geodynamic setting of the Mongolia-Okhotsk belt (for the Mesozoic of the Mongolia-Okhotsk belt whereinto Transbaikalia is also included) is similar to the Late Cainozoic geodynamic setting of the North America west with the magmatism area the core of which consists of granite-granodiorite bathylites and circumference is composed by rocks of hyperalkalinity and rare-metal granites [3, 4]. Hercynian province of rare-metal granitoids in Western Europe (Ore Mountains) is located in the zone of calc-alkaline magmatism. For Hercynian magmatic area tectono-magmatic zoning is identified similar to that of Mesozoic of the Mongolia-Okhotsk belt. According to [5], Europe in the Upper Paleozoic (270‑290 million years) was continental margin of Paleothetis with Zavarnitsky-Benioff zone dropping down under the European continent.

Petrogenesis of Proterozoic rare-metal granitoids from a perspective of plate geotectonics was described for the first time by E. B. Glevassky [6] for the Priazovsky megablock of the Ukrainian Shield. According to [3], the magmatism area from the Orekhovo-Pavlogradskaya suture zone (Zavarnitsky-Benioff zone suture) to the Eastern Priazovie (the rear subduction zone) fully corresponds to the Andean magmatism zoning: alkaline-sub-alkaline magmatism and rare-metal granites (kamennomogilsky complex) are within front-end (rear) subduction zone. These conceptions were confirmed by geoelectrical survey [7, 8] that has recorded as the increased conductivity anomalies geotectonic parts of subduction zone: Orekhovo-Pavlogradskaya suture zone in the Central Priazovie (zone of extension as a result of lifting of the secondary diapir fold) and Gruzsko-Elanchik depth faulted zone that limits megablock continental part.

The most part of Proterozoic rare-metal granitoids of East European Platform is related to rapakivi granite formation. The origin of rapakivi formation granitoids is explained mainly by plume tectonics which is based on the conception of mantle diapir lifting in the extension zones confined to the upward convective currents. There is a likeness about it, to a certain extent, between the formation of sub-alkaline-alkaline magmatism and rare-metal granites in subduction zones and formation of rapakivi granitoids due to plume. Generally rare-metal granites are located within the front-end area of sub-alkaline magmatism – for rapakivi plutons and for sub-alkaline-alkaline magmatism within the subduction zone of the Priazovsky megablock of Ukrainian Shield.

A recent exploration of the Priazovsky megablock of Ukrainian Shield [9] reveals that rare-metal granites with rare-metal mineralization take features of granitoids of sub-alkaline-alkaline pluton of the Eastern Priazovie with rare-metal mineralization similar to that of the Azov deposit. Within plutons of rapakivi granite formation rare-metal shows of ore are also known: Korosten pluton – Yastrebetskoe, Davidkovskoe; Korsun-Novomirgorod pluton – Velikoviskovskoe, Khochinskoe and Kornilovskoe. This can argue for formation of rare-metal granites from similar sub-alkaline magmas which generation took place in similar tectonic conditions.

 

References

 

1. Kovalenko V. I. Petrology and geochemistry of rare-metal granitoids. – Novosibirsk: Nauka, 1977. – 208 p.

2. Tauson L. V. Geochemical types and potential ore content of granitoids. – Moscow: Nauka, 1977. – 280 p.

3. Zonenshain L. P., Kuzmin M. I., Moralev V. M. Global tectonics, magmatism and metallogeny. – Moscow: Nauka, 1976. – 231 p.

4. Zonenshain L. P., Kuzmin M. I., Natapov L. M. Lithosphere plate tectonics at the territory of the USSR. – Moscow: Nedra, 1990. – 327 p.

5. Nicolas A. Was the Hercenian orogenic belt of Europe of the Andian type? // Nature. – 1972. – V. 236, No 5344. – Р. 221-223.

6. Glevassky E. B. Geologic-petrological model of the east part of Ukrainian Shield and regularities for location of iron-ore formations: Doctoral thesis (Geol.-Miner.) …. (Geol.-Miner.). – Kiev, 1990. – 199 p.

7. Azarov N. Ya., Antsiferov A. V., Sheremet E. M. et al. Geologic-geoelectrical model of the Orekhovo-Pavlogradskaya suture zone of Ukrainian Shield. – Kiev, Nauk. Dumka, 2005. – 190 p.

8. Sheremet E. M., Kulik S. N., Krivdik S. G. et al. Geologic-geophysical criteria of ore content and metallogeny of subduction areas of Ukrainian Shield. – Donetsk, Knowledge (Donetsk Branch), 2011. – 285 p.

9. Sheremet E. M., Sedova E. V., Strekozov S. N. et al. Petrology, geophysics and ore content of the Priazovie rare-metal granites of Ukrainian Shield. . – Donetsk, Knowledge (Donetsk Branch), 2013. – 285 p. – 225 p.