LARGE FIELDS OF SPODUMENE PEGMATITES IN THE SETTINGS OF RIFTING AND POSTCOLLISIONAL SHEAR–PULL–APART DISLOCATIONS OF CONTINENTAL LITHOSPHERE
V.E. Zagorsky1, A.G. Vladimirov2,3,4, V.M. Makagon1, L.G. Kuznetsova1, S.Z. Smirnov2,3,4, B.A. D’yachkov5,6, I.Yu. Annikova2,4, S.P. Shokal’sky7, A.N. Uvarov8
1A.P. Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, ul. Favorskogo 1a, Irkutsk, 664033, Russia
2V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
3Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia
4Tomsk State University, pr. Lenina 36, Tomsk, 634050, Russia
5Altai Geological and Ecological Institute, named after K.I. Satpaev, ul. Karla Libknekhta 21, Ust’-Kamenogorsk, 692024, Kazakhstan
6East Kazakhstan State Technical University, ul. Serikbaeva 19, Ust’-Kamenogorsk, 070010, Kazakhstan
7A.P. Karpinsky Russian Geological Research Institute, Srednii pr. 74, St. Petersburg, 199106, Russia
8Zapsibgeols”emka, ul. Shkol’naya 5, Elan’ Village, Novokuznetsk district, Kemerovo Region, 654219, Russia
Keywords: Lithium, spodumene, pegmatites, granite-pegmatite systems, geochronology, collision, rifting, Central Asian Fold Belt
Abstract
The authors analyze the geodynamic settings of large fields of spodumene pegmatites hosting Li and complex (Li, Cs, Ta, Be, and Sn) deposits of rare metals within the Central Asian Fold Belt. Most of the studied fields show a considerable time gap (from few tens of Myr to hundreds of Myr) between the spodumene pegmatites and the associated granites, which are usually considered parental. This evidence necessitates recognition of an independent pegmatite stage in the magmatic history of some pegmatite-bearing structures in Central Asia. The Precambrian-Late Mesozoic interval is marked by a close relationship between the large fields of spodumene pegmatites and extension settings of continental lithosphere. They occur either as (1) zones of long-lived deep faults bordering on trough (rift) structures experiencing the tectonic-magmatic activity or as (2) postcollisional zones of shearing and pull-apart dislocations. Thus, large fields of spodumene pegmatites might serve as indicators of continental-lithosphere extension. Important factors favoring the formation of rare-metal pegmatites both in collision zones and continental-rift settings are the presence of thick mature crust dissected by long-lived, deeply penetrating (down to the upper mantle) fault zones. They ease the effect of deep sources of energy and substance on crustal chambers of granite and pegmatite formation.
DOI: http://dx.doi.org/10.1016/j.rgg.2014.01.008
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