METASOMATIC ZONING OF SUBCRATONIC LITHOSPHERE IN SIBERIA: PHYSICOCHEMICAL MODELING
V.N. Sharapova,b, K.V. Chudnenko c , M.P. Mazurov a,b , Yu.V. Perepechko b
a Novosibirsk State University, 2 ul. Pirogova, Novosibirsk, 630090, Russia
b Sobolev Institute of Geology and Mineralogy, Siberian Branch of the RAS, 3 prosp. Akad. Koptyuga, Novosibirsk, 630090, Russia
c Institute of Geochemistry, Siberian Branch of the RAS, 1a ul. Favorskogo, Irkutsk, 664033, Russia
Keywords: Physicochemical modeling, continental lithosphere, metasomatism, melting
Pages: 1107-1118
Abstract
Nonisothermal equilibrium physicochemical dynamics has been numerically modeled to estimate the effect of reduced asthenosphere fluids on continental lithosphere profiles beneath the Siberian Platform (SP). When the over-asthenosphere continental mantle is metasomatically changed by reduced magmatic fluids, the following sequence of zones forms: (1) zone where initial rocks are intensively sublimated and depleted by most petrogenic components; the restite in this case becomes carbonated, salinated, and graphitized; (2) zone of Si and Fe enrichment and carbon deposition in initial rocks depleted in Na, K, P, Mn; (3) zone of diamond-bearing lherzolites enriched with Na; (4) zone of hydrated rocks enriched with K; (5) zone of hydrated rocks not enriched with petrogenic components. Zone 1 can be responsible for the formation of kimberlite melts, zones 3 and 4 can be substrates of alkaline magma melting, and zone 5 can be the source of mafic tholeiitic magma.
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