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
Subsection: PETROLOGY AND DYNAMICS OF LITHOSPHERE
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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