Geochemical signatures for eclogite protolith from the Maksyutov Complex, South Urals |
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| Authors: | N I Volkova A E Frenkel V I Budanov G G Lepezin |
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| Institution: | Institute of Mineralogy and Petrography, Russian Academy of Sciences, Pr. Koptyuga, 3, Novosibirsk 630090, Russia |
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| Abstract: | We conducted a geochemical study of eclogites (40 samples) from a boudin of the Lower Unit of the Maksyutov Complex in the South Urals in order to determine their protolith nature. The eclogites have major element compositions corresponding to quartz-bearing hypersthene basalts. Trace-element characteristics of the eclogites further suggest that they resemble enriched-type of tholeiites such as E-MORB. The compositional variation of eclogites was likely caused by fractional crystallization of parental melt under hypabyssal conditions, during its intrusion in thinned continental crust shortly before subduction. The high-pressure metamorphism has not affected significantly the major- and trace-element signatures of the protoliths. The compositions of co-existing minerals from the distinguished rock groups do not show significant distinctions. The considerable scatter of P–T estimates of metamorphic conditions does not depend on whole-rock composition. Therefore, the eclogitization was preceded by a chemical differentiation of an initial magmatic source, which is responsible for co-existence of rocks of variable composition in the same boudin. Dikes or sills of tholeiite basalts having geochemical characteristics of E-MORB could be the protoliths for the Maksyutov eclogites. |
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| Keywords: | Eclogite Prodith Maksyutov Complex |
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