Role of deep-seated differentiation in formation of Paleoproterozoic Sinegorie lava plateau of komatiite basalts, southeastern Fennoscandiaстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:A comprehensive geologic, petrologic, and geochemical study was performed for Paleoproterozoic (2.45-2.41 Ga) komatiite basalts in the southeastern part of the Vetreny Belt paleorift (Sinegorie). A representative section of the Sinegorie lava plateau (62 flows) > 3.15 km thick was drawn using an original method. The volume of the erupted mantle material was estimated as at least ten thousands of cubic kilometers only in the studied part of the structure. Modeling of differentiation of komatiite melts using KOMAGMAT software package showed significant role of olivine fractionation in this process. The observed natural variations in chemical compositions of lava flows can be best reproduced at pressure of about 8 kbar (about 25 km). The model of generation and evolution of the calculated primary komatiite melt suggests its differentiation in a supracrustal "plume pillow" of the Early Paleoproterozoic Windy Belt plume. It was responsible for the formation of the Vetreny Belt paleorift with its thick sequence of komatiite basalt lavas and numerous comagmatic intrusive rocks, as well as other mafic-ultramafic intrusions that were emplaced in the paleorift sides, including the Burakovo layered massif, the largest one on the Fennoscandian Shield.