Abstract
Several komatiite and komatiitic basalt occurrences have been found in the greenstone successions of the eastern part of the Baltic shield (Soviet Karelia), with both Archaean and Proterozoic ages being represented. Some flows exhibit internal layering with well-developed spinifex textures similar to those described from the classic komatiite provinces of Canada and Australia. Marked differences have been found in the trace-element geochemistry of these rocks. Some Archaean volcanics exhibit flat REE distributions with approximately chondritic ratios of Ca, Ti, Al, Zr, V and Y whereas others show depletion in LREE and Zr. Proterozoic komatiitic basalts differ from the Archaean ones by their relative LREE. Ba and Sr enrichment. These geochemical features are ascribed to an established heterogeneity in the Archaean mantle source and its further development by the Proterozoic. Major- and trace-element variations suggest relative immobility, during metamorphism, of all the analyzed elements except volatiles and alkalis. These trends being adequately explained by olivine with minor chromite fractionation.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
