Abstract
Geochronological data (∼1800 dates) have been analyzed by the probabilistic statistical analysis of samplings of different subalkaline and alkaline rocks through the whole of geological time. The distribution of five groups of subalkaline and alkaline rocks within the Late Archean-Phanerozoic are strictly controlled by mantle cycles, which were distinguished from data on the upper mantle magmatic rocks. Since high alkali rocks are plume related, their universal participation in each of the revealed mantle cycles emphasizes the importance of this magmatism in the evolution of the crustal-mantle system. The initial Sr and Nd isotope ratios are subdivided into two groups: with mantle and crustal signatures. Mantle isotope ratios are typically observed throughout the entire geological interval of dated rocks, while the role of crustal isotope signatures increases from the Archean to Phanerozoic, reflecting the increasing the role of fluids and crustal rocks in the magmatic processes during the generation of mantle magmas and their consolidation in the crust. Since alkaline magmatic sources are formed during mantle metasomatism, which enriched the magma generation zones in incompatible elements, the repeated occurrence of this process in separate mantle zones may have lead to the anomalous accumulation of these elements, which should be reflected in the alkaline magmas.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: 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.