Abstract
Hills, Wyoming, USA. The two main groups of lamproites, madupitic lamproites and phlogopite lamproites, are geochemically distinct and cannot be related to one another by either fractional crystallization or crustal contamination. It seems likely that the geochemical differences between these two rock types are related to variations in source mineralogy and depth of partial melting. The high Mg-number and large ion lithophile element abundances and negative eNd values of the lamproites indicate a mantle source that has experienced stages of both depletion and enrichment. The negative Nb, Ta and Ti anomalies in mantle-normalized trace element diagrams and low time-integrated U/Pb, Rb/Sr and Sm/ Nd ratios of both lamproite groups and other Cenozoic igneous rocks from the Wyoming Archean Province indicate an ancient metasomatic enrichment (>1.0 Ga) of the mantle source associated with the subduction of carbonate-bearing sediments. Other chemical characteristics of the Leucite Hills lamproites, especially their high K2O and volatile contents, are attributed to more recent metasomatism (<100 Ma) involving influx from upwelling mantle during back-arc extension or plume activity.
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.