Re-Os Isotope Geochemistry of Lithospheric Mantle Beneath Northeastern Yangtze Craton: Constraint on the Origin and Evolution of Continental Lithospheric Mantle

The abundances of Re and Os and the isotopic compositions of Os are reported here, for more than 20 samples of mantle peridotite xenolith from Jiangsu-Anhui basaltic province. The concentration ranges of Re and Os are (0.027-0.375)×10 -9 and (0.112-3.35)×10 -9respectively and the Os isotopic composition range is 0.117-0.134. The early melt depletion age of the lithospheric mantle beneath the Northeastern Yangtze Craton is 1.7*!Ga, from the proxy isochron of 187Os/ 188Os vs. Yb. This evidence suggests that the present lithospheric mantle beneath the area is the relic part after the lithosphere thinning in the Post-Middle Proterozoic. The lithospheric mantle has multistage evolution of depletion and enrichment. It also suggests that there may occur a lithosphere mantle replacement in Eastern China during Pre-Middle Proterozoic.