Dated isotopic ages for 15 alkaline intrusives in the Yanliao-Yinshan area, ranging from 268 to 190 Ma, ten of which are from 250 to 208 Ma, indicate that most of them were formed in the Triassic Epoch. All the εNd(t) ratios from - 17.19 to -3.21 averaging -7.09, the εSr(t) ratios from 11.7 to 71.5 averaging 36.63, and the ISr(t) ratios from 0.705 0 to 0.709 3 averaging 0.706 8, show their characteristics of enrichment. On the εNd (t) virus εSr (t) correlation diagram, the samples from these intrusives were plotted within the enriched mantle trend lines and just outside, demonstrating their close connection to materials from the enriched mantle reservoir, taking into account the same Pb isotopic composition as that of the mantle.
