摘要
A number of Triassic (245-195 Ma) alkaline or subalkaline igneous complexes were discovered in theYan-liao area in the northern part of the North China platform. These complexes are all poor in SiO_2; most ofthem are rich in Fe, Mg, K and P and such incompatible elements as Rb, Ba, U and Sr and REE; theinitial ^(87)Sr / ^(86)Sr ratios range from 0.7055 to 0.7057. They might have originated in the altered upper mantle.On that basis coupled with the distribution of the Triassic System and the tectonic deformation, it is suggestedthat there should have existed a tectono-magmatic belt in the area in Triassic time, which is an important mani-festation of the Indosinian movement in the area.
A number of Triassic (245-195 Ma) alkaline or subalkaline igneous complexes were discovered in theYan-liao area in the northern part of the North China platform. These complexes are all poor in SiO_2; most ofthem are rich in Fe, Mg, K and P and such incompatible elements as Rb, Ba, U and Sr and REE; theinitial ^(87)Sr / ^(86)Sr ratios range from 0.7055 to 0.7057. They might have originated in the altered upper mantle.On that basis coupled with the distribution of the Triassic System and the tectonic deformation, it is suggestedthat there should have existed a tectono-magmatic belt in the area in Triassic time, which is an important mani-festation of the Indosinian movement in the area.
