The osmium isotopic compositions and model age of mantle peridotite xenoliths from Jiangsu-Anhui area and their geological significance.
苏皖地区幔源橄榄岩捕瞄虏体的锇同位素组成、模式年龄及其意义

Cenozoic alkaline basalt contains abundant mantle peridotite xenoliths along the boundary between Jiangsu and Anhui provinces. This paper reports the osmium isotopic compositions of whole rock for the peridotite xenoliths, 187Os/188Os =0.119～0.129, which is mainly characterized as depletion. There is a significant linear correlation between the osmium isotopic compositions and the major element compositions among the samples. The osmium initial ratio (187Os/188Os)0 = 0.109 comes from alumichron, then the relevant model age t=2.5(±0.1)Ga is found from the evolution model of osmium isotopic composition in the convective mantle. The Re depletion age t=1.2Ga, is calculated from the lowest osmium isotopic ratio in the sample set. The longevity of sub-continental lithospheric mantle from osmium isotope systematics in peridotite xenoliths from Jiangsu-Anhui area indicates that they are the fragments of residual mantle after Phanerozoic thinning. The ancient formation age of continental lithospheric mantle is coupling with the age of overlying craton crust.