大兴安岭北部岩石圈地幔的时代与增生方式研究

Peridotite xenoliths, especially the garnet-facies xenoliths, hosted in the Cenozoic basalts, are widespread in the Arshan-Chaihe area, northern Great Xing'an Range, NE China. These xenoliths provide essence to probe into the age and characteristics of the deep lithospheric mantle beneath the Xing'an-Mongolian Orogenic Belt (XMOB). Integrated petrological, mineralogical, geochemical, and Sr-Nd-Hf-Os isotopic studies will be applied to the peridotites of both garnet- and spinel- facies, in order to determine the age and nature of the sub-continental lithospheric mantle, as well as the temporal and spatial distribution of the lithospheric mantle and temporal coupling of the crust and mantle. And then, the evolution of the lithosphere and manners of the mantle accretion beneath Great Xing'an Range are discussed based on the comparison with that of the typical orogenic lithosphere worldwide.

在大兴安岭北部阿尔山-柴河地区，大面积分布的新生代玄武岩中携带有大量的幔源橄榄岩包体，特别是兴蒙造山带罕见的石榴石相橄榄岩。这些包体为我们研究兴蒙造山带深部岩石圈地幔的时代及性质提供了重要的物质保障。本项目将以柴河地区石榴石相和尖晶石相橄榄岩包体为研究对象，通过岩石学、矿物学、岩石地球化学及Sr-Nd-Hf-Os同位素研究，确定研究区岩石圈地幔的形成时代及性质，进而限定岩石圈地幔的空间分布和壳-幔年龄耦合关系，并与世界典型造山带的岩石圈结构进行比较，讨论大兴安岭北部岩石圈的演化过程和地幔增生方式。