变质作用地质速率计和热年代学的研究

Studies on intra-crystalline composition of garnet show that the development of diffusion zoning,styles of its istribution and characteristics of compositional profile are closely and regularly related to its grain size,species of minerals in contact,content of biotite in rocks,as well as the saturation of rocks by metamorphic fluids. Most garnet and iotite can maintained their equilibriun mposition of metamorphic peak stage,and can be used as geothermometer to.yield peak temperature.Introduced and refined the way to use diffusion zoning of garnet as geospeedometry. According to geological and metamorphic features of the Jining Group of inner Mongolia and the Jingshan Group in Jiaodong,the.suitable thermodynamic parameters are estabilished.Then the cooling rate of.rocks in these two regions in post-peak stage were determined by plotting the.compositional profile on a modeling diagram and their values also be estimaled by a special equation advanced by Lindstrons et al.The cooling rate of the Jining Group is 0.3-1℃/Ma,while that of the Jingshan Group is 4.5℃/Ma,they reflect the different geodynamic proccess in the two regions. Above results have.important scientific sense,as they can promote to deal with geodynamics by micro-area composition of minerals,such as garnet.

通过微细矿物包体研究查明石榴石和锆石晶体在变质作用过程的生长和改造史。测定石榴石各种成因的成分剖面，应用Rayleigh模式和Fick定律为基础的计算程序确定变质事件增温和冷却速率。进行石榴石和锆石微区U-Pb和Sm-Nd及角闪石、云母和钾长石40Ar/39Ar定年与封闭温度相结合的热年代学研究。构筑变质作用PTA（年龄）图式，探讨构造环境。