THE PROCESS OF THE FORMATION AND EVOLUTION OF THE JILIN METEORITE

On the basis of the data from a multi disciplinary integrated study of the Jilin meteorite,we have made a discussion on the formation and evolution of it involving the following aspects: (1) the fractionation-eondensation of the solar nebula,based on the condensation conglomeration age and the mineral association of the Jilin meteorite; (2) the thermoametamorphic history of the Jilin parent body,based on the data on the loss of rare gases,the chemical composition of the whole rock,the self-purification of BEEand the compositional stability of olivine and orthopyroxene; (3) the cowling process of the Jilin parent body,in reference to the Ni content and range of taenite as well as to the retention of argon and fission tracks in the minerals: (4) the breakup of the Jilin parent body and its cosmic ray irradiation history.Based on the measurements of the cosmogenic nuclides as He³,Ne^20,21,22,Ar³⁸,Na²²,Al²⁶,Mn⁵⁴,Mn⁵³,Co⁶⁰ etc,a tw,o-stage model of irradiation history of the Jilin meteorite has been proposed.From the data on the Jilin parent body of the first stage (the age=10-11 my and r=10m) and that of the second stage (the age=0.3-0.5 my and r=80-90cm),we have defined the relative positions of the samples in the parent body,and their burial depths as well as the post-atmospheric loss on ignition,respectively; (5) the falling process of the Jilin meteorite,the orbits of the Jilin meteor in the solar system and in the atmosphere,and its falling process have been discussed.