海南岛抱板群含金岩系原岩时代及其变质事件研究

A research on the age of the protolith and the metamorphic events of the auriferous rocks of Baoban Group in Hainan Island

本文通过对海南岛抱板群含金变质岩系的Sm—Nd等时线、Rb—Sr等时线和铅同位素年龄的系统研究,认为抱板群原岩年龄为14～17亿年,属于早—中元古代地层,并经受了大小不同的五次变质事件:即1100～1341Ma的前地槽褶皱回返期区域变质事件,536.6Ma的地槽局部褶皱回返区域变质事件,263～370Ma的地褶全面褶皱回返期区域混合岩化变质事件,190～224Ma的地洼初动期的断裂动力变质事件,以及87～181Ma的地洼激烈期的岩浆热液蚀变变质事件。

Based on the systematic studies of the Sm-Nd isochronic line,Rb-Sr isochronic line and Pb isotope of the metamorphic auriferous rocks of Baoban Group in Hainan Island, this paper has proposed that the Baoban Group formed in the early-middle Proterozoic Era (1400-l700Ma) and has subjected to at least five metamorphic events. That is, the strong regional metamorphism occured during the period (1100-134lMa) of presynclinal folding} the weak regional metamorphism occured during the period (536.6Ma) of partly synclinal folding) the strong regional metasomatism occured during the wholly synclinal folding(263-370Ma);the fault-dynamic meta morphism occured during the irritial-mobility period (190-224Ma) of diwa deve lopment and; the magmatic-fluid alteration occured during the strong mobility period (87-18lMa) of diwa development.