辽吉东部层状混合岩的成因

辽吉东部的层状混合岩与上、下围岩始终保持整合接触,反映它的体系基本上是封闭的,没有外来组份的加入。其组构、岩石化学、微量元素和稀土资料等表明层状混合岩不足岩浆型的,而是重熔岩浆型的,其原岩是沉积变质岩。

ON ORIGIN OF THE BEDDED MIGMATITE IN EASTERN PARTS OF LIAONING-JILIN PROVINCES

The stratigraphical position of the bedded migmatites in Kuandian(Liaoning), Ji'an(Jilin)and Jiaodong Groups is stable, indicating unconformable contacts with the upper and lower rock strata of the groups. The bedded migmatite of the Kuandian Group may be divided into two formations, i. e. Laoyinggou formation and Liujiahe formation. The upper formation is composed of bedded amphibole migmatite, leptynite intercalated with the boron-bearing series, and the lower formation is composed of bedded streaky migmatite, amphibole Ieptite migmatite,and plagioclase amphibolite. As to the problem of its origin, there has been different opinions for many eyears. According to our research, we consider the bedded migmatites are anatexis on origin. The textures in streaky amphibole migmatite show oblique bedding, suture line, and metal residue. The mineral components of bedded migmatites in different districts are very similar. The rare element data show that most primary rocks of migmatite are sedimentary on origin, when the primary rocks were affected by high grade metamorphism, they were melted under the anatexitie condition due to the increase of temperature. The distribution pattern of REE of this bedded migmatite is nearly close to that of the country rocks, and some other data of the minerals also indicate that the protolith of the bedded migmatite is graywacke.