辽吉地区含硼岩系中斜长角闪岩地球化学

辽吉地区古元古界含硼岩系经过了中高级区域变质和混合岩化作用，主要由黑云母变粒岩、浅粒岩、电气石变粒岩、斜长角闪岩及富镁质含矿岩石组成，局部形成层状混合花岗岩。斜长角闪岩在含硼岩系内各个岩组中都有分布，岩石化学分析显示斜长角闪岩具有富钠、富镁、高铁、高钛特征，MgO含量成多众数值分布，辽东地区斜长角闪岩MgO含量高于集安地区，并且各类斜长角闪岩中硼含量都较高。辽东地区B、Cr、Ni明显高于集安地区，显示为海相地幔岩浆岩特征更为明显，集安地区则显示为变质热液改造特征。辽东地区斜长角闪岩的稀土地化显示为热液改造的幔源岩浆特征，集安地区的斜长角闪岩的稀土地化显示为壳源沉积岩特征。含硼岩系斜长角闪岩与浅粒岩稀土配分模式相似，表明部分斜长角闪岩与浅粒岩具有岩浆成因特征，而电气变粒岩、黑云变粒岩与混合岩稀土富集模式显示海相沉积泥岩变质成因，混合岩化及变质热液对原岩具有明显改造作用。斜长角闪岩石的地球化学特征表明原岩环境为富钠、富硼的海相环境，原岩主要是海相富镁拉斑玄武岩和海相泥质岩。

GEOCHEMISTY OF PLAGIOCLASE-AMPHIBOLITE OF THE BORON-BEARING ROCK SERIES IN LIAONING AND JILIN PROVINECES AND ITS ORIGIN

The Paleoproterozoic boron-bearing rock series in Liaoning-Jilin provinces, which underwent intermediate and advanced level regional metamorphism and migmatitization, consists mainly of biotite granulitite, leucoleptite, tourmaline granulitite, plagioclase-amphibolite, and Mg-rich ore-bearing rocks. Layered migmatitic granite can be obersered locally. Plagioclase-amphibolite is widely distributed among all the boron-bearing rock series. Geochemistry of plagioclase-amphibolite in this study are studied in detail so as to better understand forming environment of protolith. Lithochemical analysis shows that plagioclase-amphibolite is characteristized by enrichment of Na, Mg and Ti, with MgO abundance especial high. MgO content of plagioclase-amphibolite in the east of Liaoning province is distinctly higher than that in the south of Jilin provinces area; moreover, boron contents in various plagioclase-amphibolite is obviously high. But B, Cr and Ni contents in the east of Liaoning are distinctly higher those in the south of Jili narea,displaying typical features of sea-facies mantle magma; while in the south of Jilin area just shows the features of metamorphic hydrothermal reforming. REE geochemistry of plagioclase-amphibolite in eastern Liaoning province suggests mantle-derived magma, which was then reformed by hydrothermal fluid; whereas that in the south of Jilin shows features of crustal sedimentation. REE distribution pattern of boron-bearing plagioclase-amphibolite is similar to that of leucoleptite, indicating the both may be magmatic in origin. However, REE enrichement patterns of tourmaline granulitite, biotite granulitite and migmatite indicate a metamorphized sea-facies sedimentary rock origin. Migmatitization and metamorphic hydrothermal fluid also have distinct reconstructing effect on the protolith. The geochemistry of plagioclase-amphibolite obviously show that protolith formed under a Na-rich and B-rich sea faices environment and protolith was mainly composed of seafacies Mg-rich tholeiite and seafaices argillite.