CAJ | 학술논문

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.
료길지구고원고계함붕암계경과료중고급구역변질화혼합암화작용,주요유흑운모변립암、천립암、전기석변립암,사장각섬암급부미질함광암석조성,국부형성층상혼합화강암.사장각섬암재함붕암계내각개암조중도유분포,암석화학분석현시사장각섬암구유부납,부미、고철、고태특정,MgO함량성다음수치분포,료동지구사장각섬암MgO함량고우집안지구,병차각류사장각섬암중붕함량도교고.료동지구B、Cr、Ni명현고우집안지구,현시위해상지만암장암특정경위명현,집안지구칙현시위변질열액개조특정.료동지구사장각섬암적희토지화현시위열액개조적만원암장특정,집안지구적사장각섬암적희토지화현시위각원침적암특정.함붕암계사장각섬암여천립암희토배분모식상사,표명부분사장각섬암여천립암구유암장성인특정,이전기변립암、흑운변립암여혼합암희토부집모식현시해상침적니암변질성인,혼합암화급변질열액대원암구유명현개조작용.사장각섬암석적지구화학특정표명원암배경위부납、부붕적해상배경,원암주요시해상부미랍반현무암화해상니질암.
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.