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A Geological and Petrological Study on Plutonic and Metamorphic Rocks in the Southern Abukuma Mountains

阿武隈山脉南部深成岩和变质岩的地质和岩石学研究

基本信息

批准号：
01540649
负责人：
TANAKA Hisao
金额：
$ 1.41万
依托单位：
Yamagata University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1991
项目状态：
已结题

项目摘要

Plutonic and metamorphic rocks in the Abukuma mountains were studied. schistose tonalite, granodioritic rocks and Takanuki metamorphic rocks are distributed in the Samegawa to Hanawa area. These rocks distributing near the Tanakura tectionic line show cataclastic features, such as granulation, elongation and wavy extinction of quartz, bent cleavace and wavy extinction of plagioclase, and kink band and wavy extinction of biotite. The more close to the Tanakura tectionic line, the more intense the cataclastic features are, suggesting that the tectionic line has been active since about 100 ma ago. Partial melting of amphibolite and formation of gabbroic to trondhjemitic veins are observed in the Aakanuki amphibolite in an contact aureole of a dioritic pluton. the host amphibolite is composed of fine grain hornblende + plagioclase (An 70-80) + ilmenite and poor in SiO_2 (-45%), Na_2O and K_2O the veins continuously change their texture, Mineralogy and chemistry from a gabbroic part (SiO_2-45%) to dioritic, and finally to tonalitic or trondhjemitic (SiO_2-70%) Parts.Granitic rocks in the uzumine area, one of pegmatite-producing spots in the central Abukuma mountains are described. the younger porphyritic two-mica granitic rocks which are considered to be intimately related with pegmatite containing rare element minerals, such as euxenite, monazite and xenotime are the highest in SiO_2 content and exhibit s-type like petrological features.

对阿武熊山的深成岩和变质岩进行了研究。在Samegawa到Hanawa地区分布着片状英云闪长岩、花岗闪长岩和高贯变质岩。这些岩石分布在田仓构造线附近，具有石英粒化、拉长、波状消光、斜长石弯劈理、波状消光、黑云母扭折带、波状消光等碎裂特征。越靠近田仓构造线，碎裂活动特征越强烈，表明该构造线自约100 Ma以来一直处于活动状态。在闪长质岩体接触晕中的Aakanuki斜长角闪岩中观察到斜长角闪岩的部分熔融和辉长岩到奥长花岗岩脉的形成。寄主角闪岩由细粒角闪石+斜长石组成（70-80）+钛铁矿，贫SiO_2（-45%，Na_2O和K_2O），脉体结构、矿物学和化学性质从辉长岩部分开始不断变化（SiO_2-45%）到闪长质，最后到英云闪长质或奥长质（SiO_2-70%）部分.描述了阿武熊山脉中部伟晶岩产地之一的宇津峰地区的花岗岩。较年轻的斑状二云母花岗质岩石SiO_2含量最高，具有类S型岩石学特征，与伟晶岩关系密切，含稀土矿物如辉石岩、独居石和磷钇矿。