西藏墨竹工卡县门巴地区松多岩群变质作用特征及时代讨论

Metamorphism Characteristics of Songduo Group in Menba Township Mozhugongka County, Tibet and the Discussion on Its Age

西藏墨竹工卡县门巴地区松多岩群经历了3期变质变形作用,主期变质作用的温度为500～553℃,压力为0.93～1.15 GPa,属中低温、中高压区域动力热流变质作用,相似于板块碰撞带变质作用的特征.同位素定年资料表明,松多岩群主期变质为加里东期变质作用的产物.阳起片岩1 516 Ma的Sm-Nd表面年龄可能反映了松多岩群的原岩年龄.

Songduo Group in Mozhugongka County, Tibet had undergone deformation and metamorphism for three times. The main metamorphism （500-553℃, 0.93-1.15 GPa） belongs to middle-low temperature and middle-high pressure dynamo-thermal metamorphism, and is similar to the metamorphism formed in a plate collision zone. Isotope ages indicate that the Songduo Group is the product of metamorphism in Caledonian. The appearance Sm- Nd age（1 516 Ma） of actinote schist may imply the original rocks of Songduo Group formed in middle proterozoic era.