华北太古宙从地幔柱体制向板块构造体制的转化

ARCHEAN GEOTECTONIC TRANSITION OF SYSTEMS FROM MANTLE PLUME TO PLATE TECTONICS IN NORTH CHINA

通过对原岩建造、变质作用、ｐＴｔ轨迹和εＮｄ（ｔ）值等综合研究，提出迁安和怀安为两个不同时代不同性质的陆壳，遵化和崇礼为两个不同性质的深变质绿岩带，遵化为裂谷型绿岩带而崇礼为岛弧型绿岩带．２．７Ｇａ之前受地幔柱活动的影响，导致了上地幔的不均一性和ＴＨ１和ＴＨ２两类拉斑玄武岩的紧密共存．２．７Ｇａ之后从地幔柱体制向板块体制转化。

On the basis of the comprehensive study of protolith, metamorphism, pTt paths, ε Nd (t) and others, the authors suggest two types of ancient continental crust from Qian'an and Huai'an, different in age and in properties, and two types of high grade greenstone belt from Zunhua and Chongli with respective characters. Zunhua type is a greenstone belt of rift type and Chongli one is a volcanic arc. Before 2.7Ga, the activity of mantle plume led to magmatic source heterogeneity of the upper mantle and intimate association of TH1 and TH2. After 2.7Ga, geotectonic system transforming from plume into plate tectonics led to the crust forming events of island arc type and metamorphism of plate collision type in northwestern of Hebei Province.