Evolution of continental crust and upper mantle during the formation of Gondwana supercontinent: deduced from magma processes

本文研究了东南极Sor Ronaldo山脉冈瓦纳超大陆形成过程中的下地壳和上地幔演化。根据现场关系和部分侵入岩锆石U-Pb年龄，将岩浆活动划分为3个阶段：第1阶段1000~950 Ma，第2阶段800 Ma和第3阶段600~500 Ma。第1、2阶段为碰撞前岩浆活动，第3阶段为碰撞后岩浆活动。岩石学和地球化学特征表明，碰撞后岩浆活动以高钾玄武质岩浆为特征。岩浆活动的发生可能是由于大陆碰撞过程中相对亏损的地幔与上陆壳相互作用而形成的交代地幔部分熔融的结果。

We studied here on the evolution of lower crust and upper mantle during the formation of Gondwana supercontinent from the Sor Rondane Mountains, East Antarctica. Based on field relationships and zircon U-Pb dating for some intrusive rocks, the magma activities can be classified into the following three stages, Stage 1; 1000~950 Ma, Stage 2; ~800 Ma and Stage 3; 600~500 Ma. Stages 1, 2 are regarded as pre-collisional magmatism, while Stage 3 represents the post-collisional magma activity. Taking petrography and geochemistry into account, the post-collisional igneous activity is characterized by high-K basaltic magma. The significant magmatism can be resulted from the partial melting of metasomatized mantle that has been interaction between relatively depleted mantle and upper continental crust deduced from continental collision.