桂北新元古代两类过铝花岗岩的地球化学研究

广西北部新元古代花岗岩类岩石包括黑云母花岗闪长岩和黑云母花岗岩。地球化学特征表明，黑云母花岗闪长岩与含堇青石的过铝花岗岩（CPG）相当，而黑云母花岗岩则类似于白云母二长花岗岩（MPG）。黑云母花岗岩类是成熟地宙岩石部分熔融作用的产物，而黑云母花岗闪长岩类的形成与地幔柱起源的镁铁质岩浆和地壳起源的过铝质黑云母花岗岩浆之间的混合作用有关。这两类新元古代过铝花岗岩的形成与碰撞造山导致地壳加厚的挤压性构造无关，而与导致Rodinia超大陆裂解的地幔柱上升诱发岩石圈伸展的张性构造相联系。

Geochemical studies on two types of Neoproterozoic peraluminous granitoids in northern Guangxi

The Neoproterozoic granitoids in northern Guangxi consist of biotite granodiorite and biotite granitoids. The geochemical characteristics indicate that biotite granodiorite is equivalent to cordierite- bearing peraluminous granitoids (CPG), while biotite granitoids are similar to muscovite- monzonitic granite (MPG). Biotite granitoids are the result of partial melting of mature crust, and the formation of biotite granodiorites are related to the mixing of mantle plume- derived mafic magma and crustal- derived peraluminous biotite granitic magma. The formation of these two types of Neoproterozoic peraluminous granitoids is irrelevant to the compressional structures caused by collisional orogney which led to crustal thickening, but relevant to extensional structures caused by the ascent of mantle plume which led to the breakup of Rodinia supercontinent.