桐柏─大别地区花岗质片麻岩系地质─地球化学特征

GEOLOGY AND GEOCHEMISTRY OF THE GRANITIC GNEISSES IN TONGBAI-DABIE AREA

桐柏－大别地区，桐柏杂岩和大别杂岩内广泛分布的花岗质片麻岩系是早元古代大别造山阶段的产物。整体显示由高铝型向低铝型和钠质向钾质花岗岩演化规律，构成连续的钙碱性演化系列。其稀土配分类型与岩石的碱质组分（钾钠比值）有关。笔者认为，该区花岗质片麻岩系与ＴＴＧ岩系有明显不同，属大陆成因的Ｉ型花岗岩系列。

The granitic gneisses in Tongbai and Dabie complexes resulted from the Early Proterozoic orogenesis. On the whole, they transited from high -Al to low-Al, from Na-granite to K -granite, which comprises the continuous cafe -alkaline series with the REE distribution pattern related to alkaline compositions (ratio of K/Na). The authors suggest that these granitic gneisses, being obviously different from TTG, is I -type granitic series whose genesis is connected with continental crust.