滇西北贡山地区基础地质调研的主要进展

Current advances in the geological survey in the Gongshan region,northwestern Yunnan

贡山地区的基础地质取得如下主要进展:①贡山地区的上古生界可划分为7个岩组,分属腾冲分区、保山分区施甸小区、保山分区澜沧小区;②独龙江花岗岩可归并为两个超单元,分属壳幔混源花岗岩和壳源花岗岩,分别形成火山弧和同碰撞环境,岩浆活动时期为晚侏罗世—晚白垩世,是班公湖-东巧-怒江结合带俯冲消减和碰撞造山的物质记录;③贡山地区发现一种与韧性剪切带密切相关,与原岩建造类型、地层层位无明显关系,具多相变质特征,构造背景为碰撞造山的区域动力热流变质作用;④位于高黎贡山主峰的韧性剪切带规模较大,明显地控制了该区上古生界和中生代花岗岩的空间分布,应为一条重要的构造分区断裂,可与区域上的班公湖-东巧-怒江结合带相连接。

Current advances in the geological survey in the Gongshan region, northwestem Yunnan may be generalized as follow. （1） The Upper Palaeozoic strata may be divided into seven formation complexes that are assigned to the Tengchong stratigraphic subprovince, Shidian and Lancang microprovince of the Baoshan stratigraphic subprovince. （2） The Dulongjiang granites may be arranged into two superunits and assigned into the mixed crust-mantle granites and crustderived granites in the volcanic and syn-collision settings, respectively. The magmatism took place during the Late Jurassic to the Late Cretaceous and recorded the subduction, collision and mountain building of the Bangong Lake-Dongqiao- Nujiang suture zone. （3） The regional thermodynamic metamorphism in the Gongshan region has found to be closely relative to the ductile shear zone but irrelative to the prolith types and stratigraphic horizons, and has multiphase metamorphism in the collision and mountain building settings. （4） The large-sized ductile shear zone at the main peak of the Gaoligong Mountains has exercised a major control on the strata and magmatic rocks, which should be associated with the Bangong Lake-Dongqiao-Nujiang suture zone.