藏东地区新生代构造体系与成矿的关系

摘要

The research on the tectonics and the structures shows that the tectonic stress field of eastern Tibet varied from NE-SW compression to NNE-SSW compreso-shearing,which finds expression in four respects:①the foramation of a large scale dextral strike-shearing system along the east and west sides of Changdu block as well as the preexistent large deep-faults,and the development of intensive cataclasis,stretching lineations and theca-folds;②the superimposition of a series of echelon sub-folds and sub-shear faults on both sides of the strike-slip faults;③the formation of a series of echelon stike-slip basins;④the regular distribution of Cenozoic magmatism along both sides of the strike-slip faults.The Cenozoic tectonic regime transformation resulted in a large scale translation and enrichment of ore-bearing fluids,which made Cenozoic an important mineralization period.The northern part of Lancangjiang fault,Tuoba fault,Wenquan fault and the northern part of Chesuoxiang fault were all favorable areas for ore enrichment in this period.%区域构造和微构造分析表明，新生代藏东地区构造应力场自印支-燕山期的NE—SW向挤压向喜马拉雅山期的NNE-SSW向压扭性转变，表现在：①沿昌都地块两侧及古生代—中生代形成的深大断裂带发生了大规模的右旋走滑活动，伴生较强的碎裂岩化、拉伸线理和剑鞘褶皱等，沿主断裂两侧叠加一系列NW、NNW及NE向雁行式排列的褶皱和张扭性断裂；②在区域上，沿大规模右旋走滑断裂两侧形成一系列雁行式排列的第三系走滑拉分盆地；③新生代岩浆活动沿走滑断裂两侧的张扭性次级断裂有规律分布。新生代构造体制的转变造成大规模成矿流体的运移与富集，使新生代成为本区最重要的成矿时期，而北澜沧江、妥坝、温泉断裂带及车所乡断裂带北段是该期矿产最有利的富集部位。