北祁连山车路沟英安斑岩的年代学及地质意义

Chronology and Geological Significance of Chelugou Dacite Porphyry in North Qilian Mountains

车路沟英安斑岩产于北祁连山西段, 由大小不同的12个斑岩岩体组成,属于钙碱性系列岩石.利用锆石U-Pb法测得车路沟英安斑岩的形成年龄为(427.7±4.5) Ma,成岩时代属加里东晚期.从区域构造演化看,北祁连山西段大部分花岗质岩体的形成都与祁连山造山作用中的俯冲造山作用和碰撞造山作用有关,表现为多数同位素年龄都集中在440～380 Ma间.鉴于车路沟金矿床产于车路沟英安斑岩与凝灰岩的接触带,属于石英脉型,因此推断英安斑岩侵入体很可能是车路沟金矿床早期成矿作用的热源.同时北祁连山西段发育有较多的中酸性岩体,车路沟石英脉型金矿床的确定对于该区金矿的进一步勘探具有重要的理论和现实意义.

Located in the western part of North Qilian Mountains and composed of 12 small intrusions,Chelugou dacite porphyry shows petrochemically to be calialkelinic series. Its diagenetic age is about（427.7±4.5） Ma measured by U-Pb dating method. Most of the granitic intrusions in the western part of Qilian Mountains are closely related to subductive and collisional orogeny, intruded during 440-380 Ma. The occurrence of Chelugou gold, a quartz type deposit, inside tuff near the contact zone suggests that Chelugou dacite porphyry should be the heat source for the early mineralization. Meanwhile, many medium-acid magmatic bodies are developed in the western part of North Qilian Mountains. Therefore, the determination of Chelugou quartz type gold deposit is of theoretical and practical significance for gold exploration in the area.