内蒙古额济纳旗涌珠泉海西期侵入岩年代学特征及构造意义

Chronological characteristics and tectonic significance of Hercynian intrusive rocks at Yongzhuquan, Ejina Banner, Inner Mongolia

内蒙古额济纳旗涌珠泉侵入岩是月牙山构造混杂岩带以北规模较大的侵入体。在1∶5万区域地质调查的基础上,将该岩体解体为花岗闪长岩、二长花岗岩和正长花岗岩,获得二长花岗岩锆石U-Pb年龄为330.7±2.9Ma,确定其形成于早石炭世,表明北山地区晚古生代岩浆活动强烈。通过分析岩体的岩石化学和地球化学特征,确定其形成于拉张构造环境,说明早石炭世北山地区已进入拉伸构造环境,这对研究北山地区晚古生代地壳演化过程有积极意义。

The Yongzhuquan intrusive rocks to the north of the Yueyashan tectonic melange zone in Inner Mongolia constitute a large intrusive body.1∶50000regional geological survey shows that the rock mass is decomposed into granodiorite,monzonitic granite and syenogranite.The zircon U-Pb age of the monzogranite is330.7±2.9Ma,suggesting Early Carboniferous and indicating that the Late Paleozoic magmatism in the Beishan area was very active.Through the analysis of rock chemistry and geochemical characteristics,the authors hold that it was formed in a tension tectonic setting and that the tectonic setting of the Beishan area in the Early Carboniferous entered into a stretching environment.This conclusion is of great significance for the study of the crustal evolution of Late Paleozoic in Beishan area.