【摘要】 大地构造位置隶属乌里雅思太活动大陆边缘的内蒙古东乌旗地区,是中亚造山带的重要组成部分,其内发育有大量的岩浆岩,侵入岩时代以二叠纪及晚中生代为主,鲜有早期岩体的报道。对该区莫合尔图一带的闪长岩进行锆石LA-MC-ICP-MS U-Pb同位素测定,结果显示,24个测点的年龄值比较集中,加权平均值为(337.1±1.9)Ma(MSWD=1.3),所测锆石具岩浆锆石的特征,表明岩体应形成于石炭纪。结合区域地质资料,认为东乌旗地区可能存在时限为337~310 Ma的构造-热事件。更多还原

【Abstract】 Dongwuqi area in Inner Mongolia,which lies in Uliastai active continental margin,is a part of Central Asian orogenic belt.Numerous magmatites are exposed in this area.The intrusive rocks mainly formed in Permian and Late Mesozoic,and seldom formed in the other period according to report.Diorite was discovered in Moheertu of this area during the 1 ∶ 50,000 regional geological surveys.By LA-MC-ICP-MS U-Pb isotopic dating for 24 zircons,weighted mean age of(337.1 ± 1.9) Ma(MSWD = 1.3) was obtained from the diorite.The characteristics of these zircons accord with magmatic zircon,and the results can represent the diagenetic age of diorite.Combined with regional geology,we concluded that a tectono-thermal event occurred during 337-310 Ma in Dongwuqi area.更多还原