新疆苏普特背斜花岗岩和变安山质凝灰岩LA-ICP-MS锆石U-Pb年代学特征及意义
LA-ICP-MS Zircon U-Pb Dating for Granite and Meta-Andesitic Tuff and Its Geological Significance——Case Study Supute Anticline in the Southern Margin of the Altay, Xinjiang
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摘要: 阿尔泰南缘古生代康布铁堡组火山岩系是许多铁矿、铜锌矿以及铅锌矿的赋矿围岩,但该赋矿地层目前还缺乏精确的同位素年代学资料.通过对变安山质凝灰岩和花岗岩LA-ICP-MS锆石U-Pb定年,获得阿尔泰南缘苏普特背斜花岗岩的年龄为412.7±0.78Ma,安山质凝灰岩的年龄为411.2±3.4Ma,表明阿尔泰南缘苏普特背斜内泥盆纪早期存在着强烈的火山活动,与区内广泛发育的火山岩属于同一事件的产物,具有相同的动力学背景.为研究阿尔泰南缘古生代构造演化及苏普特背斜异常区提供了重要的理论依据.
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关键词:
- LA-ICP-MS锆石U-Pb年龄 /
- 花岗岩 /
- 变安山质凝灰岩 /
- 阿尔泰南缘 /
- 新疆
Abstract: Situated in the middle part of the Central Asian Orogenic Belt(CAOB),the Altay orogenic belt(AOB) is an important metallogenic belt in China.Many economic deposits are distributed along southern margin of the AOB,e.g.Kaktal Pb-Zn deposit,Mengku iron deposit,Abagong iron deposit,and Tiemuerte Pb-Zn deposit,etc.,which all occur in the Kangbutiebao Formation stratum comprising low grade metamorphosed volcanic rocks.Using the LA-ICP-MS zircon U-Pb method,we obtain that the age of granite is 412.7±0.78Ma and that of andesitic tuff is 411.2±3.4Ma age,representing the eruption time of the granite and the meta-andesitic tuff at the Supute Anticline.This age indicates that an intense volcanic activity may occur in the early Devonian in the Supute Anticline in the southern margin of the Altay,suggesting an active continental margin setting during this time.They belong to the same event of product and have the same dynamic background with the extensive development of volcanic in this area.The Result provides important theoretical basis for the study of the Paleozoic tectonic evolution at Supute anticline and the Southern margin of Altay. -
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