CAJ | 학술논문

阿尔泰山东部诺尔特—阿尔沙特地区晚古生代火山岩十分发育,其中阿尔沙特一带出露一套片理化蚀变流纹岩与含凝灰质英安流纹岩的岩石组合,呈北西—南东向带状展布,前人将其划为石炭系红山嘴组 a 段,其岩性组合明显区别于红山嘴组 b、c 段地层,且稳定成规模出露。本次工作笔者对其进行了 LA-ICPMS 锆石 U-Pb 测年,获得锆石的206 Pb/238 U 和207 Pb/235 U 谐和年龄为(400.5±4.6)Ma,206 Pb/238 U 年龄加权平均值为(400.4±3.6)Ma,代表岩浆结晶年龄,时代为早泥盆世,较前人认为的石炭纪早。结合区域地质资料分析认为,(400.4±3.6)Ma 区内古大洋俯冲已达到顶峰阶段,该火山岩形成于活动大陆边缘构造环境。
아이태산동부낙이특—아이사특지구만고생대화산암십분발육,기중아이사특일대출로일투편이화식변류문암여함응회질영안류문암적암석조합,정북서—남동향대상전포,전인장기화위석탄계홍산취조 a 단,기암성조합명현구별우홍산취조 b、c 단지층,차은정성규모출로。본차공작필자대기진행료 LA-ICPMS 고석 U-Pb 측년,획득고석적206 Pb/238 U 화207 Pb/235 U 해화년령위(400.5±4.6)Ma,206 Pb/238 U 년령가권평균치위(400.4±3.6)Ma,대표암장결정년령,시대위조니분세,교전인인위적석탄기조。결합구역지질자료분석인위,(400.4±3.6)Ma 구내고대양부충이체도정봉계단,해화산암형성우활동대륙변연구조배경。
The Nurt-Aershate area is located in the eastern part of Altay,where Late Paleozoic volcanic rocks are well developed. There exists a set of rock assemblages of altered rhyolite and tuff dacite rhyolite in Aershate area,which isextensively and stably distributed distribution from northwest to southeast with a zoned shape. This set of rock assemblages was originally assigned to the Member a of Hongshanzui Formation,but itslithologic characteristics is obviously different from Member b and c of Hongshanzui Formation. The altered rhyolitesare selected to determine for LA-ICP-MS zircon U-Pb ages. The result shows that the 206 Pb/238 U and 207 Pb/23 5 U concordia age is (400.5 ± 4.6)Ma,the 206 Pb/238 U weighted average age is (400.4 ± 3.6)Ma,indicating the rock crystallization age were formed in the Early Devonian,not Carboniferous. Combined with the data of southern margin of Altay,the volcanic rocks were generated in a continental arc setting of active continental margin.