新疆纸房东地区大长沟群和条山群火山岩形成时代

Formation Ages of the Volcanic Rocks of the Datanggou and Tiaoshan Group in Zhifangdong Area,Xinjiang

新疆纸房东地区广泛出露一套早中泥盆世及早石炭世钙碱性的中酸性火山岩,对Cu多金属矿床的形成十分有利。前人在该区进行过区域矿产调查工作,但至今还没有准确的同位素年龄。利用LA-ICP-MS锆石U-Pb定年方法,对早中泥盆世及早石炭世火山岩进行了精确的定年,分别测得其年龄为(377±3)Ma和(334.3±2.9)Ma。结合区域资料,认为早中泥盆世火山岩形成于拉张环境,而早石炭世火山岩形成于岛弧环境。

Lots of calc-alkaline volcanic rocks of the Early-Middle Devonian and the Early Carboniferous, exposed widely in zhifangdong area of Xinjiang, are advantageous for the formation of Cu polymetallic deposit. The predecessors had engaged in regional mineral survey work in this area, but so far no isotopic age of these volcanic rocks have been obtained accurately. By the method of LA-ICP-MS zircon U-Pb dating, This paper did with the dating for the volcanic rocks of the early-Middle Devonian and the Early Carboniferous accurately, and their ages were （377 ± 3 ） Ma and （334.3 ±2.9 ） Ma respectively. Combined with regional geological data, this paper think that the Early- Devonian volcano rocks formed in extensional environment, and the Early Carboniferous ones formed in the setting of island-arc.