LA-MC-ICP-MS U-Pb Dating of Zircons from Volcanic Rocks and Subvolcanic Intrusions in Ashele Cu-Zn Ore District, Xinjiang, and Its Geological Implications
详细信息
- 责任者：Yang Fuquan (Key Laboratory of Metallogeny and Mineral Assessment ; MLR ; Institute of Mineral Resources ; Chinese Academy of Geological Sciences ; Beijing 100037 ; China) ; Li Fengming
- 刊名：Mineral Deposits
- 出版年：2013
- 卷期：32(5)
- 关键词：铜矿 ; copper ores ; 锌矿 ; zinc ores ; 火山岩 ; volcanic rocks ; 铀—铅计时 ; U-Pb dating ; 新疆 ; Xinjiang
- 页码：p.869-883
- 图表：5 illus., 1 table, 36 refs.
- 分类号：1001
- issnNo：ISSN0258-7106
- isbnNo：CN11-1965/P
摘要
The Ashele Cu-Zn deposit is representative volcanogenic massive sulfide(VMS)deposit in China’s Altay region.The deposit occurs in the marine volcano-sedimentary sequence of the Ashele Formation in the Ashele Basin.No.Ⅰmain ore body occurs in the stratiform form between tuff and basalt,and mineralization occurs in massive,densely massive,banded,laminated,densely disseminated and veinlet forms.The hydrothermal alteration and mineralization also occur in the sub-dacite.Lots of research work has been carried out in the Ashele deposit,but the ages of its ore-hosting volcanic rock,subvolcanic rock and mineralization have not yet been clearly determined.In this paper,LA-MC-ICP-MS zircon U-Pb dating was used for studying the tuff and basalt from the direct host rocks of the ore bodies,sub-dacite and quartz diorite in the Asele Cu-Zn district.The U-Pb ages are(387.0±4.2)Ma,(388.2±3.3)Ma,(379.4±0.8)Ma,(378.5±0.9)Ma for tuff,basalt, sub-dacite and quartz diorite,respectively,suggesting that the Ashele Formation is Early-Middle Devonian in age.The Ashele Cu-Zn deposit is an syngenetic deposit,and No.Ⅰmain ore body occurs between tuff and basalt.The ages of the tuff and basalt suggest that the mineralization in the sedimentary exhalative period occurred in the late Early Devonian(388~387 Ma).The U-Pb age of the sub-dacite is(379.4±0.8)Ma,imrplying that the magmatic hydrothermal mineralization took place in the Middle Devonian.The U-Pb ages of the older zircons from tuff,basalt,sub-dacite and quartz diorite range from 743 to 2505 Ma,which represent the forming age of the Precambrian crystalline basement in Altay region.