40Ar/39Ar Dating of Hydrothermal K-Feldspar and Hydrothermal Sericite from Bolong Porphyry Cu-Au Deposit in Tibet
详细信息
- 责任者：Zhu Xiangping (Chengdu Institute of Geology and Mineral Resources ; Chengdu 610081 ; China) ; Chen Huaan
- 刊名：Mineral Deposits
- 出版年：2013
- 卷期：32(5)
- 关键词：斑岩铜矿床 ; porphyry copper deposit ; 金矿 ; gold ores ; 氩—氩计时 ; Ar-Ar dating ; 西藏 ; Tibet
- 页码：p.954-962
- 图表：4 illus., 1 table, 33 refs.
- 分类号：1001
- issnNo：ISSN0258-7106
- isbnNo：CN11-1965/P
摘要
The Bolong porphyry copper-gold deposit is the largest porphyry copper deposit discovered recently in the middle of the Tibetan plateau.Hydrothermal K-feldspar from the potassic alteration zone and hydrothermal sericite from the phyllic alteration zone were analyzed by40Ar/39Ar dating technique.The plateau age of secondary K-feldspar is(118.33±0.60)Ma,which,together with its reverse isochron age of(118.49±0.74) Ma(initial40Ar/36Ar=286.1±8.4),represents the potassic alteration age of the Bolong deposit.The plateau age of secondary sericite is(121.61±0.67)Ma,and its reverse isochron age is(121.1±2.0)Ma(initial40Ar/ 36Ar=279±19).The high37Ar/39Ar ratio of the secondary sericite sample indicates that some magmatic plagioclase was mixed in the sample,which increased the dating value.Thus,the phyllic alteration might have occurre d around 119 Ma.Taking the deviation and uncertainties of geochronologic methods into account,the authorshave found that the40Ar/39Ar ages of hydrothermal K-feldspar and hydrothermal sericite are similar to the oreforming and rock-forming agesof the Bolong deposit,suggesting that the potassic alteration and mineralization in the Bolong porphyry deposit were coeval with the intrusion of porphyries and phyllic alteration,and the magmatic-hydrothermal duration was within 121~118 Ma.
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