Geochemistry and Genesis of Middle Jurassic Adakitic Rocks in the Xietongmen Area of Southern Tibet
详细信息
- 责任者：Hu Jianxiong (Institute of Regional Geology and Mineral Resources ; Mineral Bureau of Shaanxi ; Xianyang 712000 ; China) ; Chen Jianlin
- 刊名：Geotectonica et Metallogenia
- 出版年：2013
- 卷期：37(2)
- 关键词：埃达克岩 ; adakite ; 岩石地球化学 ; lithogeochemistry ; 青藏高原 ; Qinghai-Tibetan Plateau
- 页码：p.320-332
- 图表：illus., 1 table, 77 refs.
- 分类号：0801
- issnNo：ISSN1001-1552
- isbnNo：CN44-1595/P
摘要
The Middle Jurassic diorite exposed in the Xietongmen area of Southern Tibet,have some adakitic characteristics,such as high SiO2( >59%) and Sr( 771 ～ 798 μg/g),and low HREE,and Y( <12 μg/g) concentrations,high Sr / Y( > 64) and La / Yb( 4. 4 <( La / Yb)N< 19. 2) ratios,with positive Sr anomalies but no obvious Eu anomalies. Middle Jurassic basic and acidic magmatism and related porphyry deposits( Xiongcun porphyry CuAu deposits) were recognized in Southern Tibet. In addition,the geochemical characteristics of the diorite are similar to those of the Cenozoic volcanic rocks at Bowers Ridge resulting from partial melting of slab-tearing in northwestern Pacific Ocean. So,we suggest that the diorite in the Xietongmen area was most likely derived from partial melting of the slab break-off during the northern-dipped Neotethys Ocean in Middle Jurassic.