Geochemical Characteristics and Petrogenesis of the Aikendaban Permian Shoshonite in the oft-com:office:smarttags" />
详细信息
- 责任者：Luo Yong (Guangzhou Institute of Geochemistry ; Chinese Academy of Sciences ; Guangzhou 510640 ; China) ; Niu Hecai
- 刊名：Acta Petrologica Sinica
- 出版年：2010
- 卷期：26(10)
- 关键词：火山岩 ; volcanic rocks ; 岩石地球化学 ; lithogeochemistry ; 天山 ; Tianshan Mountains
- 页码：p.2925-2934
- 图表：3 illus., 2 tables, 75 refs.
- 分类号：0801
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
Trachyandesite and trachyte from the Aikendaban Formation in the western Tianshan, are alkali-rich （Na2O+K2O>8%）, of high-aluminium （Al2O3>13.5%） and low-titanium （TiO2<1.31%）, and have typical petro-geochemical characteristics of shoshonitic volcanics. The results showed that both trachyandesite and trachyte from Aikendaban Formation as a product of post-subduction magmatism, but they were formed in different stages of subduction: the trachyandesite is a typical shoshonitic alkaline volcanics which originated by low-degree （less than 5%） partial melting of the EM in the post-subduction extension stage, with melting phase of amphibole and residual phase of abundance garnet for their high Sr/Y ratio; and the trachyte is felsic-alkaline volcanics originated by partial melting of the juvenile lower crust in the post-subduction compression stage, which formed earlier than the trachyandesite.