Geochemistry of the Basalts from the Silurian Maylashan Formation in the West Junggar and Its Tectonic Implications
详细信息
- 责任者：Yang Gaoxue (Key Laboratory of Western China’s Mineral Resources and Geological Engineering ; Ministry of Education ; Earth Science & Resources College of Chang’an University ; Xi’an 710054 ; China) ; Li Yongjun
- 刊名：Geotectonica et Metallogenia
- 出版年：2012
- 卷期：36(1)
- 关键词：玄武岩 ; basalts ; 岩石地球化学 ; lithogeochemistry ; 准噶尔盆地 ; Junggar Basin
- 页码：p.127-136
- 图表：7 illus., 1 table, 84 refs.
- 分类号：0801
- issnNo：ISSN1001-1552
- isbnNo：CN44-1595/P
摘要
The Maylashan area is situated in the southern part of the West Junggar Basin, NW China. The Middle-Upper Silurian Maylasha Formation consists of grayish green tuffaceous siltstone and fine-grained sandstone, sandstone and conglomerate, with intercalated beds of chert and basalt, and fault contacts with the Maylashan ophiolitic mélange. The basalts are of sub-alkaline tholeiitic showing geochemical characteristics similar to those of island arc basalt (IAB). It can be deduced that the volcanic rocks were derived from partial melting of spinel iherzolite mantle source (2%~10% partial melting) with the participation of small amount of subducted fluid, under back-arc basin setting different from that of the Maylashan ophiolitic mélange. Thus, an intra-oceanic subduction model was proposed for the Silurian-Carboniferous evolution of the West Junggar.