Geochemical Characteristics of Basalts in Beilike Area and Its Geological Significance, Inner Mongolia
详细信息
- 责任者：Chen Shengsheng (Institute of Tibetan Plateau Research ; Chinese Academy of Sciences ; Beijing 100085 ; China) ; Fan Qicheng
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(8)
- 关键词：拉斑玄武岩 ; tholeiitic basalt ; 内蒙古 ; Inner Mongolia
- 页码：p.2695-2708
- 图表：12 illus., 2 tables, 93 refs.
- 分类号：0801
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
The Beilike basalt,covering an area of about 400km2,consists of three levels of lava platforms at different elevations, and the age of each lava platform is 2. 31 ～ 2. 41Ma、1. 56 ～ 1. 61Ma、0. 51 ～ 0. 61Ma. The basalt which can be divided into quartz tholeiite and olivine tholeiite has an excessive nature of the characteristics,all being derived from the garnet peridotite source region. Based on the geochemistry characteristics,there does not exist the evolutionary relationship between the olive tholeiite and quartz tholeiite. They are interpreted to be resulted probably from the varying degrees of the garnet peridotite source region and the depth of partial melting. Both olive tholeiite and quartz tholeiite were affected by crustal contamination,but the latter is more obviously. Tectonically,both Beilike and Chifeng lie on the the southern margin of the Xing’an-Mongolia Orogen Belt,compared with the northern margin of North China Craton,they have a similar magma source and the lithospheric mantle thermal state,but different enrichment lithospheric mantle types,namely,the former displays a DMM-EMⅡ array different from the latter,it may be related to different ages and tectonic settings of the lithospheric mantle. Based on the asthenosphere-lithospheric mantle interaction model, lithospheric thinning phenomenon in North China is not confined to the craton,instead in northwest craton,and even the south margins of Xing’an-Mongolia Orogen Belt experienced lithospheric thinning too. They just have different time and degree of the lithospheric thinning process.