Characteristics of Petrology and Geochemistry of Volcanic Rocks in the Yinjianggou, Aershan Area
详细信息
- 责任者：Wu Chihua (Institute of Sedimentary Geology ; Chengdu University of Technology ; Chengdu 610059 ; China) ; Yi Haisheng
- 刊名：Geology and Prospecting
- 出版年：2010
- 卷期：46(3)
- 关键词：火山岩 ; volcanic rocks ; 大兴安岭 ; Greater Higgnan Mountains
- 页码：p.515-524
- 图表：9 illus., 3 tables, 26 refs.
- 分类号：0801
- issnNo：ISSN0495-5331
- isbnNo：CN11-2043/P
摘要
The study of a typical profile of the Upper Jurassic volcanic rock in the Yinjianggou area suggests that this region has a lithological combination of a suit of medium-acid and acid volcanic rocks and volcanic clastic rocks. The rock types include sakalavite, rhyolite, crystal tuff, and tuff breccia. The alternating rhythmic changes between medium-acid and acid volcanic rocks in composition is very clear, indicating two outbreak-overflow phase cycles. Geochemical analysis of the samples shows that the content of SiO2 is 68.14%～75.40%, rich in alkali, as high-alumina, high-potassium, and low-magnesium, implying a high-potassium calcalkalic volcanic rock. It demonstrates total REE and LREE enrichment with sharp negative Eu anomalies, weak negative Ce anomalies and intense fractionation between LREE and HREE. The primitive mantle-normalized spidergrams are characterized by LILE enrichment and HFSE depletion, for a significantly negative Th-Pb-Ti anomaly and an intense enrichment Ba-Rb-Sr anomaly. These medium-acid and acid volcanic rocks reflect some features of island-arc and continental arc settings.