Geochronology and Geochemistry of the Coarse-medium Grained Syenogranites in the Binbalechagan Area, Inner Mongolia
详细信息
- 责任者：Yang Junquan (China University of Geosciences（Beijing） ; Beijing 100083 ) ; Liu Yongshun
- 刊名：Geological Survey and Research
- 出版年：2012
- 卷期：35(2)
- 页码：p.128-135
- 图表：illus., 2 tables, 44 refs.
- issnNo：ISSN1672-4135
- isbnNo：CN12-1353/P
摘要
Intrusive rocks are widespread in the Binbalechagan, Dongwuqi, Inner Mongolia Autonomous Region. This paper selectes coarse-medium grained syenogranites （CMGS） in the region for isotope chronological and geochemical studies. By zircon SHRIMP U-Pb dating, weighted mean age of (220.4 ± 2.5) Ma（MSWD = 0.83） is obtained. The zircon oscillatory rings are well developed with typical pattern of magmatic zircon, so the result may represent the diagenetic age of the granite. CMGS is characterized by K enrichment, peraluminous, LREE relatively enriched, substantial negative Eu anomalies, HREE with weak negative gradient, Ba with obvious nega- tive anomalies, Rb and Th relatively enriched, other incompatible elements relatively depleted, both Y and Yb lower than the normalized values of ocean ridge granite. CMGS probably formed under post-orogenic extension setting after the convergence between the Siberian plate and Sino-Korean plaeo-plate.