Zircon SHRIMP U-Pb Age,Geochemistry and Genesis of the Youdong Granite in Northern Guangdong
详细信息
- 责任者：Huang Guolong (Research Institute No.290 ; CNNC ; Shaoguan 512026 ; China) ; Cao Haojie
- 刊名：Acta Geologica Sinica
- 出版年：2012
- 卷期：86(4)
- 关键词：二云母花岗岩 ; two-mica granite ; 湖北 ; Hubei Province
- 页码：p.577-586
- 图表：9 illus., 3 tables, 41 refs.
- 分类号：0801
- issnNo：ISSN0001-5717
- isbnNo：CN11-1951/P
摘要
The Youdong granite,located in the central part of the southern Zhuguang granitic complex,is important uranium-bearing granite.It consists mainly of medium-grained,small porphyritic two-mica granite.SHRIMP U-Pb dating of zircon collected from the granite yields an age of 232±4 Ma(MSWD=3.2),indicating it was the product of granitic magmatic activity in the early Indosinian epoch.The granite is rich in Si(average SiO2 of 72.65%) and Al(average A/CNK value of 1.12),with a high ratio of K2O/Na2O(average 1.79).It is also enriched in large ion elements including light rare earth elements,but significantly depleted in Sr,Ba P,Ti,Nb and Ta,with high ratios of Rb/Sr(average 8.08) and Rb/Nb(average 20.96).The rare earth element distribution patterns show right-inclining type with significant Eu depletion.The Youdong has high(87Sr/86Sr)i ratios(average 0.72330) and low εNd(t) values(average-11.9) with old Nd model ages(average 1954 Ma).These features consistently indicate that the Youdong complex is a typical crustal rock-sourced granite formed in an extensional tectonic environment that began shortly after the end of collision between the South China block and Indosinian block.Under such tectonic settings,the Youdong granite was formed by partial melting of Paleoproterozoic-Mesoproterozoic argillaceous and arenaceous rocks in the intermediate-lower crust sources under the influence of lithosphere thinning and asthenosphere ascending.