Geochronology and Geological Significance of the Granites from the Mahe Mo Deposit in the North Qinling
详细信息
- 责任者：Ke Changhui (Institute of Mineral Resources ; Chinese Academy of Geological Sciences ; Beijing 100037 ; China) ; Wang Xiaoxia
- 刊名：Acta Petrologica Sinica
- 出版年：2012
- 卷期：28(1)
- 关键词：钼矿 ; molybdenum ores ; 花岗岩类 ; granitoid ; 铀—铅计时 ; U-Pb dating ; 秦岭 ; Qinling Mountains
- 页码：p.267-278
- 图表：9 illus., 3 tables, 30 refs.
- 分类号：1001
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
LA-ICP-MS U-Pb dating for the granites from the Taoguanping and Xigou plutons in the Mahe Mo deposit in the North Qinling yields concordant ages of 1 57±1 Ma(NSWD=1 3)and 1 53±1 Ma(NSWD=1 4)respectively indicating that the two plutons were formed at late Jurassic.The Mahe Mo deposit is closely related to the two plutons.Therefore these ages may suggest the Mo deposit formed at Late Jurassic appreciably later than 1 57～1 53 Ma.The granites from the Taoguanping and Xigou plutons are characterized by high in silica(68.1 2%～76.33%)and alkali(Na 2 O+K2 O=6.35%～1 0.38%)with the A/CNK of 0.85～1.1 4 and lager variation of K2 O/Na2 O(0.91～1.89),showing that they are metaluminous or weakly peraluminous and high-K calc-alkaline series.The Taoguanping and Xigou granites are enriched in U,Pb,Hf,but depleted in Rb,Ba,K,Sr and P.The REE patterns are characterized by enrichment in LREE with weak negative abnormal of Eu(0.5～0.9),but a few samples have weak positive Eu anomalies(1.05 to 1.08).The granites are similar to the molybdenum deposits related granites in the southern margin of the North China Block in enriched in SiO2 and Na2 O+K2 O.However,these granites are lower in SiO 2 ,Na 2 O+K2 O and higher in CaO and MgO than the granites in the southern margin of the North China Block.It may be one reason that the Mahe Mo deposit is not as larger as the deposits in the southern margin of the North China Block.