- 责任者：Yuan Shisong (State Key Laboratory of Geo-Processes and Mineral Resources ; School of Earth Sciences and Resources ; China University of Geosciences ; Beijing 100083 ; Chian) ; Yan Fengzeng
- 刊名：Journal of Mineralogy and Petrology
- 出版年：2013
- 卷期：33(4)
- 页码：p.29-41
- issnNo：ISSN1001-6872
- isbnNo：CN51-1143/TD
EN-US>Bikou terrane is bounded by Qinling orogenic belt to the north,Songpan-Ganzi oro- genic belt to the west,and Yangtze Block to the southeast. Accompanying with Indon-China oro- genic events in Chinese continent, a lot of granitic dikes intruded in Bikou terrane and its north margin. There are mainly granitic dikes in the north margin, divided into several concentrated are- as from east to west, such as Yuezhao-Pibasi in Kangxian, Lianhecun-Yangshan in Wenxian. In these areas, large to super large gold deposits were discovered one after another, for examples Tangba, Shuidonggou, Yangshan, Lianhecun, and Jiawuchi gold deposits. However, petrogenesis, tectonic setting and relationship with mineralization of these granitic dikes have been seldom stud- ied. In this paper,new data are presented on geochemical compositions of the granitic dikes in Pi- bashi,Yangshan and Jiawuchi in order to discuss petrogenesis,sourees of magma and tectonic set- ting of diagenesis of these dikes. Study shows that the SiO2 and Al2O3 of the granites range from 67.65% to 74.86% and 13.68% to 19.61% respectively, and the A/CNK varies from 1.11 to 5.4. Rare earth elements （REE） content of the granites is low （24.22× 10 6 -97.26×10-6）, with LaN/YbN ratios of 3.29=22.40. Light rare earth elements （LREE） are concentrated evident- ly and heavy rare earth elements （HREE） are slightly negative Eu anomalies （δEu=0.70-0.79 deficient. The REE patterns are characterized by 79）. Granites are also enriched in large ion litho- phile elements （IALES） and relatively depleted in high field strength elements （HFSES）. It is showed that the granitic dikes were likely originated from subducted continental basement with greywackes as major composition. On the basis of analytical data of geochronology of granites and gold deposits in this area,it is proposed that the granites in north margin of Bikou terrane belong to post-eollisional setting with a peak activity of late Triassic and closely related to delamination of thickening crust and underplating of mantle-derived material during collisional and orogenic processes. These dikes were derived from partial melting of greywackes in middle-upper crust as a result of decompression and increasing temperature of thickening crust and upwelling of mantle- derived heat flow. Simultaneously, large-scale gold mineralization occurred in north margin of Bikou terrane at early Jurassic （190 Ma-195 Ma）, 20 Ma younger than the peak age of magma activity. Ore-forming fluids and magmatie rocks may ascend along a common path, so the concen- trated districts of granitic dikes are favorable for gathering the ore-forming fluids, and conse- quently forming super large gold deposit.