• 责任者：Wei Ping (State Key Laboratory of Geological Processes and Mineral Resources ; School of Earth Sciences and Resources ; China University of Geosciences ; Beijing 100083 ; China) ; Mo Xuanxue
• 刊名：Acta Petrologica Sinica
• 出版年：2013
• 卷期：29(11)
• 关键词：花岗岩 ; granite ; 岩石地球化学 ; lithogeochemistry ; 秦岭 ; Qinling Mountains
• 页码：p.3981-3992
• 图表：9 illus., 3 tables, 46 refs.
• 分类号：0801
• issnNo：ISSN1000-0569
• isbnNo：CN11-1922/P

     Xiahe granitoids consisting of monzogranite and granodiorite are located in West Qinling, Gansu Province, in which mafic microgranular enclaves are also well developed. The whole rock geochemical data shows that the content of SiO2 and total alkali of monzogranite （66. 07% - 69. 18%, 7. 18% - 7.69%, respectively ） are slightly higher than those of granodiorite （60. 18% 66. 22%, 4.73% -6. 72% , respectively）, while the content of Al2O3 and CaO of monzogranite （ 15.21% - 16. 37% , 2. 23% - 3.04%, respectively） are lower than those of granodiorite （ 16. 60% - 17.39%, 3.54% - 5.86%, respectively）. These granitoids characterized by high Mg# value （with an average of 55 ）, K2O/Na2O 〉 1 and A/CNK = 1.0 - 1.1 belong to the slightly-peraluminous high-K calc-alkaline rock series and show similar geochemical characteristics to I-type granite. The rocks are enriched in light rare earth elements （ Rb, Ba, Th, U and K） and depleted in Nb, Ta, P, Ti and heavy rare earth elements, having no or weak negative Eu abnormality and a wide variability of the （La/Yb） N values （ 8. 97 - 33.48）. The zircon U-Pb data show that the emplacement age of Xiahe granitoids is 244 -248Ma, belonging to the early stage of Indonian. The high （87Sr/86Sr）i（0. 70714 -0. 70743）, low eNd（t） （ -6. 21 - --8. 36 ） and high radiogenic Ph isotopic compositions （206 Pb/204 Pb = 17. 850 - 18. 003, 207 pb/204 pb = 15.489 - 15.510, 20s pb/204 Pb = 37. 815 - 37. 931 ） indicate that Xiahe granitoids were mainly originated from the partial mehing of ancient lower crustal materials and the mantle-derived magmas may play an important role in the formation of the host granitoids. Based on the existing research results, we suggest that Xiahe granitoids were formed in a continental marginal are setting which, in other words, implies that the Ahyemagen-Mianlue ocean basin closed after 244Ma in West Qinling.