Adakite Granite of Maozangsi and Its Origin in The North of Qilian Area in Gansu

详细信息   

• 责任者：Li Damin (No.4 Geology and Mineral Exploration Team ; Gansu Provincial Bureau of Geology and Mineral Exploration and Development ; Jiuquan 735000 ; China)
• 刊名：Chinese Journal of Geology
• 出版年：2012
• 卷期：47(2)
• 关键词：埃达克岩 ; adakite ; 甘肃 ; Gansu Province
• 页码：p.347～359
• 图表：illus., 3 tables, 54 refs.
• 分类号：0801
• issnNo：ISSN0563-5020
• isbnNo：CN11-1937/P

摘要

The specificity and its scientific and practical significance of Adakite deeply attracted scientists on Earth. The Qilian Early Paleozoic orogenic belt,which located in the northeastern margin of Qinghai-Tibet Plateau,is cradle of Chinese scientists to study the plate tectonics. By contrast,the characteristics of intrusive rocks in Lianhuashan of the north Qilian orogenic belt were studied. The results is：intermediate-acid intrusive rocks of Caledonian in Lianhuashan have high SiO₂, Al₂O₃, Na₂O content, Na₂O/K₂O ratio is high, while MgO is lower, LREE enrichment strong, HREE apparent loss, the majority of L/H ratio〉15 ; Th, Sr, Ba is an obvious positive anomalies, of which Sr content is more than 507 × 10^-6, Sr/Y, La/Yb （21.39 ～41.72 ）ratio is high and the Cr,Ni. values of the rock are 1.45～2.76,A/CNK were 0.83～1.15, the majority 〈1.0, the main rocks are calc-alkaline granitoids series aluminum side. Rock eigenvalue are pointing to Adakite. In the（La/Yb） N-YbN and Sr/Y-Y discriminant diagram, samples fall into the scope of the Adakite. In the SiO²-Mg^# diagram, the rock fall “slab origin Adakite” region,content of the rock, also in line with the “O” type Adakite characteristics. These show that Adakite of Lianhuashan region originated in the subduction of the partial melting of oceanic crust, which is “O” type Adakite. The geodynamic background is the subduction of the north Qilian oceanic crust to the north China plate during Early Paleozoic. Discovery of the “O” type Adakite in the region confirms previous understanding of Qilian orogenic belt and its tectonic evolution, and puts forward new ideas of mineral resources exploration in the region.