- 责任者：Ren Wenxiu (Geological Survey of Gansu Province ; Lanzhou 730000 ; China) ; Dong Guoqiang
- 刊名：Gansu Geology
- 出版年：2013
- 卷期：22(4)
- 关键词：二长花岗岩 ; monzogranite ; 甘肃 ; Gansu Province
- 页码：p.22-27
- 图表：illus., 2 tables, 15 refs.
- 分类号：0801
- issnNo：ISSN1004-4116
- isbnNo：CN 62-1191/P
The Dangjinshan monzonitic granites, located tectonically in the south margin of Alty and west of South Qilian tectonic belt, are characterized by high-K and tale-alkaline composition with SiO2 （68.69% 72.53% ）, high Na （Na2O=3.97%-4.7%）,Mg （MgO=0.98%-2.14%） and Na2O/K2O （1.1-1.38）, coupled with low Ti,A1, and metaluminous （A/NKC=0.98-1）. There is a small amount of corundum appear in the CIPW standard mineral calculation. The characteristics of REE relatively enrich LREE, deplete HREE, a weakly negative Eu anomaly. Our study results indicate that Dangjinshan monzonitic granite is I type, which was formed by basic igneous rock or metaigneous rock partial melting after intense fractional crystallization and differentiation, which was used to be heated by basaltic magma, when the study area changed from the compression to the tension system and then the crust thinning in the late Caledonian. This conclusion provides the powerful evidence for the study of magmatism and tectonic evolution in Ahy region.