Rare earth mineral characteristics of aegirine augite syenite in Changling,Luonna country,Shaanxi province
WANG Meng-ya;YIN Jing-wu;CHEN Pu-pu;NIE Xiao;ZHANG Jie;YANG Jing;Institute of Earth Science,china University of Geosciences;School of materials science and Engineering,China University of Geosciences;
Aegirine-augite orthoclase is found in the southern margin of the north China block,on the north side of black trenchLuanchuan fault zone,alkaline granite,and syenite classes. In this paper,the monazite and xenotime of containing rare earth elements were studied by using electron probe,back scattering( BSE) image morphology,element distribution and quantitative analysis methods. The monazite and xenotime are formed in the early stage of magma crystallization and in the poor calcium environment. The monazites as the cerium-monazite type,mainly exist in the forms of irregular granular and vein. The granular monazite grains are in size of 15 μm × 25 μm to 30 μm × 40 μm,and the vein monazites are associated with aegirine augite,quartz and K-feldspar. In addition,the monazites are characterized by rich in LREE,poor in HREE,low total rare earths and comparatively rich in radioactive element Th,belonging to magmatic origin. The xenotime columnar grains exist in zircon and they are of 4 μm to 9. 5 μm in size. Ce in monazite is substituted by Th,La elements; Zr and Er in xenotime are substituted by Y elements.