YE Lin1*, LIU Yuping1, YANG Yulong1,2, and GAO Wei1,2
(1. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China
2. Graduate University of Chinese Academy of Sciences, Beijing 100049, China)
Abstract Nitrogen is an important gas-phase element in geological fluid, and normally hosted in mineralizing fluid, in which the content is very low. Nearly 100% mol pure nitrogen inclusion was discovered in copper-bearing quartz vein from Xikuangshan copper deposit, Dongchuan, Yunnan Province in this research. It is between 3 and 5 μm, in shape of ellipse, occurring in group or independence without obvious orientation, and co-existed with primary gas-liquid inclusions. Inclusion analysis by using laser Raman spectroscopy shows its composition is dominated by nitrogen with minor H2O. High concentration of N2 may be the necessary and sufficient condition for forming this kind of inclusion. It is suggested that there are two genesis modes of pure N2 inclusion in the deposit, oxidation-devolativation of mantle matter and trap of metasomatic fluid in organic matter decomposition in Luoxue Formation dolomite. In conclusion, pure N2 inclusion hardly presents in the ore-forming fluids, which providing a new evidence for the genesis of Xikuangshan type copper deposit.
Key words nitrogen; fluid inclusion; oxidation; dehydration; organic matter; decomposition; Laser Raman spectroscopy; copper deposit; Xikuangshan
* Corresponding author, E-mail:yelin@vip.gyig.ac.cn
CHINESE JOURNAL OF GEOCHEMISTRY Vol. 31, No. 1, 2012, page 78-85
© Science Press and Institute of Geochemistry, CAS and Springer-Verlag Berlin Heidelberg 2012
