Geochemical and mineralogical comparison of the sulfide-bearing Pobei and sulphide-barren Luodong mafic-ultramafic intrusions in the Beishan region,Xinjiang,NW China
The Pobei and Luodong mafic-ultramafic intrusions are located in the Beishan region of Xinjiang.They occurs close to the Baidiwa-Yunihe regional fault.The Pobei intrusion hosts Ni-Cu sulphide mineralization whereas the Luodong intrusion is barren.Both of them are composed of dunite,wehrlite,olivine pyroxenite,troctolite,olivine gabbro,gabbronorite and gabbro.However,olivine pyroxenite is more abundant at Pobei and dunite is more abundant at Luodong.The Mg# of two intrusions vary from 0.55 to 0.89.Their parental magmas belong to sub-alkaline,tholeiitic,affinities.Olivine crystals from Pobei are characterized by large variation in Ni content (982-4007ppm) but similar Fo content (2 mole % variation).The Pobei and Luodong intrusive rocks have low trace element abundances,flat chondrite-normalized REE patterns,positive Eu anomalies,slight enrichments in Rb,Sr,U and Pb,and depletion in Nb.The correlations of Ta/Yb vs.Th/Yb,La/Yb vs.Ce/Pb,Ce/Yb vs.Ta/Yb and La/Yb vs.Ta/Yb,plus Ce/Pb of 0.24-4.34 (Pobei) and Ce/Pb of 1.24-7.68 (Luodong) suggest that crustal contamination is more significant in the Pobei intrusion than the Luodong intrusion.More significant crustal contamination may have promoted sulfide saturation and segregation.
Sheng-Chao Xue Ke-Zhang Qin Ya-Jing Mao Dong-Mei Tang
Key Lab.of Mineral Resources,Institute of Geology and Geophysics,CAS,Beijing
国际会议
贵阳
英文
220-223
2012-06-16（万方平台首次上网日期，不代表论文的发表时间）