Analysis on Geochemical Characterisics and Prospecting Potentia of Luodong Mafic-ultramafic Intrusion in Beishan, Xinjiang

The Luodong mafic-ultramafic intrusion is located in eastern Beishan of Xinjiang and exposed on the north of the Baidiwa-Suihehe fault with an eyeball-shape. The intrusion is composed of gabbros, peridotite, harzburgite and olivine pyroxenite. Many of them have a cumulate texture. Petrography and geochemistry of the Luodong mafic-ultramafic intrusion indicate that the intrusion belongs to tholeiitic affinity series and has undergone early fractional crystallization of olivine, pyroxene and plagioclase, as well as the mixed dyeing of the upper crust during magmatic evolution, showing good formation conditions of copper-nickel ore. The primary magma was the high-mg and high-temperature picritic and was derived from the higher degree of partial melting of the asthenosphere mantle in the spinel stable region. The MgO contents of these inrusions vary from 7% to 33.7% and the m/f ratios range from 1.7 to 6.8, indicating that they belong to copper-nickel sulfide-bearing medium mafic rock and ferruginous ultramafic rock. The geological, geophysical, and geochemical analysis of Luodong region shows that these intrusions have good prospecting potential. The construction of a comprehensive prospecting model provides experience to select the favorable ore-forming intrusions from the mafic-ultramafic intrusions in Beishan.