摘要
基于幔源岩石产出的不同岩石组合与铬镍的浓集关系得出:铬矿体的寄主岩相优选于M/F值6～12区间内,专属于超镁铁质岩区和岩体,寄主岩相造岩矿物橄榄石专属于镁橄榄石,副矿物铬尖晶石富Mg和Cr。镍矿体寄主岩相的M/F值介于2～6,造岩矿物橄榄石为贵橄榄石,副矿物铬尖晶石相对富Fe贫Mg和Cr。铬和镍对不同Si-O系统的选择,制约于系统能量效应的不同。氧逸度(fo2)达1.013×10-3.5Pa时有利于铬尖晶石的生成。镁铁质岩浆同化地壳是获取硫得以产出硫化物矿石的必要条件。岩浆中地壳Ca、Al、Na、Si等造岩组分的加入有利于镍矿浆的熔离,并导致超镁铁载镍岩相必含有少量斜长石。
Based on the relation of different rock assemblages originated from mantle to the Cr and Ni concentrations, the authors have find that the lithofacies hosting Cr ore bodies have a preference (M/F) value from 6 to 12; It belongs to the ultramafic rock provinces and rock bodies; The olivine of rock forming mineral specially belongs to forsterite; And the accessory mineral picotite must be enriched in Mg and Cr. The Ni ore-bearing lithofaces have a preference M/F value from 2 to 6. The rock forming mineral olivine belongs to chrysolite and the accessory picotite is relatively enriched in Fe and poor in Mg and Cr. The reason why Cr and Ni are preferably restricted to certain Si-O systems lies in the energy effect of a system. Picotite was formed easily when the fo(2) in the system is up to 1.013×10^(-3.5)Pa. Assimilation of the crustal materials by the mafic magma from the crust is a necessary condition of obtaining S and forming sulfide ores. The addition of the rock-forming components such as SiO(2), Na(2)O, CaO and Al(2)O(3) into magma is favorable for the liquation of Ni-bearing ore magma and for such a reason minor plagioclase is certainly present in Ni-hosting ultramafic rocks.
出处
《吉林大学学报（地球科学版）》
EI
CAS
CSCD
北大核心
2004年第2期201-205,共5页
Journal of Jilin University：Earth Science Edition
