A Study On Cr And Ni Deposits In Si-O System From The Mantle

Cr and Ni are two kinds of special metal. They are used widely in machine industry, chemicalindustry and refectory materials. In the paper, the general situation, distribution and the relation of the mineralization to the mantle-originating Si-0 system about two types of mineral deposits in the world are studied. And the main is the later.There is closed relation of Cr and Ni deposits to the mantle-originating rocks. The ore body occurs closely with intrusive body or in it. Both of them are the products of magma evolution in different phase.When discussing the relation of the two types of deposits to the mantle-originating rocks,someterms about rocks has been used indistinctly for a long time. Mantle-originating rocks in the crust can be divided into 3 types according to their occur unit: petrographic province, intrusive body and petrographic facies (basic compositional unit of a intrusive body). In the paper, we put out a new method to study the relation of the two types of deposits to mantle-originating rocks based on natural petrographic composition. According this study we have obtained following conclusion: 1) Petrographic province: Cr deposit occurs specially in ultmafic petrographic province and Ni deposit occurs specially in mafic petrographic province; 2) Intrusive body and petrographic facies: Cr deposit occurs specially in ultmafic intrusive body and ultmafic petrographic facies and Ni deposit occurs not only in mafic petrographic province but also in mafic intrusive body and petrographic facies. For the later, Ni deposit mainly exists in the position with the best M/F value. The study on rock-forming minerals and accessory minerals of ore-bearing intrusive bodies has revealed that the...