Genesis of Podiform Chromite Deposits——Evidence from the Luobosa Chromite Deposits, Tibet

<正> Taking for example the Luobosa chromite deposit in Tibet combined with other deposits of the same type in the world, the paper discusses the genetic mechanism of podiform chromite deposits. The study indicates that chromite and dunite-harzburgite are both the products of different degrees of partial melting of the same primary pyrolite(spinel lherzolite) and that chromite and dunite are the end product of higher degree of partial melting.The melting mechanism lies in the convcrsion of the two subgroups of pyroxenes(Cpx and Opx) into olivine and spinel respectively as a result of their incongruent melting, accompanied by regulation and reformation of accessory chrome spinel and such rock-forming minerals as Ol, Opx and Cpx, thus resulting in the close association of chromite deposits and dunite. The results of this study are of general significance for understanding the genesis of chromite deposits of the same type in the world.