Modes of Occurrences and Geochemical Characteristics of Ilmenite and Magnetite of the North Suoi Cun Lherzolite and Gabbroid

Modes of occurrences and geochemical characteristics of ilmenite and magnetite in the North Suoi Cun ultramafic rocks are studied to understand source, formation and evolution of magma chamber. The North Suoi Cun ultramafic block consist of plagiolherzolite and olivine melano-gabbro. The Plagiolherzolite and olivine melano-gabbro consist of large amounts of olivine and pyroxene, lesser amounts of plagioclase and sulfide minerals and small amounts of biotite, chromspinel, ilmenite and magnetite. The results suggest that: a/ There are two types of ilmenite, that were formed in two distinct stages: Early Mg-rich ilmenite was formed at intermediate magma chamber and latter Mn-rich ilmenite was formed at crystallized magma chamber; b/ Original magma of Suoi Cun plagiolherzolite and melano gabbroid was derived from sub-continental lithospheric mantle; c/ magnetite was formed at latter stage by two processes: serpentinization and alteration of early sulfide minerals.