THE CHARACTERISTICS OF THE GOLD DEPOSITS OF TECTONIC ALTERED ROCK TYPE IN THE OPHIOLOTE OF NORTH AILAO MOUNTAIN

The gold deposits of tectonic altered rock type in the ophiolite of North Ailao Mountain are located in the basalts and pyroclastic rocks of the upper ophiolite. The gold deposits are all under the control of northwest faulted structure, and associated with the different veins of lamprophyres and granodioritic porphyrys which have to do with ore-forming process. First wall-rock alteration is carbonation, second are sericitization and pyritisation. Main metallic sulphide ores are pyrites, arsenopyrites, stibnites, and form the different assemblages of min-eralization. The forming temperature of the gold deposits is low-to-moderate. The compo-sition of the fluid inclusions is abundant in Na⁺, Zn²⁺, Cl^-, SO₄^2-, H₂O, CO₂ and so on. The main enrichmicroelements of the gold deposits are As, Sb, W, and REE evolutionary charac-teristics are LREE depressing and HREE increasing. Sulfur and oxygen isotope composition displays that the gold deposits are low-to-moderate hydrothermal deposits and their ore-forming solution is mainly composed of the magmatic hydrothermal solution which is added in some underground water.