Origin of the intrusion-related Lang Vai gold-antimony district (Northeastern Vietnam): Constraints from fluid inclusions study and C O S Pb isotope systematics

•Magmatic fluid was the initial ore-forming fluid for the deposits of the Lang Vai ore district.•Boiling of fluids controlled the mineralization process.•The early fluids were dominated by CH4, the late fluids – by CO2.•Sulfur and carbon isotopes suggest a magmatic origin.•A typical intrusion-related gold deposits located in the Lo Gam domain, North East Vietnam.