Isotopic Characteristics and Causes of Formation of Mawu Gold Deposits in Minxian County, Gansu

Mawu deposit is a medium-scale gold deposit,located in the east part of Minxian and the middle of metallogenic belt Min-Li.Ore formation,source of ore-forming materials and metallogenic geological background of Mawu are similar to the gold deposits of the Zhongchuan area.The test results of quartz reef of the main ore-forming stage of Mawu show that the hydrogen and oxygen isotopes are: δD is-78～-98‰,δ¹⁸OSMOW is 18.0～20.2‰,δ¹⁸Owater is 0.45～8.54‰,and the ore-forming fluids are the magmatic water,metamorphic water,metamorphic water and atmospheric precipitation in a mixture of water,of which the magmatic water and metamorphic water are the main water.In quartz reef of the main ore-forming stage,δ³⁴S is+7.1-+7.9‰,the average is+7.65‰,and the δ³⁴S shows smaller changer in the scope,showing the characteristics of formation of stratum sulfur.Isotopic data regional geological background and diagenetic mineralization characteristics have been combined with the region,showing that the mineralization of fluids relative well to magma function and inrush of Zhongchuan rock-body,the main ore-forming fluids from the magma and the formation,and have varying degrees of mixing with meteoric water.The main sources of ore-forming materials are from the strata and deep sources.