Abstract:
The Tangba gold deposit is located at the eastern section of the Yangshan-Shijiba gold mineralization belt in the southern part of the Western Qinling. The ore body is occurred in the strata of Paleozoic Lower Devonian Qiaotou Formation, which is closely related to the granite porphyry vein in space. The ore body and the vein are controlled by the fault in the fold's axial part. The ore body is occurred as veined and lens texture. The ore minerals are mainly pyrite and arsenopyrite, and the surrounding rock alterations are mainly silicification, sericitization and carbonation. The
δ18OH
2O(V-SMOW) values of main ore-forming fluid vary from 7.89‰ to 9.97‰,
δD(V-SMOW) values range from -81.3‰ to -77.0‰, and the pyrite
δ34S(‰) change from -1.3‰ to 0.8‰, with an average of -0.23‰, showing the characteristics of deep source sulfur. The zircon U-Pb dating age is (212.8±2.7)Ma for granite porphyry. The test analysis of fluid inclusions in this mining area shows that the ore-forming hydrothermal fluid has the characteristics of medium-low temperature and low salinity. The complete uniform temperature range of CO
2 phase in the main ore-forming period is 252.6℃~342.8℃, with an average of 279.72℃. The volume uniform temperature range is 156.9℃~307.6℃, and their average value is 256.7℃. The comprehensive study considers that this deposit belongs to a medium-low temperature magmatic hydrothermal gold deposit associated with magmatic activity.