The Mazhuangshan area is located in the east of the Aqikekuduke Island Arc, where there are distributed intermediate\|acid magmatic rocks emplaced during the Middle\|Late Carboniferous. There are more than 20 orebodie...The Mazhuangshan area is located in the east of the Aqikekuduke Island Arc, where there are distributed intermediate\|acid magmatic rocks emplaced during the Middle\|Late Carboniferous. There are more than 20 orebodies in the area with an average gold grade \{6.4\}×10\+\{-6\} at present. The dominant metallic minerals are natural gold, auriferous silver, natural silver, pyrite and galena. Pyrite is the key gold carrier, high in Fe and low in S. Wall\|rock alterations mainly include pyritization, silicification, and sericitization. Carbonation alteration was extensive at the late stage, often resulting in a high\|grade orebody. Three mineralization stages may be distinguished. \; The peak homogenization temperatures of primary fluid inclusions range from 240 to 260℃. Mineralization pressures and depths are 47.2-68.8 MPa and 1.6-2.3 km respectively, showing the ore\|forming features of hypergene gold deposit. The average salinity is 15 wt% NaCl equivalent. Fluid inclusion geochemistry data show that Ca\+\{2+\} is far higher than Mg\+\{2+\}, and m\-\{K\++\}/m\-\{Na\++\}, m\+2\-\{Na\++\}/m\-\{Ca\+\{2+\}\} (\{0.001\}～\{0.338\}), m\-\{∑Cl\}/m\-\{∑S\} and m\-\{∑C\}/m\-\{∑S\} ratios change with the reduction parameter \R=(CO+CH\-4)/CO\-2\] and temperature. And the gold contents of ores and gangues are positively correlated with and temperature. And the gold contents of ores and gangues are positively correlated with R. \; The pH values of inclusion water in quartz range from 5.8 to 7.4. Oxygen fugacity (f\-\{O\-2\}) ranges from 10-55 Pa to 10-47 Pa, sulfur fugacity (f\-\{S\-2\}) is about 10-13, and Eh values are estimated to be about -0.6 eV. The \{δ\{\}\+\{34\}S\} values of the fluid were determined to be \{+3.94‰\} to \{+4.98‰\}. \{\{\}\+\{206\}Pb\}/\{\{\}\+\{204\}Pb\} and \{\{\}\+\{207\}Pb\}/\{\{\}\+\{208\}Pb\} ratios in pyrite are \{18.269\}-\{18.352\}, \{15.550\}-\{15.633\} and \{38.077\}-\{38.355\}, respectively. The ΣREE values (\{4.7\}×10\+\{-6\}～\{43.1\}×10\+\{-6\}) of ores and gangues are obviously lower than those of the host magmatic rocks, but their REE and trace element spider diagrams are similar to those of the host magmatic rocks, suggesting that the water consists dominantly of meteoric water, mixed with a part of magmatic water. The metallogenic element mostly came from magmatites. The deposit is closely related to host magmatic rocks. The deposit is classified as a Middle\|Late Carboniferous hypabyssal meso\| and hypothermic gold deposit.展开更多
文摘The Mazhuangshan area is located in the east of the Aqikekuduke Island Arc, where there are distributed intermediate\|acid magmatic rocks emplaced during the Middle\|Late Carboniferous. There are more than 20 orebodies in the area with an average gold grade \{6.4\}×10\+\{-6\} at present. The dominant metallic minerals are natural gold, auriferous silver, natural silver, pyrite and galena. Pyrite is the key gold carrier, high in Fe and low in S. Wall\|rock alterations mainly include pyritization, silicification, and sericitization. Carbonation alteration was extensive at the late stage, often resulting in a high\|grade orebody. Three mineralization stages may be distinguished. \; The peak homogenization temperatures of primary fluid inclusions range from 240 to 260℃. Mineralization pressures and depths are 47.2-68.8 MPa and 1.6-2.3 km respectively, showing the ore\|forming features of hypergene gold deposit. The average salinity is 15 wt% NaCl equivalent. Fluid inclusion geochemistry data show that Ca\+\{2+\} is far higher than Mg\+\{2+\}, and m\-\{K\++\}/m\-\{Na\++\}, m\+2\-\{Na\++\}/m\-\{Ca\+\{2+\}\} (\{0.001\}～\{0.338\}), m\-\{∑Cl\}/m\-\{∑S\} and m\-\{∑C\}/m\-\{∑S\} ratios change with the reduction parameter \R=(CO+CH\-4)/CO\-2\] and temperature. And the gold contents of ores and gangues are positively correlated with and temperature. And the gold contents of ores and gangues are positively correlated with R. \; The pH values of inclusion water in quartz range from 5.8 to 7.4. Oxygen fugacity (f\-\{O\-2\}) ranges from 10-55 Pa to 10-47 Pa, sulfur fugacity (f\-\{S\-2\}) is about 10-13, and Eh values are estimated to be about -0.6 eV. The \{δ\{\}\+\{34\}S\} values of the fluid were determined to be \{+3.94‰\} to \{+4.98‰\}. \{\{\}\+\{206\}Pb\}/\{\{\}\+\{204\}Pb\} and \{\{\}\+\{207\}Pb\}/\{\{\}\+\{208\}Pb\} ratios in pyrite are \{18.269\}-\{18.352\}, \{15.550\}-\{15.633\} and \{38.077\}-\{38.355\}, respectively. The ΣREE values (\{4.7\}×10\+\{-6\}～\{43.1\}×10\+\{-6\}) of ores and gangues are obviously lower than those of the host magmatic rocks, but their REE and trace element spider diagrams are similar to those of the host magmatic rocks, suggesting that the water consists dominantly of meteoric water, mixed with a part of magmatic water. The metallogenic element mostly came from magmatites. The deposit is closely related to host magmatic rocks. The deposit is classified as a Middle\|Late Carboniferous hypabyssal meso\| and hypothermic gold deposit.
