矿床地质2011，Vol.30Issue(6)：1085-1099,15.
甘肃西和县大桥金矿床的成因研究
Genesis of Daqiao gold deposit in Xihe County, Gansu Province
摘要
Abstract
The Daqiao gold deposit lies between the Minxian-Dangchang fault and the Yaoshang-Shixia fault. Its gold mineralization exists in the lower lithologic member of lower Triassic formation bed, in which the siliceous breccia presents itself in the bedded form. Ores are pyritized siliceous breccia with high organic carbon content, and pyrite zones are well developed. Siliceous breccia and layered siliceous rocks do not show characteristics of hot-water sedimentary origin in REE patterns. The features of the Fe/Ti-Al/(A1 + Fe+ Mn) diagram and the phenomena that SiO2 is negatively correlated with Al2O3 and Sr/Ba< 1 indicate that siliceous breccia and lamellar siliceous rocks are clastic sediments. The authors thus hold that the Daqiao gold deposit is not of the hot-water sedimentary type. Zonal pyrite, well developed pyrite veins and high Co/Ni ratios suggest that hydrothermal solution played an important role in the formation of the ore deposit. Δ 34S values of pyrites are in the range of4.21%o~9.82%o, implying that the sulfur fluids were derived from mixed magmatic and stratigraphic sulfur or from metamorphic fluids. The homogenization temperature of fluid inclusions in quartz is mainly between 270°C and 310°C , belonging to medium temperature. Cluster analysis of siliceous breccia elements shows that Au is closely related to low temperature elements Hg and As, suggesting that the decrease of temperature might have been one of the mechanisms for gold mineralization. The Daqiao gold deposit is a middle-low temperature hy-drothermal gold deposit.关键词
地质学/硅质角砾岩/环带状黄铁矿/热水沉积型金矿床/中-低温热液型金矿床/西秦岭/甘肃Key words
geology, siliceous breccia, zonal pyrite, hot-water sedimentary gold deposit, middle-low temperature hydrothermal gold deposit, West Qinling, Gansu Province分类
天文与地球科学引用本文复制引用
刘月高,吕新彪,张振杰,尤关进,曹晓峰,王玉奇,刘阁..甘肃西和县大桥金矿床的成因研究[J].矿床地质,2011,30(6):1085-1099,15.基金项目
本文得到地质过程与矿产资源国家重点实验室自主项目"西秦岭地区构造-岩浆活动与成矿作用"资助 （）
