The Xiaoban gold deposit is a large-size deposit recently found in middlearea of Fujian Province. It belongs to magmatic hydrothermal type occurred in Mayuan Groupmetamorphic rocks of Middle Proterozoic and is control...The Xiaoban gold deposit is a large-size deposit recently found in middlearea of Fujian Province. It belongs to magmatic hydrothermal type occurred in Mayuan Groupmetamorphic rocks of Middle Proterozoic and is controlled by low angle fault (detachment)structures. The contents of Au in Mayuan Group metamorphic rocks, Caledonian-Indosinian deformedgranite and early Yanshanian granite are higher with Au enrichment coefficient of 2. 06-5.68, 5.11and 6.67 than those in other geological bodies. And the higher enrichment coefficients (>2) of Ag,S, Sn and Te are similar to those of gold ore. Meanwhile, the distribution of Au in Mayuan Groupmetamorphic rocks and early Yanshanian granite with a low D-value (0.58 and 0.67) is favorable togold mineralization. REE characteristics of gold ore, ratios of (LREE/HREE), (La/Sm)_n, (Yb/Lu)_n,(La/Tb)_n and (Sm/Nd)_n are similar to Mayuan Group metamorphic rocks, only non or little normal Euabnormal of ore is dissimilar to metamorphic rocks. The δ(^(34)S) of the gold ore, with a highhomogenization, is (-4.7X10^(-3) - (-2.7X 10^(-3)). The study of inclusion indicates 180-249℃ ofmineralization temperature, 3. 69 %-11. 81 % of salinities and 0. 869-0.991 g/cm^3 of densities ofmineralization fluid. Based on hydrogen and oxygen isotope (δ(^(18)O) = 11. 0 X 10^(-3) -11.7 X10^(-3), δ(D) = (-48 X 10^(-3)) - (-62 X 10^(-3))) and initial w(^(87)Sr)/w(^(86)Sr) =0. 715,combining to the analysis of geological history, regional metamorphism and magamtic activity, theauthors confirm that the source for the ore fluid was mainly from magmatic, partly from metamorphicwater, and with a little influence of meteoric water. Isotopic dating made on Rb-Sr isochron age of182 Ma, by using alteration minerals of gold-ores from the deposit, indicates that themineralization occurs in early Yanshanian epoch. This is close to the age of 187 Ma of the Anchunmagmatite with a similar alteration and gold mineralization to the Xiaoban gold deposit. The age ofearly Yanshanian epoch of the Xiaoban gold is indentical with the characteristics of southern Chinagold metal-logenic belt and the geotectonic evolution of the transition from paleo-Asian system andpaleo-Tethyan system to paleo-Pacific active continental margin in eastern Asia.展开更多
文摘The Xiaoban gold deposit is a large-size deposit recently found in middlearea of Fujian Province. It belongs to magmatic hydrothermal type occurred in Mayuan Groupmetamorphic rocks of Middle Proterozoic and is controlled by low angle fault (detachment)structures. The contents of Au in Mayuan Group metamorphic rocks, Caledonian-Indosinian deformedgranite and early Yanshanian granite are higher with Au enrichment coefficient of 2. 06-5.68, 5.11and 6.67 than those in other geological bodies. And the higher enrichment coefficients (>2) of Ag,S, Sn and Te are similar to those of gold ore. Meanwhile, the distribution of Au in Mayuan Groupmetamorphic rocks and early Yanshanian granite with a low D-value (0.58 and 0.67) is favorable togold mineralization. REE characteristics of gold ore, ratios of (LREE/HREE), (La/Sm)_n, (Yb/Lu)_n,(La/Tb)_n and (Sm/Nd)_n are similar to Mayuan Group metamorphic rocks, only non or little normal Euabnormal of ore is dissimilar to metamorphic rocks. The δ(^(34)S) of the gold ore, with a highhomogenization, is (-4.7X10^(-3) - (-2.7X 10^(-3)). The study of inclusion indicates 180-249℃ ofmineralization temperature, 3. 69 %-11. 81 % of salinities and 0. 869-0.991 g/cm^3 of densities ofmineralization fluid. Based on hydrogen and oxygen isotope (δ(^(18)O) = 11. 0 X 10^(-3) -11.7 X10^(-3), δ(D) = (-48 X 10^(-3)) - (-62 X 10^(-3))) and initial w(^(87)Sr)/w(^(86)Sr) =0. 715,combining to the analysis of geological history, regional metamorphism and magamtic activity, theauthors confirm that the source for the ore fluid was mainly from magmatic, partly from metamorphicwater, and with a little influence of meteoric water. Isotopic dating made on Rb-Sr isochron age of182 Ma, by using alteration minerals of gold-ores from the deposit, indicates that themineralization occurs in early Yanshanian epoch. This is close to the age of 187 Ma of the Anchunmagmatite with a similar alteration and gold mineralization to the Xiaoban gold deposit. The age ofearly Yanshanian epoch of the Xiaoban gold is indentical with the characteristics of southern Chinagold metal-logenic belt and the geotectonic evolution of the transition from paleo-Asian system andpaleo-Tethyan system to paleo-Pacific active continental margin in eastern Asia.
