Abstract:Zhilintou is the place of a well-known gold-silver ore deposit ore the southeastern coastal area of China. In the mining district, there are exposed Upper Mesozoic acidic volcanic rocks and Precambrian metamorphic rocks. The metamorphic rocks, which are the host rocks of extensive quartz ore veins, consist mainly of some kinds of gneisses and have complex structures characterized by well developed fissures. In the ore, there exist such metallic minerals as pyrite, sphalerite, galena, chacopyrite and various kinds of gold and silver minerals. The metamorphic rocks in the mining district are rich in gold and silver (averagely gold 11.9 ppb, silver 550 ppb). In both sides of the ore vein, however, the gold content of the metamorphic rocks decreases evidently (merely 4.77 ppb on average), and the distribution of the gold becomes quite irregular. All this suggests that gold in these parts was mobilized and migrated in an uneven manner. The measuring of the variation in gold content along a section transecting the gold veins has confirmed this conclusion. The gold abundance increases with the distance, indicating the undoubted migration of gold from the surrounding rocks into the ore veins. The measured amount of the migrated gold is much higher than the gold reserve of the deposit. lt is also found that the Cu, Pb and Zn in the surrounding rocks show a tendency of migration into and concentration in the ore veins. The characteristics of trace elements in the ore is quite similar with those in the metamorphic rocks. The lead model dates of the ore are close to the ages of the metamorphic rocks, and the sulfur isotope composition of the ore is similar with that of the metamorphic rocks. lt is there-fore obvious that gold, silver and other ore materials in the ore must have mainly come from the metamorphic strata. ln other words, the strata must have served as the source bed. The ore-forming hydrothermal solutions bear the characteristics of "oxygen isotope shift”, that is, with the δ18O and δD data of the ore fluids, one can draw a horizontal straight line parallel to the δ18O axis of the aδD-δ18O coordinate. This is typical for the heated rain water in a convection system within the lithosphere. Considering the geological setting, the authors hold the opinion that it was the heated rain water that mobilized the ore materals in the metamorphic rocks, and then transported and concentrated them in tension-shearing fissures, thus forming the Zhilintou ore deposit.
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郑明华, 刘建明.1986.论浙江治岭头金银矿床的成矿物质来源[J].矿床地质,5(1):39~52.1986.Material Sources Of The Zhilintou Gold-Silver Ore Deposit In Zhejiang Province[J].Mineral Deposits5(1):39~52
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