江西德兴铜厂铜矿水－岩体系氢氧同位素演化

江西铜厂铜矿床露天采场岩石76个全岩氧同位素组成表明,该超大型铜矿的形成与具有5个水-岩交换成矿体系汇集在一起有关。水-岩体系计算表明,成矿流体储库形成是大气降水与千枚岩和花岗闪长斑岩在300℃以及W/R比值为0.5左右条件下形成,而后上升进入矿化沉积体系时温度降低,W/R比值超过10.0,计算的最少水量达1.9×10¹⁰t以上。

HYDROGEN AND OXYGEN EVOLUTION FOR WATER-ROCK SYSTEM IN SUPER-HUGE TONG CHANG COPPER DEPOSIT,JIANGXI PROVINCE

Tile super-Luge Tongciiang porpliyry Cu deposit in Dexin, liangxi province.characterized by dissenxinated ore, occurs in the two sides of contact zone btween the granodiorite porphry and the low grade met:smorphie talf of Sutanqiaoshan Formation, Middle Proterozoic era.A fairly systematic oxygen (hydrogen) isotope study was madc on diffcrcnt stagcs of orc-forming fluids and altered rocks in the deposit It is known that for the main ore-fornung stage of quartz veins,δ¹⁸O=1.9‰to -2.5‰ δD and δD=-54‰ to -62‰,and that for hydrothermal solution of the late stage of quartz vine, δ¹⁸O=-3.4‰ and δD=-57‰.Systematic planar sampling and oxygen isotope analysis were performed in the openpit working of the deposit, and the results reveal that the variations of oxygen isotope compositions for altered rocks from about δ¹⁸O=6‰ to 13‰and show that There are at lcast 5 water-rock interaction low 18O centers indicated. On the oxygen isotope contour map,the extent of 5 water-rock interaction renters are quite coincident with the localites of superhuge copper orebogies.The δD of al tered rocks(whole rock) and ore-forming fluid are about-85‰ and -60‰,respectively,showing an cquilibrated fractionation between altered minerals and mincralization tluids. The water content in altered rock is higher than 2% in Tongchang Cu deposit but lower than 2% in the other deposits such as Yinshan, Lengshuikeng tunic near by the Tongehang mine in which,appear H isotope kineLie fractionation in water-rock interaction system. Studies,how that the higher H₂O content in Tongchang is related to the superimposed water-rock interactions.The effective W/R ratio and temperature for the Tongchang porphyry type Cu(Mo)depusits at the hydrothermal fluid reservoir forming period is 0.5 to 1.0 and 300℃,bat it is higher than 10.0 and lower than 250℃ diaring the of water-rock interacaions mineralization deposition. In addition, the minimum etffective H₂O weight in water-rock system in super-faint copper district is about 1.9×10¹⁰tons.We conclude that the super-huge Tongchang Cu(Mo)deposit was formed at peculia water-rock system.