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大西沟-银硐子铁-银-铅锌-铜矿床位于中秦岭晚古生代弧前盆地的山阳-柞水矿集区内,矿床产于中泥盆统大西沟组中,主要发育有与地层产状相同的磁铁矿矿石、含重晶石-菱铁矿的纹层状磁铁矿矿石、磁铁矿-硫化物(黄铁矿、黄铜矿)-石英脉型及块状磁铁矿矿石。通过对4种不同矿化类型矿石的磁铁矿进行电子探针及微量、稀土元素的分析,结果显示不同类型的磁铁矿FeOt含量与Al_2O_3,CoO,MgO,SiO_2质量分数整体上均呈负相关关系;从顺层产出的矿石到块状、脉状及纹层状矿石,磁铁矿的FeOt质量分数(分别为49.65%~84.18%,91.5%8~93.39%,92.69%~93.6%,92.25%~93.39%)在逐渐增加,说明有后期含铁物质的富集。在w(TiO_2)-w(Al_2O_3)-w(MgO+MnO)和w(MgO)-w(TiO_2)-w(Al_2O_3)图解中,大西沟-银硐子矿床的磁铁矿表现出既有热水沉积成因,也有热液成因的特征。同时不同产出状态的磁铁矿均富集Mg,Mn元素,并具有相对较低的Ti(6.82×10~(-6)~451×10~(-6),平均324×10~(-6)),V(11.5×10~(-6)~625×10~(-6),平均378×10~(-6)),Sc(0.78×10~(-6)~1.49×10~(-6),平均1.03×10~(-6))质量分数及Co/Ni,Zn/V和Sn/Ga比值,显示具有热液成因特征,而且从层状矿石到块状、脉状及纹层状矿石,热液作用具有逐渐增强的趋势。不同矿化类型的磁铁矿均表现出明显的负Eu异常,但从层状矿石(δEu为0.32)到块状(δEu为0.72)、脉状(δEu为0.48~0.79)及纹层状矿石(δEu为0.57~0.58),负Eu异常逐渐减弱,说明整个成矿环境的氧化性在逐渐增强,但总体仍处于还原环境。因此,研究表明大西沟-银硐子矿床在成矿作用过程中受到后期热液活动影响,成矿作用发生于氧化性增强,还原性减弱的成矿环境。
The Daxigou-Yinshitai iron-silver-lead-zinc-copper deposit is located in the Sanyang-Zhashui coal concentration area of the Late Paleozoic forearc basin in the Qinling Mountains. The ore deposit is mainly produced in the Daxigou Formation of the Middle Devonian Magnetite ore with the same stratum shape, lamellar magnetite ore containing barite-siderite, magnetite-sulphide (pyrite, chalcopyrite) - quartz veins and massive Magnetite ore. The results showed that the content of FeOt and the mass fraction of Al 2 O 3, CoO, MgO and SiO 2 in different types of magnetite were all negative The mass fraction of FeOt (from 49.65% to 84.18%, 91.5% 8 to 93.39%, 92.69% to 93.6%, respectively) from magnetite to block, vein and laminar ore, , 92.25% ~ 93.39%) is gradually increased, indicating the enrichment of later iron-containing substances. Magnetite of the Daxigou-Yinduzi deposit shows both existing (w / v) and / or Genesis of hydrothermal deposits, but also hydrothermal causes of the characteristics. At the same time, the magnetite with different output status is enriched in Mg and Mn elements and has a relatively low content of Ti (6.82 × 10 -6 ~ 451 × 10 -6) with an average of 324 × 10 ~ (- 6), V (11.5 × 10 -6 -625 × 10 -6, average 378 × 10 -6), Sc (0.78 × 10 -6 -6.49 × 10 -6) (-6) with an average of 1.03 × 10 -6 (mass fraction) and Co / Ni, Zn / V and Sn / Ga ratios, indicating that it has hydrothermal characteristics and that from layered ore to massive, Layered ore, hydrothermal effect has a gradual increase in the trend. The magnetites with different types of mineralization all showed obvious negative Eu anomalies, but from layered ore (δEu 0.32) to massive (δEu 0.72), vein (δEu 0.48 ~ 0.79) and laminar ore (δEu is 0.57 ~ 0.58), the negative Eu anomaly gradually weakened, indicating that the oxidation of the metallogenic environment is gradually enhanced, but the overall is still in the reducing environment. Therefore, the study shows that the Daxigou-Yinduzi deposit is affected by late hydrothermal activities during mineralization, and the mineralization takes place in the ore-forming environment with enhanced oxidation and reduced reducibility.