Recent exploration of the Gorno Zn-Pb-Ag deposit in northern Italy identified 3.3 Mt of sulfides at 4.9% Zn, 1.3% Pb, and 27.2 g/t Ag (indicated+inferred resources), and a further mineralized nucleus of mixed sulfides-nonsulfides in the Val Vedra area, currently under evaluation. The ores are hosted in Triassic limestone and shale. Sulfides (sphalerite, Ag-bearing galena, minor pyrite, and chalcopyrite) paragenetically follow Mn-Fe-bearing saddle dolomite and sparry calcite. The mineral association, and the carbon and oxygen isotope ratios of the sparry calcite (avg. δ 13 C = 1.0 ± 0.6‰ V-PDB; avg. δ 18 O = 19.63 ± 1.25‰ V-SMOW), are in agreement with precipitation from hydrothermal fluids in a deep burial setting. Sulfide emplacement occurred before the Alpine orogeny, likely during the Early-Middle Jurassic, in analogy to other Alpine-type deposits. The nonsulfide ore formed at the expense of sulfides, and mainly consists of smithsonite, hydrozincite, hemimorphite, and cerussite. The C-O-isotope values of the early generations of Zn-carbonates are characterized by δ 18 O between 24.1 and 26.8‰ V-SMOW and δ 13 C ratios between − 3.1 and 1.7‰ V-PDB. The later generations have lower δ 18 O (21.9 to 23.9‰) and lower δ 13 C (− 6.2 to − 3.9‰). These compositions, as those measured on cerussite (δ 13 C = −6.3 and − 7.7‰; δ 18 O = 14.0 and 15.3‰), agree with the formation of the nonsulfides in a supergene environment, under climatic conditions warmer than today. The δ 18 O decrease from early to late generations suggests progressive involvement of meteoric water sourced from higher altitudes. These characteristics indicate that the nonsulfides formed during the exhumation of the Gorno area from Miocene to Pliocene.

中文翻译：

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Gorno Zn 项目（意大利贝加莫）中从高山型硫化物到非硫化物

最近对意大利北部 Gorno Zn-Pb-Ag 矿床的勘探发现了 3.3 Mt 硫化物，其中 Zn 含量为 4.9%，Pb 含量为 1.3%，Ag 含量为 27.2 g/t（指示+推断资源），以及进一步矿化的混合硫化物核 - Val Vedra 地区的非硫化物，目前正在评估中。矿石位于三叠纪石灰岩和页岩中。硫化物（闪锌矿、含银方铅矿、次要黄铁矿和黄铜矿）与含锰铁的鞍状白云岩和闪长方解石共生。矿物组合以及闪晶方解石的碳和氧同位素比（平均 δ 13 C = 1.0 ± 0.6‰ V-PDB；平均 δ 18 O = 19.63 ± 1.25‰ V-SMOW）与降水一致来自深埋环境中的热液。硫化物侵位发生在阿尔卑斯造山运动之前，可能发生在早中侏罗世，类似于其他高山型矿床。以硫化物为代价形成的非硫化物矿石，主要由菱锌矿、水锌矿、异极铁矿和铜辉石组成。早期碳酸盐锌的 CO 同位素值的特征是 δ 18 O 介于 24.1 和 26.8‰ V-SMOW 之间，δ 13 C 比率介于 − 3.1 和 1.7‰ V-PDB 之间。后代具有较低的δ 18 O（21.9 至 23.9‰）和较低的 δ 13 C（- 6.2 至- 3.9‰）。这些成分，如在铜辉石上测量的成分（δ 13 C = -6.3 和 - 7.7‰；δ 18 O = 14.0 和 15.3‰），与表生环境中非硫化物的形成一致，在比今天更温暖的气候条件下。δ 18 O 从早代到晚代的减少表明来自更高海拔的大气水的逐渐参与。