陕西凤太矿集区东塘子铅锌矿床地质-地球化学特征与成因

东塘子铅锌矿床位于南秦岭凤太矿集区南部，铅锌矿体产于中泥盆统古道岭组灰岩与上泥盆统星红铺组千枚岩接触界面，受背斜构造与硅钙岩性界面控制。热液成矿作用过程可划分为脉状硫化物-铁碳酸盐-石英(Ⅰ)、块状硫化物-碳酸盐(Ⅱ)、方解石石英脉-贫硫化物(Ⅲ)、厚大石英碳酸盐脉-贫硫化物(Ⅳ)4个阶段，其中，Ⅰ、Ⅱ阶段为主成矿阶段。东塘子乃至整个凤太矿集区内铅锌矿床成因认识的分歧主要集中在沉积成因和热液成因之争，进一步研究矿床成因是凤太矿集区深部找矿预测的基础。通过矿石的结构构造、黄铁矿成分、H-O同位素组成、微量元素地球化学特征等研究，对东塘子铅锌矿床成因进行探讨。结果表明:东塘子铅锌矿床脉状与块状矿石中的黄铁矿w(Co)/w(Ni)平均值分别为18.70与8.56，为热液成因；矿石δD_V-SMOW值为-94.9‰～-83.3‰，平均值为-87.0‰，δ¹⁸O_H2O值为8.0‰～11.1‰，平均值为9.8‰，成矿流体早期主要来源于岩浆水，晚期有地层水与大气降水混入。综合矿床地质、地球化学、H-O同位素等特征，认为东塘子铅锌矿床属于受中泥盆统古道岭组灰岩与上泥盆统星红铺组千枚岩之间“硅钙面”控制的岩浆热液型矿床，矿床深部可能存在隐伏岩体与成矿作用中心，深部找矿潜力较大。

Geological-geochemical Characteristics and Genesis of Dongtangzi Pb-Zn Deposit in Fengxian-Taibai Ore Concentration Area of Shaanxi,China

Dongtangzi Pb-Zn deposit is located in the southern Fengxian-Taibai ore concentration area of South Qinling. The Pb-Zn ore body develops in the contact zone between the limestone of the Middle Devonian Gudaoling Formation and the phyllite of the Upper Devonian Xinghongpu Formation, and is controlled by the anticline structure and the calceo-lithium interface. The processes of hydrothermal mineralization can be divided into four stages, including vein-like sulphide-iron carbonate-quartz(Ⅰ), agglomerate sulphide-carbonate(Ⅱ), calcite quartz vein-depleted sulphide(Ⅲ) and large quartz carbonate vein-depleted sulphide (Ⅳ), and the Ⅰ and Ⅱ are major mineralization stages. The divergence of the understanding of Pb-Zn deposits in Dongtangzi, even in the entire Fengxian-Taibai ore concentration area, mainly focuses on the disputes of depositional genesis and hydrothermal genesis, and the study on the genesis of deposits is the basis for the deep ore-prospecting prediction in Fengxian-Taibai ore concentration area. The genesis of Dongtangzi Pb-Zn deposit was discussed through the studies of ore texture and structure, pyrite components, H O isotope composition, geochemical characteristics of trace elements in wall rocks and ores. The results show that the average values of w(Co)/w(Ni) in the vein-like and agglomerate pyrites are 18.70 and 8.56, respectively, indicating a hydrothermal genesis; the δD_V-SMOW values of ores range from -94.9‰ to -83.3‰ with an average value of -87.0‰, and the δ¹⁸O_H2O values range from 8.0‰ to 11.1 ‰ with an average value of 9.8‰, indicating that the ore-forming fluids mainly come from the magma water in the early stage, and the formation water and the atmospheric precipitation mix lately. Combination of the deposit geology, geochemistry, H-O isotopes and other characteristics, Dongtangzi Pb-Zn deposit might be one of magma hydrothermal type ores, which is affected by “calceo-lithium interface” between the limestone of the Middle Devonian Gudaoling Formation and the phyllite of the Upper Devonian Xinghongpu Formation. Therefore, the concealed rock bodies and mineralization centers may exist in the deep, and have a greater prospecting potential.