浙西南龙泉塘上铅锌矿床成矿流体来源、演化及其地质意义

Fluids source,evolution and geological implications of the Tangshang Pb-Zn polymetallic deposit,Longquan,SW Zhejiang

塘上铅锌矿床是浙西南地区武夷山Cu-Pb-Zn多金属成矿带新近发现的中型铅锌多金属矿床,其空间产出受断裂构造控制,其成因类型尚不明确。本文在详细划分成矿阶段的基础上,对不同成矿阶段的流体包裹体开展显微测温、激光拉曼和H-O同位素分析。研究表明,成矿早阶段磁铁矿-石英阶段(Ⅰ)形成温度为273~348℃,主成矿阶段脉状方铅矿闪锌矿阶段(Ⅱ)均一温度为225~304℃,成矿晚阶段石英-石英脉阶段(Ⅲ)均一温度为139~163℃。激光拉曼分析结果显示主成矿阶段成矿流体液相成分以H_(2)O为主,气相成分除H_(2)O外,还有一定量的CO_(2)。石英脉中石英包裹体δD_(SMOW)主要集中在-72.5‰~-78.9‰,石英δ^(18)O _(V-PDB)数值为-27.6‰-~30.8‰,δ^(18)O_(V-SMOW)集中在-0.6‰~2.5‰,表明塘上铅锌矿床成矿流体来源于岩浆流体,并在成矿过程中有大气降水的逐渐加入。因此,塘上铅锌矿床深部可能具有进一步寻找斑岩型矿化的潜力。

The Tangshang Pb-Zn deposit is a medium-sized Pb-Zn polymetallic deposit recently discovered in the Wuyishan Cu-Pb-Zn polymetallic metallogenic belt in southwest Zhejiang.Its spatial output is controlled by fault structures,and its genetic type is not yet clear.In this paper,based on the detailed division of the mineralization stages,microthermometry,laser Raman and H-O isotope analysis were carried out on the fluid inclusions of different mineralization stages.Studies have shown that the formation temperature of the magnetite-quartz stage(Ⅰ)pre-ore period was 273-348℃,and the uniform temperature of the vein-like galena sphalerite stage(Ⅱ)during the main ore-forming period was 225-304°C,and the post-ore period was late.Stage Quartz-quartz vein stage(Ⅲ)homogeneous temperature is 139-163℃.Laser Raman analysis results show that the liquid phase composition of the ore-forming fluid in the main ore-forming stage is mainly H_2O,and the gas phase composition contains a certain amount of CO_(2) in addition to H_2O.The δD_(SMOW) of quartz inclusions in the quartz veins is mainly concentrated at-72.5‰--78.9‰,the value of quartz δ~(18)O _(V-PDB) is-27.6‰--30.8‰,and the δ~(18)O_(V-SMOW) is concentrated at-0.6‰-2.5‰,indicating that the ore-forming fluid comes from magmatic fluid,and there is gradual addition of atmospheric precipitation during the mineralization process.Therefore,the deep part of the Tangshang Pb-Zn deposit may have the potential to further exploration for porphyry-type mineralization.