金与铅锌矿化的时空关系及应用

近10年来，在秦岭铅锌矿带和青城子铅锌矿田等地相继发现了一批大、中型金矿床。铅锌矿和金矿床共同产出在同一构造背景下，金矿床通常位于铅锌矿之上，金矿的成矿时代明显晚于铅锌矿。初步的地质－地球化学研究表明：铅锌矿床形成于具高水岩比、高卤化物和高盐度特征的海底沉积喷流系统；此时，大多数的金迁移至低温热液柱中并在沉积物中初始富集。在后期（岩浆－）变质－构造作用过程中，金被转移至中高温、低水岩比和低卤化物活度的变质流体中，在有利的构造部位发生沉淀，在同一构造单元内成矿流体的成分和循环方式的差异引起金与铅锌矿床共存和分离。金与铅锌矿床的这一时空分布关系可被视为重要的勘查标志。根据金与铅锌矿化的时空关系，笔者提出应加强对我国元古宇宙裂谷、晚古生代拗陷内重要铅锌矿田的金、铅锌矿的勘查工作。

The Space-Time Relationship of Gold to Lead-Zinc Mineralization and Its Application

In 1990s, some medium-large-size gold deposits were sucessively discovered in such lead-zinc metallogenic belts of China as the Qinling lead-zinc metallogenic belt in Shaanxi Province and Gansu Province, and the Qingchengzi lead-zinc orefield in Liaoning province. Gold deposits and lead-zinc deposits spatially coexist in the same tectonic unit, whereas lead-zinc orebodies commonly occur beneath gold orebodies, with gold mineralization being obviously younger than lead-zinc mineralization. According to the preliminary geological-geochemical study, lead-zinc precipitated from the marine sedimentary-exhalative system characterized by high water/rock ratio, high salinity and abundant chlorides; at the same time, most of gold was transported into epithermal plume and primarily accumulated in sediments. At late (magmatism) metamorphism-tectonism stage, gold migrated into the medium-high temperature metamorphic fluids characterized by low water/rock ratio and low activity of chlorides, and precipitated at the favorable structural site. In the same tectonic unit, therefore, the coexistence of gold and lead-zinc deposits and the separation of gold from lead-zinc resulted from the differences in chemical constituents and circulation forms of ore-forming fluids. Such a space-time relationship between gold and lead-zinc can be used as a criterion in mineral exploration. According to the space-time relationship of gold to lead-zinc mineralization, greater importance should be attached to the prospecting for gold and lead-zinc deposits in Proterozoic rifts and Paleozoic depressed basins of China.