中文摘要:产于沉积建造包括火山沉积建造中的许多层控金属矿床,往往是沉积盆地内沉积物在沉积期后不同演化阶段上的派生产物。弥满在沉积物中的地层水,在沉积建造所经历的沉积,成岩、后生直至变质的不同演化阶段,永温和水质也随之发生变异,从而对分散在沉积物中的不
同金属成矿物质具有不同淋滤萃取能力,使它们有先有后地发生迁移,而后在地球化学障壁部位尤其是在不同水质的混合带附近发生沉淀,形成不同矿化特色的矿床。每一个汇水-径流-排泄单元,就是一个成矿地质单元。这些矿床的控矿地质因素,很大程度上就是控制沉积物形成和演化的因素,尤其是控制地层水水温水质演化和活动规律的古水文地质因素,与油气藏的形成既有相似之处也有差别。
中文关键词:沉积物演化 金属元素活化转移窗口 成矿地质单元 永质混台带
Abstract:Lots of metallic deposits, mainly volcanic hydrothermal sedimentary deposits, diagenetic deposits and epigenetic deposits, occur in definite stratigraphic horizons and might have rather differential mineralization characteristics and ore assemblages. These deposits seem to have been formed through the following processes: driven by geopressure, geothern or water head, the paleogroundwater of different qualities and temperatures enclosed in sediments of different evolutionary stages in sedimentary basins must have had physical-chemical reaction with the sediments in the runoff area it flowed through and thus leached out ore-forming substances from them. Later, these ore-forming materials precipitated at the positions where drastic physical-chemical changes took place and hence formed ore deposits. In these processes, the quality and temperature of paleogroundwater evolved with the evolution of sediments and,in conformity with the specific geological.and structural conditions,made up respective independent hydrogeologic units, whereas the metallogenic materials were leached out and then migrated in turn in accord with the different qualities and temperatures of the paleogroundwater, as exemplified by the area of Devonian sediments in northern Guangdong where the migration proceeded mainly in order of Fe-Pb, Zn, (Hg)-Sb and(Hg)-Cu, W, Sn; afterwards, ore deposits were formed through the precipitation of these elements at geochemical obstacle places, of which, the zone near the drainage area where water of different qualities mixed was of the greatest significance for ore emplacement. Every catchment-run off-drainage unit of paleogroundwater thus made up a metallogenic geologic unit in which the formation of metallic deposits was basically similar to the formation of oil-gas fields, i. e., both were derivatives of sedimentary evolution. Nevertheless, metallic deposits were most likely to be formed at geochemical obstacle places where water could flow freely and might catch ore-forming substances; mineralizations, therefore, are fossilized relics left over by this sort of paleogroundwater activities. It is therefore concluded that the so-called ore-controlling geologic factors are actually various factors governing the formation and evolution of sediments, especially paleohydrogeologic factors governing the evolution of water quality and temperature of paleogroundwater as well as its regularity of activities. This subject deserves due attention and intensive studies.
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引用文本:
赖应銭.1988.沉积物演化与某些层控矿床的形成[J].矿床地质,7(1):42~53.1988.The evolution of sedimentary materials and the formation 0f certain sorts of stratabound deposits[J].Mineral Deposits7(1):42~53
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