华北陆块南、北缘铅锌矿床成矿特征对比

华北陆块北缘是中国重要铅锌成矿带,对其南缘地区铅锌矿的勘查近年进展明显,对比南、北缘成矿地质环境和矿床地质特征,有助于南缘地区铅锌找矿方向的进一步明确。对比分析表明,华北陆块南、北缘地质特征相似:南、北缘印支期铅锌成矿作用都不太发育,均在燕山期铅锌成矿明显;以与岩浆作用有关的接触交代、热液充填和变质热液成矿以及对早先形成的矿床或矿源层的变质改造作用为主,出现斑岩型、矽卡岩型、热液脉型及蚀变岩型等矿床类型;南、北缘铅锌矿都有由"层控"向"岩控"变化的趋势,成矿元素组合也由简单变得复杂。但华北陆块南、北缘不同的地质时代成矿的主导作用有所不同:北缘有太古宙VMS型矿床,而南缘发现的都是中元古代以来的矿床;北缘主要是元古宙和燕山期成矿作用,特别是中元古代Sedex型成矿作用更为显著,形成多个大型-超大型铅锌矿床,而南缘的成矿作用主要发生在古生代和燕山晚期,矿床规模多为中、小型,研究程度相对较低。栾川断裂以北的裂谷系中碳酸盐岩台地沉积有寻找MVT矿床的前景,宽坪岩群分布区可以作为今后寻找Sedex型铅锌矿床的重要地区。

Comparison of Pb-Zn metallogenic characteristics between northern and southern margins of North China Landmass

The northern margin of North China landmass is known as an important lead-zinc metallogenic belt in China. Nevertheless, lots of lead-zinc ore deposits (ore spots) were also discovered recently along the southern margin of North China landmass. A comparison of the metallogenic geological environment and characteristics of ore deposits between the two margins helps to determine the target areas in search for lead-zinc deposits in the southern margin. Geological history of the two margins of North China landmass shows a mass of similarities, so does the lead-zinc metallogenic characteristics. There exist unique genetic types of ore deposits in each geological epoch of the two margins. A VMS type copper-zinc-gold deposit formed in Archean was discovered on the northern margin, whereas all the Pb-Zn deposits discovered on the southern margin were formed after Mesoproterozoic. The most intense dynamic periods of metallogenesis on the northern margin of North China landmass are Proterozoic and Yanshanian, especially Mesoproterozoic, during which several large lead-zinc deposits were formed. Nevertheless, the strongest dynamic periods of metallogenesis on the northern margin of North China landmass are Paleozoic and Late Yanshanian, during which many medium to small-sized ore deposits were formed. Only a few ore deposits (ore spots) formed in the Indosinian epoch have been found. During the Yanshanian period, however, numerous porphyry type, skarn type and hydrothermal vein-type lead-zinc deposits were formed. In both of the margins, lead-zinc mineralization tended to change from stratabound to rock-bound, together with the variation of main metallic element combinations from simple to complicated. More MVT deposits in carbonate formation are likely to be discovered in the rift system to the north of Luanchuan fault, and more Sedex type lead-zinc deposits will probably be found in the Kuanping Group.