玲珑金矿床的矿化垂直分带

VERTICAL MINERALIZATION ZONING OF THE LINGLONG GOLD DEPOSIT

作者用成因矿物学方法深入研究了玲珑矿(典型的石英脉型)至关重要的问题——矿床的矿化垂直分带问题。研究结果认为:过去一些认为“上有石英脉型,下有蚀变岩型”的金矿化空间分带模式是值得探讨的。在玲珑金矿中,著者认为正确的矿化分带应为:“上有蚀变岩型矿体,下有石英脉型矿体”。确定玲珑断裂将西山矿区(典型石英脉型)相对于东山矿区(过渡型)上推了至少300m,故东山矿区的深部远景将远远大于西山矿区。研究结果已被新近的探矿工程所证实。

Having been mined for about 1,000 years, the Linglong gold deposit is faced with the urgent demand of expanding prospective reserves. The future of its two ore districts(Dongshan and Xishan) depends on their respective positions in the vertical mineralization zoning of the ore deposit. As the geologic environment of the ore deposit is quite unique, this problem remained unsettled. Over the past six years, the authox has tried to solve this problem by means of genetic mineralogy. Studies show that: (1) native gold in the Dongshan ore district is mainly interstitial gold and fissure gold characterized by comparatively coarse grains (those with grain size>0.025mm make pp 62.22%), whereas the Xishan ore district contains mainly inchision gold with smaller granularity (grains with sizes)>0.025mm only make up 22.35%); (2) in the Dongshan ore district, pyrite shows rather complicated forms, commonly assuming {111} crystal habit, and is rich in As, Sb, Se and Te with thermoelectronic P-type pyrite pp to 77.4%, while in the Xishan ore district, pyrite is rather simple in crystal form ({111} crystal habit is rarely seen), and contains abundant Ti, V, Cr and Ni, with P-type pyrite only 58.8% (3) in the Dongshan ore district, quartz drusy is quite developed and shows rather complicated micromorphological features, noted for the enrichment in Al, K, Rb and Sr; in the Xishan ore district, quartz drusy is less observed and assumes simple micromorphological features, characterized by the richness in Tl and Zm; (4) ore-forming temperature, as shown by thermometry of quartz inclusions of 3rd stage, is 250—00℃ at 206m level of the Dongshan ore district. and 310—350℃ at 220m level of the Xishan ore district. These data of genetic mineralogy indicate that the Dongshan ore district shows haracteristics of an upper orebody whereas the Xishan ore district displays features of a lower orebody. The results obtained in other aspects such as shapes of ore veins, mineralization stages, mineral assemblages and wall rock alterations all support this conclusion.The quantitative analysis based on variation gradient of some physical parameters of pyrite and quartz suggests that the Linglong fault has lifted the Xishan ore district at least 300m relative to the Dongshan ore district. Therefore, the prospective reserves at the depth of the Dongshan ore district might be much greater than the reserves of the Xishan ore district, and this conclusion has been substantiated by recent exploration.