四川呷村多金属矿床的垂向分带

VERTICAL ZORNING OF THE GACUN POLYMETALLIC ORE DEPOSIT, SICHUAN

呷村多金属矿床是典型的海相火山热液一喷气沉积块状硫化物矿床。它具明显的垂向分带性,自下而上依次为铅锌矿带、铜铅锌银矿带和重晶石矿带,类似于日本黑矿型矿床的黄矿带、黑矿带和重晶石矿带。下部矿石主要呈粒状结构,脉状、网脉状构造;上部矿石常呈胶状、草莓状结构,块状、条带状、层纹状构造.围岩蚀变在铅锌矿带及其下伏火山岩中非常发育,而在上部块状矿层中却十分微弱。按蚀变的种类和强度,矿区分五个蚀变带。cu、Pb、Zn、Ag、Au、S、Ba等元素含量在含矿带内有随层位升高而增大的变化规律。研究表明,成矿溶液的温度、物质成份、fO_2、pH值,以及围岩岩性等因素控制呷村矿床的垂向分带。

The Gacun polymetallic ore deposit is a typical submarine volcanic hydrotheremal -ex-halative sedimentary massive sulfide deposit discovered in recent years in China. There exists obvious zoning of the ore deposit from its bottom to top : lead-zinc ores, copper-zinc-lead-silver ores and barites, which is similar to yellow ore belt, black ore belt and barite ore belt in Kuroko ore deposits Japan. Most ores in the lower zone are of crystalline texture and veined-network strcuture. Those in the upper often are colloform, strawberry texture and massive ,lamellar stucture. The wall-rock alteration well developd in lead-zinc zone and under-lain volcanic rocks, but poorly developed in massive ore beds that lay in a relatively higher position. Based on the varity and intensity of the alteration, five zones of hydrothermal alteration are divided. Contents of Cu, Pb, Zn, Ag, Au,S,Ba and some other elements occurred in the ore-bearing zone increase in ascending direction of the strata. Recent study shows the vertical zoning of Gacun ore deposit is controlled by many fac-tores, such as, the temperature of the the ore-forming solution, the components of the ore-forming material, fo2 and pH , wall-rock lithology.