摘要
呷村矿床是我国的一个典型黑矿型矿床,产于德格—乡城晚三叠世岛弧带中。成矿作用发生在酸性火山活动间歇期和末期,碳酸盐岩盖层形成之前。成矿时代为199.2—200Ma。有上、下两个矿带:下矿带和上矿带下部为脉状、网脉状铅锌矿,围岩蚀变和蚀变分带围绕着矿脉发育;上矿带上部为块状银多金属矿层和块状重晶石矿层。温压地球化学和稳定同位素地球化学研究表明,成矿发生在中—低温条件下,成矿时内压力较大,成矿流体属以海水为主的混合流体,成矿物质主要来自火山活动。温度、压力、硫逸度和氧逸度等条件变化决定了矿化分带和围岩蚀变分带。该矿床具有海底火山喷气-沉积成因,其成矿模式可与日本黑矿类比。
The Gacun ore deposit lies in Dege-Xiangcheng Late Triassic island arc volcanics elt. The ore-forming process took place in the terminal stage of acid volcanism prior to the ormation of carbonate cover, being closely related to Si-rich rhyolite dome. There are upper nd lower ore zones in the ore district: the lower ore zone occurs in dacitic rhyolitic and hyolitic breccia tuffaceous lava and consists of veinlike and stockwork lead-zinc ore bodies, round which alteration pipes of silicification, sericitization and pyritization are present; he upper ore zone occurs as stratiform and stratoid ore bodies overlying the lower ore zone nd rades upward into carbonate strata. The ore bodies consist of massive polymetallic ores or assive barite ores, and wall rock alterations disappear gradually in the massive sulfide ore ed. Temperature-pressure and isotopic geochemical studies show that the downward percolating ea water, driven by heat in the Si-rich rhyolite dome, circulated along the syngenetic ractures, leached ore-forming materials from the volcanic rocks and caused the alteration of olcanic rocks. When the ore-bearing hot fluids erupted out of the sea bottom, massive sulfide re and barite ore were accumulated near the mouth of the vent, and veinlike and stockwork ores ere formed in the vent. The deposit is a submarine emanated-sedimentary deposit whose etallogenic model is comparable with that of the kuroko deposit in Japan.
出处
《矿床地质》
CAS
CSCD
北大核心
1991年第2期107-118,共12页
Mineral Deposits
