摘要
四川省白玉县呷村银多金属矿床是我国著名的VMS矿床之一,具有容矿火山岩系+硫化物矿体+喷气岩的"三位一体"特征,以及下部筒状或漏斗状网脉状矿(西矿带)和上部层状块状矿(东矿带)的"双层结构"样式。其南部有热矿区找矿虽有进展,但突破不大。为确定有热矿区的找矿方向,本文对呷村矿床和有热矿区含矿带进行了精细结构对比,认为有热北部19~31线由块状硅化流纹质火山岩+条纹条带状流纹质凝灰岩+千枚状绢云母凝灰岩组成火山喷发单元,以强烈的硅化为特征,发育大量的脉状-网脉状构造,与呷村西矿带完全可以对比;而有热南部39~55线则由块状"黄矿"矿石与流纹质火山碎屑岩组成喷气-火山单元,但缺乏重晶石、硅质岩等喷气沉积岩;以"黄矿"为主,仅形成铅锌贫矿体,与呷村矿床东矿带富含重晶石、以"黑矿"为主,形成银铜铅锌富矿体的特征有较大区别。同时,有热块状矿体上部还存在厚达70~130 m的流纹质火山岩和脉状-网脉状矿体,据此认为有热矿带总体上可与呷村西矿带对比,代表热液喷流成矿系统的热水补给通道相,其中的块状(黄矿)矿体具微"双层"结构特征,有可能为早期热流成矿系统的另一个独立的"微"VMS矿床。由此判断有热矿区东部流纹质火山岩与碳质板岩的转换界面处深部存在类似呷村东矿带的以"黑矿"块状矿体+重晶石组合为代表的隐伏矿体,从而共同组成一个"下黄上黑"共两层块状矿体的"堆垛式"结构型式。寻找以"黑矿"-重晶石组合为代表的隐伏银铜铅锌块状矿体是有热矿区今后取得找矿重大突破的关键所在。
The Gacun silver-bearing polymetallic deposit in Baiyu county of Sichuan Province is a well-known VMS deposit in China,which has a'Trinity type'rock assemblage consisting of volcanic series as host rocks,sulfide ore bodies and exhalite as well as a'double-layered structure'with tubular or funnel stockwork ores at the lower part( the western zone) and laminated massive ores at the upper part( the eastern zone). However,several prospecting projects carried out within the Youre ore district,south of the Gacun deposit,had little breakthrough. To determine the direction of further prospecting in this area,we made a detailed structural comparison between the Gacun deposit and Youre ore-bearing zones. Our work suggests that the northern prospecting line 19 ~ 31 of Youre mining area,which consists of volcanic units including massive silicide rhyolitic volcanics,striped or ribbon rhyolitic tuff,phyllitic sercite tuff characterized by strong silicification and vein-network structure,correlates well with that of the Gacun deposit. On the other hand,unlike the eastern zone of the Gacun deposit,which is characterized by barite-rich with predominantly'black ore'forming the high grade silver-copper-lead-zinc ore bodies,the southern line 39 ~ 55 of the Youre ore district is just composed of exhalite-volcanic units including the massive'yellow ore'and rhyolitic clastic rock but lacking exhalite such as barite and siliceous rocks,forming the lower grade of lead-zinc ore bodies. Meanwhile,the occurrence of rhyolitic volcanics and vein-stockwork ore bodies with a total thickness of 70 ~ 130 m overlying the upper part of massive orebodies in the Youre ore district indicates that the Youre ore belt could correlate with the western zone of the Gacun deposit overall. It could represent the hot water supply pipe facies of the hydrothermal exhalative metallogenic system,wherein the massive( yellow ore) ore bodies characterized by a'double-layer'structure assembling another independent'micro'VMS deposit during the early stage of the hydrot
出处
《地质与勘探》
CAS
CSCD
北大核心
2014年第4期599-616,共18页
Geology and Exploration
