南秦岭青山金矿床地质特征、控矿因素及其成因探讨

Probe into Geological Characteristics,Ore-Controlling Factors,and Genesis of Qingshan Gold Deposit in South Qinling

青山金矿床位于南秦岭镇安盆地。矿体呈脉状、囊状、透镜状、似层状等产出,主要赋存在上泥盆统九里坪组与下石炭统界河街组假整合面之上的界河街组的黑色碳质板岩和碳酸盐岩中。在燕山早中期的陆内造山过程中,该区区域构造继承了泥盆纪奠定的棋盘构造格局,控制了矿床的定位,而矿区棋盘构造控制了矿段的分布和矿体产出。矿石分为原生的含金黄铁矿-菱铁矿型及铁帽型。矿石中主要金属矿物为菱铁矿、黄铁矿、褐铁矿,成矿元素以Au-Ag-AS-Sb-Ba组合为特征,与区域低温矿床的元素组合相一致。矿床成矿温度介于160～220℃,成矿流体为重碳酸盐-氯化钠型地下热卤水。初步研究表明,该矿床是地热驱动热卤水循环萃取矿源层中的矿质而形成的热泉型金矿床。

Qingshan gold deposit is located in Zhen＇an Basin of South Qinling. The ore bodies are located above the disconformity between Jiuliping Group and Jiehejie Group, and occur as veins, cystic pattern, lenticular form, and stratified form in the carbonaceous slate and carbonate. The structures of this region inherit the chess board structures formed in Devonian during the early-middle Yanshanian intra-continent orogeny, which control both the location of deposits and the distribution of ore bodies. The ores are divided into primary gold bearing pyrite-siderite type and gossan type. The main metallic mineral in the ore are siderite, pyrite, and limonite. The element association is Au-Ag-As-Sb-Ba, which is consistent to other deposits in the region. The metallogenie temperature ranges from 160℃to 220℃ and the ore-forming fluid is underground thermal brine. Therefore, it is the thermal brine that circularly extracts the mineral from the source bed to form this hot spring gold deposit.