投稿时间：2013-07-29
修订日期：2014-04-21
网络发布日期：2014-09-15
中文摘要:岔路口斑岩钼（锌铅）矿床是在大兴安岭北段新发现的超大型斑岩钼矿床，伴有一定规模的锌铅矿化，钼矿体呈拉长穹窿状，空间上呈上锌铅下钼的分带特征。钼成矿作用与晚侏罗世细晶斑岩和花岗斑岩的关系最为密切，矿化呈网脉状、脉状和浸染状产出，发育多期-多阶段脉体。根据形成温度、穿插关系、矿物组合和蚀变晕特征可划分出14类脉体，成矿前表现为石英±钾长石±磁铁矿±赤铁矿±硬石膏脉体（共4类），成矿期发育辉钼矿脉、钼铅锌过渡脉以及锌铅脉体（共7类），成矿后发育萤石、石膏和碳酸盐等脉体（共3类）。脉体内萤石的持续发育且早期硬石膏、磁铁矿、赤铁矿等矿物的存在，指示成矿流体具有高氟性质且早期具高氧化特征；脉体两侧蚀变晕从钾长石/黑云母→钾长石+绢云母→绢云母+黄铁矿→绢云母的变化，表明成矿流体具有从碱性向酸性演化的特征。高温脉体穿插低温脉体这类反切脉体的存在，反映岔路口矿床成矿流体具有多期脉动涌入的特征。成矿系统内脉体倾角研究表明，产状较平缓的脉体主要环绕成矿岩体分布在外围，高角度的放射状脉体（倾角>60°）主要形成于成矿岩体的顶部；且高角度脉体与高品位矿体密切相关，矿体品位高的区域同时也是脉体集中发育区。脉体-蚀变-矿化的系统研究可指示矿床的剥蚀深度，岔路口矿区地表仅出露黏土化带和青磐岩化带，产出黏土矿物脉、碳酸盐脉等低温脉体，钻孔显示金属矿化自上而下具有Ag—Pb-Zn—Mo的分带，表明岔路口矿床的剥蚀程度较低，保存完整。
Abstract:The newly-discovered Chalukou giant porphyry Mo deposit associated with polymetallic ore at the top, located in northern Da Hinggan Mountains of Northeast China, is the largest porphyry Mo deposit so far discovered in China, with 2.46 Mt Mo metal and 0.087% Mo economic grade. The shape of ore body is elongated dome. Main ore-forming intrusions consist of Jurassic aplite porphyry and granite porphyry. Molybdenite-bearing veins are the primary mineralization type, with surbodinate disseminated and breccia-type mineralization. According to the forming temperature, cutting and offsetting relationships, mineral assemblage and alteration envelope, fourteen vein types are identified. The pre-ore stage contains quartz ± K-feldspar ± magnetite ± hematite ± anhydrite veins, the main-stage consists of molybdenite-bearing veins, molybdenite-sphalerite-galena veins and sphalerite-galena veins, and the post-ore stage is characterized by fluorite/gypsum/carbonate veins. The filling minerals in veins include fluorite, anhydrite, magnetite and hematite, indicating the high fluorine and high oxidation state of the ore-forming fluids. The alteration envelope beside veins varies from K-feldspar/biotite through (K-feldspar+sericite) to (sericite+pyrite) and sericite, reflecting the evolution of ore-forming fluid from alkaline to acidic. The existence of reverse crosscutting relationship of high temperature veins cutting the low temperature veins shows the multiple pulses of hydrothermal fluids. The study of the angle of ore-bearing veins combined with Mo grade shows that the steep veins (angle > 60°) and the high grade ore are usually concentrated at the top of the ore-forming intrusion, reflecting the close relationship among steep veins, ore grade and the ore-forming intrusion. A systematic study of alteration - mineralization - veins indicates the erosion level, showing that the clay mineral veins, carbonate veins and sphalerite - galena veins are the main veins present at the surface, and argillic alteration is the main alteration type in the outcrop of Chalukou. In addition, drill cores show the successive metal zoning of Ag—Pb-Zn—Mo from the shallow part to the depth, suggesting the low erosion level and the well-preserved condition, which is consistent with the result of exploration.
keywords:geology Chalukou molybdenum-zinc-lead deposit vein classification temporal-spatial distribution ore grade mineralization indicator erosion level northern Da Higgan Mountains
文章编号：
中图分类号：P618.65;P618.42;P618.43
文献标志码：
基金项目:本文得到国家自然科学基金项目（编号：41272108）和大兴安岭金欣矿业有限公司、黑龙江省有色金属地质勘查706队“大兴安岭岔路口钼多金属矿床成矿规律与资源潜力综合研究”的联合资助
引用文本：
金露英,秦克章,孟昭君,李光明,宋国学,李真真,吕克鹏,阚学胜,赵超.2014.大兴安岭北段岔路口巨型钼(锌铅)矿床脉体特征、产状及其对成矿的指示[J].矿床地质,33(4):742~760JIN LuYing,QIN KeZhang,MENG ZhaoJun,LI GuangMing,SONG GuoXue,LI ZhenZhen,LÜ KePeng,KAN XueSheng,ZHAO Chao.2014.Features and occurrences of veins in Chalukou giant molybdenum-zinc-lead deposit, northern Da Hinggan Mountains, and their indications for mineralization[J].Mineral Deposits33(4):742~760
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