投稿时间：2024-11-19
修订日期：2025-03-07
网络发布日期：2025-04-25
中文摘要:奥罗拉（Aurora）金矿为南美洲圭亚那地盾北部典型的造山型金矿（资源量金184 t@2.54 g/t）。文章通过野外地质调查、详细的岩芯编录、岩相学以及矿相学的工作，总结了奥罗拉金矿Rory’s Knoll（RK）、Mad Kiss（MK）以及Aleck Hill（AH）矿段典型矿床的地质特征。奥罗拉金矿位于区域中酸性侵入岩岩基东侧大型NW向剪切带转折处，金矿化受构造控制且分布在晚期的构造中，与多组NW-NNW向剪切带以及紧闭褶皱密切相关。根据其矿石类型、矿体形态、脉体特征及围岩性质划分2种类型，分别为赋矿围岩为中酸性侵入体的金矿（RK和MK）和赋矿围岩为火山岩的金矿（AH）。金矿化与石英-碳酸盐脉以及黄铁矿密切相关，矿石类型包括脉状、网脉状、浸染状其次为角砾状。金矿物主要为自然金，银金矿以及少量的碲-金矿物，嵌布类型包括粒间金、吸附金、包裹金及裂隙金。矿床发育明显的蚀变分带特征，可根据矿化蚀变及围岩特征将其划分为与中酸性侵入体有关的Ⅰ型蚀变（RK和MK），其蚀变范围可达15~20 m，近矿端发育石英-钠长石-铁白云石-绢云母的矿物组合，中间带为绢云母-绿泥石-铁白云石的蚀变矿物组合，远端为磁铁矿-方解石-绿帘石-绿泥石的蚀变矿物组合；与火山岩有关的Ⅱ型蚀变（AH），蚀变范围在5~10 m，近矿端发育石英-钠长石-铁白云石-绢云母-绿泥石的矿物组合，远端发育磁铁矿-方解石-绿帘石-绿泥石的矿物组合，Ⅰ型蚀变相比Ⅱ型蚀变褪色范围较宽，而近矿端的绿泥石及远端的磁铁矿含量较少。通过系统梳理矿床地质特征以及矿体分布规律，笔者认为深边部仍有较大的找矿空间。对茂密热带雨林厚风化覆盖的圭亚那地盾的找矿勘查方法建议以大比例尺航磁+MMI（活动金属离子测量）等深穿透化探方法+RC（反循环）/DD（金刚石）钻探验证为手段，花岗绿岩带内岩体+区域性剪切带+金高值异常区是有利的找矿靶区。
Abstract:The Aurora Gold Mine, located in the northern part of the Guiana Shield in the northern Amazon Craton of South America, is a typical orogenic gold deposit with a resource estimate of 184 tons of gold at a grade of 2.54 g/t. This study, based on field geological surveys, detailed core logging, petrography, and mineralogy, provides a preliminary summary of the geological characteristics of the typical deposits in the Aurora gold mine, including the Rory’s Knoll(RK), Mad Kiss(MK), and Aleck Hill(AH). The Aurora gold mine is situated at the bend of a large NW-trending shear zone on the eastern side of a felsic intrusive rock base. Gold mineralization is structurally controlled, distributed in late-stage structures, and closely related to multiple NW-NNW-trending shear zones and tight folds. Based on the ore texture, ore body morphology, vein characteristics and wall rock properties, the type of Aurora gold mine is divided into two categories: within intermediate to acidic intrusive rocks(RK and MK) and within volcanic rocks(AH). The mineralization is closely associated with quartz-carbonate veins, with gold mainly found in quartz-carbonate-sulfide veins and disseminated pyrite on both sides of the veins. The primary ore types are vein, stockwork, and disseminated, followed by breccia. Gold mineralization predominantly occurs as native gold, electrum, and minor telluride-gold minerals, with intergranular, adsorbed, inclusional, and fracture-hosted gold as the primary textures. The deposits in the Aurora gold mine exhibit distinct alteration zoning, classified into two types based on the mineralization: Type Ⅰ alteration, associated with felsic intrusions(RK and MK), with a broader alteration zone spanning 15~20 m. The proximal zone is characterized by quartz-albite-ankerite-sericite, the intermediate zone by sericite-chlorite-ankerite, and the distal zone by magnetite-calcite-epidote-chlorite. Type Ⅱ alteration, associated with metavolcanic rocks(AH), has a narrower alteration range of 5~10 m, with a proximal zone of quartz-albite-ankerite-sericite-chlorite and a distal zone of magnetite-calcite-epidote-chlorite. Type Ⅰ alteration is characterized by a wider bleaching extent relative to Type Ⅱ alteration, accompanied by decreased chlorite concentrations in the proximal zone and diminished magnetite content in the distal zone. Based on the geological characteristics and orebody distribution of the Aurora gold mine, it is inferred that there is significant exploration potential at depth and along the edges of the deposit. For prospecting and exploration of the Guyana Shield covered by dense tropical rainforest and thick weathering, the method is based on large-scale aeromagnetic+MMI(Mobile Metal Ion) or other deep-penetrating geochemistry+Reverse Circulation/Diamond drilling verification. The granite intrusive rock+regional shear zone+high-gold anomaly area in the greenstone belt are favorable prospecting targets.
keywords:geological characteristics prospecting prediction greenstone gold deposits orogenic gold deposits Guiana Shield
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基金项目:本文得到紫金矿业集团股份有限公司科技项目（编号：4201KY2023110002）资助
引用文本：
张俊杨,单思齐,傅其斌,刘洋树,吴炳生,王勤,刘晗,李永辉,祝新友.2025.南美州圭亚那地盾北部奥罗拉金矿床地质特征及找矿预测[J].矿床地质,44(2):365~388ZHANG JunYang,SHAN SiQi,FU QiBin,LIU YangShu,WU BingSheng,WANG Qin,LIU Han,LI YongHui,ZHU XinYou.2025.Geological characteristics and prospecting prediction of Aurora gold deposit in northern Guiana Shield, South America[J].Mineral Deposits44(2):365~388
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