贵州省盘县架底金矿床成矿地质条件及找矿方向

架底金矿床位于贵州省莲花山背斜南东翼,距背斜核部3 km,是近年来在国内发现的与峨眉山玄武岩密切相关的第一个大型原生金矿床。架底金矿床与黔西南其他金矿床类似,属微细粒浸染型,成矿流体来源具有岩浆水的特点。玄武岩是矿区最主要的赋矿地层,玄武质火山角砾岩是矿区最主要的容矿岩石。矿化趋势分析显示：莲花山背斜（次级揉褶）与近东西向复式背斜的叠加区是有利的成矿部位,控制矿床中各矿体的分布规律及产出特征;近东西向复式背斜直接控制了矿体近东西向展布的特点,且越靠近莲花山背斜核部,矿体品位越高、厚度越大。原生晕地球化学分析指示：在矿区目前已发现矿体的顶部可能还存在断控型或层控型金矿体;源自深部的含金热液沿深大断裂上涌至一定位置后沿层间破碎带由东向西运移,且至少经历了2次主要的成矿作用阶段。综合研究认为整个莲花山地区具有较好的找矿远景,区内金矿床在南北方向可能按一定规律呈等距、不等距分布,推测东西方向受叠加褶皱控制的有利成矿区距莲花山背斜核部超过5 km。区内除峨眉山玄武岩外,在上二叠统龙潭组以及三叠系中都有可能在构造有利、岩性适宜的部位形成层控型或断控型金矿体。     

Geology and mineralization of the Dayin’gezhuang supergiant gold deposit (180 t) in the Jiaodong Peninsula,China: A review

The Dayin’gezhuang gold deposit is located in the central part of the Zhaoping Fault metallogenic belt in the Jiaodong gold province —the world ’s third-largest gold metallogenic area. It is a typical successful case of prospecting at a depth of 500‒2000 m in recent years, with cumulative proven gold resources exceeding 180 t. The main orebodies (No. 1 and No. 2 orebody) generally have a pitch direction of NNE and a plunge direction of NEE. As the ore-controlling fault, the Zhaoping Fault is a shovel-shaped stepped fault, with its dip angle presenting stepped high-to-low transitions at the elevation of −2000‒0 m. The gold mineralization enrichment area is mainly distributed in the step parts where the fault plane changes from steeply to gently, forming a stepped metallogenic pattern from shallow to deep. It can be concluded from previous studies that the gold mineralization of the Dayin’gezhuang gold deposit occurred at about 120 Ma. The ore-forming fluids were H₂O-CO₂-NaCl-type hydrothermal solutions with a medium-low temperature and medium-low salinity. The H-O isotopic characteristics indicate that the fluids in the early ore-forming stage were possibly magmatic water or mantle water and that meteoric water gradually entered the ore-forming fluids in the late ore-forming stage. The S and Pb isotopes indicate that the ore-forming materials mainly originate from the lower crust and contain a small quantity of mantle-derived components. The comprehensive analysis shows that the Dayin ’gezhuang gold deposit was formed by thermal uplifting-extensional tectonism. The strong crust-mantle interactions, large-scale magmatism, and the material exchange arising from the transformation from adakitic granites to arc granites and from the ancient lower crust to the juvenile lower crust during the Early Cretaceous provided abundant fluids and material sources for mineralization. Moreover, the detachment faults formed by the rapid magmatic uplift and the extensional tectonism created favorable temperature and pressure conditions and space for fluid accumulation and gold precipitation and mineralization.©2022 China Geology Editorial Office.     

柴达木盆地别勒滩杂卤石矿床特征及其沉积环境研究

别勒滩是青海察尔汗盐湖固体钾矿的主要分布区段,也是企业固转液开采和生产钾盐的主要矿区,该区段分布着大面积的杂卤石矿(K₂Ca₂Mg[SO₄]₄2H₂O)。文章利用2022年察尔汗盐湖储量核查项目获得的岩芯样品和钻孔资料,通过系统的分析测试,开展别勒滩杂卤石成矿特征及沉积环境研究。文章首次查明别勒滩区段杂卤石矿床分布面积超过150 km²,平均厚度0.8 m,w(K₂SO₄)平均大于5%,计算获得K₂SO₄资源量2089.79×10⁴t。研究认为,别勒滩杂卤石形成于钾石盐、光卤石析出阶段的高浓缩盐湖相沉积环境,周期性淡化带入的大量Ca²⁺和SO₄^2-与卤水中含量较高的K⁺、Mg²⁺离子反应形成了杂卤石矿层。别勒滩杂卤石矿层具有较好渗透性和给水...     

四川乐山地区二叠纪—侏罗纪多个含铜层位铜矿找矿工作思考

<正>铜作为我国一种大宗有色金属矿产,广泛应用于机械制造、电力电子、交通运输、建筑和国防工业等领域。据2020年统计资料,我国的铜资源消费量约占全球的60%,但全球的铜资源主要集中于智利、秘鲁、墨西哥等国家,我国铜矿资源禀赋较差,对外依存度持续多年超过70%(陈甲斌,2022)。当前国际形势复杂多变,在受全球资源问题政治化、资源民族主义全球化、矿产品价格金融化等因素影响下,我国的铜矿供应链安全常常受到威胁,我国铜资源安全形势变得更加严峻。     

北山地区古元古界北山岩群中长英质脉内锆石U- Pb年龄及其地质意义

深熔作用是大陆地壳分异、元素迁移富集的重要地质过程。位于中亚造山带南缘的北山地区,笔者等对前寒武系北山岩群进行了研究,结果表明该岩群普遍经历了角闪岩相变质及深熔作用,长英质浅色脉体分布广泛,却鲜有文献报道。绵山地区出露的古元古代北山岩群斜长角闪岩及相关的长英质浅色脉体的野外地质特征、相互关系共同指示了北山岩群变质地层经历了部分熔融,熔体在原地分凝聚积。锆石LA-ICP-MS U-Pb测定结果表明,顺北山岩群变质地层片理产出的长英质浅色脉体锆石n(²⁰⁶Pb)/n(²³⁸U)加权平均年龄约为370 Ma,表明深熔作用发生时间为晚泥盆世;一测点的n(²⁰⁷Pb)/n(²⁰⁶Pb)年龄为1623±12 Ma,与前人报道的北山岩群测年结果高度相近,虽此年龄值不足为证,但结合产出特征,可能指示长英质浅色脉体的源岩为北山岩群。此外,北山岩群中深熔作用普遍发育,露头可见大量的石榴子石、电气石、云母类矿物,指示区内部分稀有元素成矿潜力巨大。     

茶卡北山锂辉石花岗伟晶岩锂矿化特征及成矿时限

锂是重要的战略金属矿产,锂辉石花岗伟晶岩是锂矿资源的重要来源。近来柴北缘茶卡北山地区新发现锂辉石花岗伟晶岩脉群,本文对区内锂辉石花岗伟晶岩进行了岩相学、矿物学、矿物化学、年代学研究工作,确定了锂辉石花岗伟晶岩的矿化特征及矿化年限。锂辉石花岗伟晶岩存在两期矿物组合：早期由粗粒锂辉石、粗粒钾长石、粗粒白云母、粗粒更(钠)长石、粗粒石英和铌钽铁矿等组成,属熔体结晶阶段产物;晚期由锂绿泥石、富锂云母、蠕虫状锂辉石和细粒他形石英等组成,为岩浆期后热液交代产物。根据两期矿物组合判断存在两期锂矿化,认为早期锂辉石的局部蚀变与晚期锂矿物的形成指示体系内存在锂的活化和再沉淀过程。测得与锂辉石伴生的铌钽铁矿U-Pb年龄为241.0±1.3 Ma,可代表锂辉石花岗伟晶岩熔体结晶年龄,即为早期锂成矿年代,矿床为印支期产物。     

Geology,geochronology, and exploration of the Jiama giant porphyry copper deposit (11 Mt), Tibet,China: A review

Jiama, with more than 11 Mt of copper metal, is the largest porphyry-skarn copper system in the Gangdese metallogenic belt, Tibet, China, creating ideal conditions for deciphering the origin of porphyry ores in a collision setting. Despite massive studies of the geology, chronology, petrogenesis, and ore-related fluids and their sources in Jiama, there is a lack of systematic summaries and reviews of this system. In contrast to traditional porphyry copper systems in a subduction setting, recent studies and exploration suggest that the Jiama deposit includes porphyry-type Mo-Cu, skarn-type Cu polymetallic, vein-type Au and manto orebodies. This paper reviews the latest studies on the geology, chronology, petrogenesis, fluid inclusions, and isotopic geochemistry (hydrogen, oxygen, sulfur, and lead) of the Jiama deposit. Accordingly, a multi-center complex mineralization model was constructed, indicating that multi-phase intrusions from the same magma reservoir can form multiple hydrothermal centers. These centers are mutually independent and form various orebodies or are superimposed on each other and form thick, high-grade orebodies. Finally, a new comprehensive exploration model was established for the Jiama porphyry copper system. Both models established in this study help to refine the theories on continental-collision metallogeny and porphyry copper systems.©2023 China Geology Editorial Office.     

中国镓矿分布规律、成矿机制及找矿方向

金属镓资源是我国优势资源, 但随着国内外需求量不断增大, 我国金属镓的后备资源逐步短缺。本文系统搜集了我国富镓矿床研究和勘查成果资料, 初步总结了我国富镓矿的分布规律、成矿机制和找矿方向。研究认为, 我国镓矿主要伴生在铝土矿、煤矿和铅锌矿之中, 以铝土矿中伴生镓最为重要。依据不同成矿作用将我国具有工业价值的富镓矿床划分为沉积型铝土矿、堆积型铝土矿、红土型铝土矿、煤矿床和碳酸盐岩型(MVT)铅锌矿等5种伴生镓矿床类型, 并总结了不同类型镓矿床的时空分布规律。时间上, 我国富镓矿床在元古宙、古生代、中生代和新生代均有发育, 以石炭纪—三叠纪、侏罗纪—白垩纪和第四纪为主。其中, 富镓铝土矿主要形成于石炭纪、二叠纪和第四纪, 以石炭纪最为重要; 富镓铅锌矿主要形成于震旦纪和寒武纪; 富镓煤矿主要形成于石炭纪和二叠纪。空间上, 我国富镓矿床主要分布在晋豫成矿区、右江成矿区、扬子陆块西南成矿区、川—滇—黔成矿带、湘西—鄂西成矿带、湘东—赣西成矿带和华北陆块北缘成矿区等7个区带中。不同类型富镓矿床的成矿机制不同, 一般在风化-沉积作用下形成富镓铝土矿, 镓与铝常以类质同象形式存在; 在生物化学沉积作用下形成富镓煤矿, 镓常以无机态、有机态和混合形式存在, 在我国多以无机态的形式赋存于勃姆石、硬水铝石等矿物中; 在热液作用下形成富镓铅锌矿, 镓可能以类质同象形式进入以闪锌矿为主的硫化矿物晶格中。根据不同镓矿的成矿作用、富集过程和地质背景, 建立了煤矿、铅锌矿和铝土矿中镓富集成矿的理想模型, 并对铝土矿、煤矿和铅锌矿中伴生镓矿进行了找矿预测, 提出了找矿方向和重点找矿区域, 其中以沉积型、堆积型铝土矿的找矿为主攻方向, 并可兼顾煤矿和铅锌矿等其他伴生镓矿床。     

湘西北民乐锰矿成矿后变化分析

大塘坡式锰矿成矿后变化程度可从地层抬升程度、氧化程度、构造条件、裂隙与岩溶发育程度、顶底板隔水性、地表及气候等方面进行分析评价。民乐锰矿成矿后受到近地表因素、地下水的以及断层发育的影响,其成矿后变化程度可从地层抬升程度、断裂发育程度以及含锰岩系隔水性三方面进行评价。选取含矿层埋深、距断层距离、矿体上覆及下伏黑色页岩段厚度对三个评价因素进行定量表征,制作单因素等值线图并量化评分,运用层次分析法确定各因素权重,将各单因素加权叠加绘制成矿后变化程度系数等值线图,将成矿后变化程度分区与锰矿形态（品位）、厚度范围叠加,定量分析成矿后变化对找矿的指示意义。研究发现,断裂发育程度对于民乐矿区成矿后变化程度最为重要,地层抬升程度次之,含锰岩系隔水性影响较少;民乐矿区成矿后变化程度具有“两侧高、中心低”的特征,呈现从盆地中心至边缘带递增的趋势,西侧更多受地层抬升影响,东侧则以断裂影响为主;成矿后变化程度较低的区域更有利于找矿,但对于不同形态（品位）的矿体指示性并不明显;对各类地质演化过程的恢复和定量表征应成为今后大塘坡式锰矿成矿后保存改造研究的主要方向。