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71.
粤北产铀与不产铀花岗岩中铀矿物特征的电子探针研究及其找矿意义 总被引：1，自引：0，他引：1
晶质铀矿的含量、形貌、成分、铀矿物类型、与铀矿物共存的矿物组合等特征可以作为产铀与不产铀岩体的判别标志,为花岗岩型铀矿找矿工作提供了一种新的技术手段。长江岩体和九峰岩体是粤北地区典型的产铀与不产铀花岗岩体,本文利用电子探针测试了九峰岩体的铀矿物并与长江岩体进行对比研究。结果表明九峰岩体的铀矿物主要为晶质铀矿,其化学年龄可分为两组,分别为~160 Ma、~105 Ma,与长江岩体的两组晶质铀矿年龄基本一致;其中第一组年龄代表岩体的成岩年龄,第二组年龄与粤北地区~105 Ma的基性岩脉侵入时代相对应;但九峰岩体缺少长江岩体中~74 Ma的成矿年龄。相比于长江岩体,九峰岩体的铀矿物受到后期热液事件的影响较小,U没有发生明显的活化、转移,因而未能富集成矿,没有形成具有工业价值的铀矿床。 相似文献
72.
氧化还原障在热液铀矿成矿中的作用 总被引：5，自引：0，他引：5
铀是变价元素,氧化还原条件控制铀的迁移和沉淀。铀在氧化环境中呈U~(6+)形式存在,在还原条件下则以U~(4+)形式存在。氧化态六价铀主要以可溶的碳酸铀酰/氟化铀酰络合物形式在水溶液中迁移,还原态四价铀主要以沥青铀矿和铀石等形式富集沉淀成矿。热液铀矿的形成需要一对空间上密切共生的氧化障/氧化剂和还原障/还原剂,二者缺一不可。首先,氧化障中氧化剂将富铀岩石中的铀大量氧化形成U~(6+),溶解进入水溶液迁移;第二,高氧化性富铀溶液遇到还原障,U~(6+)还原成U~(4+)沉淀下来,富集形成铀矿。前人虽然对铀的地球化学性质及氧化还原反应在铀成矿中作用已比较了解,但如何在实际铀矿成矿系统中准确识别氧化还原障,有效利用氧化还原障的控矿机理指导找矿,还存在一些模糊认识,制约了铀成矿理论的发展和找矿方法的提升。本文以我国最重要的砂岩型铀矿、火山岩型铀矿、花岗岩型铀矿和变质型铀矿为例,总结了与铀矿化有关的氧化还原障的主要类型,探讨了红层等蒸发盐地层(氧化障),有机质、煌斑岩等中基性岩脉(还原障)与铀矿之间的关系及控矿机制,揭示了成矿盆地中铀-煤、铀-气(油)共生的机制,阐明了翁泉沟硼、铁、铀矿共生原因,建立了不同类型铀矿成矿模型。 相似文献
73.
Buffer zones in bo\th two-dimensional (2D) and three-dimensional (3D) spaces are commonly used in prospectivity mapping. The method completes a modelling that starts with a real example and progresses to the development of a virtual model. This includes the consideration of lithological or structural contacts at depth, which is a theoretical concept based on extrapolation of data collected in the field, rather than an empirical observation of the feature based on physical samples. This contribution documents an improved buffer analysis method for the study of 3D-space that is implicit (rapid), precise (smooth) and based on triangulated characteristics, which can be used to construct influence domains of geological models. As traditional 2D GIS-based mineral potential mapping is gradually becoming limited with time, mineral potential mapping in three dimensions (3D) is increasingly becoming an important tool in finding concealed economic mineralization. This contribution documents an improved methodology of buffer analysis for prospectivity mapping processing mineralized favourable models rather than describing an advance in the geometry of surface rendering of “geological complexity”. Measures used in this buffer analysis include the: (1) voxelization of geological objects (i.e. assigning numerical values of features on a regular cube in 3D-space); (2) revision of the 3D Euclidean distance transform and the calculation of signed distance field; (3) extracting surfaces from the field; and (4) construction of a buffer-surface based on a “discrete smooth interpolation” (DSI) algorithm. Furthermore, this contribution constructs 3D models using a buffer analysis algorithm and prospectivity mapping introduced here, which is based on real data from the Jiama Cu-polymetallic deposit in Tibet and Daye Fe deposit in the Hubei Province, China. This contribution also presents a comparison between voxel and irregular triangle models, which illustrate that irregular triangle mesh buffer analysis (ITB) can improve modelling techniques for GIS-based 3D mineral potential mapping. The outcome is an increase in the accuracy of prospectivity mapping. 相似文献
74.
西藏铁格隆南铜(金银)矿床地质特征及勘查模型——西藏首例千万吨级斑岩-浅成低温热液型矿床 总被引：16，自引：0，他引：16
唐菊兴 宋扬 王勤 林彬 杨超 郭娜 方向 杨欢欢 王艺云 高轲 丁帅 张志 段吉琳 陈红旗 粟登逵 冯军 刘治博 韦少港 贺文 宋俊龙 李彦波 卫鲁杰 《地球学报》2016,37(6):663-690
铁格隆南矿床(荣那矿段)位于多龙矿集区多不杂斑岩型铜(金)矿的北东中部,铜(金)矿体的主要赋矿围岩为早白垩世中酸性斑岩及早中侏罗统色哇组(J1-2s)复理石或类复理石建造;下白垩统美日切错组(K1m)陆相中基性火山岩建造(110 Ma)覆盖在斑岩-浅成低温热液成矿系统之上,是该矿床得以良好保存的重要原因。通过详细的地质填图、地质编录、岩石地球化学、镜下鉴定、电子探针分析、流体包裹体分析、同位素年代学、岩石地球化学测量、音频大地电磁测深和综合研究,确定了矿体形态整体上为一个似筒状体,铜(金、银)矿体总体呈北东向,控制矿体北东延长约2 000 m,南东—北西向约1 200 m,Cu平均品位大于0.5%,伴生Au品位0.08 g/t,伴生银品位2 g/t左右,单个矿床铜资源量约1 100万吨,远景资源量超过1 500万吨。矿石以典型的细脉浸染状为主,从浅部至深部,金属矿物由铜蓝、蓝辉铜矿、斯硫铜矿、雅硫铜矿、久辉铜矿、斜方蓝辉铜矿及黄铜矿、斑铜矿(微量辉钼矿),主要非金属矿物有明矾石、地开石、高岭石、水铝石、绢云母、石英、硬石膏等组成(图2-17),矿物和蚀变组合显示高硫型浅成低温热液矿体叠加于斑岩型矿体。成矿岩体为120 Ma侵位的花岗闪长斑岩,辉钼矿Re-Os同位素年龄显示斑岩成矿形成于119 Ma左右,明矾石Ar-Ar同位素测年结果为116 Ma左右,表明浅成低温热液型矿化略晚于斑岩型矿化。由于羌塘地体南缘的不断隆升,导致浅成低温热液矿化持续向深部迁移,形成巨厚典型的浅成低温热液矿物组合。流体包裹体研究表明,流体包裹体均一温度显示存在2套明显不同温度的流体,即形成斑岩及其围岩钾硅化与绢英岩化带矿化的中高温流体以及高级泥化带中的中低温流体,高温、高盐度的流体代表了斑岩系统的流体特征,而中低温、低盐度的流体代表了高硫化型浅成低温热液系统的流体特征。铁格隆南矿区的岩体侵位较浅,浅部岩体已经在ZK1604与美日切错组呈角度不整合接触,表明在美日切错组火山岩喷发覆盖于矿体上之前,含矿岩体已经出露地表,根据其估算形成深度(约1.2 km),可以判断在矿床形成之后地壳已抬升了一定高度,斑岩-浅成低温热液系统上部的矿体和独立金矿体可能已被剥蚀。岩石微量元素和稀土元素特征表明,均为高钾钙碱性,富集大离子亲石元素,亏损高场强元素,具弧岩浆地球化学特征;在Y-Th/Ta和Ta/Yb-Th/Yb图解中多龙地区主要侵入岩均位于活动大陆边缘,在Th-Co-Zr/10和Th-Sc-Zr/10微量元素构造图解中,大部分样品落在陆缘弧区域。区域上构造岩浆活动也表明多龙地区岩浆岩形成与班公湖—怒江特提斯洋早白垩世北向俯冲至南羌塘地体之下密切相关,类似于南美安第斯成矿带洋陆俯冲背景下的陆缘弧环境。锆石铪同位素落在球粒陨石与亏损地幔之间,地壳模式年龄相对年轻与多龙地区主要侵入岩一致,表明岩浆主要来源亏损地幔,同时也有部分新生地壳物质的加入,岩浆表现出角闪石源区作为主要源区熔融矿物的特征,表明班公湖-怒江特提斯洋壳俯冲至50~70 km下发生相变,从而导致类似角闪石等矿物脱水引发的楔形地幔部分熔融。短波红外光谱填图和岩石地球化学剖面测量显示在尕尔勤、地堡那木岗还有寻找铁格隆南(荣那矿段)式矿床的潜力,区域找矿潜力极大,多龙矿集区铜资源量可以达到2 500万吨以上。 相似文献
75.
Taiyangshan is a poorly studied copper–molybdenum deposit located in the Triassic Western Qinling collisional belt of northwest China. The intrusions exposed in the vicinity of the Taiyangshan deposit record episodic magmatism over 20–30 million years. Pre-mineralization quartz diorite porphyries, which host some of the deposit, were emplaced at 226.6 ± 6.2 Ma. Syn-collisional monzonite and quartz monzonite porphyries, which also host mineralization, were emplaced at 218.0 ± 6.1 Ma and 215.0 ± 5.8 Ma, respectively. Mineralization occurred during the transition from a syn-collisional to a post-collisional setting at ca. 208 Ma. A barren post-mineralization granite porphyry marked the end of post-collisional magmatism at 200.7 ± 5.1 Ma. The ore-bearing monzonite and quartz monzonite porphyries have a εHf(t) range from − 2.0 to + 12.5, which is much more variable than that of the slightly older quartz diorite porphyries, with TDM2 of 1.15–1.23 Ga corresponding to the positive εHf(t) values and TDM1 of 0.62–0.90 Ga corresponding to the negative εHf(t) values. Molybdenite in the Taiyangshan deposit with 27.70 to 38.43 ppm Re suggests metal sourced from a mantle–crust mixture or from mafic and ultramafic rocks in the lower crust. The δ34S values obtained for pyrite, chalcopyrite, and molybdenite from the deposit range from + 1.3‰ to + 4.0‰, + 0.2‰ to + 1.1‰, and + 5.3‰ to + 5.9‰, respectively, suggesting a magmatic source for the sulfur. Calculated δ18Ofluid values for magmatic K-feldspar from porphyries (+ 13.3‰), hydrothermal K-feldspar from stockwork veins related to potassic alteration (+ 11.6‰), and hydrothermal sericite from quartz–pyrite veins (+ 8.6 to + 10.6‰) indicate the Taiyangshan deposit formed dominantly from magmatic water. Hydrogen isotope values for hydrothermal sericite ranging from − 85 to − 50‰ may indicate that magma degassing progressively depleted residual liquid in deuterium during the life of the magmatic–hydrothermal system. Alternatively, δD variability may have been caused by a minor amount of mixing with meteoric waters. We propose that the ore-related magma was derived from partial melting of the ancient Mesoproterozoic to Neoproterozoic middle to lower continental crust. This crust was likely metasomatized during earlier subduction, and the crustal magmas may have been contaminated with lithospheric mantle derived magma triggered by MASH (e.g., melting, assimilation, storage, and homogenization) processes during collisional orogeny. In addition, a significant proportion of the metals and sulfur supplied from mafic magma were simultaneously incorporated into the resultant hybrid magmas. 相似文献
76.
This contribution reports on three significant gold occurrences in southern Mali, the Syama and Tabakoroni deposits and the Tellem prospect, located in what is locally known as the Syama corridor. They are part of the Syama and Tabakoroni goldfields, which are the object of a twin paper in this issue (Ballo et al., this volume). They occur in the northern part of the Bagoe greenstone belt, which, in the study area, consists of a suite of Paleoproterozoic metamorphosed volcanic and sedimentary rocks. The sediments include conglomerate, black shale, sandstone and greywacke. The volcanic rocks have basaltic, andesitic and dacitic compositions. The basalts have flat rare earth element (REE) patterns, no Nb anomaly, and very low Zr/Y, whereas the latter two rock types are enriched in light REE, depleted in Nb, Ta and Zr/Y > 7. All rock units are crosscut by spessartite-type lamprophyre sills.Even though the three gold occurrences are aligned along the same major structure, each one has distinct geological features including (i) the nature of the dominant host rock in the mineralized zone (a basaltic volcanic sequence at Syama, a diorite pluton at Tellem and a felsic volcanic sequence at Tabakoroni); (ii) the structural characteristics of the zone (highly mineralized breccias for Syama and vein stockwork for Tabakoroni and Tellem); and (iii) the main sulfides present (pyrite in association with arsenopyrite at Tabakoroni and Tellem and pyrite alone at Syama). At Tabakoroni and Tellem, gold mineralization occurred mostly during D4Sy, whereas at Syama, a large part of the visible gold occurs as infill in fractures in breccia zones, likely related to a brittle, late E–W phase of shortening (D5Sy). 相似文献
77.
近期,借助高分辨率卫星影像、风化壳填图和人工浅钻等手段,项目组在四川省攀枝花—西昌（攀西）地区摩挲营花岗岩风化壳中发现一处离子型（中—重）稀土矿。通过稀疏的人工浅钻工程控制,初步概算矿区潜在资源量达中型矿床规模,其中64%的资源量为中—重稀土为主的轻重稀土共生型,因此具有较大的潜在经济价值。该稀土矿是四川发现的首例离子吸附型稀土矿,是目前已知成矿母岩最老、赋存海拔最高、地形地貌最为复杂（中山山地地貌）条件下新发现的一处离子吸附型（中—重）稀土矿床。结合项目组近日对整个攀西地区成矿远景区的初步调查、靶区优先和查证,认为在四川攀西地区类似地貌景观具有寻找同类型矿床的广阔前景。 相似文献
78.
幕阜山岩体的内、外接触带伟晶岩密集分布,具有较好的稀有金属矿成矿地质条件和找矿潜力。为了进一步研究幕阜山地区稀有金属矿的赋存特征、成矿规律及矿产资源找矿潜力,指导下一步勘查工作,系统梳理了幕阜山地区稀有金属矿勘查工作进展,将湖南境内的幕阜山地区划分为5个成矿远景区,评价了各成矿远景区的找矿潜力,进一步探讨了该地区的找矿方向。幕阜山地区的锂铌钽铍矿资源主要集中在幕阜山岩体西南缘的仁里—传梓源与上大洲—南江桥成矿远景区; 预测Ta2O5潜在资源量约40 000 t,Nb2O5潜在资源量约49 000 t,Li2O潜在资源量约320 000 t,BeO潜在资源量约48 000 t。可对幕阜山地区稀有金属找矿勘查和研究起到指导作用。 相似文献
79.
花岗伟晶岩型稀有金属矿床主要产出于后碰撞到非造山构造背景,同期多阶段复式岩体中,侧向侵位的晚阶段高分异花岗岩是有利的成矿母岩。南岭成矿带发育稀有金属矿化的花岗岩很多,花岗伟晶岩型稀有金属矿床却较罕见。贵东岩体具备花岗伟晶岩型稀有金属的成矿条件,“界山”有利于矿体保存。笔者通过野外查证,在贵东岩体赣粤界山附近的龟尾山和牛牯石地段均发现含绿柱石花岗伟晶岩,该花岗伟晶岩脉铍矿化强烈,脉体规模和矿物分带性特征表明其找矿潜力大,综合利用价值高。此发现不仅补充了南岭成矿带的稀有金属成矿类型,还表明二（白）云母花岗岩的小岩体周边也有可能发现花岗伟晶岩型铍多金属矿床。 相似文献
80.
科学找矿是发现矿床和矿产勘查过程的总称, 在我国已探索了四十余年。它是应用当代有效的成矿学理论, 从各类资料和数据(地、物、化、遥)中提取信息, 研究区域成矿规律, 圈定不同级别的成矿区带(I—V级), 在成矿信息浓集区带或地段, 述明潜在矿床的地质条件, 判定矿床类型, 指明寻找未发现矿床的标志, 部署矿产勘查后进而发现了矿床, 公认它是矿产勘查学科各环节有机联系的系统流程。科学找矿引领地质找矿的重大突破, 促进矿产勘查工作的现代化。我国已通过矿产区划构建了科学找矿内容的基本格架, 在“新一轮固体矿产普查”、“矿产勘查跨世纪工程”、“矿产资源调查评价”和“找矿突破战略行动纲要”(又称“三五八”行动纲要)的实践中进行探索。获取的找矿成果证明, 科学找矿要以矿床成矿系列、矿产预测理论和成矿信息为指导; 矿产远景区划、地质资料的数据处理和提取成矿信息、编制矿产预测和矿床勘探系列图件是手段; 研究典型矿床, 建立区域的和矿床的成矿模式、总结区域成矿规律、圈定矿产预测远景区和找矿靶区、部署矿产勘查工作是发现矿床的科学支撑; 矿产勘查有效机制将科学找矿各个环节的内容实现有机联接, 组成获取找矿和矿床勘探成果的基本段, 概括为“三项理论”、“二个系统”、“二项技术”, 直至今日, 探索工作已获得很好的找矿效果。在未来的“战略性矿产找矿行动(2021—2035年)”实施过程中, 用科学找矿的思路构建矿产勘查新格局。 相似文献