高挂山—牛头寨地区小型环形影象构造分析及其找矿意义

高挂山—牛头寨地区,通过大比例尺航片解译,发现6个大小不等的小型环形影象信息。这些环形影象与岩浆活动、已知矿床、矿化点、重砂异常、物化探异常等的分布有着内在的联系。为预测找矿远景区和找隐伏矿床提供了影象依据。     

湖南有色金属生产矿山扩大接替资源的对策

湖南省境内有色金属矿产十分丰富,享有“有色金属之乡”的美誉,但经过多年的开采,90%以上的矿山都面临储量危机的困难,而找矿难度日益增大,常规的找矿技术路线已很难打开找矿效果不佳的局面。因此,在找矿预测过程中,必须以新的理论为指导,采用新的思路,从新的成矿与控矿因素、新的矿床成因类型与成矿模式入手,结合有效的常规手段与新技术,进行系统而科学的研究,并深入分析前人已有成果和投入大量现场调查研究工作,才有可能实现储量危机矿山找矿预测的突破。     

Nd-Sr-Pb isotopic constraints on metal and fluid sources in W-Sb-Au mineralization at Woxi and Liaojiaping (Western Hunan,China)

This paper presents Nd-Sr-Pb isotope data on scheelite, inclusion fluids and residues of gangue quartz, and sulfides from the W-Sb-Au ore deposits at Woxi and Liaojiaping (LJP) in the Xuefeng Uplift Belt (XUB), Western Hunan, China. Sm and Nd concentrations in scheelite from Woxi are much lower than in scheelite from LJP and can be distinguished by their high ¹⁴⁷Sm/¹⁴⁴Nd ratios of ~1.25 from the much lower ratios around 0.26 in scheelites from the LJP. Nd values (compared to values at 200 Ma, which is the average timing of granitoid emplacement during the Indosinian-Yanshanian periods in the XUB) are around –10 for the LJP and compare well with the range of –5 to –11 defined by the granitoids, whereas they are around –27 for scheelite from Woxi. This might indicate that REEs in the mineralizing fluids at LJP originated from granitoids that are concentrated along the southern border of the XUB, whereas in the case of Woxi, the original fluids might have been masked by REEs released during intense high-temperature wall rock alteration of unexposed Precambrian basement rocks at depth. Sr isotopes of scheelite from these two deposits show similar relations to host / nearby rocks, in that ⁸⁷Sr/⁸⁶Sr (T=200 Ma) ratios of ~0.721 for LJP scheelite agree with values ranging between 0.718 – 0.726 for granitoids, whereas these ratios are much higher (i.e. 0.745) for scheelite from Woxi and correspond to the ⁸⁷Sr/⁸⁶Sr (T=200 Ma) ratio range of 0.743 – 0.749 for Precambrian host slates. Crushing experiments to release inclusion fluids from gangue quartz and sulfides deposited during later stages of ore deposition in both deposits failed to provide accurate and geologically meaningful two-point (fluid-residue) tie lines in Rb-Sr isochron diagrams. However, Sr released from fluid inclusions generally reveals lower initial ⁸⁷Sr/⁸⁶Sr ratios than the respective residues and shows affinities to ⁸⁷Sr/⁸⁶Sr (T=200 Ma) values of Indosinian-Yanshanian granitoids, both at Woxi and LJP. Pb stepwise leaching of scheelite and sulfides did not result in sufficient spreads in Pb isotope diagrams and therefore no information regarding exact mineralization ages in the two deposits could be deduced. Overall, ore Pb isotopes reveal upper crustal signatures and are compatible with Pb isotope signatures of the predominant Precambrian slates in the Woxi area. Steep trajectories through late stage quartz-sulfide mineralization in Pb isotope diagrams may hint at mixing scenarios involving Pb from the host rocks and a component with lower ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb ratios relative to ²⁰⁶Pb/²⁰⁴Pb ratios, which cannot be linked to any known reservoir in the XUB mining district. Sr isotopes of four out of seven residual sulfide samples from Woxi plot along a paleomixing line at an age of 199 ± 8 Ma, supporting a mixing scenario for the fluids indicated by the Pb isotopes and pointing to a possible genetic relationship with the emplacement of Indosinian—Yanshanian granitoids. The budgets of REEs, Rb-Sr and Pb in the original fluids were severely affected by contamination of these elements apparently during intense wall rock alteration but, after sealing of the major pathways, the mineralizing fluids tend to have better preserved their original signatures. These attest a genetic relationship between the metallogeny in the XUB W-Sb-Au province and the emplacement of Indosinian-Yanshanian granitoids during Mesozoic intracontinental tectonic uplift and thrusting.Electronic Supplementary Material Supplementary material is available in the online version of this article at Editorial handling: B. Lehmann     

湖南6月区域持续性暴雨的强信号及预报概念模型

基于湖南汛期区域持续性暴雨典型环流分型,利用1961—2016年NCEP/NCAR再分析资料和异常度方法对湖南6月区域持续性暴雨环流型进行客观识别,并结合动力和水汽输送条件,确定湖南6月区域持续性暴雨强信号并客观量化表征,建立湖南6月区域持续性暴雨预报定量化概念模型。结果表明:43次历史区域持续性暴雨过程的回报准确率达到81%,2017—2018年3次区域持续暴雨过程试报准确率为2/3,说明该概念模型有一定预报能力,能为湖南暴雨预报业务服务提供技术支持。将该概念模型与各类模式预报产品相结合,还可开展区域持续性暴雨的中期和延伸期预报。     

湘、黔下寒武统黑色岩系型Ni、Mo矿床中有机质与PGE成矿作用研究

湘、黔地区张家界、遵义一带分布有黑色岩系型Ni-Mo-PGE矿床,测试分析表明黑色页岩样品铂族元素含量特征参数∑PGE、Ln(Pd/Pt)、(Ru/Ir)×(Pd/Pt)、Ln[(Ru/Ir)×(Pd/Pt)]均与有机质含量特征参数有较好的相关性.趋势分析显示,铂族元素含量特征参数Ln[(Ru/Ir)×(Pd/Pt)]与总有机碳含量特征参数Ln(Corg)有很好的线性相关,线性相关公式为y=0.4762x-1.1316,相关系数R为0.7584,说明该参数为一稳定性参数,主要受有机质总量决定,集中反映了生物制约性.而与湖南张家界样品有机碳含量Ln(Corg)与铂族元素含量∑PGE同步正消长关系不一样,即贵州遵义地区铂族元素总量∑PGE与有机碳含量的相关性表现出的不一致的规律,可以解释为后生期的热事件(印支海西期,Rb-Sr等时线年龄277±37Ma)导致有机质干酪根的高成熟化、大量生过气(C>2%)和石墨化趋势,或者说是芳构化效应改变了源岩有机质而导致了有机质的损耗.     

湖南锡田钨锡多金属矿床地质特征及找矿方向

锡田钨锡多金属矿床是国土资源大调查以来在南岭地区发现的又一大型矿床.矿床产于锡田复式花岗岩体内外接触带及岩体内部,其形成与燕山早期花岗岩关系密切.岩体接触面及断裂构造的控矿作用明显.矿床类型主要为矽卡岩型,其次为破碎带蚀变岩型和云荚岩脉型等.论文通过成矿地质条件、矿床地质特征的综合分析,结合近几年的找矿实践,提出了该区下一步的找矿方向主要集中在西部的垄上-狮子岩、东部的碉堡山-黄沙冲一带及地表云英岩脉带发育地段,外围找矿方向分布在南西部的花里泉一带.     

湖南省地市经济差异综合评价及分区研究

文章运用主成分分析的数理统计方法,选择14项指标,对湖南省地市经济发展水平的区域差异进行了综合评价和区域聚类划分。评价结果表明:湖南各地市的经济发展水平存在明显差异,可划分为5个层次。在此基础上,文章还提出了实现地市经济协调发展的对策:重视经济发展效率;坚持"点-轴"开发模式,优化空间开发结构;加快长株潭发展极产业一体化发展步伐等。     

湘中邵阳凹陷二叠系龙潭组页岩含气性特征与气体成因

针对湘中地区邵阳凹陷二叠系龙潭组页岩气资源评价,部署了页岩气调查井2015H-D3井,通过现场解析气等相关样品测试定量分析了页岩含气性特征及其影响因素,并借助气体稳定碳、氢同位素对气体成因进行了初步探讨.结果显示:钻深从150m处开始出现气显,随深度增加,解析气含量呈现先逐渐增大后减小的趋势,300～425m为最高含气层段,累计厚度达125m,现场解析气含量全部大于0.5m^3/t,最高为2.35m^3/t,平均1m^3/t,证实龙潭组具良好页岩气资源潜力.当埋深大于300m时,解析气含量受有机碳含量控制,而埋深小于300m时,解析气含量并不简单受控于有机碳含量,而是受到保存条件的严重制约.气体碳、氢同位素测试显示δ13C1介于-29.87‰～-36.82‰,平均为-34.52‰,δ¹³C_2介于-29.45‰～-31.02‰,平均为-30.09‰,δD1介于-131.20‰～-178.40‰,平均为-167.40‰.气体成因分析揭示龙潭组页岩气属热成因中的油型气类型.基于沉积现象判断龙潭组为海陆过渡相环境,与氢同位素判断结果基本吻合,但目前还无法确定具体判定区间.     

湖南临湘虎形山矿区蚀变地球化学过程研究

湖南省临湘市虎形山钨矿是近年来新发现的大型钨铍矿床。矿区内围岩蚀变类型较多,主要有云英岩化、硅化、绢云母化、碳酸盐化、绿泥石化等。为了探究矿区围岩蚀变与成矿的关系,对蚀变硅质板岩分别作了主微量元素分析,通过元素相关性分析探究了各元素的迁移特征,并探讨了主要蚀变过程中出现的矿化类型以及矿化过程中一些金属矿物的生成顺序;利用标准化Isocon图解法,对围岩蚀变过程中组分的带入带出进行质量平衡计算。研究结果表明,板岩中组分迁移受绢云母化影响强烈,其中云英岩化与成矿关系最为密切,碳酸盐化与钨矿化也有一定联系。通过对湘东北地区、虎形山矿区冷家溪群和上地壳W、Cu、Pb、Zn、As、Sb丰度值的对比,反映了矿区地层富含成矿物质,但并未给成矿提供物质来源。     

MATHEMATICAL GEOLOGY

正20141850 Chen Dongyue(School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China);Chen Jianping On 3D Ore Prospecting Modeling of Comprehensive Information for Huangshaping Polymetallic Deposit(Journal of Geology,ISSN1674-3636,CN32-1796/P,37(3),2013,p.489-495,12 illus.,12 refs.) Key words:polymetallic ores,data bases,Hunan Province