矿化富集动力学模型及其在矿产预测中的应用

文中研究了地壳中元素迁移聚集和成矿过程的混沌动力学机制 ,揭示了地质环境中非线性过程的相互作用是造成地壳的元素含量与矿化不均匀分布的原因 ,并由此导致元素含量、矿床储量及其空间分布的分形结构。Logistic映射为研究上述行为和过程提供了一个较好的数学模型。参数 μ ,即成矿潜能 ,可将区域划分为非成矿区和成矿区。以新疆某地金矿床为例 ,用实际数据来估计模型 (4 )中的参数 μ值 ,其预测结果与用其他方法 (例如特征分析 )的预测结果大体一致。从而为预测金矿床提供另一新的途径。     

Remote sensed data for automatic detection of land-use changes due to human activity in support to landslide studies

Slope instability studies appear to recognize a number of potential superficial slide-producing agents, which may be directly detected and monitored with Earth Observation (EO) data. The main objective of this work is to use conventional EO data and automatic techniques for providing land-use change maps useful in landslide prevention. The idea is to use the detection of changes in areas already involved in landslide events as a precursory sign of variations in the equilibrium status of the slope, independently from other natural triggering events, such as rain and seismic events. Attention is focused on man-induced surface changes, such as deforestation, urban expansion and construction of artificial structures. A historical set of 20 multi-temporal Landsat TM images, covering the period 1987–2000, was analyzed using a supervised change detection technique on a test site affected by slope instability phenomena located in the Abruzzo region in Southern Italy. A change image is obtained by comparing year-specific thematic map pairs. It contains useful information not only on the place where a transition occurred, but also on the specific classes involved in the transitions between two different years. The full set of change images is used to extract class-conditional transition probabilities, to evaluate variations in specific class distribution and the total number of changed pixels in time. Four classes and their transitions were considered in the analysis: (1) arboreous land, (2) agricultural land, (3) barren land, and (4) artificial structures. The quantitative analysis of the class-joint transition probability values of some specific class-transitions that may worsen slope stability showed that in an area prone to landslides the probability of landslide re-activation or first activation is higher where changes have occurred. Although based on a limited number of known events, such a result encourages extensive experimentation of the proposed technique on better documented landslide test sites.     

冀北蓟县系铁岭组古风化壳稀土元素富集规律及古环境意义

冀北地区蓟县系铁岭组顶部普遍发育一套古风化壳,该层位轻稀土元素和Rb均出现显著的富集现象。为了进一步探讨风化过程中元素的迁移规律以及古环境特征,文章对该套古风化壳开展了详细的地球化学研究。结果表明,古风化壳中轻稀土元素、Rb和Ti等含量自下而上表现为“先升高,后降低”的分布规律,且随着风化层中黏土物质的增加而升高,在中上部黏土岩中达到富集的峰值,推测与黏土矿物的吸附作用相关;古风化壳δCe正异常、δEu明显的负异常等特征指示轻稀土元素主要富集于中上部的氧化环境,且氧化作用越强越富集;化学蚀变指数CIA介于53.54~79.50,风化淋滤指数BA变化范围为0.39~1.08,共同指示了风化壳形成于温暖湿润的气候环境。综合稀土元素、微量元素和La/Yb-∑REE图解显示,风化壳稀土元素和微量元素主要来源于下伏铁岭组碳酸盐岩以及火山岩浆活动。     

黔北上二叠统底部发现REY、Nb、Zr和Li等关键金属异常富集层

在黔北上二叠统底部铁铝质黏土岩、下部煤层及其顶底板炭质黏土岩中发现其富集稀土、铌、锆和锂等关键金属元素,其中铁铝质黏土岩REY、Nb、Zr和Li平均含量分别为807×10- 6、143×10- 6、1107×10- 6、375×10- 6,下部煤层及其顶底板炭质黏土岩中REY、Nb、Zr和Li平均含量为分别为555×10-6、104×10-6、786×10-6、116×10-6。显示出该区域该层位具有关键金属矿床良好的找矿前景。     

The differential enrichment mechanism of thallium in the Huodehong MVT deposit,NE Yunnan Province,China: Evidence from EBSD,LA-ICPMS and TEMSCIEI北大核心CSCD

铊(Tl)是一种战略性关键金属,在高科技领域具有重要用途。作为“稀散元素”之一,Tl主要富集于低温贱金属硫化物矿床中,黄铁矿和白铁矿是其主要载体矿物。滇东北火德红MVT铅锌矿床中黄铁矿和白铁矿显示Tl的富集,其中白铁矿中Tl含量显著高于黄铁矿,为探究Tl在不同矿物之间的差异性富集机制提供了理想对象。本文对火德红矿床共生黄铁矿-白铁矿开展系统的结晶学、矿物学和地球化学研究。电子背散射衍射(EBSD)结果表明,热液黄铁矿、白铁矿晶粒组构具有一定继承性,与闪锌矿紧密共生,暗示为同一成矿事件的产物。激光剥蚀耦合等离子体质谱(LA-ICPMS)原位微量元素含量分析结果显示,黄铁矿和白铁矿中的Tl含量分别为127×10^(-6)~516×10^(-6)和356×10^(-6)~1046×10^(-6),不同含量测点Tl的激光剥蚀时间分辨元素信号曲线均较为平滑,暗示Tl主要以类质同象形式进入黄铁矿和白铁矿晶格。透射电镜(TEM)进一步证实Tl类质同象直接替换Fe为主,即2Tl^(+)←→□(空位)+Fe^(2+)。结合黄铁矿和白铁矿中Tl与Zn含量的正相关关系,本文认为白铁矿中Tl的超常富集可能与偏酸性条件下富Tl、Zn和Fe等金属成矿流体有关。综合研究表明,火德红矿床黄铁矿与白铁矿中Tl的差异性富集与晶体结构、Tl赋存状态无关,而是流体成分、物化条件共同制约的结果,受到矿物和矿床等不同尺度苛刻成矿条件的影响。与闪锌矿共生的白铁矿是未来寻找铊资源的重要方向。     

Improving settlement selection for small-scale maps using data enrichment and machine learning

Acquiring and formalizing cartographic knowledge still is a challenge, especially when the generalization process concerns small-scale maps. We concentrate on the settlement selection process for small-scale maps, with the aim of rendering it more holistic, and making methodological contributions in four areas. First, we show how written specifications and rules can be validated against the actual published map products, thus pointing to gaps and potential improvements. Second, we use data enrichment based on supplementing information extracted from point-of-interest data in order to assign functional importance to particular settlements. Third, we use machine learning (ML) algorithms to infer additional rules from existing maps, thus making explicit the deep knowledge of cartographers and allowing to extend the cartographic rule set. And fourth, we show how the results of ML can be transformed into human-readable form for potential use in the guidelines of national mapping agencies. We use the case of settlement selection in the small-scale maps published by the Polish national mapping agency (GUGiK). However, we believe that the methods and findings of this paper can be adapted to other environments with minor modifications.     

湖南龙王江锑砷金矿床地质地球化学特征、成矿分析与找矿

龙王江锑砷金矿床由石英脉、破碎蚀变岩和蚀变糜棱岩矿体构成。矿体一部分呈平行分布,另一部分呈斜列分布,受劈理化带或剪切带控制。主矿体沿倾向延伸大,可构成垂深达千米的"超深矿柱"。锑砷金矿成矿是在Sb-As-Au特定的地球化学背景基础上发生的,构造应力是完成元素活化、运移和富集的地质地球化学过程的热(动)力。矿床成因属动力变质热液型。石英脉型和破碎蚀变岩型金(锑)矿具有较大的找矿潜力。通过综合分析提出了该矿床找矿标志与找矿方向。     

湖北宜昌寒武系水井沱组页岩气藏主控地质因素和富集模式

湖北宜昌地区埃迪卡拉纪—寒武纪界线附近地层格架显示宜昌地区埃迪卡拉纪晚期—早寒武世时期的构造古地理格局具有隆、凹相间的特点。凹陷区是寒武系水井沱组下段富有机质页岩发育的有利区带。凹陷区内水井沱组下段页岩微量元素V/Cr、Ni/Co、V/(V+Ni)的比值和化学蚀变指数(CIA)指示水井沱组下段页岩总体上形成于缺氧或硫化环境,但自下而上氧化还原条件有逐步改善的趋势。与氧化还原环境变化对应,出现了总有机碳(TOC)和生源钼(Moxs)的同步减小,证明TOC受氧化还原环境和海底有机碳通量的双重影响。TOC与Moxs的相关性明显高于TOC与生源镍(Nixs)的相关性,据此,并结合同期地层有机碳同位素组成特征,推测寒武纪早期海底可能发生了天然气水合物的溶解和甲烷释放。宜昌地区寒武系水井沱组页岩TOC与页岩的含气量、石英和黄铁矿等脆性矿物含量的高度相关性证明TOC是页岩气储层品质评价的最重要参数之一,具有相对较高TOC含量的水井沱组下段中—下部无疑是水井沱组页岩气的最优质储层。宜昌地区海相地层埋藏演化史研究,揭示宜昌地区下寒武统储层中的有机质在晚三叠世中期进入生气高峰之后,再未发生二次生烃,黄陵隆起及其演化有效防止了有机质的过度热演化和页岩气储层的破坏。寒武系水井沱组页岩气富集受控于总有机碳含量和黄陵隆起及其演化。     

鄂东南铁山铁铜矿床成矿流体特征及铁的迁移与沉淀富集机制

对铁山铁铜矿床的流体包裹体研究发现,在石榴子石和透闪石中主要发育气液两相富液相、富气相和含石盐子晶三相包裹体。显微测温结果表明,进矽卡岩阶段热液流体均一温度为499.2~594.8℃,盐度多集中分布在17.3%_(Na Cl)~19.5%_(Na Cl)之间,密度为0.45~0.62g/cm~3,形成压力为58.0~90.6MPa;退化蚀变阶段成矿流体均一温度为356.2~428.6℃,盐度多集中分布在7.2%_(Na Cl)~15.5%_(Na Cl)之间,密度为0.52~0.83g/cm~3,成矿压力为23.8~29.7MPa,成矿深度为0.90~1.12km,主成矿阶段成矿流体具有高温、中-低盐度、低密度、较低成矿压力的特征,属于浅成矽卡岩型铁铜矿床。同时,群体包裹体气液相成分结果显示,气相成分以H_2O和CO_2为主,并含有少量CH_4、C_2H_6、N_2和H_2S气体;液相成分阳离子以Na~+、Ca~(2+)、K~+为主,阴离子以SO_4~(2-)、Cl~-为主。研究表明,Cl~-、SO_4~(2-)和碳酸络合物在铁质搬运与富集过程中发挥了重要作用,流体混合和成矿热液p H值的系统演变可能是导致铁山铁铜矿床铁质超常富集沉淀的重要机制。     

希腊斯克瑞斯斑岩型铜-金-铂族元素矿床地质特征和成矿模型

斯克瑞斯斑岩型铜矿位于希腊北部哈尔基迪基半岛,塞尔维亚马其顿成矿带。矿体赋存于侵入到韦尔蒂斯科斯组的古近纪—新近纪碱性岩体中,岩体的分布受深部断裂影响。截至2011年,斯克瑞斯矿床已开采5.2×108t铜,Cu平均品位为0.5%,Au平均品位为0.8×10-6,Pd平均品位为110×10-9,Pt平均品位为17×10-9。铜-金矿化呈脉状、网脉状及浸染状分布于岩体及围岩中。矿石矿物主要为黄铜矿、斑铜矿、黄铁矿等,与矿化有关的围岩蚀变主要有钾长石化、硅化、青磐岩化、绢云母化等。锆石U-Pb年龄、全岩Ar-Ar年龄和矿床地球化学特征均显示,岩浆侵位与成矿作用之间关系密切,其形成时代约为19Ma。该矿床以Pd-Pt含量较高为特征。对斯克瑞斯斑岩型富铂族元素斑岩铜矿特点及成矿规律的系统总结,可以为在中国境内寻找同类矿床提供参考。