Release of heavy metals during weathering of the Lower Cambrian Black Shales in western Hunan,China

Weathering of heavy metal enriched black shales may be one of the most important sources of environmental contamination in areas where black shales are distributed. Heavy metal release during weathering of the Lower Cambrian Black Shales (LCBS) in western Hunan, China, was investigated using traditional geochemical methods and the ICP-MS analytical technique. Concentrations of 16 heavy metals, 8 trace elements and P were measured for samples from selected weathering profiles at the Taiping vanadium ore mine (TP), the Matian phosphorous ore mine (MT), and Taojiang stone-coal mine (TJ). The results show that the bedrock at these three profiles is enriched with Sc, V, Cr, Co, Ni, Cu, Zn, Pb, Th, U, Mo, Cd, Sb, Tl, and P. Based on mass-balance calculation, the percentages of heavy metals released (in % loss) relative to immobile element Nb were estimated. The results show significant rates of release during weathering of: V, Cr, Co, Ni, Cu, Zn, U, Mo, Cd, Sn, Sb, and Tl for the TP profile; Sc, Cr, Mn, Co, Ni, Cu, Zn, Pb, Th, Cd, and Sn for the MT profile; and Sc, Mn, Co, Ni, Zn, Th, Cd, Sn, and Tl for the TJ profile. Among these heavy metals, Co, Ni, Zn, Cd, and Sn show very similar features of release from each of the three weathering profiles. The heavy metals released during weathering may affect the environment (especially topsoil and surface waters) and are possibly related to an observed high incidence of endemic diseases in the area.     

西藏冲江铜矿含矿岩体与非含矿岩体区分探讨

冲江铜矿位于世界三大斑岩成矿域的特提斯-喜马拉雅成矿域,其大地构造位置属冈底斯-念青唐古拉构造带的冈底斯陆缘火山-岩浆弧中部。矿区含矿岩体与非含矿岩体的岩性相同,很难通过肉眼或常规分析方法把它们区分开来。热释光测试结果表明,矿区岩石的热释光曲线有单峰和双峰两种,矿化主要发生在具单峰的似斑状二长花岗岩中。岩石矿化程度越强,热释光总积分强度值越小。另外,高岭土化对岩石天然热释光有叠加作用,具高岭土化的岩石明显具有更高的热释光值,且高岭土化与矿化成负相关。因此,热释光值可作为判断矿化的一个岩石标型。石英粒度统计也表明,含矿岩体的石英粒度曲线呈韵律式变化,而不含矿的岩石粒度曲线呈渐进式变化。故岩石中的石英粒度也可作为矿化的一个矿物标型。     

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     

一种基于网络拓扑关系的地图匹配算法

地图匹配是车辆导航定位系统中提高定位精度的一种方法,其精度受定位数据、地图数据质量及坐标系转换关系的影响.在分析现有算法的基础上,提出了一种基于网络拓扑关系的地图匹配算法.该算法只需将GPS定位数据和GIS 数据相结合,即可用算法的形式解决地图匹配中一些常见的问题.实验证明:该算法是一种精度高、效率好、实用性强的地图匹配算法,具有较好的实用价值.     

基于拓扑构建的多边形区域间运算的新方法

提出了一种新的直观的方法进行多边形区域之间的运算.首先将需要计算的多边形区域的边进行自动拓扑构建,利用多边形区域的边将平面划分为n个小多边形区域;然后生成这些多边形区域的内点,通过判断小多边形区域的内点是否在原始多边形区域内来确定小多边形区域是否选取;最后合并选取的小多边形即为所求.试验结果表明,该方法思路清晰、鲁棒性强,在GIS中得到了有效的运用.     

下架式陀螺经纬仪逆转点观测方法探讨

提出基于下架式陀螺经纬仪的逆转点观测方法,阐述逆转点观测法的意义,着重分析逆转点观测方法的原理及其与积分法测量的差别,并通过分别在室内和室外的实测数据对其进行验证。最后得出结论,认为逆转点观测方法也可以运用于下架式陀螺经纬仪。     

基于骨架化和蜘蛛编码的面状实体匹配方法研究

同名面实体在不同来源的地图数据库中的矛盾性表达致使相关领域的研究出现诸多瓶颈问题,由此实体匹配作为基础研究成为首要解决的关键问题,本文采用两阶段匹配策略实现面实体匹配,预匹配中通过面积相异度进行初步判定,终匹配时先对面状实体进行骨架化从而降低点和线的维度,再用基于蜘蛛编码的方法实现匹配。最终实现的匹配算法由大比例尺地图数据库中的房产图和地形图进行匹配实验,结果证明了该算法的匹配效率和准确度。     

DCT域遥感影像的自适应遗传优化增强

本文在DCT域中提出了一种基于遗传算法的遥感影像增强技术,针对DCT域遥感影像增强参数需人工设定的问题,利用自适应遗传算法对其进行优化选取:设计了一种考虑偏差的适应度函数以驱动遗传算法进化,通过无分块思想的使用实现了无人工干预、无块效应的遥感影像增强。该方法不但保持了遥感影像的原始色调而且显著提升了遥感影像方差、平均梯度、信息熵等质量测度,有效改善了遥感影像的视觉效果,便于后续影像处理及应用。     

特征驱动下区实体匹配指标自适应融合技术

空间实体匹配过程中多个指标的融合问题是影响匹配效果的关键问题之一。本文针对这一问题,以区实体为例提出了一套基于范例库的解决方案。首先提取出影响实体匹配的数据特征因子并确定了量化方法,其次选取典型的匹配指标,接下来通过建立指标权值范例库确定各指标权值,最后根据权值和数据特征因子调整匹配过程。该方法使得数据具有学习能力,达到了指标权值的自适应性的目标。实验表明该方法可行,并且可以提升空间实体匹配算法的效率、准确度和智能化程度。     

电磁散射模型应用于单景高分辨率SAR影像建筑物高度反演的解算方法

首先,测量建筑物叠掩量,反演出建筑物高度初值;然后,在相邻建筑物下垫面粗糙度相关的假设下,对重组后的电磁散射模型进行基于拟模拟退火的参数解算,实现了模型中未知参数的求解以及建筑物高度的反演。将此方法应用于真实Radarsat-2SAR场景中3座建筑物高度的反演,取得了反演高度相对误差均小于10%的结果。